Sigma Nutrition Radio

Most dietary guidelines recommend eating one to two servings of fish per week, often specifying that at least one serving should be oily fish. But how directly is that recommendation supported by evidence? And does adding fish to the diet improve outcomes?
This episode examines where current fish-intake recommendations originated, why findings may appear contradictory, and what substitution analyses can tell us about replacing fish with alternative options.
It also considers evidence from pescatarian and vegetarian cohorts, including whether adding fish would improve an already high-quality diet and whether removing it from a plant-forward diet is likely to provide further benefit.
Timestamps

[00:20] Setting out the question at hand

[03:26] Overview of typical fish intake recommendations

[07:10] Is there good evidence for suggested intakes?

[08:10] Historical context

[13:22] Key evidence: DART trial and cohort data

[19:27] Analysis from Mohan et al.

[25:04] Comparator issue: what is fish replacing?

[30:52] Fish protein vs. plant protein

[44:29] Vegetarian vs. pescatarian cohorts

[55:20] Conclusions

[01:00:50] Key Ideas segment (Premium-only)

Episode Resources

Go to episode page (with full study reference list)
Join the Sigma newsletter for free
Subscribe to Sigma Nutrition Premium
Subscribe to Alan's Alinea Nutrition Education Hub
Enroll in the next cohort of our Applied Nutrition Literacy course

Wellness and optimisation culture increasingly presents itself as "science-based". But citing studies, using technical language, or having scientific credentials does not guarantee that the underlying evidence is being represented accurately.
In this episode, exercise science researcher Dr. Nick Tiller, discusses how science can be selectively packaged, overstated, and used to support commercially attractive health claims. It explores the difference between science communication and science commodification, why scientific scepticism is distinct from cynicism, how anecdotes and mechanistic explanations can mislead, and why a single peer-reviewed study should never be treated as definitive evidence.
The conversation also looks further upstream at problems within science itself, including low statistical power, p-hacking, publication bias, questionable research practices, and academic incentives that may favour novelty and positive findings. These issues can then be amplified through media, social platforms, and the wellness industry until tentative findings become confident recommendations.
Timestamps:

[03:14] Interview start

[06:22] The health and wellness "lie"

[08:38] Optimization and the illusion of control

[11:14] Science communicators vs commodifiers

[14:21] Vitamin D hype case study

[20:54] Spotting misinformation online

[24:50] Skepticism not cynicism

[28:47] Guidelines for debunking

[33:46] Spotting the grift pattern

[41:25] Bad science in academia

[54:47] Key ideas segment (Premium-only)

Episode Resources:

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
Dr. Tiller's website
Tiller & Phillips, 2023 – How Skepticism (not Cynicism) Can Raise Scientific Standards and Reform the Health and Wellness Industry
Tiller et al., 2024 – The Nontechnical Summary: A New Initiative to Enhance the Translation of Sports Science Research and Reduce the Spread of Misinformation

Effective athlete support requires more than delivering technically correct nutrition advice. It depends on understanding the athlete's wider environment, anticipating the pressures that disrupt good intentions, and building flexible routines that remain useful across training, competition, travel and everyday life.
This episode explores how practitioners can move beyond rigid prescriptions, use "good, better, best" options, measure meaningful progress, and create environments in which athletes can communicate openly about difficulties. It also examines identity, transitions out of sport, and why sustainable support should develop an athlete's autonomy rather than dependence on the practitioner.
To discuss all this is Gemma McGuinness, registered performance nutritionist, former professional footballer and co-founder of Verus Performance.
Timestamps:

[02:38] Interview start
[03:48] Nutrition beyond performance

[10:10] Identity and food choices

[18:47] Standards versus perfectionism

[24:52] Planning that actually works

[28:32] Measuring progress in athletes

[33:37] Where discipline can cause problems

[38:40] Building high performance environments

[45:37] 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
Instagram: @gemmcguinnness
Verus Performance
Davey Nutrition
Gemma's Substack

This episode answers one of the questions raised in the most recent Q&A episode on Sigma Nutrition Premium. 
The full episode includes the following questions:
Fiber: Independent effect or proxy for healthy foods?
Exposure frequency for matched dose of red meat
MTHFR gene mutations and 5-MTHF
Typical fish oil supplements vs pharmaceutical-grade products
Health impacts of saturated fat in coconut products
Do I need to consume whole grains?
Could the increasing use of AI pose a threat to doing rigorous science?
To listen to the entire episode (plus the back catalogue of all Premium-exclusive episodes) become a member of Sigma Nutrition Premium.
For episode info and mentioned research go to the episode page here.

Medical screening is often framed as an uncomplicated good: if disease is found earlier, treatment can begin earlier and outcomes should improve.
This episode examines why that reasoning is incomplete. Screening can produce benefit, but it can also generate false positives, incidental findings, overdiagnosis, overtreatment and diagnostic cascades.
Dr. Austin Baraki discusses the distinction between screening people without relevant symptoms and investigating a clinical problem, the probabilistic interpretation of test results, biases that can make screening appear more effective than it is, and the importance of shared decision-making before a test is ordered.
Timestamps:


[03:35] What screening means
[06:36] Choosing what to screen
[11:59] Sensitivity and specificity
[16:54] Predictive value and prevalence
[22:16] Harms of screening and testing
[31:02] Overdiagnosis and biases
[41:40] The $50,000 physical
[44:49] Overdiagnosis vs false positives
[53:03] Overtreatment and surveillance
[57:22] Clinician action bias
[01:02:30] What to screen for
Links:
Go to episode page (with resources)
Join the Sigma newsletter for free
Subscribe to Sigma Nutrition Premium
Enroll in the next cohort of our Applied Nutrition Literacy course
Instagram: @austin_barbellmedicine
Twitter: @AustinBaraki