Podcast
Sigma Nutrition Radio
Hosted by Danny Lennon · EN
Discussions about the science of nutrition, dietetics and health. The podcast that educates through nuanced conversations, exploring evidence and cultivating critical thinking. Hosted by Danny Lennon.
58episodes
Episodes
Newest firstAll episodes
#613: Supplement Safety & Medication Interactions – Giulia Guerrini, MPharm
Yesterday00:57:18Summary readySupplement 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
Summary#612: Does Sweet Taste Exposure Actually Develop Preference? – Prof. Katherine Appleton
1w ago00:42:37Summary readyA common idea is that repeated exposure to sweet taste strengthens our preference for sweetness, which then drives greater intake of sweet foods and drinks. This idea is often used in arguments about fruit, low-calorie sweeteners, diet drinks, and the supposed need to "reset" taste preferences by avoiding sweetness altogether. But does the evidence actually support that causal chain? In this episode, Prof. Katherine Appleton, Professor of Psychology at Bournemouth University, discusses what is known about sweet taste exposure, sweet preference, and how these concepts are measured in the scientific literature. Timestamps: [04:26] Interview starts [05:51] Does exposure to sweetness lead to greater preference? [08:36] Sweet liking and other terminiology [10:50] Phenotypes and measurement [16:08] Do preferences develop differently in children vs adults ? [18:54] Liking versus wanting [23:21] Low calorie sweeteners [29:41] Sensory specific satiety [34:23] Practical guidance for clinicians Links: Go to episode page (incl. links to studies) Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course
Summary#611: Electrolyte Mythology: Wellness Marketing vs. Evidence - Zoë Rom & Kylee Van Horn
2w ago00:55:08Tap to summarizeElectrolytes have become one of the most heavily marketed areas of modern sports nutrition and wellness. What was once a relatively specific tool for certain endurance athletes has increasingly been reframed as an everyday requirement for hydration, energy, focus, productivity, and general health optimisation. But how much of this messaging is grounded in physiology, and how much is an example of industry taking a real mechanism and extending it far beyond the evidence? In this episode, we examine why many common use cases are unlikely to require an electrolyte product. Along the way, we explore how wellness marketing, biohacking culture, diet communities, and social media narratives can turn narrow sports nutrition applications into broad claims that many people come to accept as true. To discuss this topic, Danny is joined by Zoe Rom, a science and environmental journalist, and Kylee Van Horn, a sports dietitian, to discuss how these claims are shaped by marketing, culture, and the attention economy. Timestamps: [04:00] Interview start [07:03] Wellness industry rebrand [09:16] Electrolytes 101 [16:02] Fear marketing and vague symptoms [22:50] When athletes actually need them [28:19] Salt fix and anti science narratives [33:53] Keto biohacking and identity [43:42] How to evaluate your need [48:43] Who should skip electrolytes 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 Your Diet Sucks podcast Fly Nutrition – Endurance Sports Nutrition
Transcribe →SNP51: Understanding Blood Glucose Reponses
3w ago00:13:26Tap to summarizeThis is a Premium-exclusive episode. Go to the Premium feed to listen. Or subscribe to Premium. Blood glucose is easy to measure, but not always easy to interpret. This Premium-only episode brings together insights from several previous guests to examine blood glucose responses in more detail. We discuss the misuse of clinical thresholds, the difference between OGTT results and free-living CGM data, and whether "flatter" glucose curves are actually better in normoglycemic people. The episode also covers when repeated high glucose excursions may be worth investigating, how sugar intake should be interpreted in context, and why skeletal muscle and exercise play such an important role in glucose regulation. Overall, the aim is to clarify what glucose responses can tell us, what they cannot tell us, and how to avoid pathologizing normal physiology. 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
Transcribe →#610: Rock, Paper, Salmon – Errors in Interpreting Food Substitution Models
