Fiber 101

Fiber 101

Despite the fact that fiber doesn't contain any calories and has numerous health benefits, Americans tend to eat only about 15 grams per day, which is barely half of what is recommended. We believe that fiber is truly one of our best friends in health, so let us introduce you.

What is fiber?

Fiber is a broad term used to describe a really special group of carbohydrates. Unlike other forms of carbohydrate, fiber isn't something our bodies can digest—and the fact that it's indigestible gives it unique health properties compared with other nutrients. Although there are numerous types of fiber, the two main types are insoluble and soluble1,2.

Insoluble fiber

Insoluble fiber does not dissolve readily in water. It includes cellulose, hemicellulose, and lignins and is found mostly in the bran portion of whole grains such as brown rice and wheat.

Soluble fiber

Soluble fiber tends to swell and form a gel when mixed with water (such as in your intestine) and includes pectins, gums, and mucilages. Bacteria in the large intestine also easily metabolize soluble fiber. Oats, apples, bananas, barley, and many beans are great sources of soluble fiber.

Health benefits of fiber

  • Intestinal health Since your body cannot digest it, fiber travels through the intestine attracting water along the way. This causes the stool to enlarge and soften, which enhances your body's natural process of elimination. If you eat too little fiber, the result can be constipation or even diverticulosis3.
  • Cardiovascular health A diet high in soluble fiber, like that found in oats and oat bran, can help reduce cholesterol levels and promote cardiovascular health. The way this actually works is amazing. As soluble fiber passes through the digestive system, it binds up bile acids and removes them from the body. As it turns out, the body (actually the liver) makes bile acids from cholesterol. So, in order to make new bile acids, the liver pulls cholesterol from the bloodstream, thereby lowering the cholesterol level in your blood. Soluble fiber can also bind up or trap some of the cholesterol from your diet, which can prevent cholesterol from entering the bloodstream in the first place2,4.
  • Blood sugar control A diet high in fiber can help slow the absorption of glucose (blood sugar) from the small intestine into the bloodstream. This effect can help manage blood sugar levels, which is essential to good health1,2.
  • Weight control High-fiber foods help you feel full longer. Since weight loss ultimately boils down to reducing calories (and hopefully burning more with exercise, too), eating fiber helps you do it in a way that's still satisfying1,2.

How much fiber do you need?

The Institute of Medicine recommends that women age 50 and younger eat at least 25 grams of total fiber per day, and men in the same age group at least 38 grams per day. Women over age 50 should eat at least 21 grams per day, and men over 50 at least 30 grams per day 5.

Fabulous fiber sources

When it comes to fiber sources, plant foods really shine. Whole grains and beans are perhaps the most often overlooked terrific sources of fiber. Fruits and vegetables are also great choices when trying to increase your fiber fill. Keep in mind that animal foods, for the most part, are devoid of any fiber.

1 Marlett JA, McBurney MI, Slavin JL, et al. Position of the American Dietetic Association: health implications of dietary fiber. J Am Diet Assoc 2002;102(7):993-1000.
2 Anderson JW, Baird P, Davis RH, et al. Health benefits of dietary fiber. Nutr Rev 2009;67(4):188–205.
3 US Department of Health and Human Services. National Institute of Diabetes and Digestive and Kidney Diseases. Constipation. Bethesda, MD. Accessed January 23, 2013.
4 Brown L, Rosner B. Willett WW. Sacks FM. Cholesterol-lowering effects of dietary fiber; a meta-analysis. Am J Clin Nutr 1999;69(1):30-42.
5 US Department of Agriculture and US Department of Health and Human Services. Dietary Guidelines for Americans 2010. 7th edition. Washington, DC: US Government Printing Office. 2010;1-122.

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