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. © 2012 Macmillan Publishers Limited. All rights reserved

Dietary intake of B vitamins and methionine and prostate cancer incidence and mortality

Purpose: We investigated prospectively the relationship between dietary intakes of methionine, B vitamins associated with one-carbon metabolism, and risk of incident and fatal prostate cancer. Methods: The Melbourne Collaborative Cohort Study recruited 41,514 people aged 40-69 years between 1990 and 1994. During follow-up of 14,620 men for 15 years on average, we ascertained 1,230 incident prostate cancers and 114 prostate cancer deaths. Dietary intakes were estimated using a 121-item food frequency questionnaire. Hazard ratios (HR) and 95 % confidence intervals were estimated using Cox regression. Results: For overall prostate cancer incidence, HRs for riboflavin intake were significantly increased relative to quintile 1 (except quintile 5), with a peak for quintile 3, HR 1.29 (1.07, 1.57). A similar but non-statistically significant pattern existed between riboflavin intake and prostate cancer mortality. The HR for folate intake and overall incidence was significantly increased for quintile 4, HR 1.21 (1.01, 1.46). No association was observed between prostate cancer mortality and the intake of either folate or any other B vitamin or methionine, and no observed association varied by tumor aggressiveness (all P homogeneity > 0.1). Conclusions: We found little evidence of association between dietary intakes of B vitamins or methionine and prostate cancer risk. Weak associations between prostate cancer incidence and dietary intake of riboflavin and folate, and between riboflavin intake and prostate cancer mortality, need corroboration by other studies. © 2012 Springer Science+Business Media B.V

Dietary intake of B vitamins and methionine and breast cancer risk

Purpose: We investigated prospectively the relationship between dietary intakes of methionine and B vitamins associated with one-carbon metabolism and breast cancer risk, including modification by age, hormone receptor status and alcohol consumption. Interactions between different B vitamins and methionine were also examined. Methods: During follow-up of 20,756 women from the Melbourne Collaborative Cohort Study for an average of 16 years, we ascertained 936 incident breast cancers. Dietary intakes were estimated using a 121-item food frequency questionnaire. Hazard ratios (HR) and 95 % confidence intervals were estimated using Cox regression. Results: We found weak evidence for an inverse association between breast cancer risk and riboflavin intake (fourth versus first quartile, HR Q4 vs. Q1 = 0.84 (0.69, 1.01); p linear trend = 0.05) and a positive association for vitamin B12 (HR Q4 vs. Q1 = 1.21 (1.00, 1.46); p linear trend = 0.06). We did not find any significant interactions between alcohol consumption and any of the B vitamins or methionine intake (all p interaction > 0.17) or between methionine or folate intake and any other B vitamins (all p interaction > 0.07). No association varied by tumor hormone receptor status (all p homogeneity > 0.14). Conclusions: We found weak evidence of an inverse association between breast cancer risk and riboflavin intake and a positive association with vitamin B12. © 2013 Springer Science+Business Media Dordrecht