Smoking, Drinking May Reverse Anti-cancer effect of Beta-Carotene

Susan Aldridge, PhD

Smoking and drinking appear to reverse the anti-cancer effect of beta-carotene.
Whether vitamins can prevent cancer is a controversial question. Researchers at Dartmouth Medical School in the US now make an intriguing contribution to the debate with their study of the effect of smoking and drinking on the protective effect of beta-carotene against cancer.

Beta-carotene, a close relative of vitamin A, is the pigment that makes vegetables and fruits like peppers, carrots and tomatoes look orange or red. It is a highly effective antioxidant and could protect against cancer. In this study, people who had had colon polyps removed were given either: placebo, beta-carotene, beta-carotene plus vitamin C, beta-carotene plus vitamins C and E. The polyps are benign tumors which may develop into colorectal cancer.

The group of 864 people were followed up for recurrence of their polyps, and also questioned on their smoking and drinking habits. Among those who did not smoke or drink, beta-carotene supplementation was linked with a 44 per cent reduction in polyp recurrence. But those who smoked and also drank more than one drink a day had double the risk of recurrence. This suggests that smoking and drinking can actually reverse the protective effect of vitamins. However, this is a complex subject - more research is needed before we can be sure of the role vitamins play in the prevention of cancer.

Source Journal of the National Cancer Institute 21st May 2003

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