Dietary fiber's role in the prevention and treatment of
constipation has long been known, but now fiber is touted as a cure for many of the ills in Western countries. Although some data exist to relate
dietary fiber intake to certain diseases, lack of agreement on what
dietary fiber is and how it should be measured make interpreting the data difficult. Further, not all
dietary fiber is created equal. Water-soluble fibers, such as
pectin and gums, have little effect on stool weight and hence are not appropriate treatment for patients with
constipation. Water-insoluble fibers, such as
cellulose and
hemicellulose, are most effective in aiding laxation but may also limit absorption of minerals and possibly
vitamins.
Wheat bran is a good source of
hemicellulose; vegetables supply
cellulose to the diet. Most agencies are recommending a doubling or tripling of
dietary fiber intake. Typical recommendations are set at 25 to 50 grams of
dietary fiber daily. Different analytical methods for
dietary fiber yield conflicting fiber values, and
dietary fiber values do not exist for many foods, making fiber recommendations controversial and difficult to achieve. Fiber in the diet should ideally be increased by the consumption of unrefined breads and cereals and more fruits and vegetables. Vegetarians routinely consume 40 to 50 gm
dietary fiber daily without ill effect. Fiber supplements may be appropriate for some patients, but the composition of the fiber should be known and be appropriate for the disease being treated. Before fiber supplements are marketed, clinical trials should be conducted to support the use of the supplements in the prevention and treatment of disease.(ABSTRACT TRUNCATED AT 250 WORDS)