Vegetarian Diets : Can Veggies Prevent Cancer?

by Food and Drug Administration (FDA)

(Page 2 of 3)

The National Cancer Institute states in its booklet Diet, Nutrition & Cancer Prevention: The Good News that a third of cancer deaths may be related to diet. The booklet's "Good News" is: Vegetables from the cabbage family (cruciferous vegetables) may reduce cancer risk, diets low in fat and high in fiber-rich foods may reduce the risk of cancers of the colon and rectum, and diets rich in foods containing vitamin A, vitamin C, and beta-carotene may reduce the risk of certain cancers.

Part of FDA's proposed food labeling regulations, published in the Nov. 27, 1991, Federal Register, states, "The scientific evidence shows that diets high in whole grains, fruits, and vegetables, which are low in fat and rich sources of fiber and certain other nutrients, are associated with a reduced risk of some types of cancer. The available evidence does not, however, demonstrate that it is total fiber, or a specific fiber component, that is related to the reduction of risk of cancer."

As for increasing fiber in the diet, Joanne Slavin, Ph.D., R.D., of the University of Minnesota, in 1990 in, gives this advice: "Animal studies show that soluble fibers are associated with the highest levels of cell proliferation, a precancerous event. The current interest in dietary fiber has allowed recommendations for fiber supplementation to outdistance the scientific research base. Until we have a better understanding of how fiber works its magic, we should recommend to American consumers only a gradual increase in dietary fiber from a variety of sources."

FDA acknowledges that high intakes of fruits and vegetables rich in beta-carotene or in vitamin C have been associated with reduced cancer risk. But the agency believes the data are not sufficiently convincing that either nutrient by itself is responsible for this association.

Pointing out that plant foods' low fat content also confers health benefits, FDA states in its proposed rule that diets low in fat give protection against coronary heart disease and that it has tentatively determined, "Diets low in fat are associated with the reduced risk of cancer."

FDA notes that diets high in saturated fats and cholesterol increase levels of both total and LDL cholesterol, and thus the risk for coronary heart disease, and that high-fat foods contribute to obesity, a further risk factor for heart disease. (The National Cholesterol Education Program recommends a diet with no more than 30 percent fat, of which no more than 10 percent comes from saturated fat.)

For those reasons, the agency would allow some foods to be labeled with health claims relating diets low in saturated fat and cholesterol to decreased risk of coronary heart disease and relating diets low in fat to reduced risk of breast, colon and prostate cancer. "Examples of foods qualifying for a health claim include most fruits and vegetables; skim milk products; sherbets; most flours, grains, meals, and pastas (except for egg pastas); and many breakfast cereals," the proposed rule states.

Dwyer, in her article, summarizes these plant food benefits:

"Data are strong that vegetarians are at lesser risk for obesity, atonic [reduced muscle tone] constipation, lung cancer, and alcoholism. Evidence is good that risks for hypertension, coronary artery disease, type II diabetes, and gallstones are lower. Data are only fair to poor that risks of breast cancer, diverticular disease of the colon, colonic cancer, calcium kidney stones, osteoporosis, dental erosion, and dental caries are lower among vegetarians."

Death rates for vegetarians are similar or lower than for non-vegetarians, Dwyer reports, but are influenced in Western countries by vegetarians' "adoption of many healthy lifestyle habits in addition to diet, such as not smoking, abstinence or moderation in the use of alcohol, being physically active, resting adequately, seeking ongoing health surveillance, and seeking ... guidance when health problems arise."

Slow Switching

It's generally agreed that to avoid intestinal discomfort from increased bulk, a person shouldn't switch to foods with large amounts of fiber all at once. A sensible approach to vegetarian diets is to first cut down on the fattiest meats, replacing them with cereals, fruits and vegetables, recommends Jack Zeev Yetiv, M.D., Ph.D., in his book Popular Nutritional Practices: A Scientific Appraisal. "Some may choose to eliminate red meat but continue to eat fish and poultry occasionally, and such a diet is also to be encouraged."

Changing to the vegetarian kitchen slowly also may increase the chances of success.

"If you suddenly cut out all animal entr}es from your diet, it's easy to get discouraged and think there's nothing to eat," says lifelong veggie-eater Folkenberg. "I build my meals around a starchy carbohydrate such as pasta or potatoes. Even when I occasionally cook seafood, I center on the carbohydrate, making that the larger portion. Shifting the emphasis from animal to plant foods is easier after you've found recipes you really enjoy."

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.