Podcasts by Category
- 548 - #516: How to Read Nutrition Studies (Become Confident in Critically Appraising Research)
Links:
COURSE: Applied Nutrition Literacy Episode pageAbout This Episode:
Navigating the vast landscape of research literature, particularly in the realm of nutrition science, presents numerous challenges for readers seeking to extract meaningful insights.
Before diving into research papers, individuals should have a precise understanding of the specific questions they seek to address. Without this clarity, there is a risk of wasting time on irrelevant studies or misinterpreting findings.
Furthermore, the selective approach to sourcing research is crucial. With countless studies available, employing heuristic strategies to filter out irrelevant ones and prioritize those aligned with research goals is essential.
Effectively reading nutrition studies requires a nuanced understanding of statistical concepts and methodologies used in various studies. Developing this understanding can be challenging, especially for individuals without a background in statistics or research methodology.
How can individuals effectively navigate the vast volume of research literature to find studies relevant to their interests or research objectives? What are some common pitfalls to avoid when reading and interpreting nutrition science research? What role do external influences, such as media coverage or recommendations from experts, play in shaping perceptions of research findings? Are there specific strategies or tools that people can use to streamline their research process and optimize their time spent reading research papers?In this episode, we discuss all these issues.
Course syllabus: Applied Nutrition Literacy
Wed, 27 Mar 2024 - 1h 13min - 546 - AMA: Do Low-carbers Need Less Vitmain C? Does Omega-3 Supplementation Actually Benefit Us? & More (SNP 27)
Questions Answered in This Episode:
- [01:22] Do “low-carbers” need less vitamin C? [14.56] If you were to advise a company to establish solid workplace health fundamentals, what would you tell them? [26.20] Which compounds typically found in animal products would be interesting to supplement for health and performance purposes in vegan/vegetarian populations? [40.09] In omega 3 supplementation studies it isn’t common to see a baseline measurement of omega 3 index. Why? [44.10] What is your process for preparing for a podcast and choosing topics? [49.53] Based on the current understanding, what is the most ideal diet for people to eat? [55.26] Is there any evidence that otherwise healthy people should be consuming Omega 3 supplements?
This is a preview of is one of our Premium-exclusive AMA (ask me anything) episodes, where we answer questions submitted by Premium subscribers.
To listen to the full episode, you’ll need to be a Premium subscriber and access the episode on the private Premium feed.
Tue, 19 Mar 2024 - 12min - 545 - #515: Does Dietary Fat Quality Causally Affect Atherosclerosis Risk? – Jacob Christensen, PhD
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The question of whether dietary fat quality causally affects atherosclerosis risk has been a subject of extensive research and debate within the field of nutrition and cardiovascular health.
Atherosclerosis, the build-up of plaque in arteries, is a key factor in the development of cardiovascular diseases, including heart attacks and strokes. Traditionally, dietary fat has been implicated in contributing to atherosclerosis, with a focus on reducing overall fat intake. However, recent studies have shifted the focus towards the quality of dietary fats rather than their quantity.
Not all fats are created equal, and researchers are now paying closer attention to the types of fats consumed in the diet. Saturated fats, commonly found in animal products and some tropical oils, have long been associated with increased cholesterol levels and atherosclerosis. On the other hand, unsaturated fats, including monounsaturated and polyunsaturated fats found in olive oil, nuts, and fish, have been linked to potential cardiovascular benefits. Research suggests that replacing saturated fats with unsaturated fats may have a positive impact on blood lipid profiles and reduce the risk of atherosclerosis.
Additionally, genetic factors and individual responses to different fats may play a role in how dietary fats impact atherosclerosis risk.
In this episode, Dr. Jacob Christensen discusses the research in this area and some conclusions about whether we can say dietary fat quality causally increases atherosclerotic cardiovascular disease (ASCVD) risk. This includes looking at the relationship between low-density lipoprotein (LDL) particles and ASCVD, the link between dietary fat quality and LDL particles, and then finally the relationship between dietary fat quality, LDL particles, and ASCVD.
About the Guest:
Jacob J. Christensen is a clinical dietitian and researcher at University of Oslo. His research interests include cardiovascular diseases, lipid metabolism, nutrition, genomics and data science.
Tue, 12 Mar 2024 - 1h 14min - 544 - #514: Plant-derived Fatty Acids – Ella Baker, PhD
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There is a lot of interesting research going on related to plant-derived fatty acids, owing to their potential to help improve health and provide sustainable alternatives to other sources of healthy-promoting fatty acids.
In addition to work looking at the long-investigated alpha-linolenic acid (ALA), some research is now starting to look at more novel fatty acids like stearidonic acid (SDA), and pinolenic acid (PLA), each presenting unique structures and potential benefits within various plant sources. One intriguing focal point is Ahiflower oil, a distinctive source that harbors both ALA and SDA.
In this episode, Dr. Ella Baker of the University of Southampton discusses some of the science behind plant-derived fatty acids, offering a deeper understanding of their distinctive qualities, conversion pathways, and the captivating interplay between omega-3 and omega-6 fatty acids.
Dr. Baker’s research to date focuses on the metabolism, functionality, and underlying mechanisms of action of plant-derived fatty acids. Her interests include novel plant-derived fatty acids and exploring the effects on membrane structure and function.
Tue, 05 Mar 2024 - 33min - 543 - #513: Kidney Stones & Diet – Deepa Kariyawasam, RD
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Kidney stones, crystalline deposits formed within the kidneys, present a formidable challenge to individuals grappling with their debilitating effects. These mineral accumulations, though small in size, can inflict significant pain and discomfort as they navigate through the urinary tract.
Understanding the nuances of dietary management and treatment for kidney stones is crucial for those seeking relief and prevention.
What makes this subject particularly intricate is the diversity of kidney stones – a mosaic of compositions ranging from calcium oxalate to uric acid. Recognizing that not all kidney stones are created equal, dietitians and renal specialists tailor their recommendations to address the specific nature of the stones, unveiling a spectrum of dietary strategies that aim to alleviate symptoms and impede the recurrence of these insidious formations.
In this episode, specialist renal dietitian Deepa Kariyawasam brings us through the main causes of kidney stones, the potential dietary interventions, and how to guide individuals toward personalized pathways for kidney stone management.
Tue, 27 Feb 2024 - 31min - 542 - What are Dietary Reference Intakes? Origins, Development & Use (SNP 26)
Acronyms:
RDA = Recommended Dietary Allowance AI = Adequate Intake UL = Tolerable Upper Intake Level EAR = Estimated Average Requirement About This Episode: Dietary Reference Intakes (DRIs) are a set of nutrient reference values, developed in the US, that are used to assess and plan the nutrient intake of healthy individuals. They provide guidelines for the recommended amounts of various nutrients to maintain health and prevent deficiencies or excesses. Different countries may have their own sets of dietary reference values or guidelines that serve similar purposes but may be named differently. DRIs include several different reference values: Recommended Dietary Allowance (RDA) Adequate Intake (AI) Tolerable Upper Intake Level (UL) Estimated Average Requirement (EAR) DRIs play a crucial role in nutrition and public health for several reasons. DRIs provide specific recommendations for the intake of essential nutrients, helping individuals and health professionals understand the amounts needed to maintain good health. By establishing RDAs and ULs, DRIs help prevent nutrient deficiencies and toxicity, ensuring that individuals consume an appropriate range of nutrients. Governments and health organizations use DRIs to develop public health policies, nutrition programs, and guidelines for food fortification to improve the overall health of populations. For nutrition professionals, understanding DRIs is essential as it forms the basis for assessing and planning dietary recommendations for individuals and populations. Note: This episode is one of our Premium-exclusive episodes. To listen to the full episode, you’ll need to be a Premium subscriber and access the episode on the private Premium feed. Otherwise, you can hear a preview of the episode above or on the public feed of the podcast. Links: Go to episode page Subscribe to Sigma Nutrition PremiumTue, 20 Feb 2024 - 10min - 541 - #512: Alzheimer’s Disease – Drs. Ayesha & Dean Sherzai
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Alzheimer’s disease has a profound impact on individuals, families, and societies worldwide. As a progressive neurodegenerative disease, it not only robs individuals of their cognitive abilities but also places an immense emotional and economic burden on caregivers.
Mechanistically, the causes of Alzheimer’s are incredibly complex and not fully understood. And in terms of treatment, the landscape appears challenging. Drug discovery efforts for dementias, including Alzheimer’s, have faced setbacks, leaving a void in effective treatments. Consequently, attention has shifted toward preventive strategies, including dietary patterns.
From a prevention standpoint, both genetics and lifestyle should be considered. Which throws up many interesting questions…
To what extent do genetic factors contribute to Alzheimer’s risk compared to lifestyle choices, and how does this interaction influence disease development?
What role does lifestyle play in Alzheimer’s risk, and is there evidence supporting the influence of specific nutrients on cognitive health?
How do diet patterns impact Alzheimer’s risk? Are there discernible risk differences associated with specific dietary choices, and how do these interact with genetic factors, such as the ApoE genotype?
In this episode, Drs. Ayesha Sherzai and Dean Sherzai are on the podcast to answer these questions and discuss this topic in more depth.
About The Guests:
Dr. Ayesha Sherzai is a neurologist and co-director of the Alzheimer’s Prevention Program at Loma Linda University, where she leads the Lifestyle Program for the Prevention of Neurological Diseases. She completed a dual training in Preventative Medicine and Neurology at Loma Linda University, and a fellowship in Vascular Neurology and Epidemiology at Columbia University. She is also a trained plant-based culinary artist.
Dr. Dean Sherzai is co-director of the Alzheimer’s Prevention Program at Loma Linda University. Dean trained in Neurology at Georgetown University School of Medicine, and completed fellowships in neurodegenerative diseases and dementia at the National Institutes of Health and UC San Diego. He also holds a PhD in Healthcare Leadership with a focus on community health from Andrews University.
Tue, 13 Feb 2024 - 1h 10min - 540 - #511: Null By Design – When “No Effect” Doesn’t Mean No Effect
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Numerous nutrition studies present findings of “no effect,” but interpreting such results requires caution. A null finding, indicating an absence of impact from a nutrient or exposure, may not necessarily suggest a lack of effect overall. Instead, it could stem from issues related to the study’s design, the nature of the exposure, or participant characteristics.
We’ve often referred to such studies as being “null by design”.
These studies, often termed “null by design,” may yield inconclusive results due to insufficient contrast in exposure levels to reveal a significant effect size. Additionally, participants’ baseline nutrient status or intake can contribute to false negatives. For instance, if a study provides a nutrient to individuals already replete in that nutrient, it may lead to an erroneous conclusion. This phenomenon can be understood by considering the bell curve of activity for a nutrient.
Moreover, a lack of methodological rigor can generate ‘false negatives.’ If previous literature indicates associations between high intake of a specific food or nutrient and certain outcomes, a study comparing levels of intake well below that threshold may produce a misleading result.
Some challenges arise from an overly reductionist perspective. In disease processes, reductionism simplifies diseases to a single primary source at the cellular and molecular level. This perspective assumes that if a nutrient shows a relationship with health or disease outcomes at a population level, its biological activity should manifest in isolation. However, applying such assumptions to exposures like diet may not be tenable.
In this discussion, we delve into the concept of “null by design” and present three specific studies with null findings, emphasizing the need for careful interpretation.
Tue, 06 Feb 2024 - 54min - 539 - #510: Social Comparison: Evidence on its Impacts & What We Can Do – Shannon Beer
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Go to episode page (with supporting links/resources) Subscribe to PREMIUM Learn more about Sigma Nutrition Crushing Comparisons courseAbout This Episode:
Social comparison theory, developed by psychologist Leon Festinger in the 1950s, posits that individuals determine their own social and personal worth based on how they stack up against others. This theory suggests that people engage in social comparisons to evaluate their abilities, opinions, and attributes, often choosing relevant others for comparison.
In the realm of body image and self-perception, social comparison theory becomes particularly pertinent, as individuals tend to assess their own bodies in relation to societal ideals and the bodies of others. This process of comparison can have profound implications for body dissatisfaction and the development of disordered eating patterns.
This raises thought-provoking questions about the impact of social comparison theory on body image and eating behaviors.
In this episode, Shannon Beer explores these questions and offers valuable insights into the complex interplay between societal influences, individual perceptions, and the development of body dissatisfaction and disordered eating.
About The Guest:
Shannon Beer is a registered nutritionist, health and confidence coach and certified Compassionate Mind Training facilitator.
Shannon works with people aiming to improve their health through facilitating lasting behaviour change in their approach to diet, exercise and body image.
She has developed a coaching framework that applies motivational interviewing, cognitive behavioral coaching, and acceptance and commitment therapy-aligned processes in a client-centered alliance toward their own values-based goals.
Tue, 30 Jan 2024 - 57min - 538 - AMA: Coconut Oil, Raw Oats, Collagen, & More! (SNP 25)
Questions Answered in This Epsiode:
- [02:16] How would you implement a calorie surplus for “bulking” in healthy trainees without compromising their health markers? [15:25] If you were to advise someone with a heavy workload and busy schedule on how to establish the 80/20 of a healthy lifestyle, what would you tell them? [24:36] Is coconut oil good or bad? What about claims that it cures cancer, Alzheimer’s, etc.? [33:25] In the circumstance in which an individual has a normal ApoB yet an elevated LDL particle number, which value is more representative of risk? [41:39] Should you supplement in order to reach 100% of RDA for micronutrients? [46:35] Are raw oats a good ingredient to add to smoothies? Do they need to be cooked? [51:58] Is there any research supporting whether or not diet really impacts oral thrush? [55:21] Is there any benefit to supplemental collagen?
Note: This is a Premium-exclusive “ask me anything” episode. You can access the full episode as a Premium subscriber. Join here.
Tue, 23 Jan 2024 - 12min - 537 - #509: Helping Clients & Patients Overcome Nutrition Confusion – Jono Steedman, APD
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Go to episode page Subscribe to Premium Sigma's recommended resources Bite Me Nutrition – Australia Instagram: @jonosteedman @dannylennon_sigmaAbout This Episode:
There is no shortage of misleading, confusing and even dangerous nutrition information on the internet. And, unfortunately, much of it can sound very convincing and appealing to people who wish to improve their health. The result can be that they may end up ironically doing the opposite.
