Like starch, fiber is composed of long polysaccharide chains but the body doesn’t easily break down the bonds that connect fiber molecules. Most fibers pass through the digestive system without being digested and absorbed so they don’t contribute energy to our diets. Fiber does have many health benefits for us though.
Dietary fiber is the non-digestible parts of plants that form the support structures of leaves, stems, and seeds
Functional fiber consists of non-digestible forms of carbohydrates that are extracted from plants or manufactured in a laboratory and have known health benefits. Functional fiber is added to foods and is the form found in fiber supplements. Some sources that you may see on nutritional labels are cellulose, guar gum, pectin and psyllium.
Total fiber is the sum of dietary fiber and functional fiber. Fiber is also classified according to its chemical and physical properties as soluble and insoluble.
Soluble fibers dissolve in water. They have a gel-like consistency when they are wet and are easily digested by bacteria in the colon. These fibers are usually found in citrus fruits, berries, oat products and beans. Research suggests that regular consumption of soluble fibers reduces the risk of cardiovascular disease and type 2 diabetes by lowering blood cholesterol and blood glucose levels. Examples of soluble fibers are pectins which can be found in thickening foods such as jam and yogurt, gums which are used as thickening, gelling and stabilizing agents, and mucilages which are also used as food stabilizers.
Insoluble fibers do not typically dissolve in water. They can’t be fermented by bacteria in the colon. They are generally found in whole grains such as wheat, rye and brown rice and are also found in a variety of vegetables. They are not associated with reducing cholesterol levels but are known for promoting regular bowel movements, alleviating constipation and reducing the risk for a bowel disorder called diverticulosis. Some examples of insoluble fibers are lignins which are found in carrots, and in seeds of fruits and berries. They are also found in brans and other whole grains. Cellulose is also another form of insoluble fiber. This is found in whole grains, fruits, vegetables and legumes. It is also added to foods as an agent for thickening and texturizing foods. Hemicellulose are primary components of cereal fibers and are found in whole grains and vegetables. Some of hemicelluloses are also classified as soluble fibers.
Benefits of fiber:
- May reduce the risk of colon cancer. Researchers believe fiber binds cancer-causing substances and speeds their elimination from the colon.
- Helps prevent hemorrhoids, constipation, and other intestinal problems.
- Reduces the risk of diverticulosis
- May reduce the risk of heart disease by delaying or blocking the absorption of dietary cholesterol into the bloodstream. Also, when soluble fibers are digested bacteria in the colon produce short chain fatty acids that may lower LDL cholesterol.
- May enhance weight loss because a high fiber diet causes a person to feel more full. Fiber absorbs water and expands in our intestine and slows the movement of food through the upper part of the digestive tract
- May lower the risk of type 2 diabetes because fiber slows the release of glucose to the blood, improving the body’s regulation of insulin production and blood glucose levels.
It is important to include dietary fiber into our diets simply because of the health benefits it includes. However, if you’re not used to eating a high fiber diet, start slowly by gradually incorporating these foods into your diet because they can cause bloating and gas.