Beta-carotene supplements and cancer:
A review of 9 randomized controlled trials found that beta-carotene supplementation was not protective against primary cancer and may increase risk of lung and stomach cancers in smokers and asbestos workers. There was no statistically significant difference between the beta-carotene group and the placebo or no treatment group in the incidence of all-site cancer and of stomach, pancreas, colon-rectum, prostate, breast and skin cancers. However, the risk of lung cancer and stomach cancer were significantly higher in the beta-carotene at 20-30 mg day(-1)than the placebo group (relative risk [RR]=1.16 and RR=1.34, respectively). In subgroup analyses, among smokers and asbestos workers beta-carotene significantly increased the risk of all-site cancer (RR 1.08), lung cancer (RR 1.20) and stomach cancer (RR 1.54). In conclusion, beta-carotene supplementation should not be recommended for healthy individuals for the prevention of cancer. (10)