Cardiac autonomic dysfunction: effects from particulate air pollution and protection by dietary methyl nutrients and metabolic polymorphisms.
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]).


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
Andrea
A
Department of Environmental Health, Harvard School of Public Health, Boston, Mass 02215, USA. abaccare@hsph.harvard.edu
Cassano
Patricia A
PA
Litonjua
Augusto
A
Park
Sung Kyun
SK
Suh
Helen
H
Sparrow
David
D
Vokonas
Pantel
P
Schwartz
Joel
J
D000368:Aged; D000369:Aged, 80 and over; D001900:Boston / Q000453:epidemiology; D002316:Cardiotonic Agents / Q000494:pharmacology*; D016022:Case-Control Studies; D004032:Diet; D005492:Folic Acid; D005500:Follow-Up Studies; D020022:Genetic Predisposition to Disease; D005838:Genotype; D012696:Glycine Hydroxymethyltransferase / Q000235:genetics* / Q000502:physiology; D006329:Heart Conduction System / Q000187:drug effects / Q000503:physiopathology*; D006339:Heart Rate / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D008297:Male; D008685:Meteorological Concepts; D008715:Methionine; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics* / Q000502:physiology; D052638:Particulate Matter / Q000633:toxicity*; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors; D014803:Vitamin B Complex
D002316:Cardiotonic Agents; D052638:Particulate Matter; D014803:Vitamin B Complex; D005492:Folic Acid; D008715:Methionine; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D012696:Glycine Hydroxymethyltransferase; C520541:SHMT protein, human