At an individual level, dietitians and medical practitioners end up having to work with patients who have heard incorrect information or who have been following poor advice.
What issues does this present? What is the most productive way to help patients and clients in this situation? How can we help give better information while also listening and caring for the patient?
To discuss such questions, dietitian Jonathan Steedman is on the podcast to share his experiences and approaches to spreading evidence-based information in a palatable and productive manner.
About The Guest:
Jonathan Steedman is an Acredited Practising Dietitian (APD) in Australia. He currently works with patientes via telehealth services. He is well-known on social media for explaining confusing nutrition topics in a way that is understandable and engaging for the general population.
Tue, 16 Jan 2024 - 44min - 536 - #508: Why Athletes Can Achieve High Performance During an Energy Deficit – Jose Areta, PhD
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Insufficient energy availability can significantly disrupt normal hormonal, metabolic, and physiological processes, prompting the body to initiate a coordinated response aimed at conserving energy.
While commonly viewed as beneficial for weight loss and managing cardiometabolic conditions in the current obesity epidemic, chronic energy deficiency in the context of modern sports and exercise nutrition is linked to adverse health outcomes and diminished athletic performance.
Nevertheless, the evidence regarding the negative impact of energy deficit on physical capacity and sports performance is not entirely clear.
Although severe energy deficiency can impair physical capacity, it’s noteworthy that humans can enhance aerobic fitness and strength even in the presence of significant energy deficits. Strikingly, many elite athletes compete at the highest levels despite displaying evident signs of energy deficiency.
This raises intriguing questions about how the human body adapts to energy deficits, challenging conventional views on the relationship between energy availability and athletic prowess.
To discuss some potential reasons for this ability to maintain peak physical performance while suppressing energetically demanding physiological traits, researcher Dr. Jose Areta of LJMU is on the podcast to discuss his work in this area.
About The Guest:
Dr. José Areta currently works as a lecturer in Sports Nutrition and Metabolism at the School of Sport and Exercise Sciences at LJMU.
José’s primary interest is in the area of training-nutrient interactions in humans. In other words, he investigates how to manipulate ingestion of carbohydrates, fat and protein around training to optimise physical performance and health.
The outputs of his research have not only expanded the knowledge of the field but had significant impact and influence on determining current dietary recommendations and practices world-wide.
His work has provided novel insights in relation to the amount, timing, quantity and distribution of carbohydrates, fat and protein and dietary supplements around training. Over the last few years José has been developing his research in the area of the endocrinological, metabolic and physiological effects of energy restriction, in which he is currently growing his research team and capability.
Tue, 09 Jan 2024 - 45min - 535 - #507: Does a Higher Portfolio Diet Score Reduce Heart Disease? – Andrea Glenn, PhD
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The Portfolio diet is a nutritional approach that has garnered attention for its ability to reduce blood lipids and thus improve cardiovascular health.
While past intervention trials have demonstrated significant reductions in blood lipids, a critical aspect often overlooked is the long-term impact, both in terms of adherence and disease outcomes.
A recent study aimed to address this by looking at disease risk across three cohorts: the Nurses’ Health Study I, Nurses’ Health Study II, and the Health Professionals Follow-up Study.
The study made use of a Portfolio Diet Score (PDS), a comprehensive metric that evaluates the diet’s efficacy based on specific components.
These components include positive rankings for plant proteins (especially from legumes), nuts and seeds, viscous fiber sources, phytosterols (mg/day), and plant monounsaturated fat sources. Conversely, the PDS negatively ranks foods high in saturated fat and cholesterol.
In this episode, Dr. Andrea Glenn, the lead author of this study, discusses the intricacies of the research, providing insights into its findings and shedding light on how these findings resonate within the broader landscape of literature.
Tue, 02 Jan 2024 - 42min - 534 - Listener Q&A: Homocysteine, MUFA, Healhty BMI, and more! (Preview)
This episode is one of our Premium-exclusive AMA (ask me anything) episodes, where we answer questions submitted by Premium subscribers.
To listen to the full 90 minute episode, you’ll need to be a Premium subscriber and access the episode on the private Premium feed.
Otherwise, you can hear a preview of the episode here.
Full List of Questions:
- [01:50] How should one interpret the systematic reviews done by Hooper et al that report no association between modification or reduction of saturated fat intake with cardiovascular mortality, total mortality, non-fatal MI? [22.10] Given most people don’t meet them, are public health targets for fruit and vegetables too high? [29.10] What is the role of homocysteine in heart disese? Is it causal? [40:45] Monounsaturated Fat: Good, Bad or Indifferent? [50:13] Is there evidence to suggest an upper limit for BMI, where even individuals with a ‘healthy’ body composition would be at elevated risk? [59:32] Where does the current research stand on the impact of diet on brain health? [01:08:48] Based on recent findings, do we have to throw out previous research on diet’s impact on the gut microbiome?
Tue, 26 Dec 2023 - 19min - 533 - #506 Sports Nutrition: Translating Research to Practice – Andreas Kasper, PhD
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Navigating the intricate landscape of sports nutrition is one that constantly evolves and challenges our understanding of optimal athletic performance.
The delicate balance between advancing research and ensuring practical applicability in the high-speed realm of sports nutrition is a perpetual struggle.
Decision-making is difficult, especially when faced with a scarcity of evidence. It’s a challenge that resonates with many professionals in the field, prompting reflections on the art of making informed choices in the absence of conclusive data.
In this episode, Dr. Andy Kasper, PhD shares his experiences and research in the field of elite sports nutrition.
Dr. Kasper, a PhD in Nutrition and Physiology from Liverpool John Moores University, currently spearheads the Performance Nutrition department at Newcastle United Football Club. His illustrious career spans across elite football, rugby union, and rugby league, with notable stints at clubs like Chelsea, Fulham, Derby, England Rugby Union, Sale Sharks, London Irish, and Wasps, to name a few.
A prolific contributor to academic publications, Dr. Kasper’s insights have not only shaped the scientific landscape but have also directly influenced the nutritional strategies employed by top-tier athletes.
Our conversation will traverse a myriad of topics, from the transformative changes witnessed in sports nutrition to invaluable advice for practitioners navigating this intricate terrain.
We’ll also delve into the delicate balance between advancing research and ensuring practical applicability in the fast-paced world of sports nutrition. Dr. Kasper will shed light on the Paper-to-Podium Matrix, a concept that bridges the gap between scientific discoveries and their real-world implementation in the pursuit of athletic excellence.
Tue, 19 Dec 2023 - 49min - 532 - #505: Oslo Diet-Heart Study: Cholesterol-lowering Diets & Cardiovascular Events
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The Oslo Diet-Heart Study was one of the earliest randomized controlled trials to explore the relationship between diet and heart disease. It aimed to investigate the impact of dietary interventions, specifically the reduction of saturated fat intake and an increase in polyunsaturated fat intake, on cardiovascular health.
The Oslo Diet-Heart Study involved 412 men who had already suffered a myocardial infarction 1-2 years before the start of the intervention.
Despite some known limitations, the Oslo Diet-Heart Study played a role in shaping early understanding on the relationship between dietary fat, cholesterol levels, and heart disease. Subsequent research and larger studies have contributed to a more nuanced understanding of the complex factors influencing cardiovascular health.
In this episode we discuss why this trial is important in the history of diet-heart research and how it connects to other seminal work in the field.
Tue, 12 Dec 2023 - 40min - 531 - #504: Vegetable Oil vs. Saturated Fat – Analysis of the LA Veterans Study
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In 1959 a landmark clinical trial, often referred to as the LA Veterans Study, began with the aim to investigate the effects of replacing dietary saturated fats with polyunsaturated fats, on the progression of atherosclerosis and cardiovascular outcomes.
This was an eight-year clinical trial in 846 domiciled male veterans in the US. The diets between the control and experimental groups differed by saturated fat and polyunsaturated fat (particularly linoleic acid) content, but were similar in calories and total dietary fat.
The findings of the study suggested that replacing saturated fat with polyunsaturated fat was beneficial for reducing heart disease risk. However, the study also reported an unexpected increase in non-cardiac mortality in the intervention group, which raised concerns.
In this episode, we discuss why the LA Veterans Study was such a seminal trial and what we can learn from it.
Tue, 05 Dec 2023 - 42min - 530 - #503: Lyon Diet Heart Study – Canola Oil, “Mediterranean” Diets & Minimizing Bias
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The Lyon Diet Heart Study (LDHS) is often cited as one of the pivotal studies that helped establish the Mediterranean diet as a recognized and recommended dietary pattern for cardiovascular health.
A clinical trial conducted in Lyon, France, the LDHS showed significant reduction in cardiac death could be achieved in secondary prevention patients using a dietary intervention.
Conducted between 1992 to 1996, the study involved 605 participants who had previously experienced a heart attack (myocardial infarction).
LDHS showed an incredible 75% lower risk of cardiac death in these patients. This remarkable reduction was unexpected and led to considerable attention from the medical and scientific communities.
LDHS is interesting to dig into for several reasons. First, it’s clever methodology was able to account for some challenges of doing nutrition research. Second, the dietary intervention, whilst named as a “Mediterranean diet”, should perhaps be considered differently.
In this episode, Alan and Danny dig into all the details, highlighting some important lessons we can take from LDHS.
Tue, 28 Nov 2023 - 43min - 529 - #502: Sydney Diet-Heart Study – Is Linoleic Acid Causing Heart Disease?
Links:
Go to episode page (with study links) Subscribe to Premium Past episodes referenced: Episodes 493, 481 & 317 Further reading: How Diet Influences Heart Disease RiskAbout This Episode:
The Sydney Diet-Heart Study was a clinical trial conducted in the 1960s and 1970s that aimed to examine the hypothesis that reducing saturated fat intake in the diet would lead to a reduced risk of heart disease.
However, it really only gained attention after a more recent re-analysis by Ramsden et al., which in recent years has been used as supporting evidence for the idea that increased polyunsaturated fat (PUFA), and specifically linoleic acid, in addition to reduced saturated fat intake, can increase heart disease risk.
This was based on the findings that substituting linoleic acid in place of saturated fat increased all-cause, CVD and CHD mortality.
This is of course counter to prevailing consensus and guidelines in this area, which routinely show reduced risk on replacing SFA with PUFA.
Could this trial undermine the common conclusions that replacing saturated fat with polyunsaturated fat decreases heart disease risk?
In this episode Alan and Danny discuss some of the crucial aspects to understand about this study and what it means for what conclusions can be made about the impact of PUFA broadly, and linoleic acid specifically, on our health.
Tue, 21 Nov 2023 - 40min - 528 - Addressing Some Criticisms of Nutritional Epidemiology (SNP 23)
Note: This is a Premium-exclusive episode, so in order to listen to the full episode you’ll need to subscribe to Sigma Nutrition Premium.
About This EpisodeNutritional epidemiology has faced strong criticism over time. While some of the methodological limitations are fair, often there are criticisms that are misguided and inaccurate.
In this episode, Danny touches on a few examples of the misunderstandings of the field and how such claims can be addressed in a more accurate manner.
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Subscribe to Premium Go to episode page See recommended resources Receive weekly emails from SigmaTue, 14 Nov 2023 - 10min - 527 - #501: Sex-based Training Recommendations: Evidence-based or Hype? – David Nolan, PhD
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The field of research exploring sex differences in exercise response has yielded intriguing findings, shedding light on the complex interplay between biology, physiology, and training adaptations.
One of the fundamental areas of investigation pertains to sex disparities in strength, power, and hypertrophy. Historically, it’s been well-established that males, on average, exhibit greater absolute strength and muscle mass compared to females. This discrepancy often traces its roots back to inherent physiological distinctions.
However, when it comes to responses to strength and hypertrophy training, the narrative becomes more nuanced. Research indicates that, when individuals of both sexes follow matched resistance training protocols, the relative improvements in strength and hypertrophy are quite similar.
So, do women need to be trained differently than men? The answer, it appears, is not as much as one might assume. The principles of progressive overload, specificity, and other training fundamentals remain constant. While individualization is key, the idea of drastically distinct training guidelines based on sex lacks compelling empirical support.
The guest in this episode, Dr. David Nolan, is a researcher in the area of sex differences in exercise response, and has looked at the influences of menstrual cycle and hormonal contraceptive use in female athletes on their performance.
In this episode, we discuss the research to date, and what this means practically for athletes and coaches.
Tue, 07 Nov 2023 - 1h 13min - 526 - #500 – The Big Unanswered Questions in Nutrition Science
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Subscribe to PREMIUM to get study notes to this episode Go to episode page to see background detail & links See our recommended resources for further learning Previous episodes referenced: SNP17: Is Personalized Nutrition Superior to General Nutrition Advice? 414: Will Machine Learning Overtake Traditional Nutrition Research Methods? 469: Chrononutrition – New Findings & Updated Views About This Episode: To mark the 500th episode of the podcast, Danny and Alan take a look at some of the current outstanding questions in nutrition science, what areas have largely been resolved, and how their own thinking has evolved and changed over time. This brings them into areas such as personalized nutrition, ultra-processed foods, time-restricted eating, salt & health, and the difference between being “evidence-based” and “reference-based”. We Discuss: Outstanding questions in nutrition science Personalized nutrition Ultra-prosessed foods (UPFs) Diet-Microbiome-Health Omega-3 Fatty Acids Largely resolved questions Sodium & CVD risk TRE/TRF Macronutrient breakdown & weight loss Evolution in our thinking Epistemology at the forefront “Reference-based” to evidence-based Reading research: understanding “highest quality evidence”Tue, 31 Oct 2023 - 1h 19min - 525 - #499: How Sensory Cues Impact Food Choice & Behavior – Prof. Ciarán Forde
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Sensory cues, comprising taste, smell, texture, and appearance, serve as the initial drivers that influence our food preferences and liking for particular items. These sensory cues can be both inherent, such as the natural sweetness of fruit, and learned, as in the association between a particular aroma and a favorite dish.
One crucial aspect of this research is delving into how sensory properties of food, like texture and taste, contribute to our choices and consumption patterns. Food texture, for example, plays a key role in determining how quickly we consume a meal, with softer textures often being associated with faster eating rates.
