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Short Summary: How diet shapes the gut microbiome and impacts health, with microbiologist Dr. Peter Turnbaugh breaking down the complex science.

About the guest: Peter Turnbaugh, PhD is a professor of microbiology and immunology at the University of California, San Francisco, where he leads a lab studying the gut microbiome’s role in nutrition and drug response.

Note: Podcast episodes are fully available to paid subscribers on the M&M Substack and everyone on YouTube. Partial versions are available elsewhere. Full transcript and other information on Substack.

Episode Summary: Nick talks to Peter Turnbaugh discuss the pitfalls of oversimplified diet labels in research, Turnbaugh’s studies comparing plant-based and animal-based diets in humans, and how these shifts rapidly alter gut microbes and short-chain fatty acid profiles.

Key Takeaways:

• The term “high-fat diet” in research is often misleading, as it can include high carbs and vary widely, complicating study comparisons.
• In a 2014 study, switching humans to a plant-based (high-fiber) or animal-based (ketogenic, no-fiber) diet changed their gut microbiome within one day, showing its remarkable adaptability.
• Ketogenic diets reduce Bifidobacterium in the gut, which may lower inflammation-linked immune cells (Th17), potentially aiding conditions like multiple sclerosis.
• Short-chain fatty acids (e.g., butyrate) don’t just come from fiber; they persist even on zero-fiber ketogenic diets, hinting at alternative microbial pathways.
• Gut microbes can activate or deactivate drugs, like antibiotics or digoxin, suggesting microbiomes may explain why drugs work differently across individuals.
• Ketone bodies like BHB alone can mimic some ketogenic diet effects on the microbiome and immunity, simplifying research and hinting at therapeutic potential.

Related episode:

• M&M #203: Metagenomics, Microbiome Transmission, Gut Microbiome in Health & Disease | Nicola Segata

*Not medical advice.

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