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Sorting out fiber.


As new forms of beneficial fiber proliferate, a noted medical expert explains how to make the most of fiber in your diet.

Few nutrition topics have attracted as much attention in recent years as fiber has. Newspapers, magazines, TV commercials, talk shows, and even cereal boxes regularly feature fiber. Food companies now offer a wide array of high-fiber cuisine, and new products enter the market weekly. Fiber has become a household word, but few of us really understand the potential health benefits of fiber.

Fiber Fights the Big Five

Fiber holds great potential to help prevent or treat many chronic diseases of our society. Fiber combats the five major causes of death and disability in the United States: heart disease, cancer, high blood pressure, obesity, and diabetes.

Interest in fiber first started in the early 1970s, when two researchers, Denis Burkitt and Hugh Trowell, introduced the dietary-fiber hypothesis--that fiber deficiency contributes to many Western diseases. Their observations of disease patterns among rural Africans compared to those of Western people stimulated many other researchers to confirm the health benefits of fiber.

Several scientists note that populations with high fiber intakes have low rates of heart disease. This relationship appears to be independent of fiber's effects on other heart disease risk factors, such as blood fat levels.

In a Netherlands study, men with the lowest fiber intake had a four times higher death rate from heart disease than men with the highest fiber intake. A fiber intake of at least 37 grams daily seemed to protect against heart disease.

In the same study, men with the lowest fiber intake also had three times as many deaths from cancer as men with the highest fiber intake. Other studies show that people with high cereal-fiber intake develop colon cancer less frequently than people with low cereal-fiber intake. Studies also link breast cancer to a high-fat, low-fiber diet.

Nutrition plays a role in about 35 percent of all cancers. The National Cancer Institute recommends that Americans increase their fiber intake to help protect against cancer.

High fiber intake may also help lower blood pressure. Vegetarians with high fiber intakes maintain lower average blood pressures than meat eaters with low fiber intakes. We lowered the blood pressures of 12 lean diabetic men by about 10 percent by feeding them a high-fiber diet.

Individuals with diabetes greatly benefit from high fiber intake. We first began treating diabetic individuals with high-fiber diets in 1974. Our own studies and those of others show that high fiber intake lowers blood sugar levels up to 40 percent and greatly reduces the need for insulin or diabetes pills in some individuals.

High fiber intake also lowers blood-fat levels in diabetic individuals. Maintaining normal blood-fat levels is especially important for them, because they experience three times the heart attacks and four times the strokes non-diabetic individuals do. The American Diabetes Association recommends that diabetic individuals double their fiber intake to up to 40 grams of fiber daily.

Obesity aggravates heart disease, high blood pressure, diabetes, and many other diseases. High-fiber meal plans contribute to weight loss and weight maintenance because they usually contain fewer calories, take longer to eat, give a feeling of fullness, and increase satiety. Individuals in our studies reported significantly more fullness and less hunger after high-fiber meals than after low-fiber meals.

What Fiber Can Do for You

Fiber's specific effects on the body fall into four categories: laxation, regularity, effects on blood cholesterol. Different types of fibers are more effective than others in each of these categories.

Fiber aids laxation and regularity by making stools larger, softer, and easier to pass. Wheat bran, which contains primarily insoluble fiber, has long been recognized for its ability to help prevent and treat constipation, diverticular disease, irritable bowel syndrome, and hemorrhoids. Psyllium fiber used in bulk laxatives and soy fiber have effects similar to the effects of wheat bran. Some gummy and highly water-soluble fibers, such as guar gum or pectin, lack this effect and can slow passage of the stool through the body.

Both soluble and insoluble fiber help improve blood sugar control in diabetic and nondiabetic individuals. Fiber smooths out the blood sugar curve, reducing the high and low swings in blood sugar after meals. Fiber also helps the body use the hormone insulin better, by letting blood sugar into the cells where it can be used for energy and growth.

Certain fibers effectively lower blood cholesterol levels. Wheat bran has little effect on cholesterol levels, but oat bran, soy fiber, psyllium, guar gum, and pectin lower cholesterol levels up to 20 percent. Research shows that for every one percent you lower your cholesterol level, you reduce your risk for heart disease 2 percent.

High-Fiber Foods

Try to eat a variety of foods to obtain a variety of fiber types, because each type of fiber offers unique health benefits. Fruits, vegetables, and whole-grain products are good sources of dietary fiber and provide the backbone for your high-fiber diet.

Fruits and vegetables contain both soluble and insoluble fiber; most whole-grain products contain primarily insoluble fiber. Much of the fiber in fruits and vegetables is in the peel, so leave it on whenever possible.

In addition to these basic fiber foods, certain foods particularly rich in fiber have specific health effects.

