Dietary intake of B vitamins and methionine and risk of lung cancer

Background/Objectives: B vitamins and related enzymes involved in one-carbon metabolism are necessary for DNA replication, DNA repair and regulation of gene expression. Disruption of one-carbon mechanism may affect cancer risk. We investigated prospectively the relationship between dietary intakes of methionine, B vitamins associated with one-carbon metabolism and risk of lung cancer. Subjects/Methods: The Melbourne Collaborative Cohort Study recruited 41 514 men and women aged 40-69 years between 1990 and 1994. During follow-up of 14 595 men and 22 451 women for an average of 15 years, we ascertained 348 incident lung cancers. Dietary intake of B vitamins and methionine was estimated from a 121-item food frequency questionnaire. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox regression. Results: In current smokers, dietary intake of riboflavin was inversely associated with lung cancer risk (HR = 0.53; 95% CI: 0.29-0.94, fifth versus first quintile; P-linear trend = 0.01). No associations were found for former or never smokers or for dietary intake of any of the other B vitamins or methionine. Conclusion: Overall, we found little evidence of an association between B vitamins or methionine and lung cancer risk. The weak inverse association between riboflavin and lung cancer risk in current smokers needs further investigation. European Journal of Clinical Nutrition (2012) 66, 182-187; doi:10.1038/ejcn.2011.157; published online 31 August 2011