Several studies have strongly suggested that antioxidants might significantly accelerate the spread of cancer among people who have the disease and increase the odds of getting cancer among people in high-risk groups. This might come as a shock to anyone used to reading about the health benefits of antioxidants such as vitamins C and E and beta-carotene. Research has suggested that antioxidants might protect our cells from certain types of damage, slowing the aging process and providing some defense against serious health problems, including heart disease.
Why would antioxidants also promote cancer? The most likely explanation is that they provide the same protection to cancer cells that they do to normal, healthy cells. In fact, cancer cells appear to benefit even more than normal cells. One study of more than 35,000 men over age 50 found that taking large doses of vitamin E increased their risk for prostate cancer by 17%…another study of more than 18,000 former smokers and workers exposed to asbestos found that taking large doses of beta-carotene and retinol (a form of vitamin A) increased their risk for lung cancer by 28%.
Bottom line: I would not take antioxidant supplements if I had been diagnosed with cancer…or was at high risk for cancer, perhaps because of family history or a long-term smoking habit. There is not enough evidence to state whether people who currently are healthy and not in a high-risk group are better or worse off if they take antioxidant supplements regularly. But everyone should continue to consume foods that contain antioxidants, such as berries, nuts and leafy green vegetables.