What's Up Docs? Doctors' Notes: Fibre
Sep 23, 2025
Dr. Deirdre Tobias, an obesity and nutritional epidemiologist at Brigham and Women's Hospital and Harvard Medical School, shares her insights on fibre and the microbiome. She emphasizes the complexity of gut health, cautioning against the oversimplification of microbiome tests and isolated supplements. The discussion also highlights how fibre-rich diets reflect whole foods and tackles the socioeconomic challenges tied to accessing healthy options. Listeners will come away with practical tips on increasing fibre intake, including budget-friendly options.
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Microbiome Benefits Are Not Proven
- We lack conclusive science linking specific gut bacteria compositions to clear health outcomes.
- Deirdre Tobias warns that optimal microbiome profiles and their health roles remain uncertain.
Don't Rely On Microbiome Tests
- Avoid spending on commercial microbiome tests because actionable guidance is lacking.
- Deirdre Tobias recommends generic advice: increase fiber from fruits, vegetables and whole grains for most people.
One Molecule Won't Explain Fiber
- Measurable metabolites like butyrate are tempting mechanistic explanations but may oversimplify.
- Deirdre Tobias says linking one compound to all benefits of fiber is likely misleading.