Relation of serum antioxidant vitamins to the risk of colorectal adenoma.

The relation between risk of colorectal adenoma and serum concentrations of vitamins A, C, E and carotene was examined in a population-based case-control study of 105 cases of colorectal adenoma and a similar number of hospital controls showing no polyps at colonoscopy and a second control group of population controls. There were no significant associations with serum concentrations of vitamins C and E and carotene. Serum concentrations of vitamin A were significantly inversely related to the risk of colorectal adenoma when cases were compared with both control groups. After adjustment for energy intake, smoking, alcohol, estrogen therapy, body-mass-index and social class the inverse association between vitamin A and colorectal adenoma was even more marked. For the highest versus the lowest quartile of serum levels the adjusted RR was 0.23 (0.07-0.73) in relation to hospital controls and 0.08 (0.02-0.25) in relation to population controls. These findings suggest that the risk of developing colorectal adenomas is reduced in those with high vitamin A levels.