Low circulating folate and vitamin B6 concentrations: risk factors for stroke, peripheral vascular disease, and coronary artery disease. European COMAC Group.
BACKGROUND
A high plasma homocysteine concentration is a risk factor for atherosclerosis, and circulating concentrations of homocysteine are related to levels of folate and vitamin B6. This study was performed to explore the interrelationships between homocysteine, B vitamins, and vascular diseases and to evaluate the role of these vitamins as risk factors for atherosclerosis.


METHODS
In a multicenter case-control study in Europe, 750 patients with documented vascular disease and 800 control subjects frequency-matched for age and sex were compared. Plasma levels of total homocysteine (before and after methionine loading) were determined, as were those of red cell folate, vitamin B12, and vitamin B6.


RESULTS
In a conditional logistic regression model, homocysteine concentrations greater than the 80th percentile for control subjects either fasting (12.1 micromol/L) or after a methionine load (38.0 micromol/L) were associated with an elevated risk of vascular disease independent of all traditional risk factors. In addition, concentrations of red cell folate below the lowest 10th percentile (<513 nmol/L) and concentrations of vitamin B6 below the lowest 20th percentile (<23.3 nmol/L) for control subjects were also associated with increased risk. This risk was independent of conventional risk factors and for folate was explained in part by increased homocysteine levels. In contrast, the relationship between vitamin B6 and atherosclerosis was independent of homocysteine levels both before and after methionine loading.


CONCLUSIONS
Lower levels of folate and vitamin B6 confer an increased risk of atherosclerosis. Clinical trials are now required to evaluate the effect of treatment with these vitamins in the primary and secondary prevention of vascular diseases.
Robinson
K
K
Department of Cardiology, The Cleveland Clinic Foundation, Ohio 44195, USA. robinsk@ccsmtp.ccf.org
Arheart
K
K
Refsum
H
H
Brattström
L
L
Boers
G
G
Ueland
P
P
Rubba
P
P
Palma-Reis
R
R
Meleady
R
R
Daly
L
L
Witteman
J
J
Graham
I
I
D000328:Adult; D000704:Analysis of Variance; D001161:Arteriosclerosis / Q000097:blood; D001361:Avitaminosis / Q000097:blood; D016022:Case-Control Studies; D002561:Cerebrovascular Disorders / Q000097:blood* / Q000453:epidemiology*; D003327:Coronary Disease / Q000097:blood* / Q000453:epidemiology*; D005260:Female; D005492:Folic Acid / Q000097:blood*; D006710:Homocysteine / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D016491:Peripheral Vascular Diseases / Q000097:blood* / Q000453:epidemiology*; D011736:Pyridoxine / Q000097:blood*; D012307:Risk Factors; D014652:Vascular Diseases / Q000097:blood; D014815:Vitamins / Q000097:blood
D014815:Vitamins; D006710:Homocysteine; D005492:Folic Acid; D011736:Pyridoxine