4w ago00:57:04Tap to summarizeWhen considering the health impact of foods, it is important to consider "compared to what?". Increasing the amount of a certain food or nutrient in the diet, typically implies a displacement of another. While comparisons are more obvious in trials, in epidemiology food substitution models can be useful to help us determine the health effects of increasing/decreasing intake of a food, food group or nutrient. However, these models are often misinterpreted and miscommunicated as if they are a game of "rock, paper, scissors", where one food beats another, and the losing food must be removed from the diet or considered harmful to health. In this episode we discuss the problem of treating substitution analyses as food-ranking contests, rather than context-dependent comparisons shaped by the comparator, the unit of substitution, the baseline diet, and the outcome being studied. Timestamps: [01:30] Misuse of "compared to what?" [06:39] What substitution models do [10:43] Specified vs unspecified substitution [16:57] Why the units used matter [26:45] Example: organic vs conventional produce [31:22] When substitutions are useful [34:35] If legumes beat fish, does that mean fish intake should be zero? [44:31] Naive vs bias-adjusted: artificial sweeteners case study [49:14] Checklist: how to interpret food substitution analyses Links: Go to episode page (all study references linked) Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Subscribe to Alinea Nutrition Education Hub Enroll in the next cohort of our Applied Nutrition Literacy course Episode #472: Compared To What? Episode #589: Causal Inference in Nutrition Science – Daniel Ibsen, PhD
Transcribe →#609: Unprocessed Red Meat & Cancer Risk
Jun 901:09:44Summary readyUnprocessed red meat and cancer risk remains one of the most debated topics in nutrition science, partly because the evidence is often presented in overly simplistic terms. The key question is not whether to adopt a vague "balanced" position on red meat, but whether the evidence clearly identifies intake levels at which colorectal cancer risk increases and whether controlled human trials support plausible mechanisms for that risk. A second issue is whether claims that fibre, vegetables, or an otherwise "healthy diet" can neutralise high red meat intake are actually supported by the mechanistic evidence, or whether they overstate what dietary context can plausibly offset. In this episode, Danny and Alan examine the evidence base by moving beyond the usual epidemiology-only debate. They discuss why regional intake patterns and dose thresholds matter, then explore controlled human feeding studies showing how higher red meat intake can increase endogenous N-nitroso compound formation, faecal water genotoxicity, and other mechanistic biomarkers linked to colorectal carcinogenesis. Timestamps: [01:11] Defining the exposure and outcome [02:34] Carcinogen labels explained [07:54] Epidemiology and dose thresholds [14:04] Interpreting null findings [19:09] Bingham 1996 nitroso study [25:20] Hughes dose response trial [33:49] Cross 2003 heme iron mechanism [42:55] Fecal water genotoxicity [55:42] Tumor mutational signatures [59:38] What we can conclude now [01:04:10] Practical intake recommendations [01:08:41] Key ideas segment (premium-only) Links: Go to episode page (includes links to studies mentioned) Subscribe to Sigma Nutrition Premium Join the Sigma newsletter for free Enroll in the next cohort of our Applied Nutrition Literacy course
Summary#608: Performance Nutrition in Elite Rugby – James Morehen, PhD
Jun 201:08:02Tap to summarizePerformance nutrition in elite sport is often discussed in terms of meal plans, supplements, and macronutrient targets. However, effective practice in professional environments depends just as much on education, trust, communication, and the ability to translate scientific principles into decisions athletes can act on under real-world constraints. In this episode, Dr James Morehen discusses his work across elite rugby, football, and combat sports, with particular attention to the demands of professional rugby. The conversation explores how practitioners support athletes in a high-impact collision sport, including fuelling for training and match play, managing body composition without reducing athletes to arbitrary numbers, addressing recovery from muscle damage and injury, and developing practical systems around game-day nutrition. The episode also provides insight into the realities of building a career in performance nutrition, including the importance of applied experience, interdisciplinary collaboration, and learning how to coach athletes rather than simply prescribe to them. Timestamps: [03:31] Interview starts [10:26] Educating athletes on nutrition [13:55] Breaking into elite sport [26:26] Physiological demands of rugby [30:53] Energy needs and timing [38:28] Body composition measurements: utility? [46:16] Game day fuelling strategy [01:07:09] 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 James' Instagram: @morehenperformance James' LinkedIn: Dr. James Morehen Related episodes: #573: A Philosophy of Elite Performance Nutrition – Daniel Davey #286: Fuelling Elite Sport – James Morton, PhD #506: Sports Nutrition: Translating Research to Practice – Andreas Kasper, PhD
