Live Well Vitamins & Lifestyle Guide

Fiber

Fiber is the general name for certain carbohydrates -- usually parts of vegetables, plants, and grains -- that the body can't fully digest. While fiber isn't broken down and absorbed like nutrients, it still plays a key role in good health.

There are two main types of fiber. They are soluble fiber (which dissolves in water) and insoluble fiber (which does not.) Combined, they're called total fiber.

Fiber Uses

A number of studies have found that a high intake of total fiber, from foods and supplements, lowers the risk of heart disease. High-fiber diets have also been associated with a reduced risk of type 2 diabetes.

Insoluble fiber adds bulk to stools. It helps treat constipation and diarrhea, and may benefit people with irritable bowel syndrome (IBS.) Some studies seemed to show that insoluble fiber could reduce the risk of colon cancer. However, larger and more recent studies have shown no benefit.

Soluble fiber seems to lower cholesterol levels. It binds with cholesterol in the intestines and prevents it from being absorbed.

Since fiber is filling and has very few calories, high-fiber foods may also help with weight loss. However, studies have not found that the fiber supplement ingredient chitosan -- which is marketed for weight loss -- is effective.

Fiber Dose and Instructions for Use

Fiber that comes from whole foods is called dietary fiber. Fiber that's sold in supplements, or added to fortified foods, is called functional fiber. The Institute of Medicine has set an adequate intake (AI) for total fiber, which includes all sources. Getting this amount of fiber should be enough to keep healthy. Doctors may recommend higher doses of fiber.

Even in high amounts, fiber seems safe. Experts have not discovered an amount of fiber that's harmful.

Fiber Food Sources

Most people in the U.S. take in much less fiber than they should. The best way to get it is from whole foods, like a variety of fruits, vegetables, and grains. Some good sources of soluble fiber include:

• Oatmeal and oat bran
• Apples, citrus fruits, and strawberries
• Beans, peas, and lentils
• Barley
• Rice bran

And some sources of insoluble fiber are:

• Whole grains, like barley
• Whole-wheat breads, wheat cereals, and wheat bran
• Vegetables like carrots, cabbage, beets, and cauliflower

Fiber Supplement Information

Many people rely on fiber supplements. They're often sold as pills, powders, and liquids and use different ingredients. One of the most common -- and best-studied -- is the husk of psyllium seeds. Ask your doctor what type of fiber supplement would be best for you.

Like any supplement, keep fiber supplements in a cool, dry place, away from humidity and direct sunlight.