Sensory intensity and palatability are also central themes in this research. Moreover, research into dietary fat reveals intriguing phenomena like “fat blindness,” where the ability to discriminate different levels of fat diminishes as taste intensity increases. Understanding these relationships can help shed light on factors contributing to overeating and potential avenues for behavior modification.
To give us a better insight into this field of research, Professor in Sensory Science and Eating Behavior at Wageningen University, Prof. Ciarán Forde, is on the podcast to discuss these ideas.
Tue, 24 Oct 2023 - 1h 02min - 524 - The PREDIMED Trial – Controversy, Criticisms, & Lessons Learned (SNP 22)
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PREDIMED (Prevención con Dieta Mediterránea) is a landmark clinical trial conducted in Spain.
The study made a huge splash due to the rarity in nutrition of having large RCTs with hard endpoints. In addition, it had results of a large magnitude; showing a 30% reduction in cardiovascular events.
But the study did face criticisms and controversies over methodological issues, including randomization procedures at certain centers, ultimately leading to a retraction of the original paper and a re-analysis.
Participants in the PREDIMED trial were randomly assigned to one of three groups:
A Mediterranean diet supplemented with extra-virgin olive oil. A Mediterranean diet supplemented with mixed nuts (walnuts, almonds, and hazelnuts). A control group following a low-fat diet.Despite the issues it still ends up being an incredibly useful source of data.
In this episode we discuss the findings from PREDIMED, some of the potential limitations, and where it sits among the wider Mediterranean Diet literature.
Note: This is a Premium-exclusive episode, so in order to listen to the full episode you’ll need to subscribe to Sigma Nutrition Premium.
Tue, 17 Oct 2023 - 17min - 523 - #498: The PROPEL Trial & Weight Loss Interventions in Primary Care – John Apolzan, PhD
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The PROPEL (Promoting Successful Weight Loss in Primary Care in Louisiana) trial was a cluster-randomized weight loss trial, specifically tailored to address the pressing health concerns of an underserved population in Louisiana, where obesity rates have reached alarming levels.
The core of the intervention comprises a pragmatic, high-intensity lifestyle-based obesity treatment program, thoughtfully designed to be integrated within primary care settings. Over a 24-month duration, this multi-component weight loss program is delivered by skilled health coaches who are embedded in primary care clinics, with the aim of instigating substantial and sustainable weight loss outcomes.
In this study, 803 participants were enrolled, of whom 67% identified as Black and 84% as female, thereby ensuring a diverse representation. The research design randomized 18 clinics, allocating them equally into two groups: usual care and an Intensive Lifestyle Intervention (ILI). The usual care group continued to receive their customary primary care, serving as the benchmark against which the ILI’s efficacy will be measured.
In this episode we have the opportunity to delve deeper into the intricacies of the PROPEL trial and gain insights from one of its lead researchers, Dr. John Apolzan of the Pennington Biomedical Research Center.
Tue, 10 Oct 2023 - 35min - 522 - #497: Are Food Frequency Questionnaires Reliable?
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Food frequency questionnaires (FFQs) have been widely employed in nutrition research to assess dietary intake patterns among study participants. However, debates surrounding the reliability of FFQs have persisted both inside and outside the academic community.
These debates primarily revolve around issues related to measurement error, recall bias, and the appropriateness of FFQs for diverse populations.
One prominent concern is the potential for measurement error in FFQs. These questionnaires rely on self-reported data from participants, which can introduce inaccuracies due to memory limitations and social desirability bias. Participants may not accurately recall their food consumption frequencies and portion sizes, leading to imprecise estimates of nutrient intake.
Recall bias is another critical issue in the reliability debate. Participants may selectively remember or misreport the consumption of certain foods or nutrients, leading to an overestimation or underestimation of actual dietary intake.
Two concepts are crucial to understand: validity and reproducibility. FFQs are validated by cross-referencing the FFQ data with other dietary assessment tools (or other methods). It’s also important to consider if an FFQ gives reproducible results when used on multiple occasions.
When we ask “are FFQs reliable?”, we must first understand the conceptual exposure of interest: average intake over time. Second, we must consider what nutrients we are looking at. And third, in what population.
In this episode, Danny & Alan discuss the reliability of FFQs and how to have a deeper, more accurate understanding of their use. They take a look at valid critcisms of FFQs, as well as some of the more ill-informed criticisms.
Tue, 03 Oct 2023 - 1h 08min - 521 - SNP21: Sick Individuals and Sick Populations
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In 1985 a paper titled “Sick Individuals and Sick Populations” was published in the International Journal of Epidemiology.
The paper, authored by eminent epidemiologist Geoffrey Rose, can be considered as seminal and important because it brilliantly raised the concept of the “prevention paradox” and challenged traditional approaches to public health and preventive medicine.
The paper’s insights have had a lasting impact on how we understand and approach population health interventions. And it raised many contentious public health issues, which are still debated and relevant today.
The ideas have very important implications for how we can tackle diet-related diseases in meaningful ways.
In this episode, Danny and Alan discuss the central themes of the paper, why they are so crucial to understand, and what this means for our understanding of diet and chronic disease prevention.
Tue, 26 Sep 2023 - 17min - 520 - #496: ATBC Cancer Prevention Study – Crucial Lessons
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The Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (ATBC) stands as a seminal and pioneering research endeavor within the domain of epidemiology and cancer prevention. Conducted in Finland, the study aimed to examine the potential protective effects of alpha-tocopherol (vitamin E) and beta-carotene supplementation against the occurrence of various cancer types, particularly lung cancer, among male smokers. Initiated in the early 1980s, the study’s comprehensive design, rigorous methodology, and its focus on a specific high-risk population have contributed significantly to the understanding of the interplay between dietary antioxidants and cancer risk.
The ATBC study was founded on a growing body of evidence suggesting the potential role of antioxidants in mitigating the deleterious effects of oxidative stress and free radical damage, which are recognized as contributors to carcinogenesis. The selection of male smokers as the study cohort was strategically significant, given the heightened susceptibility of this group to lung cancer and other malignancies due to the synergistic action of smoking and oxidative stress. The study’s rigorous double-blind, placebo-controlled design ensured a high degree of scientific rigor, minimizing biases and confounding factors that might influence the outcomes.
One of the primary reasons for the study’s seminal status is its contribution to the understanding of the complex relationship between antioxidants and cancer risk. While the study did not find a significant reduction in lung cancer incidence among the intervention group receiving alpha-tocopherol and beta-carotene supplements, its findings spurred critical discussions within the scientific community. The neutral or inconclusive results underscored the intricate nature of carcinogenesis and highlighted the limitations of simplistic cause-and-effect interpretations in the context of cancer prevention. Moreover, the ATBC study contributed to a shift in research paradigms, prompting scientists to explore broader dietary and lifestyle factors that influence cancer risk beyond single-nutrient interventions.
In this episode we discuss the three most important publications from the study, with a specific look at what crucial lessons they teach us about the nuances, challenges, and unique aspects of nutrition as a scientific field.
Tue, 19 Sep 2023 - 1h 01min - 519 - #495: Circadian Clocks in Muscle & Exercise as a Time Cue – Prof. Karyn Esser
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The field of circadian biology has long been associated with regulating diurnal physiological processes, notably the sleep-wake cycle. However, recent advances have unveiled a broader role for circadian clocks across various tissues, including skeletal muscle.
Within this context, the investigation of circadian clocks within the skeletal muscle milieu has emerged as a frontier of scientific inquiry. These intrinsic timekeeping mechanisms exhibit multifaceted regulatory capacities beyond mere temporal synchronization.
This episode delves into the implications of “circadian clocks” operating within skeletal muscle tissue, with the esteemed Prof. Karyn Esser as this week’s guest. Her pioneering work has been instrumental in understanding the interplay between circadian rhythmicity and muscular physiology.
Tue, 12 Sep 2023 - 35min - 518 - #494: Multiple Risk Factor Intervention Trial
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The Multiple Risk Factor Intervention Trial (MRFIT) was a groundbreaking clinical trial conducted in the 1970s and 1980s. Its main objective was to investigate the relationship between various risk factors and the incidence of heart disease.
The study aimed to determine whether modifying risk factors, such as high blood pressure, high cholesterol levels, and smoking, could lead to a reduction in cardiovascular events.
The trial spanned several years, with participants being followed up for a period of approximately six years to assess the incidence of cardiovascular events and mortality. The primary outcome measures included coronary heart disease (CHD) mortality and overall mortality.
The MRFIT trial yielded several important findings that have significantly influenced our understanding of cardiovascular health and prevention strategies.
In this episode we take a look at why this is such seminal research, as well as the contribution of one of the greatest researchers ever in the field, Jeramiah Stamler.
Tue, 05 Sep 2023 - 54min - 517 - #493: The Keys Equation – How Dietary Fats Impact Blood Cholesterol
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One of the most important and influential papers in nutrition science is one by Ancel Keys and his colleagues that was published in The Lancet in 1957. This seminal paper examined the relationship between dietary fat intake and serum cholesterol levels. The researchers investigated how different types of fats in the diet affected cholesterol levels in a series of their previous tightly-controlled dietary experiments..
Those studies involved feeding the participants various diets with different compositions of fats. The researchers analyzed the participants’ blood samples to measure changes in serum cholesterol levels in response to dietary changes.
The most important aspect of this paper is the presentation of the ‘Keys Equation’; a predictive equation for the impacts of saturated, monounsaturated, and polyunsaturated fats, and dietary cholesterol, on blood cholesterol levels.
Crucially, the Keys Equation identifies the importance of the ratio of polyunsaturated to saturated fats in the diet; known as the ‘P:S ratio’. It showed that the P:S ratio is the most important dietary factor impacting blood cholesterol levels. And specifically that saturated fats increase total and LDL cholesterol twice as much as polyunsaturated fats lower them.
The findings of this study were significant in highlighting the potential impact of dietary fat subtypes on serum cholesterol levels and heart disease risk. It contributed to the growing body of evidence supporting the hypothesis that high serum cholesterol levels, particularly due to a diet rich in saturated fats, were associated with an increased risk of cardiovascular diseases.
In this episode, as part of our new series taking an in-depth look at seminal nutrition studies, we go through this influential paper from Keys, Anderson and Grande.
Tue, 29 Aug 2023 - 58min - 516 - SNP20: The Cumulative Exposure Model of LDL-C & Heart Disease
This is a Premium-exclusive episode, so here you'll only hear a preview. In order to listen to the full episode you’ll need to subscribe to Sigma Nutrition Premium.
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It has been clearly demonstrated that elevated LDL-cholesterol (LDL-C), or perhaps more specifically pro-atherogenic lipoproteins, is causal in atherosclerosis development in humans.
One crucial concept within this is that the risk relates not only to the magnitude of elevated LDL-C, but the duration of exposure. Thus, the role of LDL-C in driving atherosclerosis is referred to as a “cumulative, integrated exposure over the lifecourse”.
But, what exactly does this mean?
In this episode, Danny discusses the cumulative exposure model of LDL-C in atherosclerosis, the evidence supporting it, and the implications of this for the “debates” that get raised in relation to LDL-C (or apoB-containing lipoproteins) and heart disease.
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Subscribe to PREMIUM See more episodes on heart disease and lipids Receive the free Sigma email newsletterTue, 22 Aug 2023 - 13min - 515 - #492: How Does Weight Cycling Impact Long-term Health?
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Losing at least 5% of one’s initial body weight is associated with improvements in glycaemic control, blood pressure, triglyceride levels, and other positive outcomes. Due to these reasons, it is typically recommended that individuals classified as overweight or obese should engage in effective weight loss interventions.
However, despite the potential for clinically significant weight loss through these interventions, weight regain is a common occurrence. This can be attributed to a combination of low adherence to weight control strategies and compensatory physiological mechanisms that influence weight regain.
Consequently, this may result in a cycle of losing and regaining weight over the long term, which is commonly referred to as “weight cycling.”
There are concerns regarding the potential harm to health and increased risk of chronic diseases associated with weight cycling. Some mechanisms have been proposed, such as the loss of lean mass during weight loss periods that is not regained when weight is regained. However, the evidence supporting the harmful effects of weight cycling on health is incomplete and many unanswered questions remain.
In this episode, we will examine the evidence published to date and draw evidence-based conclusions regarding the impact of weight cycling on long-term health.
Tue, 15 Aug 2023 - 1h 06min - 514 - #491: Do High Protein Intakes Cause Insulin Resistance?
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There has been interest in, and debate about, how protein intake impacts metabolic health, particularly in relation to insulin resistance and type 2 diabetes risk.
Recently, there has been interest in higher protein intakes as an intervention in diabetes, owing to a variety of potential mechanisms. For example, the satiety value of protein, the promotion of insulin secretion by protein, and imapcts on incretin hormones.
However, others have warned against high protein intakes. With some going as far as to claim high, or even moderate, protein intakes can lead to insulin resistance or negatively effect beta-cell function.
In this episode, we look at the research typically cited in support of such claims, and dig into the details. We consider the overall evidence in this area to answer the question ‘do high protein diets cause insulin resistance or increase diabetes risk?’.
Tue, 08 Aug 2023 - 1h 02min - 513 - #490: How Does Exercise Impact Beta-cell Function in Type 2 Diabetes? – Mark Lyngbæk, MD
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Go to episode page Subscribe to PREMIUM Receive our free weekly emails About This Episode: The management of type 2 diabetes has long been a challenge, but a new study conducted by researcher Mark Lyngbaek and his colleagues has the potential to add important considerations to the approach to treatment. Titled the “DOSE-EX” randomized clinical trial, their study uncovers the impact of exercise and weight loss on beta-cell function, a key factor in diabetes progression. DOSE-EX is a four-armed randomized trial involving 82 individuals with newly diagnosed type 2 diabetes. The participants were divided into four groups: standard care, calorie restriction, calorie restriction with exercise three times per week, and calorie restriction with exercise six times per week. Over a span of 16 weeks, the researchers assessed the effects of these interventions on beta-cell function using various indicators. The study’s findings are incredibly interesting, demonstrating that exercise in combination with diet-induced weight loss leads to a substantial improvement in glucose-stimulated beta-cell function. Importantly, the results indicate the importance of considering both: a) the exercise dose, and b) the methodology of assessing beta-cell function, when evaluating intervention effectiveness. In this episode, Dr. Lyngbaek will elucidate the implications of these findings for the management of type 2 diabetes. We will explore the potential of exercise as a therapeutic tool, its optimal dosage, and the considerations for integrating it into individualized treatment plans. About The Guest: Dr. Mark Lyngbæk is a physician, currently in an introduction position at the Department of Rheumatology and Internal Medicine 2 at Holbæk Hospital, and also a PhD student at the Centre for Physical Activity Research at Rigshospitalet. His research has looked at exercise, beta-cell function and type 2 diabetes. He is supported by a research grant from the Danish Diabetes Academy, which is funded by the Novo Nordisk Foundation (grant number NNF17SA0031406). The Centre for Physical Activity Research is supported by TrygFonden (grants ID 101390, ID 20045, and ID 125132).Tue, 01 Aug 2023 - 58min - 512 - What is a Causal Risk Factor? (AMA with Alan)
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We've just released a lengthy 'ask me anything' episode, where Dr. Alan Flanagan addressed specific listener questions, over on the Sigma Nutition Premium feed. In this episode, you'll hear one detailed answer from that AMA, in which Alan discusses the concept of "causal risk factors".
