Dietary fiber is critical for overall gut health, which can impact immune functioning, mental health, and more. One common misconception about fiber is that it goes into the mouth, through the intestine, and immediately leaves through the colon. You know—digestion. However, there’s much more to it than that.
While insoluble fiber may work that way, soluble fiber acts differently. When fiber gets to the colon, the microbes get into a feeding frenzy, Bulsiewicz explains. These microbes will then transform those fibers into short-chain fatty acids, called butyrate, acetate, and propionate. “These short-chain fatty acids, to me, are the definition of anti-inflammatory,” he says.
To reap these benefits, it’s not enough to just eat a certain amount of fiber. According to Bulsiewicz, it’s the source of the fiber that matters more.