Health & Nutrition

Dr. Will Bulsiewicz on Fiber, the Microbiome, and the Future of Human Health

Dr. Will Bulsiewicz, known as Dr. B, returns to the show following the success of his book Fiber-Fueled, which sold 200,000 copies, to introduce its follow-up, The Fiber-Fueled Cookbook.

Vegans Explore Podcast

Episode 49 · Dec 19, 2025 · 58 min

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Fiber as Food for Your Microbes

Dr. B explains that humans lack the enzymes to digest fiber directly, so it travels to the large intestine where gut microbes break it down into short-chain fatty acids, compounds he calls among the most healing and anti-inflammatory substances in the body. He points to a study out of MD Anderson showing that every additional 5 grams of daily fiber intake was linked to a 30 percent increase in melanoma survival.

A Cookbook Built as a Gut-Health Toolkit

The new book includes 125 plant-based recipes, fermentation and sprouting instructions, and a game Dr. B invented called "plant points" to track how many different plants make it into a meal, since variety on the plate is what drives a diverse, resilient microbiome.

Every 5 grams of added daily fiber was linked to a 30 percent increase in melanoma survival in MD Anderson research
Fermented vegetables offer fiber and live cultures that fermented dairy products do not
The Fiber-Fueled Cookbook includes 125 plant-based recipes and step-by-step fermentation guides

Dr. B closes with a story about a patient whose ulcerative colitis symptoms resolved only after she left a toxic job, a reminder that gut health is shaped by more than diet alone.