Genetic, dietary, and other lifestyle determinants of plasma homocysteine concentrations in middle-aged and older Chinese men and women in Singapore.
BACKGROUND
Epidemiologic studies have identified the plasma homocysteine concentration as a risk factor for atherothrombotic vascular disease. There is little information on the distributions and determinants of homocysteine concentrations in Asian populations.


OBJECTIVE
The present study was designed to examine the relations between genetic and lifestyle factors and plasma homocysteine concentrations among Chinese in Singapore.


METHODS
Plasma total homocysteine, folate, vitamin B-12, and vitamin B-6 concentrations and genetic variation at the methylenetetrahydrofolate reductase (MTHFR) locus were measured in 486 Chinese men and women aged 45-74 y in Singapore. Data on dietary and other lifestyle factors were collected in face-to-face interviews.


RESULTS
Men had higher plasma concentrations of total homocysteine than women (P = 0.0001). Age was positively associated with plasma homocysteine in both sexes (P for trend = 0.0001). Plasma concentrations of folate, vitamin B-12, and vitamin B-6 were inversely associated with homocysteine concentrations. Among individuals with low plasma folate, those possessing 2 copies of MTHFR mutant alleles had significantly higher homocysteine concentrations than did those with > or = 1 copy of the wild-type allele. Cigarette smoking, daily coffee consumption, and physical inactivity were positively related to plasma homocysteine concentrations in both sexes (P < 0.05). However, these associations disappeared after adjustment for plasma folate concentrations.


CONCLUSIONS
Age, sex, plasma folate, vitamin B-12 and B-6 concentrations, and MTHFR genotype are independent determinants of plasma homocysteine in middle-aged and older Chinese in Singapore. These factors combined could account for up to 40% of the total variation in homocysteine concentrations in this Asian population.
Saw
S M
SM
Department of Community, Occupational, and Family Medicine, National University of Singapore.
Yuan
J M
JM
Ong
C N
CN
Arakawa
K
K
Lee
H P
HP
Coetzee
G A
GA
Yu
M C
MC
D000368:Aged; D000375:Aging / Q000097:blood*; D044466:Asian People / Q000235:genetics*; D015331:Cohort Studies; D015444:Exercise; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage / Q000097:blood; D005838:Genotype; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007407:Interviews as Topic; D008019:Life Style; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D008875:Middle Aged; D009154:Mutation; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000235:genetics; D011446:Prospective Studies; D011736:Pyridoxine / Q000008:administration & dosage / Q000097:blood; D012307:Risk Factors; D012737:Sex Factors; D012846:Singapore / Q000453:epidemiology; D012907:Smoking; D014652:Vascular Diseases / Q000453:epidemiology / Q000235:genetics / Q000517:prevention & control; D014805:Vitamin B 12 / Q000008:administration & dosage / Q000097:blood
D006710:Homocysteine; D005492:Folic Acid; D000587:Oxidoreductases Acting on CH-NH Group Donors; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D011736:Pyridoxine; D014805:Vitamin B 12