Brain Fog, Bloating, & Microbiome Health: Evidence-Based Fixes with Dr. Will Bulsiewicz

23 Sept 2025 · 71 min
1:11:16

In this hour‑long interview, host Brigid Titgemeier talks with gastroenterologist, author, and microbiome researcher Dr. Will Bulsiewicz about why the gut microbiome is the "epicenter" of human health. Dr. Bulsiewicz explains the sheer scale of the microbiome (≈38 trillion microorganisms, outnumbering human cells) and how it influences digestion, metabolism, immunity, hormones, mood, and even gene expression. The conversation moves to why nutrition—despite its central role in shaping the microbiome—is routinely ignored in conventional medical practice, citing systemic pressures (shortened visits, lack of nutrition education, pharmaceutical‑driven curricula) and cultural inertia among gastroenterologists. They discuss the gut barrier (intestinal permeability or “leaky gut”), its downstream effect on the blood‑brain barrier, and how this underlies common symptoms such as brain fog, fatigue, and chronic low‑grade inflammation, which Dr. Bulsiewicz argues is the root cause of most chronic disease. The interview then covers therapeutic approaches: the evidence for fecal microbiota transplantation (FMT) in melanoma immunotherapy and recurrent C. diff difficile, the limitations of FMT for chronic conditions, and the necessity of pairing microbiome‑based therapies with dietary change. Dr. Bulsiewicz describes his work at Zoe, where a 300 k‑person microbiome‑CGM database revealed that the microbiome strongly predicts post‑prandial triglycerides and insulin sensitivity, while blood glucose is driven primarily by carbohydrate intake. He critiques extreme low‑carb or carnivore diets for depriving microbes of fermentable fiber, leading to loss of short‑chain fatty acids and potential inflammation. The conversation also touches on elimination diets (FODMAP, low‑histamine), emphasizing that restriction should be temporary and strategic, not lifelong, and that over‑restriction can harm microbial diversity. Dr. Bulsiewicz stresses the need for personalized nutrition beyond population‑level RCTs, noting that clinicians must balance evidence with individual response. He announces his upcoming book, Plant‑Powered Plus, which offers a flexible, evidence‑based framework for reducing inflammation through diet and lifestyle, and introduces his supplement line 38 Tara. Throughout, personal anecdotes (his own health crisis, being a father of four, frustrations with the healthcare system) illustrate why he is passionate about translating microbiome science into practical, patient‑centered care.

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