Oat products made with oat bran or oatmeal provide generous amounts of soluble fiber. Studies using Quaker oats show that including about one cup of oatmeal or oat bran per day in a typical Western diet lowers blood cholesterol levels 12 to 20 percent in a few weeks. Smaller amounts of oatmeal or oat bran, such as one-half to two-thirds cup, lower blood cholesterol levels up to 26 percent over several weeks.

Dried beans and peas, such as navy beans, kidney beans, pinto beans, chickpeas, and lentils, are also rich in soluble fiber. Including one-half to one cup of cooked dried beans or peas lowers blood cholesterol levels about 26 percent over the long term. Canned beans also lower blood cholesterol levels to a lesser extent.

Wheat bran and wheat-bran cereals provide generous amounts of insoluble fiber. These products have little effect on blood cholesterol, but they aid in laxation and regularity by increasing stool bulk and moisture content. They may also help protect against colon cancer and other bowel disorders.

Other cereal brans, such as corn bran, can be purchased at most health-food stores. These brans contain primarily insoluble fiber, and they have effects similar to wheat bran.

Concentrated Fiber Sources

Certain individuals may benefit from taking in concentrated forms of fiber as a complement to their high-carbohydrate, high-fiber, low-fat (HCF) nutrition plan. Psyllium, a fiber extract from the psyllium seed rich in soluble fiber, is widely used in bulk laxatives. Our research shows that two to three daily doses of the psyllium-containing laxative Metamucil reduce blood cholesterol 15 percent in men with high initial levels. Metamucil and Fiberall are well-accepted, and they have few side effects.

A new fiber source, Fibrim brand soy fiber, contains both soluble and insoluble fiber. Fibrim exerts all the beneficial effects of fiber, and it is well-accepted. It aids laxation and regularity, improves the body's ability to handle sugar, and reduces blood cholesterol levels.

Though Fibrim has only recently become available to the public, research with Fibrim began 15 years ago. Early studies showed that supplementing diets with 25 grams of Fibrim daily increased stool bulk and water content, improved blood sugar control, and produced no negative effects on vitamin or mineral balance in healthy college students.

Later studies showed that taking 25 grams of Fibrim daily reduced blood cholesterol levels 5 to 11 percent in individuals with high levels and an additional 5 percent in individuals already on a National Institutes of Health cholesterol-reducing diet. Fibrim also improved blood sugar control in diabetic individuals.

Guar gum and pectin are also available in several forms in health-food stores. Guar gum, an extract from the Indian cluster bean, is rich in soluble fiber. It lowers blood cholesterol levels about 10 to 15 percent and blood sugar levels about 13 percent. Pectin exerts a similar effect.

Guar gum and pectin produce such gastrointestinal side effects as nausea, cramping, and gas in some individuals. Both fibers slow passage of the stool through the body, and neither fiber increases stool bulk.

Alpha-cellulose, an insoluble fiber sometimes used in supplements, exerts little effect on blood sugar or blood cholesterol levels. Alpha-cellulose can increase stool bulk without increasing water content, making stools harder and more difficult to pass.

Getting Your Fiber In

A number of U.S. health organizations, including the American Dietetic Association, the American Diabetes Association, the Food and Drug Administration, and the National Cancer Institute, recommend that Americans increase their fiber intake to about 25 to 35 grams daily. On the average, Americans now eat only about 13 to 18 grams of fiber daily.

Increase your fiber intake gradually and include a variety of food sources daily. Try to eat at least three servings each of fruits and vegetables and six servings of starches and cereals daily. Use mostly whole-grain products, such as whole-wheat or rye bread or rolls, whole-wheat or rye crackers, whole-wheat pasta, brown rice, and whole-grain cereals.

In addition to these basic foods, emphasize other fiber-rich foods in your diet. Use dried kidney, navy, and pinto beans, as well as chickpeas and lentils, in soups, stews, casseroles, and salads. These foods, good protein sources, can substitute for meat dishes.

Use high-fiber cereals for breakfast and snacks. Oatmeal or oat bran can replace some flour in baked goods, and either can be used as a filler in casseroles, soups, or stews.

As mentioned earlier, some people, particularly those with heart disease or diabetes, may benefit from a higher fiber intake than the general public. Concentrated fiber sources may complement the positive effects of a high-fiber diet but should not replace one.

If you have difficulty getting all your fiber from food, you may want to use concentrated sources of fiber. Choose one that meets your health needs. Two to three doses of Metamucil daily can lower your cholesterol and aid with laxation and regularity. About four tablespoons (25 grams) of Fibrim soy fiber daily can lower your cholesterol, aid with laxation and regularity, and also help control blood sugar. You can use Fibrim in cooking much the same as oat bran.

Getting adequate fiber is one of the most important dietary steps you can take toward being heart smart. Focusing on fiber will also help you reduce your risk for developing cancer, diabetes, obesity, and high blood pressure--the other leading killers of our time.
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Title Annotation:HeartBeat; includes recipes
Author:Anderson, James W.
Publication:Saturday Evening Post
Date:Mar 1, 1990
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