PM2.5 exposure was associated with an 8.8% decrease in heart rate variability per 10-μg/m³ increase in [CT/TT] MTHFR carriers (P=0.047), an effect abrogated by higher B-vitamin intake.
Cohort (n=549)
Does dietary intake of methyl nutrients and related gene polymorphisms modify the effect of PM2.5 on heart rate variability in elderly men?
Genetic and nutritional variations in the methionine cycle can modify the adverse effects of PM2.5 air pollution on heart rate variability.
Effect estimate: 8.8% decrease (95% CI 0.2-16.7)
p-value: p=0.047
BACKGROUND: Particulate air pollution is associated with cardiovascular mortality and morbidity. To help identify mechanisms of action and protective/susceptibility factors, we evaluated whether the effect of particulate matter <2.5 mum in aerodynamic diameter (PM(2.5)) on heart rate variability was modified by dietary intakes of methyl nutrients (folate, vitamins B(6) and B(12), methionine) and related gene polymorphisms (C677T methylenetetrahydrofolate reductase MTHFR and C1420T cytoplasmic serine hydroxymethyltransferase cSHMT). METHODS AND RESULTS: Heart rate variability and dietary data were obtained between 2000 and 2005 from 549 elderly men from the Normative Aging Study. In carriers of CT/TT MTHFR genotypes, the SD of normal-to-normal intervals was 17.1% (95% CI, 6.5 to 26.4; P=0.002) lower than in CC MTHFR subjects. In the same CT/TT MTHFR subjects, each 10-mug/m(3) increase in PM(2.5) in the 48 hours before the examination was associated with a further 8.8% (95% CI, 0.2 to 16.7; P=0.047) decrease in the SDNN. In CC cSHMT carriers, PM(2.5) was associated with an 11.8% (95% CI, 1.8 to 20.8; P=0.02) decrease in SDNN. No PM(2.5)-SSDN association was found in subjects with either CC MTHFR or CT/TT cSHMT genotypes. The negative effects of PM(2.5) were abrogated in subjects with higher intakes (above median levels) of B(6), B(12), or methionine. PM(2.5) was negatively associated with heart rate variability in subjects with lower intakes, but no PM(2.5) effect was found in the higher intake groups. CONCLUSIONS: Genetic and nutritional variations in the methionine cycle affect heart rate variability either independently or by modifying the effects of PM(2.5).
Baccarelli et al. (Mon,) conducted a cohort in Cardiac Autonomic Dysfunction (n=549). Particulate matter <2.5 μm (PM2.5) vs. Lower PM2.5 exposure was evaluated on Decrease in SD of normal-to-normal intervals (SDNN) per 10-μg/m3 increase in PM2.5 in [CT/TT] MTHFR carriers (8.8% decrease, 95% CI 0.2-16.7, p=0.047). PM2.5 exposure was associated with an 8.8% decrease in heart rate variability per 10-μg/m³ increase in [CT/TT] MTHFR carriers (P=0.047), an effect abrogated by higher B-vitamin intake.