The Fiber Gap: How Our Modern Microbiome Is Failing

A guide to feeding the gut bacteria responsible for endogenous GLP-1 regulation.

Fermentable fiber is the substrate for short-chain fatty acid production in the colon, and butyrate in particular is tied to intestinal barrier integrity and endogenous GLP-1 secretion. The average intake in high-income countries sits at roughly half the level used in the trials that produced the strongest cardiometabolic results.

Closing that gap is less about supplements than about repeated dietary defaults: legumes several times per week, intact grains rather than milled flours, and a wider rotation of plant species rather than a larger volume of the same three.

Adaptation is real and often mistaken for intolerance. Increasing fiber by 5 g per week rather than 20 g overnight resolves most of the bloating that causes people to abandon the change.

Editorial note: this article summarises published research for general information. It is not medical advice. Discuss any intervention with a qualified clinician.