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. [ABSTRACT FROM AUTHOR]