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United States Department of Agriculture

Agricultural Research Service

Should You Take Nutrient Supplements to Reduce Cancer Risk?
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Cindy D. Davis

Colorectal cancer is one of the most common cancers in the United States. Approximately 130,000 new cases of colorectal cancer are diagnosed each year. Over 40 percent of that number die of this cancer each year. It has been estimated that three in every four cases of colon and rectal cancers could be prevented with healthier diets. Current research shows that colorectal cancer is linked to diets low in vegetables, fruits and dietary fiber, and high in fat, red meat, processed meat, sugar and alcohol.

Recent studies at the Grand Forks Human Nutrition Research Center have shown increased incidence of precancerous lesions in colons of copper-deficient rats when they are challenged with a carcinogen. Increased intestinal tumor incidence has also been seen in a mouse model for human genetic susceptibility to colon cancer when they are fed a copper deficient diet. These results indicate that deficient dietary copper is a risk factor for colon cancer susceptibility. These results have practical implications because more than 60% of the diets consumed in the United States do not contain the recommended amount of copper Does this mean that you should take copper supplements?

There is no magic pill that will help prevent cancer, but a healthy diet can. Supplements seem like an easy way to bolster vitamins, minerals and fiber in your diet, but research shows that consuming these nutrients in wholesome foods is the best way to achieve cancer protection. Many epidemiologic studies have consistently shown that diets high in beta-carotene, which is found in fruits and vegetables, protect against lung cancer. These observations prompted scientists to test the benefits of beta-carotene supplementation in three large intervention trials. In two of these trials, small, but statistically significant, increases in incidence and mortality from lung cancer were observed in the group that took beta-carotene supplements, particularly in people at higher risk for lung cancer, such as heavy smokers. In the third trial, no effect of beta-carotene was apparent. Thus, supplemental beta-carotene is not beneficial and even may be harmful.

There are many reasons to promote getting nutrients from foods rather than from pills. First, many compounds may work together in food that will not be found together in pills. Second, toxicities and nutrient imbalances are less likely to occur when nutrients are derived from foods. For example, high intakes of some nutrients may decrease absorption of other nutrients.

Third, there may be compounds in foods that are protective against cancer but haven’t been discovered yet. Finally, foods offer more than cancer protective substances- protein, carbohydrates and fat provide energy and tissue building capabilities. Therefore, dietary supplements are probably unnecessary, and possibly are not helpful, for reducing cancer risk.

Last Modified: 10/23/2006
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