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Can broad-spectrum vitamin and mineral supplements improve anxiety, depression or emotional regulation?  In this Premium-exclusive episode, we examine three randomised, placebo-controlled trials from Professor Julia Rucklidge's research group: NoMAD, investigating anxiety and depressive symptoms in adults; NUTRIMUM, examining depressive symptoms during pregnancy; and BEAM, studying irritability and emotional dysregulation in adolescents. These studies offer an opportunity to explore some central challenges in interpreting nutrition and mental health research. What does "faster improvement" mean when groups reach similar outcomes by the end of a trial? How should improvements in overall functioning be weighed against results from depression-specific measures? And how much confidence should we place in a large treatment effect found within a small subgroup? Links: Go to episode page Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course Studies discussed: NoMAD trial – Blampied et al., 2023 NUTRIMUM trial – Bradley et al., 2024 BEAM trial – Rucklidge et al., 2026 Related episodes: #117: Prof. Julia Rucklidge – Role of Micronutrients in Mental Health & Psychiatric Disorders #473: Diet & Depression (What Do We Actually Know?) – Nicole Lippman-Barile, PhD

Claims about "improving the gut microbiome" are widespread, but what would improvement actually mean?  How do we establish which microbial changes contribute to disease, and which simply reflect it? Research on bacterial metabolism of medications raises questions about how the microbiome might influence treatment efficacy and toxicity. What would it take to translate these findings into reliable tests and effective therapies? In this episode, gastroenterologist and researcher Prof. Harry Sokol examines these questions, discusses the development of Faecalibacterium prausnitzii as an investigational treatment, and considers what current evidence can tell us about dietary advice and commercial microbiome testing. Timestamps [02:50] Harry Sokol's work [04:36] Defining healthy microbiome [06:48] Do we have causal evidence? [11:05] FMT evidence [15:29] Diet-microbiome claims [20:45] Emulsifiers & IBD research [22:54] Microbiome-drug interactions [30:23] Bacteria as a drug? [38:09] Microbiome testing [44:36] Key ideas segment (Premium-only) Introduction Claims about "improving the gut microbiome" are widespread, but what would improvement actually mean?  How do we establish which microbial changes contribute to disease, and which simply reflect it? Research on bacterial metabolism of medications raises questions about how the microbiome might influence treatment efficacy and toxicity. What would it take to translate these findings into reliable tests and effective therapies? In this episode, gastroenterologist and researcher Prof. Harry Sokol examines these questions, discusses the development of Faecalibacterium prausnitzii as an investigational treatment, and considers what current evidence can tell us about dietary advice and commercial microbiome testing. Timestamps [02:50] Harry Sokol's work [04:36] Defining healthy microbiome [06:48] Do we have causal evidence? [11:05] FMT evidence [15:29] Diet-microbiome claims [20:45] Emulsifiers & IBD research [22:54] Microbiome-drug interactions [30:23] Bacteria as a drug? [38:09] Microbiome testing [44:36] Key ideas segment (Premium-only) On this episode: Host: Danny Lennon Guest: Prof. Harry Sokol Episode Resources: Go to episode page Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course Exeliom Biosciences Book: MICROBIOME: Science, Promises and Lies Instagram: @harry_sokol LinkedIn: Prof. Harry Sokol

Can an athlete reduce the environmental impact of their diet while still meeting the demands of training, competition and recovery? Peter Res argues that these aims can be compatible, provided dietary changes are planned around the athlete's needs. The discussion looks at practical changes athletes can make to make their diets more environmentally sustainable. This includes tips on increasing the contribution of plant proteins, maintaining adequate energy intake, and making plant-rich eating practical within sporting environments. Timestamps [04:21] Peter Res' background [05:22] Defining sustainability metrics [08:17] Biggest diet change to make it more environmentally sustainable [09:23] Is local and organic actually better? [13:44] Athlete fears about protein [18:07] Barriers for athletes [19:37] Fueling high calorie needs [21:26] Micronutrients [24:02] Performance effects [26:32] Athletes as role models [30:17] Easy first steps [34:21] Premium-only: key ideas segment Links: Go to episode page Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course LinkedIn: Peter Res Fork Ranger Related episodes: #320: Hannah Ritchie, PhD – Environmental Impacts of our Diet: Climate, Carbon Footprint & Land Use #446: How Climate Change Impacts Nutrient Status #584: EAT-Lancet: Does the Planetary Health Diet Improve Human Health?

