those in the bran of wheat) that appear to have an effect on serum cholesterol. Indeed, studies have shown that guar gum, pectin, and oat bran—all soluble fibers—seem to lower LDL-cholesterol. The connection between high-fiber diets and fewer heart attacks is less clear. Some studies suggest that it is the low-fat content of high-fiber diets that reduces the risk of heart disease. Other studies, however, show that eating a diet high in fiber, regardless of its fat content, reduces the risk of developing heart disease. For now, the question of whether or not a high-fiber diet will protect you against heart disease remains unanswered. What is clear, though, is that a high-fiber eating pattern will help to lower your serum cholesterol and also help to lower your risk of heart disease.
Cancer of the large intestine is rare in Africa, where people eat diets high in fiber, which suggests that fiber may protect against colon cancer. But studies of groups of people who differ in the amount of fiber they eat have not proven this idea true. The conflicting results—some studies showed a protective effect and others showed no effect—may stem from the problems of comparing fibers from different sources.
Fiber, according to what you might read in magazines and newspapers, seems to be the one dietary component that affords some protection against nearly every chronic disease known. While that may, indeed, prove to be true, the scientific evidence so far is sketchy. Various studies have shown, for instance, that diets high in fiber may benefit people with noninsulin-dependent diabetes and may even help prevent this disease. Other studies have suggested that high-fiber diets can lower high blood pressure and reduce the chances of developing gallstones. But all of these studies focus on fiber-rich diets, not fiber itself. It may be that other components of