This is a term that is regularly mentioned on the podcast, and has a very specific and important meaning. This episode will give you an in-depth understanding and comfort with the term, which will enhance your future understanding and learning.
If you wish to hear the other 10 questions Alan answered, you can subscribe to Sigma Nutrition Premium here.
Tue, 25 Jul 2023 - 31min - 511 - #489: Inequalities in Diabetes Outcomes for African & Caribbean Communities – Prof. Louise Goff
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In the UK, there is a threefold higher incidence of type 2 diabetes in UK African and Caribbean (AfC) communities, compared to the general population. And ethnic inequalities in type 2 diabetes treatment and outcomes have been documented. And so addressing these inequalities is an urgent healthcare priority in the UK.
Differences in outcomes relate to physiological differences as well as pragmatic issues and structural barriers. Professor Louise Goff has done pioneering work in relation to both aspects.
Prof. Goff’s research has highlighted ethnic differences in type 2 diabetes pathophysiology between those in UK African and Caribbean groups and white Europeans. This means that typical screening for diabetes may not be as useful for AfC communities, in addition to treatments not being as appropriate.
In addition, there are noted differences in engagement with diabetes education services and self-management advice. This may be due to the fact that the delivery of information is not culturally relevant to those in AfC communities. And so diabetes structured education programs have been found to be less successful in people from minority ethnic groups.
Prof. Goff has attempted to address this by developing a culturally tailored self-management education and support program for type 2 diabetes in black-British adults. This program, called the Healthy Eating and Active Lifestyles for Diabetes (HEAL-D) program, has initially been trialed with local Black African and Caribbean communities and healthcare providers in South London.
In this episode, Prof. Goff discusses the ethnic differences in diabetes pathophysiology and the other factors underlying the inequalities in diabetes outcomes in black African and Caribbean communities.
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Tue, 18 Jul 2023 - 51min - 510 - #488: Does Time of Day Impact Hunger, Appetite & Satiety?
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The topic of whether hunger and satiety are affected by the time of day has generated considerable interest within the nutrition research community. Researchers have been particularly intrigued by the potential influence of circadian rhythms on caloric intake throughout the day.
Initially, a number of studies proposed that consuming high energy intakes in the morning could lead to significantly greater weight loss compared to evening consumption. And while much attention was placed on the hypothesis that differences in expenditure were the cause, more recent research has called that into doubt.
And so, it is crucial to consider the possibility that other factors may be contributing to the outcomes observed in the intervention trials. In recent years, a series of papers has suggested an alternative explanation; the impact of time-of-day energy intake on appetite and hunger.
In this episode, Alan and Danny take a look at the current evidence related to this connection between time-of-day, appetite, and energy intake. And then, from that, what does this mean for how calorie distribution may affect dietary intake, body composition and health.
Tue, 11 Jul 2023 - 1h 27min - 509 - #487: Weight Cutting in Combat Sports – Jordan Sullivan
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“Weight cutting” is a common practice in weight-class based sports. And typically, combat sport athletes have reported cutting the largest amounts of weight for competition.
The concept of cutting weight is based on the assumption that a size advantage gives a performance advantage in combat sports. And by getting into a lower weight class than their “normal” weight, athletes can enjoy an advantage (or, more accurately, not be at a disadvantage).
The decrease in weight from an athlete’s habitual weight to their weight-class limit typically has two phases: a chronic weight loss phase (gradual dieting to lose fat mass), and an acute weight loss phase (rapid declines in weight due to losses of water, glycogen and gut residue).
To discuss the science, practical application and dangers of weight cutting strategies, performance dietitian Jordan Sullivan is on the podcast.
Jordan has been the performance dietitian for several years to Israel Adesanya, Alexander Volkanovski, Leon Edwards, Dan Hooker, Kai Kara-France, and many other well-known names.
And he is the co-author, along with Danny, of the new textbook ‘Making Weight: The Ultimate Science Based Guide to Cutting Weight for Combat Sports’.
Wed, 05 Jul 2023 - 1h 15min - 508 - #486: Blood Glucose Spikes: How High is Too High? – Mario Kratz, PhD & Nicola Guess, PhD
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Peaks in blood glucose (or “blood sugar spikes”) are commonly highlighted as something harmful to health. And, of course, an excessively high blood glucose response to a meal can be problematic, or at least indicate there is a problem.
However, elevations in blood glucose after eating are a normal physiological response. And “bad” blood glucose responses are those that stay high for a prolonged period; i.e. after elevating, they don’t return to normal within an appropriate period of time.
But now many normoglycemic people are worrying about normal blood glucose responses, due to information that portrays even moderate elevations in blood glucose as harfmul. To add to the confusion, people are looking at standardized cut-off thresholds for diabetes and pre-diabetes, and mistakenly using them to label their own response to eating as measured by a continuous glucose monitoring (CGM) device.
When it comes to normoglycemic people, there is still a grey area in relation to how much of a glucose spike is a cause for concern. And given that there are still open questions that evidence has not fully answered yet, there is room for different interpretations of how to answer this question.
So what actually is a blood glucose peak that is “too high”? Is it 7.8 mmol/L (140 mg/dL)? 10.0 mmol/L (180 mg/dL)? 11.1 mmol/L (200 mg/dL)? Or do we even need to think about this once standard measures (e.g. HbA1C) are normal?
To discuss this interesting area, Dr. Mario Kratz and Dr. Nicola Guess are on the podcast to offer some perspectives and their conclusions from the current evidence base.
Blood Glucose Unit Conversions:
1.7 mmol/L = 30 mg/dL 7.0 mmol/L = 126 mg/dL 7.8 mmol/L = 140 mg/dL 9.0 mmol/L = 162 mg/dL 10.0 mmol/L = 180 mg/dL 11.0 mmol/L = 198 mg/dL 11.1 mmol/L = 200 mg/dLTue, 27 Jun 2023 - 1h 21min - 507 - #485: Does Menopause Alter Appetite?
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Menopause is commonly associated with hormonal changes and physical symptoms, such as hot flashes, mood changes, sleep issues, and weight gain. Based on anecdotal reports, another interesting question emerges: what is the potential impact of menopause on appetite?
As women undergo this transformative phase, many report fluctuations in their food intake and body weight, raising the question: Does menopause alter appetite?
Understanding the relationship between menopause and appetite is of great significance, as it can potentially provide insights into the mechanisms behind weight gain and obesity risk that often accompany this stage of life. Furthermore, comprehending the factors that contribute to changes in appetite during menopause could aid in the development of tailored interventions and strategies to support women’s overall health and well-being.
In this episode, we delve into the research to see if we can unearth any answers. What studies have been done? What results do we see? What conclusions does this allow us to make? And what does future research need to do in order to provide better answers?
Tue, 20 Jun 2023 - 45min - 506 - SNP18: What is a Healthy Low-Carb Diet?
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Low-carbohydrate diets come with a list of reported benefits, and research does show benefit for a number of different outcomes. However, many influencers and advocates of low-carb diets routinely add commentary that is misleading, incorrect, and possibly dangerous. This has led to us highlighting such incorrect information on this podcast before and pushing back against central claims of the “big names” in the “low-carb community”.
However, low-carbohydrate diets can indeed be a viable dietary pattern for people who wish to consume a healthy diet… provided they meet a few criteria. In other words, it is possible to consume a low-carb diet that still largely fits in with the evidence we have on healthy dietary patterns.
In this episode, Danny discusses what health outcomes may result from low-carb diets, and what distinguishes a “healthy low-carb diet” from an “unhealthy low-carb diet”. This includes some pragmatic tips for nutritionists, health professionals and consumers, who are choosing to use a low-carbohydrate diet.
Tue, 13 Jun 2023 - 13min - 505 - #484: Is Metabolic Adaptation an Illusion? – Eric Trexler, PhD
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Metabolic adaptation refers to the process by which the body adjusts its metabolism in response to changes in energy intake or body mass. This adjustment can occur in both directions, meaning that the body can increase or decrease its energy expenditure in response to changes in energy intake or body weight.
When someone consumes fewer calories than their body requires for energy, the body will respond by slowing down its metabolism to conserve energy. This can make it harder to lose weight and maintain weight loss over time. Conversely, when someone consumes more calories than their body needs, the body will increase its metabolic rate in order to burn off the excess energy.
There are several open debates in science about metabolic adaptation, including the actual magnitude of it, its relevance to weight loss, what measurement methods should be used, and the mechanisms underlying the contributory factors.
Some people have framed metabolic adaptation as so significant that it makes weight loss attempts futile. While others, including in research, have referred to metabolic adaptation as an “illusion”. So what do we actually know about this concept and what is the pragmatic significance of it?
To discuss the nuances of the topic, Alan and Danny are joined by Dr. Eric Trexler, who has published on this topic and has followed recent publications closely.
About The Guest:
Dr. Eric Trexler is Director of Education at Stronger By Science, where he co-hosts the SBS podcast. He also is one of the four contributors to the MASS Research Review.
Eric has a prolific background in exercise science research, with more than 30 publications to his name by the time he completed his PhD at UNC-Chapel Hill.
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Tue, 06 Jun 2023 - 1h 15min - 504 - #483: What are the Effects of Very High Fiber Intakes?
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The benefits of consuming a higher fiber diet have been consistently demonstrated in nutrition research. Epidemiology clearly shows that higher intakes, compared to lower intakes, leads to a risk reduction for a range of diseases, including cardiovascular disease and colon cancer.
And based on this epidemiological evidence, most dietary guidelines recommend dietary patterns that provide adults with 30-35g of dietary fiber per day.
However, what do we know about intakes beyond this?
Do we continue to see benefit in a linear fashion? Is there a ceiling to benefit? At what level would we see “optimal” benefit or the greatest magnitude of risk reduction?
The ability to answer such questions is hampered by the fact it’s difficult to find cohort studies where the “high” fiber level is high enough to relate to this issue. However, there have been some controlled studies looking specifically at “very high” intakes, i.e. those far above current recommendations. In addition, there are some populations where habitual dietary intake gives a fiber intake far above the typcial intakes in Western cohorts.
So in this episode we go through this data to try to see what we can conclude about this fascinating question of ‘what are the health effects at very high fiber intakes?’
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Tue, 30 May 2023 - 1h 18min - 503 - #482: Carbohydrate Quality & Health – Andrew Reynolds, PhD
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In the last couple of decades, carbohydrates have experienced an increasing amount of negative campaigning. In general, the main argument is that carbohydrates have been viewed as the root cause for obesity, diabetes and several other diseases including heart disease and behavioral disorders. However, there can often be a lack of appreciation that not all carbohydrates are equal in their health effects.
Beyond this, now there has even been confusion as to whether high fiber diets with whole grains are good for you or bad. This is mostly a result of strong claims made by people with large online followings and promoting specific diets.
What does the best evidence tell us about different carbohydrate types and impacts on health outcomes? Should carbohydrates be viewed as inherently harmful? How solid is the evidence on whole grains, legumes and other high-fiber carbohydrate-rich foods?
To help us tease through the science in this area, in this episode we get some answers from nutrition epidemiologist, Dr. Andrew Reynolds.
About the Guest:
Dr. Andrew Reynolds is a nutrition epidemiologist working with achievable lifestyle and environment change in the prevention and management of non-communicable diseases, such as type 2 diabetes and cardiovascular disease. He primarily conducts randomised controlled trials and meta-analyses. Much of his work is to inform evidence-based dietary or clinical guidelines, policy, and food reformulation.
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Go to episode page (with resources) Subscribe to PREMIUM Receive Danny's weekly emailTue, 23 May 2023 - 1h 06min - 502 - Is Personalized Nutrition Superior to General Nutrition Advice? (SNP 17)
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“Personalized nutrition” has been promoted as an approach that will improve people’s health by prescribing them specific dietary recommendations based on their own genetic and phenotypic data.
The premise is that given we each respond differently to foods, having general dietary recommendations may be doing many people a disservice. And by using an array of personal data, it is now possible to give unique diets that improve health.
The early and interesting findings of research in this area was met with much fanfare, and indeed, many companies are now offering commercial direct-to-consumer services based on genetic and physiological testing, followed by “personalized” dietary prescription. Such testing may include genetic tests, microbiome testing, glucose monitoring data, and more. This data is then fed into machine learning algorithms to prescribe dietary recommendations.
However, do the marketing claims match the current evidence? Does the “proof” it works that is often cited, actually back up the claims? Do personalized nutrition diets actually lead to improved health outcomes over generic, conventional dietary recommendations? Do personalized nutrition diets lead to better outcomes than standard dietetic/nutrition practice?
To answer these questions, we go through the main studies cited in favor of personalized nutrition being superior to typical dietary advice, and see if they indeed support the claims.
So is personalized nutrition superior to standard dietary advice? Let’s find out…
Note: This is a Premium-exclusive episode, so in order to listen to the full episode you’ll need to subscribe to Sigma Nutrition Premium. However, you can listen to a preview here.
Tue, 16 May 2023 - 22min - 501 - #481: Why Saturated Fat Really Does Impact Heart Disease Risk
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While it has long been acknowledged that high intakes of saturated fat can increase risk of atherosclerotic cardiovascular disease due to their impact on blood lipids, there are some who question the association between saturated fat and heart disease.
