Vitamin supplementation has not been proven effective in the prevention of cancer. The components of food are also proving to be more numerous and varied than previously understood, so patients are increasingly advised to consume fruits and vegetables for maximal health benefits.

Vitamin D

Low levels of vitamin D is correlated with increased cancer risk. Whether this relationship is causal is yet to be determined.

Beta carotene

Beta-carotene supplementation has been found to increase slightly, but not significantly risks of lung cancer.

Folic acid

Folic acid supplementation has not been found effective in preventing colon cancer and may increase colon polyps