Fiber

Fiber supports gut health and is associated with lower mortality; a varied intake of roughly 30–60 grams per day was suggested as a potential health target, adjusted to what you tolerate comfortably. 1

• 10 grams and mortality: In a large meta-analysis discussed in the episode, each additional 10 grams of fiber per day was associated with about a 10% lower mortality risk, including from cardiovascular disease and cancer. 2
• Prebiotic and gut effects: Fiber—especially soluble fiber—can feed gut microbes, which ferment it into short-chain fatty acids. Greater microbial diversity was described as beneficial, and butyrate supplementation has shown positive effects on insulin sensitivity. 3
• Varied food sources: Aim for a range of sources, including fruits, vegetables, whole grains, and cereals; no single source was established as best. 4
• Individual responses: Fiber’s effects can differ among people. In one small study, participants with lower baseline microbial diversity had a more inflammatory response to increased fiber, while those with higher diversity benefited. 5

Increase fiber in a way that feels comfortable, since very high intake can cause discomfort. 6