The Health Benefits of Fiber

W. Steven Pray, PhD, DPh


US Pharmacist. 2006;31(6):20-28. 

In This Article

The Definition and Categories of Fiber

At one time, fiber was defined as any part of ingested plants that human enzymatic actions cannot digest, such as cell wall components (e.g., waxes, lignin, pectin, celluloses).[5] However, during the 1970s, the meaning of "fiber" gradually broadened to encompass and embrace a physiological definition that has greater use for the medical profession.[5,6] The expanded definition of fiber now includes ingested materials that are not components of plant cells (e.g., noncellulose plant storage saccharides such as gums, modified celluloses, mucilages, oligosaccharides, and beta-glucans), although they are still resistant to degradation by human enzymes.[7]

Fibers are most usefully categorized for the medical professional on the basis of their inability to dissolve in water.[8] Fibers that do dissolve in water (e.g., celluloses, pectin, other cell wall components, as well as gums and psyllium) form gels, some of which have one or more health benefits. Found in such foods as wheat, rice, maize, leafy vegetables, peas, beans, and rhubarb, soluble fibers are able to sequester cholesterol and fats, facilitating their elimination. Fibers that do not dissolve in water bind water in the distal colon.[9] Their sponge-like effect bulks stools and also binds various materials such as bile acids and carcinogens. Insoluble fibers are found in whole-grain cereals, breads, vegetables, and wheat bran.

Beware the Low-Fiber Atkins Diet


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