Men commonly feel that if their testosteone isn't "optimized" and high, they are missing out on greater health in a variety of ways. But what can a testosterone result actually tell us? How can results be interpreted with appropriate nuance that is needed? How low is low enough to be problematic? In situations where a test flags testosterone as low, there is a belief this means automatically starting testosterone replacement therapy. While TRT can be an excellent intervention in appropriate cases, when is it actually likely to benefit someone, and when is it not? For many people the decision seems straightforward: get a blood test, see whether testosterone is a little low, and start TRT. However, this simplistic thinking is full of potential issues that are important to understand. Dr. Austin Baraki returns to discuss how testosterone testing should inform treatment decisions, what benefits to expect, and the questions surrounding fertility and long-term safety. Timestamps: [03:50] Dr Austin Baraki's work [06:33] When and why test? [10:36] Probability and context impacts interpretation [14:13] What labs measure [21:15] Specific vs nonspecific symptoms [28:35] Primary vs secondary hypogonadism [32:30] Lifestyle vs TRT decisions [35:21] TRT risks [39:32] Testing timing and variability [41:55] Androgen receptor genetics [44:28] Free vs total testosterone [48:57] Low-normal results: what now? [57:45] TRT risks?: heart and prostate [01:03:55] Side effects and monitoring Links: Go to episode page & resources Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course Instagram: @austin_barbellmedicine Barbell Medicine McCormack & Holmes, 2020 – Your results may vary: the imprecision of medical measurements #417: Austin Baraki, MD – What Do Nutrient Blood Tests Actually Tell Us?: Understanding Biomarkers #334: Austin Baraki, MD – Potential Harms of Screening, Overdiagnosis and Overtreatment

Body composition testing is widely used in research, sport and clinical practice. But what are these methods actually measuring, and how much confidence should we place in the numbers they produce? In this episode, we examine the assumptions behind common approaches including DXA, bioelectrical impedance, and skinfold measurements. We discuss the distinction between accuracy and reliability, the value and limitations of repeated measurements, and how coaches, clinicians, researchers and individuals can select an appropriate method and interpret the data without overstating its precision. Joining Danny to discuss these issues is Professor Grant Tinsley, Professor of Human Performance at Texas Tech University and Director of its Energy Balance and Body Composition Laboratory. Timestamps: [03:04] Grant Tinsley's research [05:25] What body composition means [08:50] Skeletal muscle mass vs. fat-free mass vs. lean soft tissue [11:51] How different methods estimate body composition [23:38] Group vs individual accuracy [31:09] Standardizing testing conditions and assessments [36:36] Reliability testing thresholds [40:08] Understanding phase angle in bioelectrical impedence results [45:02] Consumer devices [50:55] Not all benefit from monitoring [54:14] Using data wisely [01:02:55] Key Ideas (premium-only) Links/Resources: Go to episode page (references, bio, study notes) Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course

