Expert Q&A

Daily fiber intake: How much is ideal?

How much fiber should I eat every day? Which foods have the most fiber?

-Sally from Ontario, Canada

Most nutrition experts recommend that most American adults consume 25-35 grams of dietary fiber daily. Some nutrition experts recommend even more fiber: 35-45 grams daily. Fiber is necessary to stimulate the wavelike contractions that move food through the intestine. Dietary fiber is indigestibe; it is the residue of the food we eat. Fruits, vegetables, grains, legumes, nuts and seeds are fiber-rich foods. High fiber foods are essential to your body’s health because they help to expand the inside walls of the colon to ease the passage of waste. As fiber passes through the intestine (undigested), it absorbs large amounts of water, to form softer and bulkier stools. This is why it is very important to drink plenty of water when consuming a fiber-rich diet. This prevents constipation and straining (helping to avoid or prevent hemorrhoids). Less pressure on the colon is beneficial in treating irritable bowel syndrome, diverticulosis and other digestive problems. Dietary fiber speeds up the time required to digest food and expel waste and harmful substances (toxins).

Foods or pills: which is best?

It is best to get fiber from natural foods, not fiber pills as they contain little fiber and can be addictive to the colon. Fiber-containing foods are much better choices as they not only provide fiber, but important nutrients as well.

What's the difference between soluble and insoluble fiber?

There are two primary types of dietary fiber: soluble and insoluble.  Soluble fibers are the fibers that bind dietary cholesterol and carry it out of the body as well as help to stabilize blood sugar by slowing the release of sugar into your bloodstream. Soluble fiber-rich foods include oatmeal, oat bran, flaxseeds, beans, strawberries, psyllium seed and fruit pectin (citrus fruits, apples). Insoluble fibers provide roughage that speeds the elimination of feces, decreasing the time that the body is exposed to harmful substances. Normal transit time is health-promoting because environmental and dietary toxins have less time to come in contact with the colon lining and therefore have less of a chance to be reabsorbed into your blood stream. Insoluble fiber is found in wheat bran, whole grain products, brown rice, nuts and in cellulose's from vegetables and fruits. Therefore, a fiber-rich diet (more than 25 grams) can help prevent constipation, and may decrease the risk of developing diseases of the colon, including colon cancer. Dietary fiber may also help protect against diabetes, heart disease and high blood pressure.

For further information on the benefits of a fiber helping lower your cholesterol see the following article from TheDietChannel: Fiber & Cholesterol: How Fiber Helps Lower Your Cholesterol.


American Dietetic Association Nutrition Fact Sheet: “Dietary Fiber: An Important Link in the Fight Against Heart Disease.” Available online at:

American Dietetic Association Nutrition Fact Sheet: “Go with Whole Grains for Fiber.” Available online at:

Michèle Turcotte, MS, RD/LDN
Contributing Expert

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