Transcribe →#607: Gut Health & Microbiome Testing: What Evidence Do We Actually Have? – Emily Leeming, PhD
May 2600:50:41Summary readyGut health has become a major focus in nutrition, medicine, and consumer wellness, but the term is often used loosely. Claims about microbiome testing, probiotics, fermented foods, fibre, and "boosting" the gut microbiome are now common, yet the evidence behind these claims varies substantially. In this episode, Dr. Emily Leeming examines what gut health actually refers to, why it cannot be reduced to the microbiome alone, and where current microbiome science is being applied before it is ready. The discussion covers the limits of commercial stool testing, the difficulty of defining a healthy microbiome, and the practical strategies most strongly supported by current evidence. Timestamps: [02:48] Interview start [04:17] Defining gut health [09:03] What is a "healthy microbiome"? [15:25] Microbiome testing - any clinical utility? [24:08] Interpreting microbiome studies [34:39] "30 plants a week" is not evidence-based [39:53] Serotonin and gut brain [45:34] Fiber research frontier Links/Resources: Go to episode page (w/ links to mentioned studies) Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course Dr. Leeming's newsletter: Second Brain
SummaryPMOS (PCOS) and Diet: What Can Nutrition Realistically Do? - SNP#50
May 2100:19:13Tap to summarizeIn this episode, we examine what nutrition can realistically do in the condition historically known as PCOS, now renamed polyendocrine metabolic ovarian syndrome, or PMOS. We begin by explaining why the name change matters: the condition is not defined by ovarian cysts, but is better understood as a broader endocrine-metabolic and ovarian syndrome involving insulin resistance, androgen excess, ovulatory dysfunction, metabolic risk, and psychological burden. We then assess the nutrition evidence, including energy restriction, weight loss, carbohydrate quality, glycaemic index and load, protein intake, fat quality, appetite regulation, fertility outcomes, and phenotype differences. Rather than seeking a single "PCOS diet", the episode asks which dietary features may plausibly help, how strong the evidence is, and where uncertainty remains. This is a Premium-exclusive episode. To listen to the full episode, subscribe to Premium. Links: Go to episode page and resources Subscribe to Sigma Nutrition Premium Join the Sigma newsletter for free
Transcribe →#606: Practical Nutrition Strategies for Fat Loss – Luke Hanna
May 1900:41:23Tap to summarizeBody composition goals, particularly bodyfat loss, are among the most common reasons people seek support from a nutritionist or health and fitness professional. While the principles are well established, the challenge is helping individuals apply them consistently in real-world conditions. Many people struggle due to hunger, unrealistic expectations, emotional eating, inconsistent routines, or overly restrictive dieting approaches. These challenges can make fat loss difficult to sustain, even when someone understands what they "should" be doing. In this episode, Luke Hanna discusses practical strategies for improving body composition, including food diaries, energy-density manipulation, preloads, mindful eating, and realistic goal-setting. The discussion emphasizes identifying individual barriers, collaborating with clients, and building repeatable behaviours that support both fat loss and long-term maintenance. Luke Hanna holds a Master's degree in Obesity and Clinical Nutrition from University College London and a degree in Sport and Exercise Science from the University of Portsmouth. He currently works as a nutrition coach and personal trainer. Timestamps: [03:15] Interview [05:39] Client assessment basics [11:59] Alternatives to tracking [13:57] Volume eating [18:56] Preloads before meals [22:25] Snacking and hunger types [26:44] Habits and food environment [30:40] Managing expectations [33:51] Transition to maintenance [39:09] Key ideas (premium-only) Links: Go to episode page (with resources) Join the Sigma newsletter for free Subscribe to Sigma Nutrition Premium Instagram: @lukehannanutrition
Transcribe →