Why do some foods feel difficult to stop eating, while others can be highly enjoyable without prompting the same tendency to overconsume? Answering this requires a clearer understanding of food reward, including the distinction between liking a food, wanting it, and perceiving it as easy to overeat. In this episode, we examine how nutritional composition, sensory characteristics, learned beliefs and the eating context may shape hedonic overeating. It also considers the limits of using broad food categories to explain complex eating behaviour. Discussing all this is Professor Graham Finlayson, professor of Psychobiology at the University of Leeds, whose research focuses on human appetite, food reward and the psychological processes involved in eating behaviour and weight control. Timestamps [04:02] Prof. Finlayson's research [06:06] Food reward [07:13] Liking versus wanting [12:43] Measuring wanting in research [15:27] Does wanting predict overeating? [16:36] Study on hedonic overeating [23:19] Perception and context effects [26:24] Does ultra processing classification add anything? [36:09] Key takeaways and future work [40:35] Premium key ideas Links/Resources: Go to episode page Subscribe to Sigma Nutrition Premium Join the Sigma newsletter for free Enroll in the next cohort of our Applied Nutrition Literacy course Study: Finlayson et al., 2025 – Food-level predictors of self-reported liking and hedonic overeating: Putting ultra-processed foods in context

Commonly people are talking about "peptides" to refer to a heterogeneous group of peptide medications or investigational compounds. These are increasingly promoted for injury recovery, tissue repair, performance and longevity, with BPC-157 attracting particular attention. But what evidence supports the claims made about these compounds? How should animal studies, biological mechanisms and personal anecdotes be interpreted? What is currently known about their safety? And what do recent regulatory discussions actually mean for their medical status and availability? In this episode, physician and Barbell Medicine founder Dr. Jordan Feigenbaum examines the evidence surrounding BPC-157 and other peptide medications, alongside the wider questions of risk, access and informed decision-making. Timestamps [00:13] What we want to address [04:47] Interview start [05:29] What do we mean by "peptides"? [10:32] BPC-157 evidence [16:49] Sourcing of peptides [20:19] The gray zone of pro-peptide communication [24:16] Risk sourcing vs drug effects [26:25] FDA lists and compounding [31:05] Risk tolerance and informed consent [43:02] Why did pharma abandon peptide research? [47:44] Harm reduction debate [51:48] Practical takeaways [56:20] Key Ideas segment (Premium members only) Episode Resources Go to episode page  Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course Barbell Medicine Instagram: jordan_barbellmedicine Book: Signal: What Testosterone Levels Are Telling You About Your Health Related episode: #524: Strength & Fitness Levels for Reducing Chronic Disease Risk & Promoting Health Ageing – Jordan Feigenbaum, MD Further reading: Emerging use of BPC-157 in orthopaedic sports medicine: a systematic review. 2025. Ruenzi M, Stolte M, Veljaca M, et al. Efficacy and safety of PL 14736 (BPC 157) in patients with active ulcerative colitis. Gastroenterology. 2005. Meeting abstract; full study not published.

Most dietary guidelines recommend eating one to two servings of fish per week, often specifying that at least one serving should be oily fish. But how directly is that recommendation supported by evidence? And does adding fish to the diet improve outcomes? This episode examines where current fish-intake recommendations originated, why findings may appear contradictory, and what substitution analyses can tell us about replacing fish with alternative options. It also considers evidence from pescatarian and vegetarian cohorts, including whether adding fish would improve an already high-quality diet and whether removing it from a plant-forward diet is likely to provide further benefit. Timestamps [00:20] Setting out the question at hand [03:26] Overview of typical fish intake recommendations [07:10] Is there good evidence for suggested intakes? [08:10] Historical context [13:22] Key evidence: DART trial and cohort data [19:27] Analysis from Mohan et al. [25:04] Comparator issue: what is fish replacing? [30:52] Fish protein vs. plant protein [44:29] Vegetarian vs. pescatarian cohorts [55:20] Conclusions [01:00:50] Key Ideas segment (Premium-only) Episode Resources Go to episode page (with full study reference list) Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Subscribe to Alan's Alinea Nutrition Education Hub Enroll in the next cohort of our Applied Nutrition Literacy course

