Vitamin B6 intake, alcohol consumption, and colorectal cancer:: A longitudinal population-based cohort of women

Background & Aims: Vitamin 136 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 136 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 136 was significantly inversely associated with risk of colorectal cancer (P value for trend = .002). Compared with women in the lowest quintile of vitamin 136 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 136 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 136 may play a role in the prevention of colorectal cancer, particularly among women who drink alcohol.