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, according to data from a randomized controlled trial in the Journal of the National Cancer Institute.
Previous studies have shown that people whose diets are high in fresh vegetables and fruit - sources of antioxidants - have a lower risk of cancer. As a result there have been several trials investigating the possible effects of widely marketed antioxidant supplements.
In this study, Jeniffer Lin, of the Brigham and Woman's Hospital and Harvard Medical School in Boston, USA and colleagues, investigated the effect of antioxidant supplements on the incidence of cancer. They looked at more than 7000 women, who were at high risk of cardiovascular disease, who were randomly assigned to take vitamin C, vitamin E or beta-carotene. Over 9.4 years of follow up there was no statistically significant different in the incidence of cancer between the women who took supplements and the control group. Overall, 624 women developed cancer and 176 died from cancer during the follow-up time.
'Supplementation with vitamin C, vitamin E, or beta carotene offers no overall benefits in the primary prevention of total cancer incidence or cancer mortality,' the authors conclude. 'In our trial, neither duration of treatment nor combination of the three antioxidant supplements had effects on overall fatal or nonfatal cancer events. Thus, our results are in agreement with a recent review of randomized trials indicating that total mortality was not affected by duration of supplementation and single or combined antioxidant regimens.'
