Links:  Go to episode page Subscribe to Premium Join the Sigma mailing list Sigma's Recommended Resources  About This Episode: 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.

#514: Plant-derived Fatty Acids – Ella Baker, PhD

Links:  Go to episode page Subscribe to Premium Sigma's recommended resources Join our email newsletter for free  About This Episode: 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.

#513: Kidney Stones & Diet – Deepa Kariyawasam, RD

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 Premium

What are Dietary Reference Intakes? Origins, Development & Use (SNP 26)

Links:  Go to episode page (with episode resources) Subscribe to PREMIUM Get the Sigma email newsletter See Sigma's recommended resources  About This Episode: 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.

#512: Alzheimer’s Disease – Drs. Ayesha & Dean Sherzai

Links:  Go to episode page (with episode resources) Subscribe to Premium Receive the Sigma Nutrition newsletter  About This Episode: 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.

#511: Null By Design – When “No Effect” Doesn’t Mean No Effect

Links:  Go to episode page (with supporting links/resources) Subscribe to PREMIUM Learn more about Sigma Nutrition Crushing Comparisons course  About 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.

#510: Social Comparison: Evidence on its Impacts & What We Can Do – Shannon Beer

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.

AMA: Coconut Oil, Raw Oats, Collagen, & More! (SNP 25)

Links:  Go to episode page Subscribe to Premium Sigma's recommended resources Bite Me Nutrition – Australia Instagram:  @jonosteedman @dannylennon_sigma    About 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.

#509: Helping Clients & Patients Overcome Nutrition Confusion – Jono Steedman, APD

Links:  Go to episode page (with study links) Subscribe to Premium Sigma's recommended resources Get our weekly email newsletter  About This Episode: 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.

#508: Why Athletes Can Achieve High Performance During an Energy Deficit – Jose Areta, PhD

Links:   Episode page (with study links) Subscribe to Premium Join Sigma email newsletter  About This Episode: 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.

#507: Does a Higher Portfolio Diet Score Reduce Heart Disease? – Andrea Glenn, PhD

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?

Listener Q&A: Homocysteine, MUFA, Healhty BMI, and more! (Preview)

Links:  Go to episode page (with links to studies) Subscribe to PREMIUM Join Sigma's email newsletter Sigma's Recommended Resources  About This Episode: 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.

#506 Sports Nutrition: Translating Research to Practice – Andreas Kasper, PhD

Links:  Go to episode page (with study links) Subscribe to PREMIUM Receive our email newsletter  About This Episode: 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.

#505: Oslo Diet-Heart Study: Cholesterol-lowering Diets & Cardiovascular Events

Links:  Go to episode page (with study links) Receive Sigma's email newsletter Subscribe to PREMIUM - get study notes to this episode  About This Episode: 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.

#504: Vegetable Oil vs. Saturated Fat – Analysis of the LA Veterans Study

Links:  Go to episode page (with resources) Subscribe to Premium Learn more about Sigma Nutrition  About This Episode: 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.

#503: Lyon Diet Heart Study – Canola Oil, “Mediterranean” Diets & Minimizing Bias

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 Risk  About 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.

#502: Sydney Diet-Heart Study – Is Linoleic Acid Causing Heart Disease?

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 Episode   Nutritional 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. Links:  Subscribe to Premium Go to episode page See recommended resources Receive weekly emails from Sigma

Addressing Some Criticisms of Nutritional Epidemiology (SNP 23)

Links:  Go to episode page (with study links) Subscribe to PREMIUM Receive emails from Sigma Nutrition Sigma's Recommended Resources  About This Episode: 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.

#501: Sex-based Training Recommendations: Evidence-based or Hype? – David Nolan, PhD

Links:  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”

#500 – The Big Unanswered Questions in Nutrition Science

Links:  Subscribe to PREMIUM Go to episode page (with further reading links) Receive our weekly emails  About This Episode: 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.

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