Sigma Nutrition Radio

Claims about "improving the gut microbiome" are widespread, but what would improvement actually mean?  How do we establish which microbial changes contribute to disease, and which simply reflect it?
Research on bacterial metabolism of medications raises questions about how the microbiome might influence treatment efficacy and toxicity. What would it take to translate these findings into reliable tests and effective therapies?
In this episode, gastroenterologist and researcher Prof. Harry Sokol examines these questions, discusses the development of Faecalibacterium prausnitzii as an investigational treatment, and considers what current evidence can tell us about dietary advice and commercial microbiome testing.
Timestamps

[02:50] Harry Sokol's work

[04:36] Defining healthy microbiome

[06:48] Do we have causal evidence?

[11:05] FMT evidence

[15:29] Diet-microbiome claims

[20:45] Emulsifiers & IBD research

[22:54] Microbiome-drug interactions

[30:23] Bacteria as a drug?

[38:09] Microbiome testing

[44:36] Key ideas segment (Premium-only)

Introduction

Claims about "improving the gut microbiome" are widespread, but what would improvement actually mean?  How do we establish which microbial changes contribute to disease, and which simply reflect it?
Research on bacterial metabolism of medications raises questions about how the microbiome might influence treatment efficacy and toxicity. What would it take to translate these findings into reliable tests and effective therapies?
In this episode, gastroenterologist and researcher Prof. Harry Sokol examines these questions, discusses the development of Faecalibacterium prausnitzii as an investigational treatment, and considers what current evidence can tell us about dietary advice and commercial microbiome testing.


Timestamps

[02:50] Harry Sokol's work

[04:36] Defining healthy microbiome

[06:48] Do we have causal evidence?

[11:05] FMT evidence

[15:29] Diet-microbiome claims

[20:45] Emulsifiers & IBD research

[22:54] Microbiome-drug interactions

[30:23] Bacteria as a drug?

[38:09] Microbiome testing

[44:36] Key ideas segment (Premium-only)




On this episode:

Host: Danny Lennon
Guest: Prof. Harry Sokol




Episode Resources:

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Exeliom Biosciences
Book: MICROBIOME: Science, Promises and Lies
Instagram: @harry_sokol
LinkedIn: Prof. Harry Sokol

Can an athlete reduce the environmental impact of their diet while still meeting the demands of training, competition and recovery? Peter Res argues that these aims can be compatible, provided dietary changes are planned around the athlete's needs.
The discussion looks at practical changes athletes can make to make their diets more environmentally sustainable. This includes tips on increasing the contribution of plant proteins, maintaining adequate energy intake, and making plant-rich eating practical within sporting environments.
Timestamps

[04:21] Peter Res' background

[05:22] Defining sustainability metrics

[08:17] Biggest diet change to make it more environmentally sustainable

[09:23] Is local and organic actually better?

[13:44] Athlete fears about protein

[18:07] Barriers for athletes

[19:37] Fueling high calorie needs

[21:26] Micronutrients

[24:02] Performance effects

[26:32] Athletes as role models

[30:17] Easy first steps

[34:21] Premium-only: key ideas segment

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LinkedIn: Peter Res
Fork Ranger
Related episodes: #320: Hannah Ritchie, PhD – Environmental Impacts of our Diet: Climate, Carbon Footprint & Land Use
#446: How Climate Change Impacts Nutrient Status
#584: EAT-Lancet: Does the Planetary Health Diet Improve Human Health?

Men commonly feel that if their testosteone isn't "optimized" and high, they are missing out on greater health in a variety of ways. But what can a testosterone result actually tell us? How can results be interpreted with appropriate nuance that is needed? How low is low enough to be problematic?
In situations where a test flags testosterone as low, there is a belief this means automatically starting testosterone replacement therapy. While TRT can be an excellent intervention in appropriate cases, when is it actually likely to benefit someone, and when is it not?
For many people the decision seems straightforward: get a blood test, see whether testosterone is a little low, and start TRT. However, this simplistic thinking is full of potential issues that are important to understand.
Dr. Austin Baraki returns to discuss how testosterone testing should inform treatment decisions, what benefits to expect, and the questions surrounding fertility and long-term safety.
Timestamps:

[03:50] Dr Austin Baraki's work

[06:33] When and why test?

[10:36] Probability and context impacts interpretation

[14:13] What labs measure

[21:15] Specific vs nonspecific symptoms

[28:35] Primary vs secondary hypogonadism

[32:30] Lifestyle vs TRT decisions

[35:21] TRT risks

[39:32] Testing timing and variability

[41:55] Androgen receptor genetics

[44:28] Free vs total testosterone

[48:57] Low-normal results: what now?

[57:45] TRT risks?: heart and prostate

[01:03:55] Side effects and monitoring

Links:
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Instagram: @austin_barbellmedicine
Barbell Medicine
McCormack & Holmes, 2020 – Your results may vary: the imprecision of medical measurements
#417: Austin Baraki, MD – What Do Nutrient Blood Tests Actually Tell Us?: Understanding Biomarkers
#334: Austin Baraki, MD – Potential Harms of Screening, Overdiagnosis and Overtreatment

Body composition testing is widely used in research, sport and clinical practice. But what are these methods actually measuring, and how much confidence should we place in the numbers they produce?
In this episode, we examine the assumptions behind common approaches including DXA, bioelectrical impedance, and skinfold measurements. We discuss the distinction between accuracy and reliability, the value and limitations of repeated measurements, and how coaches, clinicians, researchers and individuals can select an appropriate method and interpret the data without overstating its precision.
Joining Danny to discuss these issues is Professor Grant Tinsley, Professor of Human Performance at Texas Tech University and Director of its Energy Balance and Body Composition Laboratory.
Timestamps:

[03:04] Grant Tinsley's research

[05:25] What body composition means

[08:50] Skeletal muscle mass vs. fat-free mass vs. lean soft tissue

[11:51] How different methods estimate body composition

[23:38] Group vs individual accuracy

[31:09] Standardizing testing conditions and assessments

[36:36] Reliability testing thresholds

[40:08] Understanding phase angle in bioelectrical impedence results

[45:02] Consumer devices

[50:55] Not all benefit from monitoring

[54:14] Using data wisely

[01:02:55] Key Ideas (premium-only)

Links/Resources:
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Why do some foods feel difficult to stop eating, while others can be highly enjoyable without prompting the same tendency to overconsume? Answering this requires a clearer understanding of food reward, including the distinction between liking a food, wanting it, and perceiving it as easy to overeat.
In this episode, we examine how nutritional composition, sensory characteristics, learned beliefs and the eating context may shape hedonic overeating. It also considers the limits of using broad food categories to explain complex eating behaviour.
Discussing all this is Professor Graham Finlayson, professor of Psychobiology at the University of Leeds, whose research focuses on human appetite, food reward and the psychological processes involved in eating behaviour and weight control.
Timestamps

[04:02] Prof. Finlayson's research
[06:06] Food reward
[07:13] Liking versus wanting
[12:43] Measuring wanting in research
[15:27] Does wanting predict overeating?
[16:36] Study on hedonic overeating
[23:19] Perception and context effects
[26:24] Does ultra processing classification add anything?
[36:09] Key takeaways and future work
[40:35] Premium key ideas
Links/Resources:

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Study: Finlayson et al., 2025 – Food-level predictors of self-reported liking and hedonic overeating: Putting ultra-processed foods in context