This material passes through the GIT as bulk fiber , undergoing modification and digestion by colon microorganisms. Several fibers have benevolent roles. The benefit seems to be the absorption or neutralization of the irritation or toxicity of other foods. Increased dietary fiber over a lifetime is associated with decreased incidence of bowel cancer and cardiovascular disease. The colon's dense population of microorganisms are very important to us in health and disease.
Many vegetables contain indigestible carbohydrate, welcomed by the colon flora.
The gas associated with beans is produced by the fermentation of these carbohydrates. Colon fermentation produces hydrogen gas, which may distend the GIT and produce pain. Methane and carbon dioxide are other odorless gases produced by fermentation. The foul smells of colon gas are mostly volatile substances produced by the putrefaction of undigested protein, and indicate a maldigestive state. Many chemical substances are produced by colon bacteria and may be absorbed into the body.