Vitamin B6 Intake, Alcohol Consumption, and Colorectal Cancer: A Longitudinal Population-Based Cohort of Women

Background & Aims: Vitamin B6 has a crucial role in 1-carbon metabolism, which involves DNA synthesis and DNA methylation. Aberrations in these processes have been implicated in colorectal carcinogenesis. We examined the association between long-term dietary vitamin B6 intake and risk of colorectal cancer and whether this association is modified by consumption of alcohol, which may disrupt 1-carbon metabolism. Methods: Our study population comprised 61,433 women in the population-based Swedish Mammography Cohort. The women were aged 40 to 76 years, had no history of cancer, and completed a food-frequency questionnaire at baseline in 1987–1990. Dietary information was updated in 1997. During a mean follow-up of 14.8 years, 805 incident colorectal cancer cases were diagnosed. Results: After controlling for age and other potential confounders, long-term intake of dietary vitamin B6 was significantly inversely associated with risk of colorectal cancer (P value for trend = .002). Compared with women in the lowest quintile of vitamin B6 intake, those in the highest quintile had a 34% lower risk (multivariate rate ratio, 0.66; 95% confidence interval, 0.50–0.86). The association was most pronounced among women with moderate to high alcohol consumption. The multivariate rate ratio of colorectal cancer comparing extreme quintiles of vitamin B6 intake was 0.28 (95% confidence interval, 0.13–0.59) among women who consumed ≥30 g/wk of alcohol (approximately equivalent to 2 drinks per week). Conclusions: Findings of this study suggest that vitamin B6 may play a role in the prevention of colorectal cancer, particularly among women who drink alcohol.