Fiber and gastrointestinal microecology.

The gastrointestinal tract contains a unique microecology. Microorganisms living in the mouth, stomach, and most importantly in the small and large intestines produce enzymes which help metabolize certain ingested foods, as well as maintain important body homeostatic mechanisms such as the bile salt enterohepatic circulation. Recent awareness of the importance of poorly digested foods such as cellulose, hemicellulose, pectins, and lignins, as well as selectively absorbed long-chain polysaccharides, has stressed the importance of the relationship of food to the microflora. This intestinal microecology has definite effects on the human host in cholesterol metabolism, glucose tolerance, and may explain such diseases as carcinoma. The exacting details of the intestinal microecology need further elaboration.