Food intake of folate, folic acid and other B vitamins with lung cancer risk in a low-income population in the Southeastern United States.

PURPOSE: We prospectively examined associations of lung cancer risk with food intake of B vitamins involved in one-carbon metabolism and the use of folic acid-containing supplements among a low-income population of black and white adults in the Southeastern US. METHODS: Within the Southern Community Cohort Study, we included 1064 incident lung cancer cases among 68,236 participants aged 40-79 years at study enrollment. Food intake and the use of folic acid-containing supplements were assessed using a validated food frequency questionnaire at study enrollment. Multivariate Cox regression was used to estimate hazards ratios (HRs) and the 95% confidence intervals (CIs). RESULTS: Folate and/or folic acid intake from food were not associated with lung cancer risk; HRs (95% CI) for highest compared with lowest quartile were 1.08 (0.91-1.29) for total dietary folate, 1.00 (0.84-1.19) for food folate, and 1.09 (0.91-1.30) for food folic acid, respectively. Similarly, no associations were observed after stratifying by sex, race and smoking status, except for a positive association with total dietary folate intake among black women (HR 1.46, 95% CI 1.04-2.05 for the highest quartile compared with the lowest quartile, P trend = 0.02). Neither the use of folic acid-containing supplements nor food intake of vitamin B6, vitamin B12 and riboflavin were associated with lung cancer risk. CONCLUSIONS: Our findings do not support a protective effect of folate or folic acid for lung cancer prevention in a low-income population of black and white adults in the Southeastern US. Our finding of a positive association with total dietary folate intake among black women needs to be interpreted with caution and replicated in other studies.