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

PurposeTo evaluate the influence of alcohol consumption on the risk of colorectal cancer according to folic acid fortification period in the United States.MethodsWe 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.ResultsAlcohol 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.ConclusionsFolic acid fortification may attenuate the adverse effect of high alcohol consumption on the risk of colorectal cancer.