Wellness and optimisation culture increasingly presents itself as "science-based". But citing studies, using technical language, or having scientific credentials does not guarantee that the underlying evidence is being represented accurately. In this episode, exercise science researcher Dr. Nick Tiller, discusses how science can be selectively packaged, overstated, and used to support commercially attractive health claims. It explores the difference between science communication and science commodification, why scientific scepticism is distinct from cynicism, how anecdotes and mechanistic explanations can mislead, and why a single peer-reviewed study should never be treated as definitive evidence. The conversation also looks further upstream at problems within science itself, including low statistical power, p-hacking, publication bias, questionable research practices, and academic incentives that may favour novelty and positive findings. These issues can then be amplified through media, social platforms, and the wellness industry until tentative findings become confident recommendations. Timestamps: [03:14] Interview start [06:22] The health and wellness "lie" [08:38] Optimization and the illusion of control [11:14] Science communicators vs commodifiers [14:21] Vitamin D hype case study [20:54] Spotting misinformation online [24:50] Skepticism not cynicism [28:47] Guidelines for debunking [33:46] Spotting the grift pattern [41:25] Bad science in academia [54:47] Key ideas segment (Premium-only) Episode Resources: Go to episode page Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course Dr. Tiller's website Tiller & Phillips, 2023 – How Skepticism (not Cynicism) Can Raise Scientific Standards and Reform the Health and Wellness Industry Tiller et al., 2024 – The Nontechnical Summary: A New Initiative to Enhance the Translation of Sports Science Research and Reduce the Spread of Misinformation

Effective athlete support requires more than delivering technically correct nutrition advice. It depends on understanding the athlete's wider environment, anticipating the pressures that disrupt good intentions, and building flexible routines that remain useful across training, competition, travel and everyday life. This episode explores how practitioners can move beyond rigid prescriptions, use "good, better, best" options, measure meaningful progress, and create environments in which athletes can communicate openly about difficulties. It also examines identity, transitions out of sport, and why sustainable support should develop an athlete's autonomy rather than dependence on the practitioner. To discuss all this is Gemma McGuinness, registered performance nutritionist, former professional footballer and co-founder of Verus Performance. Timestamps: [02:38] Interview start [03:48] Nutrition beyond performance [10:10] Identity and food choices [18:47] Standards versus perfectionism [24:52] Planning that actually works [28:32] Measuring progress in athletes [33:37] Where discipline can cause problems [38:40] Building high performance environments [45:37] Key ideas (Premium-only) Links: Go to episode page Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course Instagram: @gemmcguinnness Verus Performance Davey Nutrition Gemma's Substack

This episode answers one of the questions raised in the most recent Q&A episode on Sigma Nutrition Premium.  The full episode includes the following questions: Fiber: Independent effect or proxy for healthy foods? Exposure frequency for matched dose of red meat MTHFR gene mutations and 5-MTHF Typical fish oil supplements vs pharmaceutical-grade products Health impacts of saturated fat in coconut products Do I need to consume whole grains? Could the increasing use of AI pose a threat to doing rigorous science? To listen to the entire episode (plus the back catalogue of all Premium-exclusive episodes) become a member of Sigma Nutrition Premium. For episode info and mentioned research go to the episode page here.

Medical screening is often framed as an uncomplicated good: if disease is found earlier, treatment can begin earlier and outcomes should improve. This episode examines why that reasoning is incomplete. Screening can produce benefit, but it can also generate false positives, incidental findings, overdiagnosis, overtreatment and diagnostic cascades. Dr. Austin Baraki discusses the distinction between screening people without relevant symptoms and investigating a clinical problem, the probabilistic interpretation of test results, biases that can make screening appear more effective than it is, and the importance of shared decision-making before a test is ordered. Timestamps: [03:35] What screening means [06:36] Choosing what to screen [11:59] Sensitivity and specificity [16:54] Predictive value and prevalence [22:16] Harms of screening and testing [31:02] Overdiagnosis and biases [41:40] The $50,000 physical [44:49] Overdiagnosis vs false positives [53:03] Overtreatment and surveillance [57:22] Clinician action bias [01:02:30] What to screen for Links: Go to episode page (with resources) Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course Instagram: @austin_barbellmedicine Twitter: @AustinBaraki