Specifically, they may state that the evidence for this association is weak or non-existent, typically by pointing to some commonly cited studies that show null associations between saturated fat and CVD outcomes.
On this basis, they may conclude that there is no basis to aim to limit saturated fat intake to current recommended levels or that reducing saturated fat intake will not actually improve health outcomes.
In this episode, Alan and Danny look at the four most commonly cited publications showing a null association, highlighting some key issues. Beyond that, they look at a number of other lines of evidence on saturated fat that allows one to come to a confident answer on this question.
So does reducing saturated fat intake to recommended levels actually reduce heart disease risk? Let’s discuss…
Tue, 09 May 2023 - 1h 30min - 500 - #480: How Much Fiber Do We Need for Good Health? – Prof. Joanne Slavin
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The beneficial impact of a high-fiber diet is something that has been promoted in nutrition for a long period of time. But there remain a variety of interesting questions to researchers, practitioners and the general public alike.
How much fiber do we actually need? What are current fiber recommendations based on? What outcomes have the strongest evidence for benefit? Should we have targets for fiber sub-types? Are some types of fiber “better” than others? Do functional fibers added to food products still retain the benefits we see with dietary fiber?
To help get to some evidence-based answers on these issues, our guest in this episode is one of the researchers at the forefront of dietary fiber research for decades, Professor Joanne Slavin.
Tue, 02 May 2023 - 1h 10min - 499 - #479: Blood Glucose, CGM Use, Diabetes Remission & High-Protein for Diabetes – Nicola Guess, PhD, RD
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Blood glucose responses play a crucial role in maintaining good health, and any abnormalities in glucose regulation can lead to several chronic conditions. Diabetes is one such disease that results from a lack of insulin production or the body’s inability to use insulin effectively, leading to elevated blood glucose levels.
There has been debate about what exactly constitues a “healthy” and “unhealthy” blood glucose response. While it is suggested that unhealthy blood glucose responses are characterized by erratic and unpredictable “spikes” in blood glucose levels, sometimes vague terminology leads to people worrying about normal blood glucose responses. This may be particularly related to the increasing prevalence of continuous glucose monitoring (CGM) devices that allow individuals to track their glucose levels in real-time. While these devices can be helpful for people with diabetes to manage their glucose levels, they can also lead to unnecessary concern and anxiety about small, normal glucose elevations.
In recent years exciting advances have been made in diabetes remission research. And off the back of that, more research has looked at various dietary interventions that could either directly impact remission, or act as an adjuct to other interventions.
In this discussion with Dr. Nicola Guess, we discuss a range of topics related to glycemia, diabetes, and diet. This includes the potential for high-protein interventions, what utility CGMs actually have, what to make of diabetes remission trials, and future directions for the field.
Tue, 25 Apr 2023 - 50min - 498 - #478: Exposures in Nutrition – Why They’re Crucial to Understand
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Understanding the concept of an “exposure” is a critical aspect to nutrition science literacy. The ‘exposure of interest’ refers to the variable or factor that is being studied to determine its relationship with a particular health outcome.
For example, in a study examining the relationship between diet and heart disease, the exposure of interest may be a particular nutrient or food group, such as saturated fat or red meat consumption.
But when reading research we need to be able to critically examine the levels of an exposure and ask were these suitable for the research question at hand.
For example, is there a sufficiently wide contrast in the exposure between the groups being compared? How do the reported levels of intake relate to what we know about this exposure from the wider literature?
Much has been made of the many ’null’ associations found in nutrition epidemiology. But in many cases, these may be accounted for by looking at the exposure contrast or absolute intakes in those studies. Something we referred to as “null by design”.
In this episode, Danny and Alan go through the most crucial aspects to understand about the exposure of interest in nutrition, hopefully leading to an enhanced understanding of interpreting nutrition research.
Tue, 18 Apr 2023 - 1h 02min - 497 - SNP16: A Dairy Fat Paradox? – Saturated Fat, Food Matrices & Heart Disease
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Episode page with related links Subscribe to Sigma Nutrition Premium Receive Danny's free weekly emailDescription:
Substantial evidence shows that a high intake of saturated fat in the diet has the potential to significantly raise LDL-C and ApoB-containing lipoproteins in many people, and in turn increase their risk of developing atherosclerotic cardiovascular disease (ASCVD).
However, people may raise what seems to some contradictory evidence, or what is sometimes thought of as a paradox: the impact of full-fat dairy on CVD risk.
This paradox arises because given the saturated fat content of full-fat milk, yogurt and cheese, we typically don’t see the same impact on blood lipid profiles. In addition, epidemiology can often show such foods in a favourable light. And the dairy fat story gets more interesting when we look at evidence showing there is a huge difference in the impact of consuming different dairy foods (e.g. butter vs cheese/yogurt).
So this leads to many questions that people rightly ask, which we aim to address in this episode. Questions such as:
Why doesn’t increased dairy consumption lead to same increases in CVD risk as other saturated fat sources? Do results from full-fat dairy studies prove that saturated fat isn’t a problem? What is it about cheese/yogurt that makes it different to butter? How do low-fat and full-fat dairy compare? Diets including/excluding dairy: how to compare?Subscribe to Sigma Nutrition Premium
Tue, 11 Apr 2023 - 22min - 496 - #477: Effect of Different Diets on Cholesterol, Lipoproteins and Discordance – Ian Davies, PhD
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Go to episode page (with resources) Subscribe to Sigma Nutrition Premium Receive our free weekly emailsIntroduction:
Discordance between low-density lipoprotein particle (LDL-p) and low-density lipoprotein cholesterol (LDL-C) occurs when the levels of these two biomarkers do not match up as expected. Discordance between Apolipoprotein B (ApoB) and low-density lipoprotein cholesterol (LDL-C) is similar, except rather than counting just LDL particles, ApoB is a measure of the numbers of lipoproteins that have an ApoB attached.
Discordance between ApoB and LDL-C can lead to either an underestimate or overestimate of ASCVD risk. And therefore there may be important implications for someone who does have discordance. Additionally, it is such cases that suggest that a measurement of ApoB may provide additional information beyond traditional lipid measures in assessing a person’s cardiovascular risk.
Recent work from researchers at Liverpool John Moores University has investigated whether discordance is associated with certain dietary patterns.
In this episode, one of the researchers involved, Dr. Ian Davies, is on the podcast to discuss this work in addition to wider questions in the diet-lipids-CVD field that remain to be answered.
Tue, 04 Apr 2023 - 54min - 495 - #476: Fructose in Perspective – Dietary Villain or Misunderstood Nutrient?
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Go to episode page (w/ resources) Subscribe to PREMIUM Receive Danny's free weekly emailDescription:
Fructose is a type of sugar that is commonly found in fruits, vegetables, and many processed foods. In recent years, there has been a lot of discussion and debate about the impact of fructose on health, with some claiming that it is a major contributor to obesity, diabetes, and other chronic diseases. However, these claims are often at odds with what the scientific literature actually says.
One of the most common claims about fructose is that it is inherently “bad” for health, and that consuming too much of it can lead to a wide range of health problems. This idea has been popularized in many popular diet and health books, and has led to a widespread fear of fructose among the general public. However, many of these claims are based on outdated or oversimplified research, and do not reflect the complex reality of how fructose interacts with the human body.
Another common claim about fructose is that it is uniquely responsible for the current obesity epidemic, and that reducing fructose intake is the key to weight loss and better health. While it is true that excessive consumption of sugary foods and beverages can contribute to weight gain and other health problems, the idea that fructose is uniquely responsible for these issues is not supported by the scientific evidence. In fact, many studies have found that total sugar intake, rather than fructose specifically, is the most important factor in the development of obesity and related health problems.
In this episode we discuss the unique aspects of fructose metabolism, why some studies appear to show unique harm of fructose, and the implications of this for dietary choices.
Tue, 28 Mar 2023 - 52min - 494 - #475: Is Food Addiction Real? – Charlotte Hardman, PhD
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Go to episode page Subscribe to Premium Sign-up for our free weekly email: The Sigma SynopsisDescription:
The idea of food addiction has gained a lot of attention in recent years, as obesity rates continue to rise around the world. Many people struggle with overeating and find it difficult to resist certain foods, leading to a cycle of guilt and shame. The concept of food addiction suggests that there may be a biological explanation for this behavior, and that certain foods may be especially “rewarding” to the brain, leading to a kind of addiction.
To help look at the evidence in this area, our guest in this episode is Dr. Charlotte Hardman, who is a leading researcher in the field of appetite and obesity. Dr. Hardman’s research focuses on the psychological and biological processes that contribute to overeating and obesity. She is particularly interested in the concept of “food addiction,” which suggests that certain foods may be addictive and lead to compulsive overeating, similar to substance addiction.
In this podcast, we will explore the latest research on food addiction with Dr. Hardman. We will delve into the evidence for and against the idea of food addiction, as well as discuss the potential implications for public health and policy. Join us as we explore this fascinating topic and learn more about the complex relationship between food and the brain.
Wed, 22 Mar 2023 - 55min - 493 - SNP15: AMA – Semaglutide, “Carni-nutrients”, Sweating From Caffeine, & More
Questions Answered in this AMA
[00:03:01] Mechanisms that keeps weight stable over time? [00:11:52] Semaglutide: Game-changer? Weight regain? [00:30:42] How to further lower LDL-C? Can I avoid statins? [00:43:52] Glyphosate: A cause for concern in food? [00:48:30] High caffeine intake is making me sweat more. What’s going on? [00:55:16] Should I avoid non-organic meat? [01:00:08] Is there evidence on iron and zinc co-ingestion for anemia of prematurity? [01:03:09] “Carni-nutrients”: Can vegan diets cause brain issues due to lower choline, creatine and taurine? [01:12:10] Are energy drinks bad for us? [01:17:43] What are some resources for doctors and patients that simply explain obesity & treatments?This is an episode exclusive to Premium subscribers. To listen to the full episode you’ll need to subscribe. However, you can listen to a preview here.
Fri, 17 Mar 2023 - 27min - 492 - #474: Glucose Peaks & Variability – Is Lower Better?
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Go to episode page (with links & resources) Subscribe to Sigma Nutrition Premium Receive our free weekly email, The Sigma SynopsisAbout This Episode:
Often claims are made recommending that people should aim to keep peaks in blood glucose low in terms of both magnitude and frequency.
And while many claims about blood glucose “spikes” are incorrect or purposefully exaggerated to grab attention, there are some reasonable and interesting hypotheses put forward in relation to blood glucose variability and excursions.
For example, interesting questions have been raised in relation to the impact of blood glucose excursions in seemingly normoglycemic and/or healthy people.
In this episode, we look at three specific elements of this: average blood glucose, glucose variability, and glucose peaks. All in the context of people without prediabetes or type diabetes, who have typical blood glucose measures in the ‘normal’ range.
Specifically, we look at three hypothesized recommendations made elsewhere:
- “The lower you average blood glucose (HbA1C) is better, even if already in normal range” “The more you can minimize glucose variability, the better.” “Minimizing the number of glucose “peaks” is important, even if they don’t meet the threshold for hyperglycemia”
Can normoglycemic people benefit from further reducing these measures? Let’s take a look…
Mon, 13 Mar 2023 - 1h 22min - 491 - #473: Diet & Depression (What Do We Actually Know?) – Nicole Lippman-Barile, PhD
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Episode page (with more links) Subscribe to Premium IntroductionDepression is a common disorder and is a leading cause of disability worldwide. Depression results from a complex interaction of social, psychological, and biological factors.
Diet has been one area that has been suggested in playing a role; from potential for exacerbating symptoms to being a treatment. And while some associations have been noted, many claims far exceed what (little) evidence exists.
Online it is common to see people claiming certain diets can treat depression or that certain foods will improve outcomes. However, does the evidence match such claims?
In trials that have been published on diet-depression, there has been considerable media attention and fanfare around some results. For example, the SMILES trial published out of Australia. However, some have raised considerable concerns about the interpretation of such findings.
In this episode, clinical psychologist Dr. Nicole Lippman-Barile is on the podcast to discuss what we currently know about diet and depression, what issues exist with current studies, and why many nutrition-mental health studies are being incorrently interpreted.
Tue, 07 Mar 2023 - 1h 12min - 490 - #472: Compared To What? – Understanding Food Substitution Analysis & Adjustment Models
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Subscribe to Premium Go to this episode's page (with links) Live event: London - March 18th Receive 'Sigma Synopsis' emailsDescription:
When thinking about the effect of eating or not eating a certain food or nutrient, we can’t consider this in isolation. Meaning, we need to evaluate the impact within the context of what such an inclusion/exclusion does to an individual’s overall diet pattern.
Thinking about this concept, the phrase “compared to what?” has been colloquially used. And while this is an important idea, there has been some misapplication of this principle.
In nutrition science, this is related to the concept of food or nutrient “substitution”. And this concept is crucial to understanding the issues that can arise in nutrition studies, particularly when it comes to single food analyses in nutritional epidemiology.
This concept of substitution is quite intuitive in controlled feeding studies. However, it is not as obvious when considering nutrition epidemiology studies. As noted by Ibsen & Dahm (2022):
“Whereas studying the effects of eating one food instead of another is typically explicit in interventional study designs, it is often implicit and sometimes hidden in analyses of observational studies.”
However, in nutrition epidemiology substitution is still happening, but it typically emerges as a consequence of adjustment models. In nutritional epidemiology, it is essential to adjust for confounders. E.g., one vital adjustment is often for total calorie intake. However, when our exposure is a specific food/nutrient, we must think about confounding by other foods.
So knowing what, and how, a study is adjusting for variables helps us interpret it better.
In this episode, Dr. Alan Flanagan and Danny Lennon discuss these crucial ideas of food substitution, adjustment models, and “compared to what?”.
Go to this episode's page (with links)
Tue, 28 Feb 2023 - 53min - 489 - #471: Salt & Bone Health – Is There Cause For Concern?
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Episode page Subscribe to Premium Live Event: London, UK Receive the Sigma Synopsis emailsAbout This Episode:
Does sodium lead to calcium losses? Do high-salt diets harm bone health? At what thresholds could there be an impact? Does any of this change our recommendations around salt/sodium intake?
