Last reviewed by Faculty of Harvard Medical School on August 28, 2012
By Julie Redfern, R.D., L.D.N.,
Fiber is the part of plant foods that the body cannot digest. It moves through the digestive system, absorbing water. This helps eliminate food waste from the body more quickly. Since fiber is not absorbed, it is not a nutrient. Rather, we refer to fiber as a "component" of food.
Fiber is found in plant foods such as fruits, vegetables, dry beans and peas, nuts, seeds, bread, and cereals. (It is not found in animal products meat, milk, eggs.) Fiber can also be added to foods during processing.
Fiber comes in two varieties: soluble, which dissolves in water, and insoluble, which does not. Although fiber does not nourish our bodies, it has other ways of promoting good health as the chart below illustrates.
How much fiber do you need each day? The current recommendation for adults is 20 to 35 grams. Children over age 2 should consume an amount equal to their age plus 5 grams a day, (So a four year old, for example, should get 9 grams a day). The average American falls short of the ideal and eats only 10 to 15 grams of dietary fiber a day.
To get more fiber add more fruits, vegetables, and whole grains in your diet with these easy tips:
Start slowly when you up your fiber intake. This will help relieve the bloating, cramping, and gas that some people experience when eating more fiber. Be sure to drink more water as well to help the fiber pass through the intestines more easily. Getting fiber naturally from foods assures you all of the other phytonutrients as well. Fiber-only supplements, however, are available for a fiber boost.
You can figure out how much fiber a food contains by reading the package label. Keep in mind that the amount of fiber listed is based on the serving size, not the entire package. Foods that are an excellent source of fiber contain 5 grams or more per serving. See the chart below for examples of the fiber content of various foods.
Juice is the concentrated form of fruit. Even though no sugar is added to the juice, it has more sugar than the whole fruit. Juice also lacks the fiber that naturally occurs in fruit. In general, the closer foods are to their natural, unprocessed state, the better. The chart below provides some examples:
Julie Redfern , R.D.,L.D.N. is a registered dietitian and manager of the Nutrition Consultation Services at Brigham and Women's Hospital. She specializes in nutrition counseling for the obstetrics and gynecology department. She is a graduate of the University of Vermont and completed her dietetic internship at the Universit of Cincinnati Medical Center.
Lauren Solomon is currently a dietetic intern at Brigham and Women's Hospital. She graduated from the University of Vermont.