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?
What Are the Facts? ^
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.
How Much Fiber Do I Need? ^
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
How Do I Increase the Amount of Fiber in My Diet? ^
It is easier than you think 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.
- Try a whole grain cereal that contains at least 5 grams of fiber per serving. Slice a banana on top, or add some raisins or berries to increase the fiber even more.
- Sprinkle a few teaspoons of wheat germ, ground psyllium, or ground flaxseed on your food.
- Try eating some vegetables raw. Cooking can break down some of the fiber content. If you do cook vegetables, steam them lightly, so they are tender but still firm.
- Leave the skin on fruits and vegetables. Just make sure you rinse them well with warm water to remove any dirt or bacteria.
- Eat the whole fruit or vegetable instead of drinking the juice made from it. Juice does not contain the skin or membrane of the fruit or vegetable, and therefore its fiber content is substantially reduced.
- Try adding whole, unprocessed grain to your diet. Substitute brown rice for white rice. Or opt for whole wheat bread or pasta.
- Add beans to your soups, salads, and stews. Throw some beans on top of a salad or add lentils to soup while cooking.
- Snack on fresh and dried fruit. Chomp some raisins or dried apricots in the afternoon, instead of a bag of potato chips or pretzels.
Choose My Plate—US Department of Agriculture
Eat Right—Academy of Nutrition and Dietetics
Dietitians of Canada
Health Canada Food and Nutrition
Dietary guidelines for Americans 2010. US Department of Health and Human Services website. Available at: http://www.health.gov/dietaryguidelines/dga2010/DietaryGuidelines2010.pdf. Accessed January 14, 2015.
Dietary interventions for cardiovascular disease prevention. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated January 6, 2015. Accessed January 14, 2015.
Eat 3 or more whole grain foods every day. American Heart Association website. Available at: http://www.heart.org/HEARTORG/GettingHealthy/WeightManagement/LosingWeight/Eat-3-or-More-Whole-Grain-Foods-Every-Day_UCM_320264_Article.jsp. Updated February 24, 2014. Accessed January 14, 2015.
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 14, 2015.
Shamliyan T, Jacobs D, et al. 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, et al. Dietary fiber intake and mortality in the NIH-AARP diet and health study. Arch Intern Med. 2011;171(12):1061-1068.
Whole grains and fiber. American Heart Association website. Available at: http://www.heart.org/HEARTORG/GettingHealthy/NutritionCenter/HealthyDietGoals/Whole-Grains-and-Fiber_UCM_303249_Article.jsp. Updated January 7, 2015. Accessed January 14, 2015.
Last reviewed January 2015 by Michael Woods, MD Last Updated: 1/14/2015