Thanks to Sigma Nutrition Premium subscriber Kate Wall for submitting a question in the member’s area that inspired this episode.
Kate asks: “Salt can impact calcium excretion in the urine and it is said that a high salt diet can increase risk of osteoporosis as it draws calcium from the bone and excretes it. How much of an impact does dietary salt intake actually have on bone health and how high would salt intake have to be for this to be a concern? Obviously high salt intakes are not something to aim for in general, but just wondered if this was a mechanism that could remove meaningful amounts of calcium in a way that I should be advising around this in those that we work with as nutritional professionals. Thanks!”
So in this episode, Danny and Alan look at some of the evidence in this area to see if there are impacts that have pragmatic implications for nutrition and medical professionals, as well as health-concious people.
Tue, 21 Feb 2023 - 57min - 488 - SNP14: Nutrition Coaching Roundtable (Helms, Huschtscha & Baker)
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Subscribe to Premium Episode pageDescription:
Nutritionists, dietitians and other health & fitness professionals face many challenges when attempting to help their clients and in understanding what approaches are best in a given situations.
There are often discussions around improving client adherence to dietary recommendations. However, sometimes we need to think deeper about this topic. Is there really just a tool to fix this? Or could the problem be the recommendations themselves?
Similarly, while quantifying dietary intake in terms of calorie and macronutrient amounts can be useful in some cases, it’s clear that this isn’t the best approach in many cases. So for coaches aiming to help athletes or those with body composition goals, how do we use “non-tracking” approaches effectively?
This episode brings you a roundtable discusssion between three accomplised and insightful nutrition professionals; Dr. Eric Helms, Dr. Zoya Huschtscha, and Mackenzie Baker. In the episode we discuss the above-mentioned topics and more.
Tue, 14 Feb 2023 - 09min - 487 - #470: Melatonin, Meal Timing & Glucose Tolerance
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Episode page Subscribe to Premium Live event in London, UK Description: Meal timing has been a popular, and at times controversial, topic of interest in nutrition. Despite much speculation over the years as to potential advantages to specific meal timing or meal frequencies, for many outcomes there seems to be little pragmatically meaningful difference. For example, when accounting for calorie and macronutrient intake, there is little to no effect of meal timing on body composition, blood pressure, and energy expenditure. However, just because there is little evidence for the importance of meal timing in relation to those outcomes, this should not be interpreted to mean there is no impact of meal timing on all health outcomes. One area where meal timing may be an important factor is in relation to glucose tolerance and glycaemic control. For example, it has been consistently shown that eating at ‘biological night’ leads to worse postprandial glucose responses. And this could be particularly important for those with insulin resistance, pre-diabetes or type 2 diabetes. Some of the most influential work in this area has been done by Marta Garaulet’s lab at the University of Murcia. One of the central aspects they have published on has been the interaction between food timing and melatonin levels, and how this in turn affects glucose tolerance and cardiometabolic markers. In this episode, Danny and Alan discuss the topic of meal timing and glucose tolerance, using a recent study from Garaulet et al. to highlight some important concepts.Tue, 07 Feb 2023 - 1h 11min - 486 - #469: Chrononutrition – New Findings & Updated Views
Research in the field of ‘chrononutrition’ has continued to grow in the past couple of years, with some important studies being published in recent times. Chrononutrition is a research area that looks at the relationship between temporal (time-related) eating patterns, circadian rhythms, and metabolic health.
While past podcast episodes have covered various aspects of chrononutrition, the latest research has added important pieces to the puzzle and has lead to both Alan and Danny updated their views on certain sub-topics.
In this episode, we look at recent research (including that from the Big Breakfast Project) and how understanding and conclusions from the field have shifted over time. Dr. Flanagan also gives some insight into the important chrono work published in the UK, which his dotoral work contributed to.
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Episode page Subscribe to Premium Live event: LondonTue, 31 Jan 2023 - 1h 18min - 485 - #468: High Sugar Intakes Without Excess Calories: Harmful or Benign?
There is almost universal agreement that excess added sugar in the diet is detrimental to health. However, much of this negative health impact clearly relates to the ability of high sugar intakes to drive excess calorie intake and fat accumulation, which cause health issues.
But what about situtaions of where there is not a calorie surplus (hypercaloric diet) or weight gain?
Some people claim that sugar is inherently damaging. While others push back and claim sugar is only a problem in the context of a hypercaloric diet. So which position is more accurate? What evidence do we have?
In this episode, Dr. Alan Flanagan and Danny Lennon take a look at situations of eucaloric (or even hypocaloric) diets, and what impact sugar has. Specifically, they investigate: in a situation where someone is not overconsuming calories or gaining weight, what health impacts do added sugars have? And if there are these calorie-independent effects, at what thresholds do they occur?
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Episode page (incl. all links) Live event: London, UK - March 2023Tue, 24 Jan 2023 - 1h 34min - 484 - SNP13: Intuitive Eating Debate – with Jackson Peos, PhD
This episode brings you a “debate” between Danny Lennon and Dr. Jackson Peos on the utility of intuitive eating. Specifcally, they make a case for and against, respectively, for the position: “Intuitive eating can be recommended eating approach for those with fitness and/or physique goals”.
This episode is a Premium-exclusive episode, so you’ll need to be a Premium subscriber to listen to the full discussion but you can hear a preview here.
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Subscribe to Premium Live event: London, UK - March 2023 Buy UEBC 22 ReplayTue, 17 Jan 2023 - 12min - 483 - #467: Iron Issues in Athletes – Prof. Pete Peeling
Iron is an important nutrient for athletes, given that it is used for oxygen transport and energy production. However, research on athletes often reports a relatively high prevalence of iron deficiency. Common symptoms of low iron status like lethargy, fatigue and negative mood states are naturally of concern to athletes. But there is also the potential for low iron to directly impact work capacity. Therefore, maintaining adequate iron status (and knowing the signs of iron deficiency) is crucial for athlete health and performance. In this episode, Professor Pete Peeling of the University of Western Australia discusses the role of iron in performance, iron deficiency in athletes, the impact of exercise-induced inflammation, and other important issues. Links:
Episode page Live event: London, UK - March 2023Tue, 10 Jan 2023 - 50min - 482 - #466: Iron Absorption from Foods & Supplements – Prof. Paul Sharp
Iron deficiency is a prevalent issue. Worldwide, it is the leading nutritional deficiency. And although there is lower prevalence in high-income countries, a significant number of people are still affected.
Iron deficiency may be a result of too little iron coming in (i.e., via diet choices or low absorption), or from excess losses (e.g., commonly from blood losses). Understanding how these can impact iron status is crucial for both accurate diagnosis and treatment.
In relation to dietary iron, the source of iron is a common talking point, as there are two forms of iron that we can consume. Heme iron is found in meat, fish, and poultry, while non-heme iron is found in plant foods. It is known that heme iron is more readily absorbed than non-heme iron. However, there is much more to this story that makes things complicated.
To discuss some of the nuances of iron bioavailability, absorption, and metabolism, leading expert in the area Professor Paul Sharp of King’s College London is on the podcast. Prof. Sharp discusses crucial aspects of dietary iron sources, bioavailability, supplementation, and impacts in the body.
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Episode page (with links/resources) Subscribe to Premium Live event: London, UK - March 2023Tue, 03 Jan 2023 - 1h 00min - 481 - #465: Diagnosing & Treating Iron Deficiency & Excess – Austin Baraki, MD
Iron is involved in a whole range of biological processes and a consistent supply of iron is crucial for cellular turnover. But despite iron being an essential mineral for human function, it is highly toxic to cells and tissues if present at high levels. Therefore an intricate and tight regulation of iron is necessary.
If iron status gets too low, iron-deficiency anaemia can result. In such situations there is a shortfall in hemoglobin production, which leads to a range of issues in the body.
So how is iron status measured? Which biomarkers are most useful? Where can errors in diagnosis occur? What problems arise with iron deficiency? And what problems occur with iron overload?
In this episode, these questions (and more) are put to Dr. Austin Baraki, a practicing Internal Medicine physician and Assistant Professor of Medicine at William Beaumont Army Medical Center in Texas.
This episode is the first in a three-part series on iron.
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Episode page & relevant links Subscribe to Premium Live event in LondonTue, 27 Dec 2022 - 1h 19min - 480 - #464: Do Sugar Taxes Work?: Evidence on Potential Policies - Kathryn Backholer, PhD
The current food environment is continuously highlighted as a problem for public health. And so there is a strong focus in both public policy and research circles to determine which strategies could lead to a healthier food environment. One potential strategy that is widely recommended by public health experts is the use of fiscal/taxation policies to decrease the consumption of unhealthy foods and beverages. By making unhealthy foods and beverages relatively more expensive than healthy foods and beverages it is hoped that this would alter the composition of the average diet in a favorable manner. This is based on economic theory and evidence showing that most foods are relatively price “inelastic”. This means that increases in the prices of particular foods can be expected to lead to reductions in the purchase of those foods. But there have also been some concerns raised about the potential effectiveness of strategies aimed at taxing a certain nutrient (e.g. sugar) or a group of foods. There are worries that such policies wouldn’t lead to healthier diets; with people either not changing behavior or just substituting in other processed foods that industry has formulated to avoid a specific nutrient tax. So what does the current evidence say? With a number of countries having implemented a range of taxes or health levies, what lessons can we learn from these? And what does the best public health nutrition currently tell us about the likely effectiveness of different policies or interventions? To get to some evidence-based answers, Dr. Kathryn Backholer, an Associate Professor at Deakin University, is on the podcast to discuss the current state of the evidence on various taxes and levies on different nutrients and unhealthy foods. Links:
Episode page Subscribe to Premium Live event in LondonTue, 20 Dec 2022 - 44min - 479 - SNP12: The Big Breakfast Study
In October 2022, Ruddick-Collins et al. published results of an RCT looking at the impact of different calorie distributions across the day. This study was from the ‘Big Breakfast Study’ project, primarily from the University of Aberdeen.
In this study, 30 subjects underwent two 4-week calorie-restricted diets that were matched for calories. One diet was “morning-loaded”, meaning that daily calories were distributed as 45% at breakfast, 35% at lunch, and 20% at dinner. The other was “evening-loaded”, with an opposing calorie distribution; i.e., 20% at breakfast, 35% at lunch, and 45% at dinner.
The trial received a lot of commentaries online after it was published. However, much of it lacked sufficient context, nuance, and understanding of the implications.
In this episode, Dr. Alan Flanagan, who was one of the researchers involved in some of the work of the Big Breakfast Study, gives an insight into the recently published paper by Ruddick-Collins et al., and highlights some important aspects to be aware of.
This is an episode exclusive to Sigma Nutrition Premium subscribers.
To listen to the full episode and access the transcript, you must subscribe to Sigma Nutrition Premium.
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Subscribe to Premium Links to mentioned studiesTue, 13 Dec 2022 - 30min - 478 - #463: Do Vegan Diets Cause Depression?
In this episode, the Sigma team explores the question: “Do vegan diets increase the risk of depression?”
This is a question that emerges from a few different places. First, it’s common to hear such a claim from proponents of largely animal-based diets. Some reference is often made about how vegan diets can, at best, worsen symptoms or, at worst, even cause depression. Or conversely, they may state that moving away from a plant-based diet will improve mental health outcomes, including depression.
And while all of those specific claims aren’t within the scope of this episode, such claims do get people wondering if a plant-exclusive diet is actually a cause of various mental health ailments.
But is there a basis for such claims?
In this episode, we explore the evidence from two ends: 1) research related to the proposed mechanisms by which a vegan diet could cause problems, and 2) outcome data looking at the impact of such diets.
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Subscribe to Premium Episode notes page Live event: London, UK (early bird ends Dec 19)Tue, 06 Dec 2022 - 1h 41min - 477 - #462: Gyorgy Scrinis, PhD – Ultra-Processed Foods, Nutritionism and Current Food Systems
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Show notes page (incl. study links & related episodes) Subscribe to Sigma Nutrition Premium Live event in London, UKAbout this episode:
Over the past decade, the increasing uptake and acceptance of the Nova food processing classification system has placed focus on one of the categories in Nova; ultra-processed foods (UPFs). Ultra-processed foods (UPFs) are products created from deconstructed (and recombined) food components, usually with the goal of creating a highly palatable, convenient, and profitable product. This typically means such products are high in nutrients of content (e.g. sugar, sodium, saturated fat, etc.). But in addition, they have other characteristics that may make them detrimental to health, particularly when they replace unprocessed or minimally processed foods in the diet.
There is now clear evidence showing that when such products make up a large proportion of the diet, such a dietary pattern has negative health effects. However, there are still many unanswered questions and many debates within nutrition science about how to best classify UPFs, to what degree they need to be limited, whether some can be beneficial, and what to do with policy going forward.
To offer one perspective on this issue, Associate Professor of Food Politics and Policy at the University of Melbourne, Dr. Gyorgy Scrinis, is on the podcast to discuss his work in the area.
While we have discussed the problem of reductionism in nutrition science previously on the podcast, Dr. Scrinis’ use of the term ‘reductionism’ does differ a bit from the way others use the term. For example, he suggests that nutrition science has been too reductive even at the food-level and dietary-pattern level.
His work on ultra-processed foods and the Nova classification system has attempted to understand the technological and corporate character of ultra-processed foods, the power of food corporations, and how food corporations shape and capture nutrition science for the purposes of promoting and defending their products.
Tue, 29 Nov 2022 - 1h 10min - 476 - #461: Prof. Emma Boyland – How Food Marketing Impacts Eating Behaviour
Research has shown that food marketing strongly impacts children’s eating behaviour. Marketing influences food purchase requests, purchases, and preferences.
And the evidence of a relationship between food marketing exposure and obesity meets epidemiological criteria for causality. The evidence suggests that the impact of food marketing is a function of both exposure to the marketing message and its persuasive power.
What does the current evidence tell us about the exact effect of marketing on food choices? And beyond that, what strategies are likely to yield the best results in terms of mitigating the harms of food marketing on eating behaviour, particularly in children and adolescents?
To help answer these questions, subject area expert Prof. Emma Boyland is on the podcast to discuss what is currently known.
