Influence of vitamin intake and MTHFR polymorphism on the levels of DNA damage in tobacco farmers

Background: Genetic damage may occur spontaneously under normal metabolic circumstances, inadequate intake of nutrients, and excessive exposure to environmental mutagens. Objectives: To evaluate the influence of the intake of micronutrients vitamin B-12, vitamin B-6, and folate and of the polymorphism methylenetetrahydrofolate reductase (MTHFR) C677T on the induction of DNA damage in tobacco farmers. Methods: The study involved 66 men and 44 women engaged in tobacco cultivation in the region of Venancio Aires (Rio Grande do Sul state, Brazil). Peripheral blood samples were collected to analyze DNA damage using the Comet assay, the micronucleus (MN) test and MTHFR C677T polymorphism. Dietary intake was evaluated based on the mean values obtained from three 24-h diet recall questionnaires, and nutrient intake data were computerized and estimated in the Food Processor SQL 10.9 program. The statistical tests used to generate the stated results were Kruskal-Wallis test, Exact Fisher's test, and multivariate linear regression analysis. Results: DNA damage was significantly higher in individuals who had an inadequate intake of folate, vitamin B-12, and vitamin B-6 (P<0.01) assessed by Comet assay. In relation to MN test results, buccal cells showed MN frequency higher in individuals with inadequate intake of vitamin B-6 (P<0.01). No difference was observed in MN lymphocytes frequency. No significant association was detected between MTHFR C677T polymorphism and DNA damage in tobacco farmers. Conclusion: Our results suggest that folate, vitamin B-12, and vitamin B-6 deficiency may be associated with genotoxic effect in individuals exposed to pesticides.