Vitamins C, E, Beta-Carotene Do Not Reduce Cancer Risk
The many Americans who take high-dose supplements of antioxidant vitamins may be doing so in vain. Numerous research studies in 2008 showed that many vitamins that were thought to offer some protection from chronic diseases, such as cardiovascular disease and cancer, failed to do so.
In a new study adding to this growing body of evidence, researchers at Brigham and Women's Hospital show that supplemental vitamins C, E and beta-carotene also fail to provide protection against cancer for middle aged women. In this study, women who took beta-carotene or vitamin C or E or a combination of the supplements had a similar risk of cancer as women who did not take the supplements.
"Our finding is what is called a null result, meaning that no benefit was found from supplementation," said Jennifer Lin, PhD, a researcher at Brigham and Women's Hospital and lead author of the study. "However, this finding and other similar ones are still important not only because many Americans take vitamin supplements with belief that they are obtaining some benefit, but also because these findings help to shed light on both the causes of cancer and the prevention of it."
Previous research suggests that people whose diets are high in fruits and vegetables, and thus antioxidants, may have a lower risk of cancer, however; results from previous randomized trials that address the issue, rarely supported that observation. "Our study is another case where vitamin supplements failed to prevent against cancer," said Lin.
Lin and colleagues tested the impact of antioxidant supplements on the development of cancer in 8,171 women who were at high risk of cardiovascular disease. The women were randomly assigned to take vitamin C, vitamin E, or beta-carotene. After following the women for an average of 9.4 years, there was no benefit from taking the supplements compared with placebo in terms of the development of cancer or death from cancer
"Supplementation with vitamin C, vitamin E, or beta carotene does not appear to lower cancer incidence or deaths from cancer," said JoAnn Manson, chief of Preventive Medicine at Brigham and Women's Hospital and senior author on the paper. "Although a healthful dietary pattern rich in fruits and vegetables may lower cancer risk, such benefits cannot be mimicked by simply popping a few vitamin supplements."