DIETARY FIBRE

Although classified as a Carbohydrate, fiber supplies no VITAMINS, MINERALS or even CALORIES. It does, however, play important roles in the body. Basically, there are two types of fibers: those that dissolve in water (water-soluble or, more simply, soluble fiber) and those that don't (water-insoluble or insoluble fiber). The other types are pectins, gums and mucilages.

Function

In the body, the water-soluble fibers -- pectins, gums and mucilages -- bind bile acids (the liver synthesizes these out of cholesterol), and as the acids are bound, cholesterol is withdrawn from the blood and converted to bile acids to replace the deficit. The cholesterol-lowering effect may be subtle; still, it reduces the risk of heart disease. Water-soluble fiber also lowers -- or at least stabilizes -- blood sugar (glucose) levels.

The two most common water-insoluble fibers, cellulose and lignin, bulk up stools and speed the passage of waste through the intestines, functions believed to prevent constipation and to reduce the risk of colon cancer.

Sources

Grains, brans especially wholemeal cereals, unpolished (brown) rice, fresh vegetables and fruits. No animal food (meat, eggs, milk, cheese, etc.) provides any fiber whatsoever.

Precautions

If you haven't been eating enough fiber, it's wise to increase your intake slowly. Doing so all at once can cause gas, bloating, diarrhea. It's also important to drink plenty of water when eating lots of fiber. Otherwise, you may irritate, even block your digestive tract.