#577: Ultra-processed vs. Minimally Processed Diets: UPDATE Trial – Samuel Dicken, PhD
Recently a new trial was published in Nature Medicine comparing the effect of ultra-processed versus minimally processed diets. Specifically, the UPDATE trial compared these two diets in the context of a healthy dietary pattern (in line with the UK’s EatWell Guide). This eight-week randomized, crossover trial generated a lot of discussion and was largely seen as being a really useful addition to the evidence base, and providing answers to some previously unexamined questions. In this episode the study’s lead author, Dr. Samuel Dicken, explains the background context for the UPDATE trial, provides an insight into its execution, and puts some of the results in context. There is also a discussion about the current state of evidence more broadly and the leading hypotheses around the mechanisms that drive the observations seen with consuming ultra-processed foods. This episode is particularly noteworthy because it provides fresh evidence on an important question: does following dietary guidelines with minimally processed foods confer extra benefits over following the same guidelines with ultra-processed foods? Timestamps [02:48] Interview with Dr. Samuel Dicken [03:08] Background and research interests of Dr. Samuel Dicken [04:31] Details of the update trial [09:48] Trial design and methodology [15:45] Results and findings of the update trial [18:46] Secondary outcomes and craving control [25:43] Hypotheses and mechanisms behind UPF effects [40:28] Policy implications and future research directions Related Resources Subscribe to Sigma Nutrition Premium Go to episode page Join the Sigma email newsletter for free Enroll in the next cohort of our Applied Nutrition Literacy course Study: Dicken et al., 2025 – Ultraprocessed or minimally processed diets following healthy dietary guidelines on weight and cardiometabolic health: a randomized, crossover trial LinkedIn: Samuel Dicken X: @SamuelDickenUK
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#576: The Social Psychology of Health Beliefs and Misinformation – Matthew Facciani, PhD
In this episode, Dr. Matthew Facciani explores how social psychology influences health beliefs and the spread of misinformation. The conversation delves into why people adopt certain nutrition or health beliefs so strongly, how identity and group membership shape our interpretation of evidence, and what makes us susceptible to false or misleading health claims. Dr. Facciani’s interdisciplinary background (spanning neuroscience, psychology, and sociology) allows him to offer a unique evidence-informed perspective on these issues. The episode centers on understanding the social forces behind health-related attitudes and how we might improve communication and critical thinking in the face of rampant misinformation. This topic is highly relevant for health professionals and researchers because misinformation about nutrition, health, and medicine can lead to poor decisions, vaccine hesitancy, or harmful fad diets. By understanding the psychological drivers that cause people to cling to unscientific beliefs, practitioners can better address patients’ concerns and correct false claims. Matthew Facciani is a postdoctoral researcher at The University of Notre Dame in the Computer Science and Engineering Department. He is an interdisciplinary social scientist with a background in neuroscience and psychology and holds a PhD in sociology. His research focuses on media literacy, misinformation, social networks, political polarization, identities, and artificial intelligence. Timestamps [01:41] Interview start [06:57] The role of identities in belief formation [16:01] Health attitudes and political identities [25:28] Improving dialogue and addressing misinformation [31:59] Does fact-checking work? [35:41] Media literacy and pre-bunking [44:03] Optimism and pessimism for the future [52:28] Key ideas segment (premium-only) Related Resources Go to episode page Join the Sigma email newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course Matthew’s book: ‘Misguided’ Matthew’s academic publications Recommended episode: #365: David Robert Grimes, PhD – Conspiracy Theories & Bad Information: Why Are We Susceptible?