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Episode page, resources & links Subscribe to PremiumTue, 22 Nov 2022 - 1h 00min - 475 - SNP11: The Death of Domain Expertise
Never before has there been greater access to information about nutrition and health. But never before has there been such a low barrier to being seen as an “expert”. There are large numbers of people getting information from, and basing their health decisions on, people who don’t have direct expertise in the field in which they are talking about.
Moreover, some promote the lack of domain expertise as a feature, not a bug. They claim that those that were conventionally seen as domain experts are either brainwashed, lazy in their thinking, or outright corrupt. And the solution is instead to look to those with a fresh perspective that can illuminate us on the “truth”.
In this episode, Alan and Danny discuss this “death of domain expertise”, how it plays out online, and its ramifications for people’s ability to get good information.
This is a Premium-exclusive episode. To listen to the full episode and access the transcript, you must subscribe to Sigma Nutrition Premium.
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Episode page Subscribe to PremiumTue, 15 Nov 2022 - 33min - 474 - #460: Dr. Priya Sumithran – Body Fat Regulation, Pros & Cons of Weight Loss Interventions, and GLP-1 Receptor Agonists
Obesity increases the risk of a range of chronic diseases and negative health outcomes. And trials where a sufficient amount of weight loss is achieved show health improvements. However, despite the “straightforward” nature of causing weight loss through a hypocaloric diet, it is clear that most people who lose weight will regain some or all of the weight.
This is a result of both the physiologic control of intake and expenditure (i.e. homeostatic regulation by the body to avoid staying at a lower body or fat mass), and environmental factors. Diet-induced weight loss is followed by a number of hormonal change that encourage weight regain. So how do we tackle this problem?
In this episode, Dr. Priya Sumithran discusses this physiologic control of body mass, in addition to environmental and behavioural factors that make weight loss maintenance difficult. Dr. Sumithran also discusses what this means for setting weight loss targets, choosing the correct intervention, and looking to non-weight-centric approaches for certain individuals. We also discuss the evidence on GLP-1 receptor agonist drugs, such as Semaglutide, as a treatment for obesity.
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Episode page Subscribe to Premium Sigma live event - Berlin Sigma recommended resourcesTue, 08 Nov 2022 - 56min - 473 - #459: Nicky Keay, MB BChir – Hormones & Healthspan: The Endocrine System Across the Life Course
The endocrine system plays a central role in growth, development, metabolism, reproduction, and physical well-being throughout life. Hormones interact in complex networks, orchestrating a range of critical functions. Over the life course, we experience various changes in hormone levels, fluctuations, patterns, and actions. Additionally, lifestyle factors and disease processes can impact the levels and functions of hormones.
In this episode, Dr. Nicky Keay, a medical doctor with expertise in the field of exercise endocrinology, is on the podcast to discuss a variety of endocrine-related issues, including: hormone diurnal variation, bone health, amenorrhoea, HRT, perimenopause, and thinking about hormones and aging.
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Episode page Subscribe to Premium Sigma live event in Berlin Sigma recommended resourcesTue, 01 Nov 2022 - 51min - 472 - What Are Stable Isotopes? How Are Tracers Used in Nutrition Research? (Preview)
Stable isotopes have been used as tracers in human nutritional studies for many years. But what are they? Why do we use ‘tracers’ in nutrition studies? And what are some practical examples?
A chemical element can have different forms or ‘isotopes.’ These different isotopes have the same atomic number and position in the periodic table but have different atomic masses and physical properties. An isotope that is not radioactive is said to be ‘stable’.
In physiology and metabolism research, stable isotopes are used as ‘tracers.’ As the name implies, it allows us to ‘trace’ the fate of compounds, thus giving a very detailed insight into the metabolism of nutrients and the regulation of many disease processes.
In this episode, Dr. Alan Flanagan explains what stable isotope tracers are, how they are used to answer nutrition science questions and some examples that you may come across.
This is a ‘Nutrition Science Explained’ episode. These episodes are exclusive to Sigma Nutrition Premium. To listen to the full episode and access the transcript, you must subscribe to Sigma Nutrition Premium.
Tue, 25 Oct 2022 - 12min - 471 - #458: How Foods Impact Satiety, Hunger & Appetite
Given the negative consequences of consistent overconsumption of food (leading to a caloric surplus), having a dietary intake that is of appropriate calorie intake is an important aspect of long-term health. Therefore, thinking about which foods and diets can help promote appropriate satiety to keep calorie intake in check is a key focus for many researchers and practitioners.
There is a complex system of human appetite control. This appetite system influences food consumption and associated motivational drives such as hunger, as well as interacting with and being influenced by energy expenditure. Satiety is an important psycho-biological process involved in the expression of human appetite, inhibiting hunger and intake following food or beverage consumption.
In this episode, the Sigma team discusses the human appetite system, how different nutrients and foods impact satiety, and the implications of this research.
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Subscribe to Premium Show notes for this episode Live event in Berlin, Germany Sigma Recommended ResourcesTue, 18 Oct 2022 - 1h 35min - 470 - #457: Austin Robinson, PhD – Salt Sensitive vs Salt Resistant, Impacts of Sodium on Health, & Racial Differences in Risk
Hypertension (elevated blood pressure) is a condition that significantly increases the risk of several diseases and is a major cause of premature death worldwide. In the US, recent estimates suggest that about half of the adult population has hypertension. At a population level, high sodium intake is one of the main dietary risk factors. All population health guidelines recommend keeping sodium intake below certain levels. While, on average, blood pressure correlates with sodium intake, there is a wide range of responses on an individual level. People who see increasing sodium intake lead to increased blood pressure are termed “salt sensitive”. Others, however, don’t see much change in blood pressure with increased dietary sodium. Such individuals are classed as “salt resistant”. In this episode, Assistant Professor at Auburn University, Dr. Austin Robinson, is on to discuss whether people who are salt resistant need to keep their sodium intake low or not. And other individual and group differences that exist for hypertension risk and sodium physiology? Links:
Subscribe to Premium Episode overview Live event in Berlin Recommended ResourcesTue, 11 Oct 2022 - 1h 09min - 469 - #456: Prof. Glenn McConell – Glucose Uptake During Exercise & Muscle Insulin Sensitivity
Exercise improves metabolic control both via increasing muscle glucose uptake during muscle contractions by insulin-independent mechanisms and by increasing skeletal muscle insulin sensitivity after physical activity. A reduction in skeletal muscle insulin sensitivity is an early event in the development of not only prediabetes, metabolic syndrome, and type 2 diabetes but is also associated with other conditions such as cardiovascular disease and some cancers.
One of the researchers that has been at the forefront of research in this area for many years is Professor Glenn McConell. In this episode we discuss glucose uptake during and after exercise, looking at both insulin-dependent and insulin-independent mechanisms. In addition we discuss the crucial importance of muscle insulin sensitivity and some important research breakthroughs on the topic.
Links:
Subscribe to Premium Episode show notes Live event: BerlinTue, 04 Oct 2022 - 1h 03min - 468 - #455: Jill Joyce, PhD – Improving the Diets of Tactical Populations
The term ‘tactical populations’ has been applied to those working in law enforcement, fire, first responders, and military. In addition to the importance of their work, the work they do itself presents some challenges for health and nutrition.
Despite the fact that such individuals make up a significant number of the population and their work plays a crucial role in society, there is currently very little research on fire and law enforcement nutrition. Most research is on the prevalence of disease and the occupational risk factors and related pathophysiology. Lifestyle research, descriptive and interventions, is way behind.
Dr. Jill Joyce is the co-director of the OSU Tactical Fitness and Nutrition Lab at Oklahoma State University. She does research looking at real-world interventions in these populations, particularly firefighters, in an attempt to improve their diets and health.
In this episode, we look at both the theoretical and pragmatic realities of improving diet and health in firefighters and some other tactical populations.
Links:
Subscribe to Premium Access show notes Live event in BerlinTue, 27 Sep 2022 - 47min - 467 - SNP9: AMA – Blood Pressure, LDL Lowering, PCOS & More!
In this Premium-exclusive ‘Ask Me Anything’ episode, Alan & Danny answer a range of listener questions. Topics include obesity rates, lowering blood pressure, cholesterol drugs, PCOS, and what issues they have changed their minds on. See the full list of questions below. [02.37] Do you feel that there is hope (or an effective way forward) for obesity rates to come down? Based on your response, why/why not? [11.28] In this field, it seems like so many of us have had positions we’ve held very seriously that we now see as poorly supported by research, or just have a significant paradigm change. It would be great to hear you look back to how your views have evolved over the years. [30.34] Apart from lowering salt intake and eating foods high in potassium are there other things you can take or do to reduce blood pressure? [40.34] What is the best ratio of DHA vs EPA to increase my Omega 3 index? [46.20] Statins v Ezetimibe: Differences between the two? Mechanism of action? Are there situations, conditions, genetic markers where one may work better than the other? [56.20] I’m starting a PhD in the fall concerning the pathophysiology of metabolic diseases and I’d like to take some courses that would help me in my research. Would you have any recommendations for a beginner scientist? [59.01] Is astaxanthin a good substitute for algae oil for someone who follows a vegan diet? [60.45] Do you have any suggestions how to better manage hunger in obese women with PCOS? [64.33] Do you have any recommendations for anyone wanting to get involved in chrononutrition research? Links:
Subscribe to Premium Live Event: Berlin, Germany on November 26th 2022 Episode transcript Resources mentioned in this episodeTue, 20 Sep 2022 - 15min - 466 - #454: Eric Helms, PhD – Plant or Animal Protein: Rethinking Protein & Muscle
When it comes to eating to promote muscle hypertrophy, muscle repair/recovery and maintenance of mass and function, protein has been an obvious focus. Indeed muscle mass and quality are dependent on the continuous remodeling of skeletal muscle proteins. This is related to the amount of muscle protein balance, i.e. the net difference between muscle protein synthesis (MPS) and muscle protein breakdown (MPB). Because of this, MPS has long been used as a proxy measure for muscle repair and/or growth of muscle.
Protein feeding increases MPS, with the amino acid leucine having a specifically strong impact on MPS. Therefore both the dose of protein and the amino acid profile of the protein have been looked at to assess which protein sources are “superior” for muscle mass and function. This has typically led to viewing animal proteins as better than plant proteins.
But many assumptions are layered into conversations on the topic. In this episode we explore some important points that are often neglected. Is MPS as reliable as we assume? Does the amino acid profile tell us everything about the anabolic effect of a protein? Does dose and timing matter as much as we think? How does the picture change when we look at whole foods or mixed meals?
Link:
Subscribe to Premium Go to show notes Live Event: Berlin, Germany MASS Research Review Muscle & Strength Pyramids: Training & Nutrition BooksTue, 13 Sep 2022 - 1h 25min - 465 - #453: Nick Gant, PhD – Cognitive Performance: Impact of Caffeine, Nicotine & Creatine (Rebroadcast)
The brain plays a central role in both physical and psychological function and performance. The brain also has a very high energy demand. In addition, fatiguing conditions can cause impairment of cognitive performance.
One area of research in neurometabolism related to the potential use of nutrients on improving cognitive function, as well as “rescuing” the fatigue-related declines in performance.
Nick Gant is Director of the Exercise Neurometabolism Laboratory at the University of Auckland. His group uses interdisciplinary approaches from the nutritional sciences and neurosciences to investigate the role of nutrition in brain health and performance. Nick is particularly interested in foods and supplements that prevent brain fatigue and improve physical and cognitive function.
Tue, 06 Sep 2022 - 1h 12min - 464 - #452: Stuart Phillips, PhD - Bacterially Synthesized Whey, Plant vs. Animal Proteins, Muscle & Extended Fasts, & Much More
This episode was oringally published as one of our “Expert – ask me anything” (AMA) episodes, which we published for Premium prescribers. In such bonus episodes, we collect questions from Premium subscribers and ask them direct to a world-class expert and past podcast guest.
If you’re interested in subscribing to Sigma Nutrition Premium, then check all the details here.
In this episode Prof. Stu Phillips takes questions about synethized whey protein, plant proteins, post-exercise MPS, and many other topics related to protein, muscle function and ageing.
Tue, 30 Aug 2022 - 55min - 463 - #451: Potassium & Blood Pressure: Influence of Sex & Sodium
It has been consistently shown in research that elevated dietary sodium consumption is associated with high blood pressure and an increased risk of cardiovascular disease. In addition, low levels of dietary potassium intake are associated with these same risks. However, there is some debate on how to characterize these relationships.
In a study published in European Heart Journal in July 2022, using data from the EPIC-Norfolk study, researchers attempted to answer whether the associations between potassium and both blood pressure and cardiovascular disease: 1) differ between men and women? and 2) depend on daily sodium intake.
In this episode Dr. Alan Flanagan and Danny Lennon discuss the details of this study and then link it to the overall evidence base and what this may mean for potassium (and sodium) intake considerations.
Access show notes Subscribe to PremiumTue, 23 Aug 2022 - 55min - 462 - #450: Megan Rossi, PhD, RD – Diet For a Healthy Gut: Diversity, Fiber Types & Gut Health Pseudoscience
With the advances in understanding the importance of the gut (including its bacterial contents) for human health, much interest and attention has been placed on how to eat to promote positive ‘gut health’. This has led to many exciting research questions and labs doing fascinating work. However, on the opposite side, it has led to a spike in opportunistic quacks to jump on the wave of enthusiasm and promote diets, supplements, testing kits and products that don’t reflect the current evidence base. So what do we actually know? What aspects of diet should we focus on to improve gut health? For those with gut symptoms (bloating, pain, irritable bowel, etc.) is it possible to include more vegetables and fiber without the pain? In this episode, gut health researcher at King’s College London, Dr. Megan Rossi, discusses some simple heuristics to follow that will likely improve overall health, and promote positive gut health. Access show notes here Subscribe to Premium
Tue, 16 Aug 2022 - 53min - 461 - #449: Do Artificial Sweeteners Increase Cancer Risk? (Study Analysis)
A study published in March 2022 suggested that consumption of artificial (non-nutritive) sweeteners is associated with a 13% increase in risk of cancer.
And so in this episode, Dr. Alan Flanagan, Dr. Niamh Aspell, and Danny Lennon discuss this specific study and give their thoughts on what are fair conclusions to come to.
