Nutrient density refers to the concentration of vitamins and minerals in crops relative to their yield. There are widespread claims that today's fruits, vegetables, and grains contain fewer micronutrients than in decades past, often linked to modern farming practices or soil degradation.

This issue is important because if staple crops become less nutritious, it could silently undermine dietary quality and contribute to micronutrient deficiencies ("hidden hunger") in populations.

Dr. Edward Joy is uniquely qualified to address this topic. As a senior research fellow in food systems and nutrition at Rothamsted Research and an associate professor at the London School of Hygiene & Tropical Medicine, his work centers on the intersection of agriculture and nutrition.

In this conversation, Dr. Joy draws on evidence from agronomy and public health to clarify whether the nutrient content of crops has indeed declined, what factors might be responsible (from soil health to plant breeding and climate change), and what we can do to improve the situation.

The discussion emphasizes an evidence-based perspective on soil nutrients, crop varieties, and interventions, cutting through myths to identify real concerns and practical solutions.

• [00:55] Interview
• [04:49] Understanding nutrient density and soil health
• [10:25] Historical evidence and crop experiments
• [20:39] Impact of climate change on crop nutrition
• [24:05] Potential solutions and future research
• [30:34] Translating research to human health

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• Rothamsted Research
• Dr. Joy's profile page
• X/Twitter:
  • @edward_joy1
  • @NutritionDanny

This is a Premium-exclusive episode of the podcast. To listen to the full episode you need to be subscribed to Sigma Nutrition Premium.

Recently we (Danny Lennon & Alan Flanagan) were invited to 'Processing the Evidence', a "behind closed doors" workshop to discuss the latest scientific evidence on the role of processed foods in human health. The event was organized by Professors Ciarán Forde and Vincenzo Fogliano of Wageningen University in the Netherlands.

The workshop attendees included a range of prominent researchers across a range of domains related to food processing, nutrition science, and public health. The sessions included open discussions on current evidence, knowledge gaps and challenges within the UPF debate.

There were several structured sessions looking at different sub-topics, such as:

• • Emulsifier-gut interactions
  • Ultra-processing and its effect on food matrix and bioavailability
  • Food liking and hedonic overeating
  • UPFs: Interpreting nutritional epidemiology and RCTs
  • New trial data: the PROMENADE trial, the RESTRUCTURE Trial, etc.

In this episode, Alan and Danny review some of the key talking points and their takeaways from this event.

• • [00:31] Event overview: processing the evidence
  • [04:44] Conference insights with Dr. Alan Flanagan
  • [07:52] Hypotheses on ultra processed foods
  • [11:53] Microbiome and additives panel
  • [21:51] Food science and technology panel
  • [33:21] Behavioral aspects of food consumption
  • [38:10] Nutritional epidemiology session
  • [47:19] Discussion on dietary pattern classification
  • [50:19] The role of ultra-processed foods in public health policy
  • [54:18] Clinical and metabolic data on processed foods
  • [01:00:55] Critique of the NOVA classification system
  • [01:08:03] Concluding thoughts on ultra-processed foods
  • [01:23:12] Key ideas and methodological standpoints

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This episode explores how asking better questions and using stronger methods can resolve much of the confusion in nutrition science. Dr. Daniel Ibsen discusses why nutrition research often produces conflicting results and how careful methodological thinking can clarify true diet-disease relationships.

Nutrition science has unique challenges – diets are complex, people self-report their food intake imperfectly, and we can't easily run long-term diet experiments on people. Dr. Ibsen explains how embracing concepts like food substitution analysis, the "target trial" framework, and objective dietary assessment can strengthen evidence.

The episode centers on methodological insights that make nutrition research more reliable and actionable. Key themes include defining dietary comparisons explicitly (the "compared to what?" question), considering people's starting diets, and using causal inference techniques to design better studies.

Daniel B. Ibsen is an epidemiologist and nutritional scientist whose work bridges rigorous causal inference methods with real-world diet and cardiometabolic disease research. He is an Associate Professor at Aarhus University, Denmark.

• [00:13] Introduction to the topic
• [03:23] Interview start
• [08:02] The importance of asking the right questions in nutrition science
• [22:18] Understanding causal inference in nutrition
• [28:58] Challenges and approaches in nutrition epidemiology
• [32:07] Mimicking dietary interventions in studies
• [32:55] Target trial framework
• [39:52] Objective vs. subjective dietary assessment
• [47:01] Why causal effects of ultra-processed foods cannot be identified

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How much do hormonal fluctuations really influence performance and recovery? Should women be adjusting their training and nutrition based on the menstrual cycle? And do female athletes need different protein strategies or recovery protocols than men?

These are questions that have fuelled countless online claims, from rigid "cycle syncing" programmes to supposedly gender-specific nutrition rules. But how much of that is actually grounded in evidence?

In this episode, the conversation tackles those debates head-on, exploring what we truly know about female physiology, adaptation, and recovery, and where confident narratives outpace the science.

You'll hear from four leading experts: Professors Kirsty Elliot-Sale, Stu Phillips, Shona Halson, and Dr. Eric Helms, as they unpack the data on menstrual-cycle variation, autoregulation, and the real determinants of muscle growth and recovery in women.

These discussions were originally recorded live as part of "The Inside Advantage" event hosted by Optimum Nutrition at the McLaren F1 Performance Centre in the UK, where Danny Lennon moderated the session.