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#575: How Does Dairy Impact Cardiometabolic Health? – Prof. Jean-Philippe Drouin-Chartier
Dairy is often treated as a single food group, yet milk, yogurt, cheese, and butter can have very different effects on health. Some evidence links yogurt to favourable outcomes, while butter is known to raise LDL cholesterol. And then there’s the paradox of cheese: high in saturated fat, but not consistently associated with higher heart disease risk. These complexities raise the question of whether the “dairy matrix” (the combination of nutrients and food structure) explains why not all dairy acts the same. In this episode, Prof. Jean-Philippe Drouin-Chartier, a nutrition researcher and registered dietitian, is on the show to examine what recent trials and large population studies tell us about dairy foods and cardiometabolic health. The discussion covers blood lipids, blood pressure, glucose metabolism, and how guidelines should interpret this evolving evidence. Timestamps [02:18] Interview start [09:38] Dairy consumption and type 2 diabetes [16:06] Dairy and cardiovascular disease [21:42] Dairy, blood pressure, and hypertension [25:56] Dietary guidelines and dairy [43:30] Key ideas segment (Premium-only) Related Resources Subscribe to Sigma Nutrition Premium Join the Sigma email newsletter for free Website: sigmanutrition.com Enroll in the next cohort of our Applied Nutrition Literacy course Referenced studies linked here
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#574: Microplastics & Health: What Do We Know? – Prof. Ian Mudway
They’re in our oceans, our air, our food, and now even in our bodies. Microplastics, once a distant environmental issue, have become a topic of urgent relevance in medicine, public health, and nutrition. The idea that tiny plastic particles are circulating through the food chain and accumulating in human tissues has sparked headlines, speculation, and concern. But how much of this fear is grounded in solid science? And how much is still unknown? As the research into microplastics rapidly grows, so too does the confusion. Claims range from the plausible to the alarmist, yet the real picture is far more complex. What does current evidence actually tell us about the health implications of microplastic exposure? How do we weigh these emerging signals against the backdrop of other environmental threats we understand much better? And how should scientifically-minded practitioners think about this issue, especially when patients begin asking questions? This is a conversation that calls for clarity, nuance, and a rigorous look at what we know versus what remains speculative. In this episode, Professor Ian Mudway, an environmental toxicologist, discusses the current scientific understanding of microplastics and human health. Timestamps [03:31] The public’s fascination with microplastics [08:35] Defining microplastics and nanoplastics [11:35] Environmental presence of microplastics [14:54] Human exposure to microplastics [18:23] Challenges in measuring microplastics [21:38] Public perception vs. scientific reality [27:08] Challenges in microplastic research [29:53] Environmental impact and human health [33:08] Complexities of plastic additives [40:34] Future directions in microplastic research [48:09] Key ideas segment (Premium-only) Resources Subscribe to Sigma Nutrition Premium Join the Sigma email newsletter for free Enroll in the next cohort of our Applied Nutrition Literacy course Gresham College YouTube lectures Go to sigmanutrition.com
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#573: A Philosophy of Elite Performance Nutrition – Daniel Davey
In this episode, performance nutritionist Daniel Davey discusses how his approach to elite sports nutrition has evolved over his career. Davey reflects on his decade working with top Irish teams (Dublin GAA/football and Leinster Rugby) and how stepping away from those environments led him to rethink the role of a nutrition practitioner. The central theme is a shift from a traditional prescriptive model, where the expert provides meal plans and quick solutions, to a philosophy centered on athlete empowerment, education, and long-term habit development. Davey emphasizes that true high performance is achieved not by spoon-feeding athletes every nutrient, but by cultivating their independence, adaptability, and ownership of the process. This episode delves into practical strategies for fostering that ownership, such as encouraging self-reflection, building a supportive “nutrition culture,” and focusing on sustainable habits over short-term fixes. This discussion is highly relevant to nutrition science and clinical practice because it addresses the often-overlooked behavioral and cultural aspects of dietary change. Health professionals will recognize parallels to coaching clients in any setting: the importance of engaging individuals in their own nutrition planning, the value of reflective practice, and the balance between providing support and encouraging autonomy. Timestamps [02:38] Interview start [07:29] Empowering athletes [12:36] Challenges and reflections [16:53] Practical applications and philosophy [23:33] Building sustainable habits [28:00] Empowering decision-making through clarity [30:03] The importance of consistency and planning [31:47] Leadership and team dynamics [34:38] Personal growth and overcoming challenges [40:27] The concept of non-negotiables [52:31] Key ideas segment Resources Join the Sigma email newsletter for free Subscribe to Sigma Nutrition Premium Enroll in the next cohort of our Applied Nutrition Literacy course See Sigma's Recommended Resources Daniel Davey’s previous appearences on the podcast: go to episodes 306 and 194
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.
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