Dietary fiber, sometimes called roughage, is a group of very complex carbohydrates – found mostly in plants – whose chemical structure prevents them from being digested by humans. Although some metabolism of fiber (by certain bacteria) occurs in the intestines, we lack the digestive enzymes needed to break down the bonds that hold together fiber’s sugar units. Therefore, fiber cannot be converted to glucose and contributes no calories to our diet. Most dietary fiber passes through the intestinal tract undigested.
Â Types of Fiber There are two basic types of dietary fiber:
- Soluble fiber
- Insoluble fiber
The best sources of fiber include beans, wholegrain cereals, fruits, vegetables and nuts. Examples of fiber include: Cellulose, Lignin, Hemicellulose, Pectin, Beta-glucans and Arabinose. Although insoluble fiber and its health benefits have been known for some time, the benefits of soluble fiber have only recently appeared.
Health Benefits However, although dietary fiber has no caloric or nutritional value, it does have significant health benefits and may assist weight control. Dietary fiber-deficiency in the average Western diet is now linked to a higher risk of digestive complaints (like constipation, diverticulosis), raised cholesterol levels and some intestinal cancers. Presence of dietary fiber in carbohydrate foods helps to slow digestion thus reducing their glycemic index and their affect on blood glucose levels.