Vitamin supplements fail new cancer test
Wednesday December 31st, 2008
Vitamin supplements may not offer any protection against cancer, according to a large study.
In the study, women who took vitamin supplements had similar rates of cancer to women who took placebo tablets. Previous research has indicated that a diet high in fruits and vegetables may prevent the development of cancer. But the results from trials of antioxidant supplements have been mostly negative.
Dr Jennifer Lin of Harvard Medical School in Boston, USA, and colleagues carried out a trial on 8,171 women. The participants took either vitamin C, vitamin E, or beta carotene regularly, or placebo.
After approximately nine and a half years, there had been 624 cases of cancer, leading to 176 deaths. But "there were no statistically significant effects of use of any antioxidant on total cancer incidence", say the researchers in the Journal of the National Cancer Institute.
They report that, compared with the placebo group, women taking each of the three tablets alone had a statistically similar risk of cancer. The same was true for women taking all three antioxidants combined.
The team conclude that supplementation with these compounds "offers no overall benefits in the primary prevention of total cancer incidence or cancer mortality."
However, there was a link between vitamin E supplementation and reduced risk of colon cancer, and a higher lung cancer risk in the beta carotene group, points out Dr Demetrius Albanes of the US National Cancer Institute, in an accompanying editorial.
"Null trials or those with unexpected outcomes should not be viewed as failures; they have and will continue to shed light on the causes of cancer and help us discover the means for its prevention," he concludes.
Lin, J. et al. Vitamins C and E and Beta Carotene Supplementation and Cancer Risk: A Randomized Controlled Trial. The Journal of the National Cancer Institute, Vol. 101, January 7, 2009, pp. 14-23.
Albanes, D. Vitamin Supplements and Cancer Prevention: Where Do Randomized Controlled Trials Stand? The Journal of the National Cancer Institute, Vol. 101, January 7, 2009, pp. 2-4.
Tags: Cancer | North America | Nutrition & Healthy Eating
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