The Importance of Fiber, Part 2

by Food and Drug Administration (FDA)

(Page 2 of 2)

As it passes through the gastrointestinal tract, soluble fiber binds to dietary cholesterol, helping the body to eliminate it. This reduces blood cholesterol levels, which, in turn, reduces cholesterol deposits on arterial walls that eventually choke off the vessel. There also is some evidence that soluble fiber can slow the liver's manufacture of cholesterol, as well as alter low-density lipoprotein (LDL) particles to make them larger and less dense. Researchers believe that small, dense LDL particles pose a bigger health threat.

Recent findings from two long-term large-scale studies of men suggest that high fiber intake can significantly lower the risk of heart attack. Men who ate the most fiber-rich foods (35 grams a day, on average) suffered one-third fewer heart attacks than those who had the lowest fiber intake (15 grams a day), according to a Finnish study of 21,903 male smokers aged 50 to 69, published in the December 1996 issue of Circulation. Earlier in the year, findings from an ongoing U.S. study of 43,757 male health professionals (some of whom were sedentary, overweight or smokers) suggest that those who ate more than 25 grams of fiber per day had a 36 percent lower risk of developing heart disease than those who consumed less than 15 grams daily. In the Finnish study, each 10 grams of fiber added to the diet decreased the risk of dying from heart disease by 17 percent; in the U.S. study, risk was decreased by 29 percent.

These results indicate that high-fiber diets may help blunt the effects of smoking and other risk factors for heart disease.

Obesity: Because insoluble fiber is indigestible and passes through the body virtually intact, it provides few calories. And since the digestive tract can handle only so much bulk at a time, fiber-rich foods are more filling than other foods — so people tend to eat less. Insoluble fiber also may hamper the absorption of calorie-dense dietary fat. So, reaching for an apple instead of a bag of chips is a smart choice for someone trying to lose weight.

But be leery of using fiber supplements for weight loss. In August 1991, FDA banned methylcellulose, along with 110 other ingredients, in over-the-counter diet aids because there was no evidence these ingredients were safe and effective. The agency also recalled one product that contained guar gum after receiving reports of gastric or esophageal obstructions. The manufacturer had claimed the product promoted a feeling of fullness when it expanded in the stomach.

An Apple a Day and More

Recent research suggests that as much as 35 grams of fiber a day is needed to help reduce the risk of chronic disease, including heart disease. A fiber supplement can help make up the shortfall, but should not be a substitute for fiber-rich foods. "Foods that are high in fiber also contain nutrients that may help reduce the risk of chronic disease," Saltsman notes. In addition, eating a variety of such foods provides several types of fiber, whereas some fiber supplements contain only a single type of fiber, such as methylcellulose or psyllium.

To fit more fiber into your day:

Read food labels. The labels of almost all foods will tell you the amount of dietary fiber in each serving, as well as the Percent Daily Value (DV) based on a 2,000-calorie diet. For instance, if a half cup serving of a food provides 10 grams of dietary fiber, one serving provides 40 percent of the recommended DV. The food label can state that a product is "a good source" of fiber if it contributes 10 percent of the DV — 2.5 grams of fiber per serving. The package can claim "high in," "rich in" or "excellent source of" fiber if the product provides 20 percent of the DV — 5 grams per serving.

Use the U.S. Department of Agriculture's food pyramid as a guide. If you eat 2 to 4 servings of fruit, 3 to 5 servings of vegetables, and 6 to 11 servings of cereal and grain foods, as recommended by the pyramid, you should have no trouble getting 25 to 30 grams of fiber a day.

Start the day with a whole-grain cereal that contains at least 5 grams of fiber per serving. Top with wheat germ, raisins, bananas, or berries, all of which are good sources of fiber.

When appropriate, eat vegetables raw. Cooking vegetables may reduce fiber content by breaking down some fiber into its carbohydrate components. When you do cook vegetables, microwave or steam only until they are al dente — tender, but still firm to the bite.

Avoid peeling fruits and vegetables; eating the skin and membranes ensures that you get every bit of fiber. But rinse with warm water to remove surface dirt and bacteria before eating. Also, keep in mind that whole fruits and vegetables contain more fiber than juice, which lacks the skin and membranes.

Eat liberal amounts of foods that contain unprocessed grains in your diet: whole-wheat products such as bulgur, couscous or kasha and whole-grain breads, cereals and pasta.

Add beans to soups, stews and salads; a couple of times a week, substitute legume-based dishes (such as lentil soup, bean burritos, or rice and beans) for those made with meat.

Keep fresh and dried fruit on hand for snacks.

"So many foods contain fiber that it's really not that hard to get your intake up where it should be," Saltsman says.

Slow Going

A word of caution: When increasing the fiber content of your diet, it's best to take it slow. Add just a few grams at a time to allow the intestinal tract to adjust; otherwise, abdominal cramps, gas, bloating, and diarrhea or constipation may result. Other ways to help minimize these effects:

• Drink at least 2 liters (8 cups) of fluid daily.
• Don't cook dried beans in the same water you soaked them in.
• Use enzyme products, such as Beano or Say Yes To Beans, that help digest fiber.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.