Understanding Fiber

Many people know that good health requires a balanced diet of carbohydrates, protein, and fats. But there is a fourth pillar to good health — fiber. It’s universally beneficial throughout our lives and, unfortunately, most of us don’t eat enough of it.

1. What is fiber?

Fiber is a complex carbohydrate found in fruits, vegetables, legumes, and grains. There are two types of fiber, soluble and insoluble. They are distinguished from other complex carbohydrates by the fact neither can be digested by the human body. Is this a good thing? Absolutely, and in fact, this is one of the main reasons why fiber is so healthy.

2. What does fiber do?

The better question is, “What does fiber not do?” Diabetes researchers have noted a relationship between an increasing level of dietary fiber and a decreasing level of risk for diabetes. Heart researchers point to a connection between higher dietary fiber intakes resulting in lower cholesterol and triglyceride levels. Fiber can affect blood pressure, too — a high fiber, high protein diet can significantly reduce blood pressure in people suffering from hypertension, according to published studies. The U.S. Federal Drug Administration (FDA) sanctions health claims on fiber-rich foods for fiber’s apparent role in reducing the incidence of some types of cancers. FDA consumer literature also points out the utility of fiber in a weight management program — fiber-rich foods are more filling than other foods so people tend to eat less.

3. How much fiber should we eat?

The World Health Organization recommends that adults consume a minimum of 25 grams per day and a maximum of 40 grams. This represents essentially 1 gram of fiber for every 100 calories you eat. Children should consume the equivalent of their age plus five — a ten-year old would consume 10+5 = 15 grams.

4. Sources of fiber

Good sources of insoluble fiber include whole wheat and wheat bran cereals, whole grain foods such as whole wheat or rye bread, brown rice, root vegetables, and fruit — particularly if the skin of the fruit is eaten. Good sources of soluble fiber include oat bran, oatmeal, dried beans, peas, lentils, psyllium, and pectin-rich fruits such as apples or citrus.

RESOURCES

1. Insel P, Turner ER, Ross D (ed.). Nutrition. Sudbury, MA. Jones and Bartlett Publishers, Inc., 2001.

2. Jalili T, et al. “Nutraceutical roles of dietary fiber.” Journal of Nutraceuticals, Functional, and Medicinal Foods. 2000;2(4):19-34.

3. Marlett JA, Slavin JL. Health Implications of dietary fiber: Position of ADA. Journal of American Dietetic Association. 1997;97:1157-1159.

4. U.S. Food and Drug Administration, FDA Consumer, Bulking up fiber’s healthful reputation , available at the USDA web site.