Dietary fiber and gastrointestinal disease.

Fiber is an important physiologic component of the diet. Dietary fiber contains soluble and insoluble substrates. Soluble fiber components are fermented by colonic microflora, with the resultant production of SCFAs and gas. SCFAs are important fuels, not only for colonic mucosa, but also for the small intestine through secondary metabolism to glutamine and ketone bodies. The clinical importance of dietary fiber and its metabolic products on gastrointestinal and nongastrointestinal functions have yet to be fully realized.