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By Louis Neipris, M.D., HealthAtoZ writer
Fruits and vegetables are rich sources of antioxidants - those natural substances that are said to help ward off heart disease and cancer. There is still debate, though, on how beneficial antioxidants really are.
What are antioxidants?
Antioxidants are substances found in the diet and produced by the body. These substances help repair the damage to cell membranes and DNA caused by free radicals. This damage contributes to various disease processes. When free radicals interfere with cell growth, cancer could result. Vitamins and similar substances found in our diet are antioxidants, which disable the toxic effects of free radicals.
Antioxidants and specific cancers
There is conflicting evidence about whether or not vitamin supplements containing antioxidants can prevent disease. Vitamin A studies in smokers showed no protection against lung cancer. Another study showed that vitamins A and C might prevent adenomas (pre-cancerous polyps) in the stomach from progressing to cancer. Of all the antioxidants, perhaps one called lycopene is the most powerful. Lycopene is a member of the same chemical family as vitamin A (beta-carotene), and is found in tomato products. Studies have shown that it protects against prostate and colorectal cancers.
Does taking vitamins help fight heart disease?
It is clear that the body needs antioxidants and even produces its own. There is conflicting evidence about whether or not antioxidant vitamin supplements prevent heart (or any) disease. For example, the strong antioxidant vitamin E - once believed to be heart-healthy - may interfere with the effects of cholesterol-lowering drugs. No one study has presented overwhelming evidence favoring any one vitamin or antioxidant, let alone specific information about how much of that supplement is needed in our diets.
A balanced diet is still your best source of antioxidants.
Two and a half cups of vegetables and two cups of fruit supply all the antioxidants we need each day. However, most Americans take some kind of vitamins, which are probably beneficial, especially if their diets are deficient in required nutrients. Talk to your doctor first if you think you need to take vitamins, minerals or any dietary supplement. There are several commercial over-the-counter brands to choose from. However, while there are plenty of antioxidants in these pills, there is no clear added benefit over those supplied in a balanced diet.
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External Sources
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Houston, Denise K., et al. "Dairy, fruit, and vegetable intakes and functional limitations and disability in a biracial cohort: the Atherosclerosis Risk in Communities Study." Am. J. Clinical Nutrition 81 (Feb. 2005):515-522.
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Erhardt, J. et al. "Lycopene, beta-carotene, and colorectal adenoma." Am. J. Clinical Nutrition 81 (Dec. 2003) 1219-1224
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American Federation for Aging Research
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This article was reviewed and updated June 2007.
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