Fiber. You know you need to eat it. You are pretty sure it is good for you. But what is fiber, really? And why is it good for you?
Fiber is found only in plants. It is from the plant cells, particularly the cell walls. The plant fiber that we eat is called dietary fiber. It is unique from other components of the plant because humans lack the enzymes necessary to digest it.
Dietary fiber is made up of two types of fiber: soluble and insoluble. Soluble means that when the fiber is mixed with a liquid, it forms a gel-like solution. Insoluble fiber does not mix with liquid and passes through the digestive tract largely intact. Both types of fiber help maintain bowel regularity.
When eaten as part of a low-fat, low-cholesterol diet, soluble fiber can help lower cholesterol and may help lower your risk cardiovascular disease. Examples of foods high in soluble fiber include oatmeal, beans, peas, and citrus fruits.
Insoluble fiber is important for normal digestive health. Insoluble fiber speeds up movement through the small intestine and helps to alleviate constipation. Foods that are high in insoluble fiber include apple skin, wheat cereal, whole-wheat breads, and carrots.
The Academy of Nutrition and Dietetics recommends that women consume 25 grams of fiber daily, while men consume 38 grams. Fiber needs drop after the age of 50. Women older than 50 should consume 21 grams of fiber daily, and men should consume 30 grams daily. This includes both soluble and insoluble fiber. The following table lists how much fiber you can find in some common foods.
|Soluble Fiber||Insoluble Fiber|
|Broccoli, cooked||½ cup||1.5||1||0.5|
|Brussels sprouts, cooked||½ cup||4.5||3.0||1.5|
|Carrots, cooked||½ cup||2.5||1||1.4|
|Artichoke, fresh||½ cup||4||3||1|
|Citrus fruit (orange, grapefruit)||1 medium||2-3||1||1-2|
|Black beans, cooked||½ cup||5.5||2||3.5|
|Kidney beans, cooked||½ cup||6||3||3|
|Lima beans, cooked||½ cup||6.5||3.5||3|
|Navy beans, cooked||½ cup||6||2||4|
|Northern beans, cooked||½ cup||5.5||5||0.5|
|Pinto beans, cooked||½ cup||7||2||5|
|Lentils, cooked||½ cup||8||1||7|
|Peas, cooked||½ cup||6||1||5|
|Whole grain cereals|
|All Bran cereal||1/3 cup||8||0.7||7.3|
|Oatmeal, cooked||½ cup||2||1||1|
|Oat bran||½ cup||3||2||1|
|Shredded wheat||2/3 cup||3||0.3||2.7|
|Wheat germ||2/3 cup||8||1||7|
|Pearl barley, cooked||½ cup||5||2||3|
|Brown rice||½ cup||4||0.5||3.5|
|Psyllium seeds||1 tablespoon||6||5||1|
Source: Journal of Family Practice. 2006;9:761-769
It is easy to increase the fiber in your diet. It just takes a little thought and some action. Here are a few ideas to help you get on track to getting your daily recommended amount of fiber.
Academy of Nutrition and Dietetics
US Department of Agriculture Choose My Plate
Canada's Food Guide
Dietitians of Canada
Dietary guidelines for Americans 2010. US Department of Health and Human Services website. Available at: http://www.health..... Accessed January 31, 2013.
Eat 3 or more whole grain foods every day. American Heart Association website. Available at: http://www.heart.o.... Updated December 23, 2010. Accessed January 31, 2013.
Fiber. Academy of Nutrition and Dietetics website. Available at: http://www.eatright.org/Public/content.aspx?id=6796&terms=fiber. Updated January 2013. Accessed January 31, 2013.
Shamliyan T, Jacobs D, Raatz S, Nordstrom D, Keenan J. Are your patients with risk of CVD getting the viscous soluble fiber they need? J Fam Prac. 2006;9:761-769.
3/28/2011 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed/: Park Y, Subar AF, Hollenbeck A, Schatzkin A. Dietary Fiber Intake and Mortality in the NIH-AARP Diet and Health Study. Arch Intern Med. 2011 Feb 14. [Epub ahead of print]
Whole grains and fiber. American Heart Association website. Available at: http://www.heart.o.... Updated January 24, 2011. Accessed January 31, 2013.
Last reviewed January 2013 by Brian Randall, MD
Last Updated: 1/31/2013