• [02:07] Introducing the topics of discussion
• [07:46] Understanding the menstrual cycle
• [09:22] Recovery and hormonal impact
• [10:23] Where did "cycle syncing" claims originate?
• [15:01] Indirect effects of hormones on performance
• [17:28] Sleep and menstrual cycle
• [18:46] Training adaptations and hormonal differences
• [26:29] Do we have research on female athletes?
• [29:20] Muscle building: are there sex differences?
• [34:01] Do hormones influence training?
• [45:08] Key ideas segment (Premium-only)

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• Watch: Optimum Nutrition's 'Inside Advantage' event
• Previous episodes with these guests: #'s 452, 280, 192, 454

This episode centers on the critical gap in nutrition education within medical training and efforts to bridge it. Guest Akash Patel, a medical student who led a pilot nutrition curriculum, discusses why doctors receive little formal training in nutrition despite poor diet being a major driver of disease. With diet-related conditions (obesity, diabetes, cardiovascular disease, etc.) contributing heavily to morbidity and healthcare costs, the conversation highlights a pivotal push to better equip physicians in nutritional knowledge and counseling.

Patel's work comes at a turning point: there are now calls for standardized nutrition competencies in medical education (e.g., a recent JAMA consensus) and a growing recognition that improving doctors' nutrition literacy could enhance patient care and public trust. But at the same time, medical programs already have a huge workload and little space is available for appropriate training. Others state that nutrition shouldn't fall within the remit of doctors. So how do we reconcile all this?

While this episode focuses on the United States context, the concepts apply to other countries, as it outlines both the challenges and the emerging solutions for closing the nutrition training gap in medicine.

• [03:21] Akash Patel's background and interests
• [05:22] Current state of nutrition education in medical schools
• [07:55] Akash's pilot program and initial findings
• [13:37] Challenges and considerations for curriculum integration
• [15:11] Effective curriculum design for nutrition education
• [23:38] Debating the role of nutrition education in medical training
• [29:00] Practical scenarios and the role of doctors
• [33:58] Advice for implementing nutrition education initiatives
• [38:15] Future directions in nutrition and medicine
• [43:07] Key ideas segment

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• Instagram:
  • @withakashpatel
  • @dannylennon_sigma
  • @sigmanutrition

Never before has there been greater access to information about nutrition and health. But never before has there been such a low barrier to being seen as an "expert". There are large numbers of people getting information from, and basing their health decisions on, people who don't have direct expertise in the field in which they are talking about.

Moreover, some promote the lack of domain expertise as a feature, not a bug. They claim that those that were conventionally seen as domain experts are either brainwashed, lazy in their thinking, or outright corrupt. And the solution is instead to look to those with a fresh perspective that can illuminate us on the "truth".

In this episode, Alan and Danny discuss this "death of domain expertise", how it plays out online, and its ramifications for people's ability to get good information.

Note: This episode was originally published as an exclusive episode for Sigma Nutrition Premium subscribers. If you wish to get more Premium-only episode or read study notes to our episodes, you can subscribe to Sigma Nutrition Premium.

• [03:21] The manufactured collapse of expertise
• [09:58] Understanding domain specific expertise
• [15:10] Cross domain expertise and its limits
• [33:07] The illusion of learning from popular podcasts
• [38:26] The problem with self-proclaimed experts
• [46:11] The challenge of identifying true expertise
• [50:39] The impact of institutional distrust
• [56:30] Navigating the information landscape

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• Mentioned books & studies:
  • Tom Nichols – The Death of Expertise
  • Jonathan Haidt – The Righteous Mind
  • Ionnidis, 2018 – The Challenge of Reforming Nutritional Epidemiologic Research

This is a Premium-exclusive episode of the podcast. To listen to the full episode you need to be subscribed to Sigma Nutrition Premium.

Each year, the conversations on Sigma Nutrition Radio aim to examine the ideas that shape how we understand nutrition, health, and human behavior. This episode brings together the key insights from those discussions, revisiting the most important themes, emerging evidence, and shifts in understanding from the past year.

Across topics such as dietary guidelines, ultra-processed foods, sleep, metabolism, environmental exposures, and the psychology of eating, this review distills what the science actually shows and what remains uncertain.

Whether you have followed throughout the year or are tuning in for the first time, this episode provides a concise synthesis of what truly mattered and what these ideas imply for how we interpret nutrition science moving forward.

• [02:23] Christopher Gardner, PhD – How dietary guidelines are shaped, misused, and what the evidence really supports.
• [13:10] Marie-Pierre St-Onge, PhD – The bidirectional relationship between sleep quality, circadian timing, and diet.
• [20:03] Duane Mellor, PhD – Rethinking ultra-processed foods: mechanisms, misconceptions, and policy realism.
• [29:26] Samuel Dicken, PhD – The UPDATE trial and what nutrient-matched processing tells us about satiety and intake.
• [35:37] Ian Mudway, PhD – Microplastics, pollution, and why evidence must outrun public fear.
• [43:46] Martin Caraher, PhD – The financialization of food systems and its impact on inequality and diet quality.

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We take a look at critical thinking in science and healthcare, examining how we often fall prey to cognitive biases, emotional reasoning, and flawed thinking. Drawing from six different experts in their respective fields, the episode explores why we sometimes believe we are being rational when in fact our conclusions aren't truly evidence-based. The discussion spans what genuine evidence-based practice means, how domain expertise matters, and how factors like identity, beliefs, and emotions can derail objective reasoning.

• [02:56] Dr. David Nunan on evidence-based medicine
• [15:30] Dr. John Kiely on translating research into practice
• [26:10] Dr. Gil Carvallo on emotion and decision making
• [30:10] Dr. David Robert Grimes on webs of belief
• [37:18] Dr. Matthew Facciani identity and belief formation
• [42:31] Dr. Alan Flanagan on domain-specific expertise in nutrition science

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• Alan Flanagan's Alinea Nutrition Education Hub