July 20, 2015

Fiber is the name given to complex carbohydrates that are resistant to human digestion. Examples of fiber include cellulose and pectin.  Fiber comes from plants, and the usual sources are vegetables, cereals, bread, nuts, seeds and fruit.

Medical researchers have been recommending high fiber diets, yet dietary patterns in North America show no significant increase in fiber consumption from food. This means that the fiber intake of most people is far below recommended levels.

As part of a balanced diet, intake of fiber may help to protect against weight gain, heart disease, and intestinal infection.  Fiber from food is more complex than fiber sold in a jar.

Soluble fiber from food sources, for example from apples, produces short chain fatty acids (SCFAs) in the intestine. SCFAs have a number of positive effects on the body: they nourish the cells of the large intestine, stimulating healing. When absorbed from the intestine, they travel to the liver and can decrease the liver’s production of cholesterol, lowering cholesterol levels. That’s why eating oat bran, which contains fibers of moderate solubility can lower cholesterol levels. Within the intestinal canal, SCFAs can inhibit the growth of yeast and disease-causing bacteria.

Fiber may also help increase longevity and protect against the development of parasitic infection.  Excellent sources of mixed fibers are unrefined cereal grains (oats, brown rice, whole wheat), peas, beans and squash.

Among fruits, one gets the most fiber per serving from apples and berries.

Reference:

Nutr Rev. 2009 Apr;67(4):188-205. Health benefits of dietary fiber. Anderson JW, Baird P, Davis RH Jr, Ferreri S, Knudtson M, Koraym A, Waters V, Williams CL.

J Am Diet Assoc. 2008 Oct;108(10):1716-31. Position of the American Dietetic Association: health implications of dietary fiber. Slavin JL.

Erratum in: J Am Diet Assoc. 2009 Feb;109(2):350.

Crit Rev Food Sci Nutr. 2008 Nov;48(10):905-12. Dietary fiber in the prevention and treatment of metabolic syndrome: a review. Aleixandre A, Miguel M.