We hear a lot about the virtues of eating foods such as fruits and vegetables that are high in fiber and know that there are two kinds of fiber, soluble and insoluble. Why are they good for us? What is the difference and are the effects of eating both the same?
Fiber is one of the major components of cell walls so we eat it every time we eat a vegetable or fruit. The human body can not digest the fiber and it passes through us without adding calories to our diet. Fiber may be of composed of insoluble substances such as lignin or cellulose that contribute structure to cells, or soluble substances such as pectin and natural gums that are the “ glue” that helps hold the insoluble fibers together. Insoluble fiber absorbs water, adds bulk to the mass of indigestible foods passing through the colon and helps move them and quickly through the digestive tract. Insoluble fiber also bonds with toxins and chemicals that damage DNA thus removing them from our bodies as they are excreted. Soluble fiber, on the other hand, dissolves during digestion, forms a gelatinous mass, and is partially broken down by bacteria in the colon into short-chain fatty acids that lower total and LDL cholesterol, thus reducing heart disease. The short-chain fatty acids also slow the rise of blood glucose after eating, especially important to diabetics. The operative bacteria also strengthen the immune system, increase mineral absorption, and inhibit the formation of polyps in the colon that can lead to colon cancer.
Both soluble and insoluble fiber are important to good health. The best sources of soluble fiber are legumes especially black beans, navy beans, and light red kidney beans, oatmeal, Brussels sprouts, oranges, and flaxseed. The best sources of insoluble fiber are wheat bran, All Bran cereal, legumes, especially lentils, and pinto, kidney, and navy beans, whole grains such as bulgar, shredded wheat, flax seed, okra, and the skins of fruits and vegetables. Many fruits and vegetables are good sources of both kinds of fiber and eating a wide variety of them is the best way to provide the body with what it needs.