Sigma Nutrition Radio

When 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

This is a Premium-exclusive episode of the podcast. To listen to the full episode you need to be subscribed to Sigma Nutrition Premium. This episode examines dietary fiber through the lens of a practical, clinically relevant question: if higher fiber intakes are consistently associated with reduced chronic disease risk, what intake level should we be aiming for to meaningfully improve health outcomes? The discussion deliberately spans from common online claims that fiber is "not essential" (and therefore unnecessary), through to mechanistic reasoning and the highest-quality evidence we have for hard outcomes and accepted intermediate cardiometabolic endpoints. Across the episode, we'll hear from six expert perspectives to integrate epidemiology, controlled feeding studies, and clinical guideline contexts. We will consider how the dose–response patterns, fiber type/source, individual tolerance, and the limitations of nutrition trials all influence what can be recommended with confidence. Timestamps [03:51] Addressing the claim "fiber is not an essential nutrient" [11:23] Carbohydrate quality and fiber [17:16] Dietary recommendations for fiber [20:01] Portfolio diet and cardiovascular health [26:48] Comparing fiber sources [36:07] Epidemiological evidence on fiber [41:57] Understanding fiber intake and coronary heart disease [43:23] Fiber intake and colorectal cancer [54:06] Diet swap study: south african vs. african american diets [01:01:47] High fiber diets and diabetes [01:16:18] Challenges in fiber intake and IBS [01:21:45] Concluding thoughts on fiber intake Related Resources Subscribe to Sigma Nutrition Premium Go to episode page (with links to mentioned studies) Join the Sigma email newsletter for free Enroll in the next cohort of our Applied Nutrition Literacy course

While the term "hyperpalatable" has been used frequently for considerable time to refer to foods that are so appealing and tasty that they drive overeating, this term hasn't been well-defined nor has there been a universal standard for what it means. One researcher who set out to create an objective definition for hyper-palatable foods (HPFs) is Dr. Tera Fazzino. Using specific defined thresholds of sugar, fat and salt combinations, Dr. Fazzino and colleagues have looked at the impact of consumption of these HPFs. In this episode, we delve into defining HPFs and their nutrient profiles, whether they have addictive-like properties, how HPFs differ from (and overlap with) ultra-processed foods (UPFs), the mechanisms by which these foods drive overconsumption, and the broader public health implications. Tera Fazzino, PhD, is an associate professor of psychology at the University of Kansas. Her research focuses on addiction, obesity, and eating-related behaviors. Timestamps [03:39] Interview begins [05:05] Attempting to define hyper palatability [10:03] Nutrient combinations in hyper palatable foods [14:54] Prevalence of hyper palatable foods [17:43] Debate on ultra processed foods [30:02] Mechanisms behind hyper palatability [35:06] Addiction theory and hyper-palatable foods [43:38] Early exposure and long-term effects [50:53] Key ideas recap Related Resources Go to episode page (with links to studies mentioned) Join the Sigma email newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course

Maintaining the ability to carry out everyday tasks and live independently is often described as a cornerstone of healthy ageing. But what actually happens to muscle strength, power, and functional ability as we get older? And how inevitable is their decline? At what point do changes in muscle function really begin to matter for day-to-day life? Is loss of strength an unavoidable consequence of ageing itself, or does it reflect something more modifiable? If declines are not fixed, what kinds of training or lifestyle interventions genuinely make a difference, and how strong is the evidence behind them? In this episode, exercise physiologist Dr Brendan Egan examines these questions through the lens of both epidemiological data and controlled training studies in older adults. What do we learn from short-term resistance training interventions lasting just a few months? Do the gains persist once supervised training ends? And what does this tell us about the practical challenges of maintaining functional capacity over the long term? The conversation also explores the idea of "use it or lose it" in muscle function, the role of resistance training in extending healthspan, and how exercise programmes can be designed to support independence later in life. Ultimately, the episode asks a simple but crucial question: what does the evidence actually say about staying strong, capable, and functionally independent as we age? Dr. Brendan Egan is an Associate Professor of Sport and Exercise Physiology the School of Health and Human Performance at Dublin City University. Currently, he is Associate Dean for Research in the Faculty of Science and Health. Timestamps [03:49] Understanding functional capacity [05:56] The importance of muscle strength and mass [14:09] Epidemiology and strength training [25:07] Concurrent training in older adults study [31:05] Barriers to strength training in older adults [34:18] Misconceptions about older adults and exercise [39:13] Exercise snacking and SBAE [51:04] Key ideas segment (Premium-only) Links & Resources Go to episode page (with links to studies) Join the Sigma email newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course