It is now generally accepted that dietary fiber is very important for our health and wellbeing. Its role as a natural laxative is well known but there is much more to fiber than that. Dietary fiber is key to the maintenance of a healthy intestine and this in turn will promote a feeling of wellness and vitality. Here, we will review why the consumption of adequate amounts of fiber is so important for our health.
What is fiber?
Fiber is a collective term applied to a group of carbohydrate compounds found exclusively in plants. There are two classes of dietary fiber; soluble fiber which dissolves in water, and insoluble fiber which does not. Both are important in our diet. Foods high in soluble fiber include apple pulp, citrus fruits, strawberries, oatmeal, barley, beans, peas, lentils and rice bran. Foods rich in insoluble fiber include apple skin, beets, Brussels sprouts, cabbage, carrots, cauliflower, whole wheat breads, bran and cereals.
Why is fiber important?
Here are 7 reasons why we should include plenty of fiber in our diet.
1) Weight Control. Our stomachs are conditioned to hold a certain weight or volume of food. The presence of fiber serves to reduce the calorie-density of food because it is not readily digested. So if we fill up with foods rich in fiber such as beans, peas, lentils, fresh fruits, vegetables and whole grain foods such as whole wheat bread, couscous, Bulgar wheat, and brown rice, we will have less room for high calorie foods such as cake and pie. (If you are allergic to wheat, you should avoid products containing it.)
2) Regularity. The presence of insoluble fiber in the intestine attracts water and this adds to bulk and stimulates the transit of unwanted material so that we are more regular. In this way, any toxins and carcinogens (cancer-causing substances) that might be present will be eliminated from our system more rapidly so they will have less time to be in contact with our body.
3) Removal of Excess Estrogens. The principal estrogen, estradiol, is removed from the circulation by the liver, chemically altered and sent down the bile duct into the intestine for disposal where it is escorted out of the body by dietary fiber. If there is not enough fiber present to retain the estrogen, it may be reabsorbed and reactivated. Excess estrogens in the circulation have been implicated in severe premenstrual syndrome (PMS) and in the genesis of hormonally-sensitive cancers such as breast cancer in post-menopausal women.
4) Bile Acid Control. Dietary fiber can influence the types of bacteria that live in the intestine and these in turn can reduce the production of carcinogenic secondary bile acids. The presence of fiber also serves to absorb and dilute bile acids.
5) Reducing Glucose Absorption. A diet high in fiber, particularly soluble fiber, has been shown to lower the rate of glucose absorption into the blood stream and this in turn lowers the rate of insulin production. A reduction in insulin production will lower the rate of fat formation.
6) Lowering Blood Cholesterol. Cholesterol is a component of bile acids which function in the digestive process. It is thought that soluble fiber increases the transit and expulsion of bile acids from the body and so more cholesterol is removed from the blood to manufacture replacement bile acids. It has been shown that 5-10 grams of soluble fiber per day reduces serum LDL-Cholesterol, the so-called “bad” cholesterol, by approx. 5%.
7) Promoting Intestinal Health. Although soluble and insoluble fiber are not digested by human enzymes, they can be fermented by friendly intestinal bacteria to yield simple organic acids that are a preferred energy source for the cells lining the intestine. One of these organic acids, butyrate, has been shown to have powerful anti-inflammatory properties and may protect against colon cancer. In addition, the intestine is richly supplied with nerves and is also a center of our immune system. Clearly, the health of these key elements will be optimized if the intestine itself is maintained in peak condition. The presence of fiber in our diet therefore promotes intestinal health and strengthens our immune and nervous systems, promoting overall well-being.
How Much Fiber?
Most people in the U.S. consume 10-15 grams of fiber per day and the American Diabetes Association, American Dietetic Association and National Cancer Institute recommend doubling this amount to 20-30 grams per day.
© Christopher J. Jones, M.Sc., Ph.D.
{ 1 trackback }
Comments on this entry are closed.