Diabetes Care, Vol 11, Issue 2 160-173, Copyright © 1988 by American Diabetes Association
Dietary fiber in management of diabetes
AI Vinik and DJ Jenkins
Department of Internal Medicine, University of Michigan, Ann Arbor.
Current evidence suggests that high-fiber diets, especially of the soluble
variety, and soluble fiber supplements may offer some improvement in
carbohydrate metabolism, lower total cholesterol and low-density
lipoprotein (LDL) cholesterol, and have other beneficial effects in
patients with non-insulin-dependent diabetes mellitus (NIDDM). Diets
enriched with wheat bran and guar gum induce 10-20% reductions in serum
cholesterol and LDL in both normo- and hypercholesterolemic subjects and
have the ability to blunt the hypertriglyceridemic effects of diets high in
carbohydrate and low in fiber. In insulin-dependent diabetes mellitus
(IDDM) the situation is less clear, but a decrement of the circadian
glucose profile has been shown. Americans, in general, consume too little
fiber. With the need to restrict fat and reduce protein, an increase in
carbohydrates is mandatory. A practical goal would be to establish the
present level of fiber intake (15-30 g/day) and to gradually increase it.
An intake of up to 40 g of fiber per day or 25 g/1000 kcal of food intake
appears beneficial; in many individuals on weight-reducing diets higher
levels may be unacceptable because of gastrointestinal side effects. The
level of maximum benefit has not been determined. Fiber supplementation
appears beneficial only if given with a diet comprising approximately half
of the calories as carbohydrate. Foods should be selected with moderate to
high amounts of dietary fiber from a wide variety of choices to include
both soluble and insoluble types of fiber. Insufficient data are available
on the long-term safety of high-fiber supplements. People at risk for
deficiencies, such as postmenopausal women, the elderly, or growing
children, may require supplements of calcium and trace minerals. People
with upper gastrointestinal dysfunction are at risk of bezoar formation and
cautioned against a diet high in fiber of the leafy vegetable type. Careful
attention must be paid to insulin dose because hypoglycemia can result if
there is a radical change in fiber intake and insulin dose is not reduced
appropriately. Care must be exercised in the use of "novel" fibers,
including the wood celluloses, because little is known of their safety and
efficacy.