Origin, chemistry, physiological effects and clinical importance of dietary fibre

Dietary fibre is plant material that cannot be digested by human gastrointestinal tract enzymes. Most dietary fibre is contained in the cell wall of plant cells. The two major chemical classes of fibre are the polysaccharides and the lignins; the former are further subdivided into cellulose and noncellulosic polysaccharides. Recently an excellent method for measuring the different chemical types of fibre has been developed. The effects of fibre in the gastrointestinal tract depend upon digestibility of the material by colonic bacteria. Fibre holds water, forms gels, has cation-exchange and adsorptive capacity and may alter redox conditions. These actions may be important in the treatment and prevention of disease in humans. Use of fibre in constipation and in diverticular disease of the colon is well established. Incomplete evidence suggests that fibre may have an important role in carcinoma of the colon, hypercholesterolemic states, cholesterol cholelithiasis, and functional and postgastrectomy hypoglycemia.