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.

• [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)

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• Paper: Plant-Based Diets, Ultra-Processed Foods, and Risks of Mortality and Major Chronic Diseases: A Prospective Cohort Study

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.

• [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.
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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.

• [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

A 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:

• [04:23] Interview starts
• [07:35] Sweetness terms explained
• [10:17] Sweet liker phenotypes
• [14:03] Liking vs wanting vs preference
• [19:18] Trial evidence overview
• [23:48] Policy and practical impact
• [30:41] Why we eat foods

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

Electrolytes 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

This 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
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• Enroll in the next cohort of our Applied Nutrition Literacy course

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.

• [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

Unprocessed 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.

• [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