Prospective study of alcohol consumption and the risk of colorectal cancer before and after folic acid fortification in the United States

Abstract

Purpose: To evaluate the influence of alcohol consumption on the risk of colorectal cancer according to folic acid fortification period in the United States. Methods: We evaluated the association between alcohol consumption and colorectal cancer by fortification period (before 1998 vs. after 1998) in 2 prospective cohort studies, the Nurses' Health Study (NHS) of women and the Health Professionals Follow-up Study (HPFS) of men, in which 2793 cases of invasive colorectal cancer were documented. Results: Alcohol consumption was associated with an increased risk of colorectal cancer. Among nonusers of multivitamins and/or folic acid supplements, the pooled multivariate relative risk for >= 30 g/d drinkers versus nondrinkers was 1.36 (95% confidence interval [95% CI], 1.09-1.70; P for trend, 0.02). The effect of alcohol consumption was slightly stronger in the prefolic acid fortification period (1980 NHS/1986 HPFS-1998) than in the postfortification period (1998-2008); the pooled multivariate relative risks for >= 30 g/d drinkers versus nondrinkers were 1.31 (95% CI, 1.00-1.71; P for trend, 0.10) in the prefortification period and 1.07 (95% CI, 0.69-1.65; P for trend, 0.67) in the postfortification period. Conclusions: Folic acid fortification may attenuate the adverse effect of high alcohol consumption on the risk of colorectal cancer.