Are you getting enough fibre in your diet? How many times have we as patients heard this question from our health care providers? Numerous studies have been conducted in the area of dietary fibre, and for the most part, a regular intake of fibre in our diets is crucial. Researchers claim that fibre can keep your bowel movements regular, decrease cholesterol levels and decrease the likelihood of colon cancer. But how?

Dietary fibre can be divided into two classes: soluble and insoluble. Soluble fibre has the ability to absorb water like a sponge, swelling and therefore increasing the bulk of the intestines' contents.1 Like soluble fibre, insoluble fibre increases the bulk of the intestines' contents, but does not have the capability to absorb water. Soluble fibre can be found in such foods as apples, pears, oats, barley, and beans. Wheat and wheat bran are excellent sources of insoluble fibre.

Almost everyone has experienced the uncomfortable feelings associated with constipation. Some individuals experience minimal symptoms of being bloated or gaseous. Yet others experience severe pains in the abdomen or anus. Although an increase in fibre is known to decrease the effects of constipation, the average American is still only consuming between 10-15g of dietary fibre per day as compared to the recommended 20-35g per day.2 (Canadian information was unavailable) One of fibre's actions is to increase the bulk of the intestinal contents thereby stimulating the bowel to contract. These bowel contractions are necessary for the movement of food along the intestines towards the anus for defecation. With little or no fibre in the diet, the intestinal contents are not as bulky and will not stimulate the bowel to contract as rapidly. The contents will be moved along the intestines at a much slower rate, leading to the uncomfortable condition of constipation. Insoluble fibre has the ability to accelerate the movement of food along the intestines. Therefore, an increase in insoluble fibre intakes is recommended to decrease constipation.

In addition to the positive effects fibre has on constipation, it also plays an important role in decreasing cholesterol levels in the body. Dietary fibre traps bile in the large intestine and the dietary fibre along with the bile are carried out of the body with the feces.1 Because cholesterol is needed to make bile, the excretion of bile effectively reduces blood cholesterol.1 Soluble fibre is the most effective at lowering blood cholesterol.

Fibre also has important anti-cancer causing effects. The current theory for these anti-cancer causing effects is that fibre either dilutes cancer-causing chemicals in the colon, or that it ushers the chemicals out before they can have prolonged contact with the colon wall, or both.2 Both insoluble and soluble fibre help to decrease cancer causing effects. Soluble fibre helps to attract these chemicals to it, and insoluble fibre aids in accelerating the movement of these chemicals out of the colon.

Although an increase in current average fibre intakes is essential, too much fibre can be detrimental. Excess fiber can lead to a reduction in energy intakes in some people. Since fibre holds little caloric energy value in our diets, a diet very high in fibre can run the risk of not accumulating enough caloric energy. In addition, for individuals who have health problems associated with decreased absorption of nutrients (e.g. Ulcerative Colitis), excessive insoluble fibre intakes can be problematic. Insoluble fibre can bind to nutrients, particularly minerals and interfere with their absorption.1 Therefore, for these individuals, decreased absorption of nutrients can further be complicated by an excess amount of insoluble fibre.

The key to optimal health is finding the right amount of dietary fibre that provides beneficial effects for your body without decreasing caloric intake or nutrient absorption. For most people this means eating 20-35g of dietary fibre daily.1 In addition to the recommended amount of fibre intakes, it is necessary to note that fibre should come from a variety of sources to ensure ingestion of both insoluble and soluble fibre. This will ensure optimal health results while decreasing the possibility of future health problems. As in any diet related matter, variety and moderation are key.