Fiber Overview

Most people know that fiber is an important part of a healthy diet. Fiber has been found to have numerous health benefits, from supporting bowel regularity to lowering cholesterol. Fiber might also help prevent serious diseases such as diabetes and cancer.

When it comes to increasing fiber in your diet, think plants--grains, fruits and vegetables, and beans, seeds, nuts and legumes. 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.

There are 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, on the other hand, does not mix with liquid, and it passes through the digestive tract largely intact. Both types of fiber help maintain bowel regularity.

• Soluble fiber has been found to provide some additional health benefits. When eaten as part of a low-fat, low-cholesterol diet, soluble fiber can help lower cholesterol. Weaker and somewhat inconsistent evidence hints at a link between soluble fiber intake and a reduced risk of certain cancers, diabetes, digestive disorders, and heart disease.
  • Examples of foods high in soluble fiber include pears, Brussels sprouts, lima beans, Northern beans, and psyllium.

• 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 apples, beans (eg, black beans, navy beans, pinto beans), lentils, All Bran cereal, wheat germ, and brown rice.

Flaxseed, a source of both soluble and insoluble fiber, has being studied for its ability to lower cholesterol and decrease constipation. Researchers are also investigating whether these seeds have anti-cancer properties. Just one tablespoon of ground flaxseed provides 2.2 grams of total fiber, as well as 1.8 grams of alpha-linolenic acid, a type of omega-3 fatty acid.

It is easy to increase the fiber in your diet. The best option is to increase your consumption of fiber-rich foods--that way, you're getting your fiber as well as the other beneficial components of fruits and vegetables, whole grains, etc. Another option is to take fiber supplements, such as glucomannan and psyllium.

Here are a few ideas to help you get on track to 30 grams of fiber a day:

• 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.

A really important thing to keep in mind:

When you begin to increase the fiber in your diet, take it slow! Increasing too quickly can upset your intestinal tract and you may experience gas, bloating, cramps, or even constipation or diarrhea. By increasing your fiber intake just a few grams a day, your intestinal tract will have time to adjust. Other tips to help minimize upset include:

• Drink at least eight 8-ounce cups of water a day.
• Use enzyme products, such as Beano, to help you digest fiber.
• Do not cook dried beans in the same water in which you soaked them.

Health experts recommend eating a minimum of 20-30 grams of fiber daily. This includes both soluble and insoluble fiber. Most Americans eat about 11-15 grams a day—about half of what is recommended. A quick internet search will provide you with lists of how much fiber you can find in common foods.

American Dietetic Association website. Available at: http://www.eatright.org . Accessed February 19, 2009.

Fiber. American Heart Association website. Available at: http://www.americanheart.org/presenter.jhtml?identifier=4574 . Accessed February 19, 2009.

Flax—a healthy food. Flax Council of Canada website. Available at: http://www.flaxcouncil.ca/english/index.jsp?p=g1mp=nutrition. Accessed April 21, 2010.

Flaxseed. EBSCO Natural and Alternative Treatments website. Available at: http://www.ebscohost.com/thisTopic.php?marketID=15topicID=114. Updated February 2010. Accessed April 21, 2010.

Shamliyan T, Jacobs D, Raatz S, Nordstrom D, Keenan J. Are your patients with risk of CVD getting the viscous soluble fiber they need? Journal of Family Practice. 2006;9:761-769. EBSCO Consumer Health Complete website. Available at: http://www.ebscohost.com/thisTopic.php?marketID=15topicID=114. Published September 2006. Accessed April 20, 2010.