Tue, 09 Aug 2022 - 1h 05min - 460 - #448: Prof. Norman Temple – Can Science Answer Diet-Health Questions?
While we’ve never known more about diet and health, there remain many unanswered questions in nutrition science. However, there is often disagreements on how best to answer these questions, particularly in relation to informing practical diet advise that meaningfully improves health.
Prof. Norman Temple is one academic who has written on a number of these issues. One issue he highlights is the large discrepency in the practical value we have attained from cohort studies and RCTs, relative to mechanistic research. Another is the limitations of RCTs for nutrition-specific research questions.
In this episode, Prof. Temple discusses these issues, as well as what strategies can actually improve population diet, and thus health.
Tue, 02 Aug 2022 - 50min - 459 - #447: Does Eating Fish Increase Skin Cancer Risk? Study Analysis
A recent study reported a higher risk of developing melanoma in people who ate a relatively high intake of fish. This study caused headlines and it was picked up by many outlets (including the New York Times, Sky News, etc.).
In this episode, Alan and Danny dig into the nuances of this study to see if the headlines are justified.
Tue, 26 Jul 2022 - 58min - 457 - SNP7: Stephan Guyenet, PhD - Ask Me Anything!
This is an “ask me anything” (AMA) episode, which means a world-class expert and past podcast guest comes on the podcast to answer questions submitted by you, our podcast listeners.
Stephan Guyenet spent 12 years in academia studying neurodegenerative disease and obesity neuroscience. He was a postdoctoral fellow at the Univeristy of Washington, studying the neuroscience of obesity and eating behavior. Previous to that he completed a PhD in neuroscience.
Stephan is the author of the popular and well-received book ‘The Hungry Brain‘, which lays out the science behind the brain’s role in obesity.
To subscribe to Premium (and get the full episode) go here.
Questions Answered In Full Episode- “When someone undergoes liposuction or other surgery that removes adipose tissue, is there a sudden reduction in leptin levels? While this may reduce leptin resistance, could the drop in leptin lead to increased hunger over time?” “What is the current research around how chronic energy restriction (or following crash diets) affects appetite hormones and/ or appetite regulation long term? Is there a physiological mechanism influencing overeating attributable to appetite dysregulation caused by chronic dieting? I ask as this is something I am often tackling in my nutrition consultancy but research in biochemical and physiological mechanisms seems lacking.” “Can you talk about the conditions of anorexia and morbid obesity and how they essentially defy the rules of metabolic compensation? In other words- I understand anorexia to be a mental health condition where the individual starves themselves with a purpose to control weight. And morbid obesity being excessive consumption despite over fatness, etc. If the body has these numerous mechanisms by which calorie restriction or calorie over- consumption results in these compensatory processes-driving us to eat more/less slow us down/speed us up, and many more; do these individuals not “hear” these signals or are they just adept at ignoring them or is it that their bodies have lost the ability to compensate for their under or over consumption? Additionally, can anyone become anorexic or morbidly obese? Or is it merely genetics?” “Why do some SDRIs (serotonin–dopamine reuptake inhibitors) and serotonin precursors reduce hunger/appetite? E.g. 5-HTP and Wellbutrin (Bupropion)” “Question about the ideal weight program: As an iOS developer, my instinct is to assume determinism and quantifiability of the entire universe. I believe this to be fundamentally true. But what is hypothetically possible differs from what we can realistically know. I worry that attempts like yours to quantify some seemingly qualitative measures are doomed. I have similar concerns about happiness research. How do you reassure yourself you can really construct an algorithm that deciphers the “ideal weight program” for any given user – do you rely on averages?” a. Quick explanation of the ideal weight program “In 2018 a poster was presented at the annual meeting of the Society for Neuroscience titled ‘The human brain microbiome; there are bacteria in our brains!’ which showed bacteria apparently penetrating and inhabiting the cells of healthy human brains. While the work was preliminary, have you heard of any further work in this area? What is your opinion on the possibility that, if bacteria do inhabit the brain, they could play a part in appetite regulation and/or obesity similar to how the gut microbiome can affect our health?” “It seems like there are significant differences in policies put forth between researchers from biomedical backgrounds and ones from public health policy backgrounds. Dr [David] Allison touched on this during recent interviews, noting that there is very little evidence regarding the efficacy of upstream obesity prevention interventions, such community gardens, combatting food deserts, nutrition education, and cooking classes. On the other hand, governments are increasingly turning to such interventions, as well as policies such as front of pack labelling (Canada, 2022), nutrition facts tables, calorie labelling on menus, as well as the aforementioned ones. Given your research on determinants of health and obesity, what are some of the most promising interventions to prevent NCD morbidity, as well as stones unturned in public health policy? Would you agree with individuals such as Dr Allison that in our current environment, the only efficacious interventions are drugs and bariatric surgery?” Question based on your debate on JRE with Gary Taubes: “Would the insulinogenic effect of protein, specifically something like whey protein which causes an insulin response, be something that should automatically refute Taubes arguments about insulins inherent role in increasing adiposity? Second, would overeating on any macronutrient increase insulin simply because you are eating more food (i.e. hypercaloric)?” “Are there best practices for the maximum duration someone should spend in fat loss (or weight gain) phases? Or perhaps an optimal ratio of fat loss phase duration to “maintenance” phase duration? For example, should fat loss phases be for a maximum of 12 weeks followed by maintenance of at least equal duration before resuming a fat loss phase? “I’m a naturally skinny guy who helps other naturally skinny guys bulk up. I think it largely comes down to a blunted pleasure response to food, smaller stomachs, and/or higher NEAT. A lot of us seem to be taller and more thinly built, too. But why do you think things are things so different for us? Why is it so hard to gain weight? And what can we do about it?”
To subscribe to Premium (and get the full episode) go here.
Tue, 19 Jul 2022 - 16min - 456 - #446: How Climate Change Impacts Nutrient Status
Climate change refers to long-term shifts in temperatures and weather patterns. These shifts may be natural, such as through variations in the solar cycle. But since the 1800’s, human activities have been the main driver of climate change, primarily due to burning fossil fuels like coal, oil and gas.
Climate change has the potential to negatively impact the nutrient value of plants, soil organisms, food stuffs, via a variety of ways. Climate change puts food supplies at risk. Floods, droughts, more intense hurricanes, heatwaves and wildfires can drive down crop yields, destroy livestock, and interfere with the transport of food. And rising carbon dioxide levels from human activity can make staple crops like rice and wheat less nutritious.
In this podcast the Sigma team take a look at the evidence on how climate change will impact nutrient status, if left unchecked. There will be also a look at what solutions have been put forward to tackle this issue. This episode will focus more on how climate change impacts nutritional & nutrient status, as opposed to converse (but equally important) issue of how food systems impact climate change.
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Wed, 13 Jul 2022 - 1h 14min - 455 - #445: Dr. Hazel Wallace - Nutrition for Women’s Health
When it comes to specific questions related to diet and health for women, there is often a shortage of consensus answers from research, for a variety of reasons. In addition, there are clearly aspects of biological sex that have implications for health and also the interaction with diet. For example, the impact of the menstural cycle, of menopause, and differences in nutrient requirements.
In this episode, Dr. Hazel Wallace discusses some of these key considerations. Some things covered include: the impact of menstrual cycle phase on cravings, at-risk nutrients in pre-menopausal women, functional hypothalamic amenorrhea, interaction of diet and PMS, the physiological changes at menopause and potential role of diet.
Click here for show notes to this episode Click here for Premium Click here for live event detailsThu, 07 Jul 2022 - 54min - 454 - SNP6: GRADE System: What is it? And How Does it Apply to Nutrition? [Preview]
This is a preview of the second episode in a new series called “Nutrition Science Explained”, in which members of the Sigma team will take a concept commonly mentioned in discussions about nutrition science, and explain what it is, give more background context, and highlight important aspects to know. The goal is to aid listeners to have a deeper understanding of other episodes when such concepts are mentioned.
In this episode Alan Flanagan discusses the concept of the GRADE system, and specifially how it applies to evaluating nutrition research and coming to conclusions for practice.
GRADE (Grading of Recommendations, Assessment, Development and Evaluations) is a framework for developing and presenting summaries of evidence and provides a systematic approach for grading the quality of evidence and making clinical practice recommendations.
In order to listen to the full episode, you will need to subscribe to Sigma Nutrition Premium.
Mon, 04 Jul 2022 - 07min - 453 - #444: Folate – Intake, Genetics & Health Outcomes
Folate (also known as viatmin B9) actually relates to a collection of folates; both natural dietary folates and synthetic forms, primarily folic acid. This folate/folic acid that is consumed via the diet or supplementation is a precursor for the formation of tetrahydrofolate (THF), which is a carbon donor and acts a cofactor for a number of enzymes that play important roles in several processes. In this episode, Alan and Danny discuss the role of folate in the methlyation cycle, the impact of folate insufficiency/deficiency, genetics variatnts of the MTHFR gene (and other genes) that impact folate metabolism, and the impact of folate on health outcomes; including heart disease, birth defects, cancer, and brain health & cognition. Detailed study notes and transcript to this episode
Tue, 28 Jun 2022 - 1h 12min - 452 - #443: Kevin Klatt, PhD, RD - Can Choline Help Improve DHA Status?
A recently published study by Klatt and colleagues examined the impact of choline supplementation alongside DHA supplementation, versus DHA supplementation alone, on DHA status in pregnancy. It is known that DHA is a critical nutrient at this time for healthy development of the child. And through a number of mechanisms discussed later, it has been hypothesized that choline could lead to greater DHA status. We discuss:
What is the connection between choline and DHA? What is the PEMT pathway? Study design for the choline + DHA trial Are there risks of high-dose choline? Main findings of the trial How DHA status is not just a function of DHA intake, but also methyl metabolism too Issues with omega-3 trials; e.g. not taking baseline status into account Pragmatic recommendations for health professionals and patients Different forms of choline supplements Choline supplementation vs. food-derived choline Access the show notes here Subscribe to Premium hereWed, 22 Jun 2022 - 1h 11min - 451 - #442: Are Vegetables Detrimental to Health?
In this episode Alan and Danny aim to address the idea that you shouldn’t eat vegetables, or that they aren’t beneficial. We will specifically look at a number of claims that relate to:
- The claim that vegetables aren’t beneficial for health, or that there is no health benefit to high vegetable intake. The claim that vegetables are actually detrimental to health, and their removal improves health.
This episode was orignally published to Sigma Nutrition Premium. If you wish to get more of these Quack Asylum episodes (and lots of other features, including detailed study notes) then subscribe to Sigma Nutrition Premium.
Click here to access show notes
Wed, 15 Jun 2022 - 1h 35min - 450 - SNP5: Prof. Stuart Phillips - Ask Me Anything! [Preview]
This is an "ask me anything" (AMA) episode, with Prof. Stuart Phillips of McMaster University. Prof. Phillips takes questions on protein intake, sources, muscle function, and healthy ageing.
To listen to the full AMA, click here to subscribe to Sigma Nutrition Premium.
Questions answered:
Mon, 13 Jun 2022 - 17min - 449 - #441: Julie Abayomi, PhD, RD - Diet During Pregnancy
Consuming a healthy diet during pregnancy is an obvious and accepted recommedation. However, what exactly is a "healthy diet" in this context? In addition, there are specific nutrients which are crucial for the healthy development of the child, including nutrients which may be difficult to consume enough of. In addition there are nutrients and foods that need to limited or avoided during this period. In this episode, researcher and dietitian Dr. Julie Abayomi discusses important nutrients in pregnancy (e.g. iodine, DHA, and folic acid), as well as potentially problematic nutrients/foods (e.g. high-mercury fish and caffeine). In addition, she discusses the current debates about weight gain/loss during pregnancy, as well as what supports are needed for health professionals supporting pregnant women. Click here for show notes
Tue, 07 Jun 2022 - 55min - 448 - #440: Are Dietary Guidelines Trying To Kill Us?
It has become common rhetoric for those promoting various types of diets to suggest that dietary guidelines published by government departments are at best, unhealthy, or at worst, causative in driving obesity and chronic disease in the population.
While different countries and organizations produce their own guidelines, with slight differences, most of the conversation has focused on the Dietary Guidelines for Americans, that are created by the USDA.
Often the claims is that following these guidelines actually harms health, rather than promote it. And the guidelines are simply a result of industry forces, long-standing bias, and shoddy science.
But do these claims hold up to scrutiny? In this episode Alan and Danny look at some of the arguments put foward, and take a look at the science underpinning dietary guidelines in a number of countries.
In this episode:
[0.01.46] Examples of arguments put forward stating that it’s not healthy to follow dietary guidelines [0.12.50] History of the development of guidelines in the US & narratives around Ancel Keys [0.23.50] Misrepresentation of what the guidelines say [0.30.49] What are actually in the current Dietary Guidelines for Americans? [0.33.10] Changes to guidelines over time [0.36.05] Other countries’ guidelines: UK, Canada, Nordic countries [0.40.50] Investigating the rise in obesity/disease prevalence with the roll out of the guidelines [0.56.34] Do people follow the guidelines? [1.00.01] The negative role of the food industry [1.03.50] Potential issues with dietary guidelinesLinks:
Subscribe to Premium Show notes to this episodeTue, 31 May 2022 - 1h 13min - 447 - SNP4: Detoxification Protocols [Preview]
There have been many claims made about the benefits of a detoxification "protocol" or "plan", based on specific dietary and supplemental regimens. Many of the arguments propose that many things we come into contact with are toxins and they can accumulate and compound in effect over time, causing a range of issues. Therefore, by removing these toxins (via a “detoxification protocol”), we can have better health.
And indeed it is well known that there are a large number of toxins in the environment, many of which can potentially be deleterious to health. And it also known that many nutrients are involed in processes of the body's detoxification pathways.
However, is there any evidence that a detoxification diet, plan or "protocol" improves health? Is there any reason to suggest targeting certain nutrients or supplements leads to "better detoxification"? And do we need to avoid non-organic food, toothpaste and non-stick frying plans in avoid to avoid these toxins? This Quack Asylum episode evaluates these claims.
Study notes available at sigmanutrition.com/detox/
Subscribe to Premium at sigmanutrition.com/premium/
Thu, 26 May 2022 - 16min
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