What does the evidence actually show when we look at plant-based dietary patterns through the lens of food processing? And does classifying foods as "ultra-processed" meaningfully change how we interpret the relationship between plant-based diets and long-term health outcomes? A recent large prospective cohort analysis examined both healthful and unhealthful plant-based dietary patterns, and importantly, stratified the contributing foods based on whether they were classified as ultra-processed or non-ultra-processed. In this episode, the study's lead author Dr Alysha Thompson, discusses the many intesresting aspects to the analysis. These include how the dietary indices were constructed, the challenges of applying NOVA classification to self-reported dietary data, the role of residual confounding in observational nutrition research, and the extent to which we can or cannot infer independent effects of processing from these findings. We also consider the broader implications for the use of processing-based classifications in nutrition science and whether this adds meaningful explanatory value beyond traditional assessments of diet quality. Timestamps [03:02] Interview start [05:08] The key research question [07:52] Study design [17:25] Building diet scores [21:11] NOVA classification challenges [25:04] Key findings [38:30] NOVA debate and stance [43:44] Adjustments and mediators [48:11] Future research directions [54:37] Key ideas (premium-only) Resources: Go to episode page Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course Paper: Plant-Based Diets, Ultra-Processed Foods, and Risks of Mortality and Major Chronic Diseases: A Prospective Cohort Study

In nutrition and health coaching, one of the central challenges is understanding how people actually change, particularly when life is complex, motivation fluctuates, and behaviour is shaped by emotion, identity, environment, and relationships. In this episode, Dr. Krista Scott-Dixon discusses the human skills that underpin effective coaching practice. We discuss the importance of the coach–client relationship, the role of therapeutic alliance, and how concepts from counselling and psychology can be used appropriately within scope of practice. The discussion also explores autonomy-supportive coaching, self-regulation, compassion, acceptance, feedback, and the meta-skills practitioners need in order to improve over time. Timestamps [06:10] What makes a competent practitioners? [11:17] Scope of practice line [17:49] Therapeutic alliance [23:33] Applying compassion and acceptance [31:18] LLMs vs human connection [34:40] Meta skills for practitioners [38:51] Getting better feedback [44:23] Collaboration and autonomy [55:44] Key ideas recap Links: Go to episode page Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course Past episode #326: Adaptability & Autonomy in the Nutrition Coaching Process Krista's website: kristascottdixon.com Instagram: @stumptuous 1% Better Academy The textbook: Applied Nutrition Coaching and Counseling: ebook version US Canada UK International

Supplement safety is often discussed in very general terms, but in practice the risks depend heavily on the individual. A supplement that is reasonable for one person may be inappropriate for another based on their medications, health conditions, dose, formulation, or the other products they are already using. This becomes especially important when supplements interact with medications or underlying medical conditions. Some interactions can change how a drug is absorbed, metabolised, transported, or cleared from the body. Others can amplify or oppose the drug's clinical effect, such as increasing sedation, lowering blood pressure or blood glucose, or affecting bleeding risk. In this episode, Giulia Guerrini, a GPhC-registered pharmacist and researcher at Examine, talks about how clinicians and practitioners can think more systematically about supplement safety, side effects, contraindications, and drug–supplement interactions. Timestamps: [02:39] Interview start [05:21] Why context matters [06:38] Timing and formulation [12:58] Rating interaction risk [22:39] Berberine benefits and interactions [27:33] Adaptogens quality concerns [30:15] Melatonin safety questions [36:30] Stacking supplements risks [41:50] Quality control and regulation [55:35] Key ideas segment (premium-only) Links: Free trial of Examine Clinician Edition – For health & nutrition professionals. Includes the Supplement Navigator (safety and interaction checking), plus all other Examine tools (study summaries, supplement database, in-depth guides, etc.) Free trial of Examine+ – For anyone wanting to make evidence-based decisions about supplements and health. Includes: 100+ study summaries a month. The full supplement database. In-depth guides. ExamineAI. Doesn't include the Supplement Navigator. Go to episode page Subscribe to Sigma Nutrition Premium