HOMOCYSTEINE AND CORONARY-ARTERY DISEASE IN FRENCH-CANADIAN SUBJECTS - RELAXATION WITH VITAMINS B-12, B-6, PYRIDOXAL-PHOSPHATE, AND FOLATE

We determined plasma levels of homocysteine in 584 healthy subjects (3 80 men and 204 women) from a major utility company in the province of Quebec, Canada, and in 150 subjects (123 men and 27 women) with angiog raphically documented coronary artery disease (CAD) (age <60 years). P lasma levels of vitamins B-12, B-6, pyridoxal phosphate (a vitamin B-6 derivative), and folate were also determined. Mean homocysteine revel s were higher (p <0.05) in the bottom quartiles for folate, vitamin B- 12, and pyridoxal phosphate. A significant correlation was noted betwe en homocysteine levels and folate and vitamin B-12 levels. No signific ant correlation was found between plasma homocysteine levels and age, lipids and lipoprotein cholesterol, glucose, and the presence of hyper tension or cigarette smoking in healthy subjects or in patients with C AD. Control men had higher homocysteine levels than control women (p < 0.005). Men and women with CAD had higher levels of homocysteine than controls (11.7 +/- 5.8 vs 9.7 +/- 4.9 nmol/ml [p <0.001] and 12.0 +/- 6.3 vs 7.6 +/- 4.1 nmol/ml, p <0.01, respectively). Women and men with CAD had similar homocysteine levels. The proportion of patients with CAD having homocysteine levels >90th percentile of controls was 18.1% for men and 44.4% for women (both p <0.01). Significantly lower pyrido xal phosphate levels were seen in subjects with CAD, men and women com bined (27.7 +/- 29.5 vs 42.1 +/- 38.4 ng/ml, p <0.005). No significant differences were observed for B-12, folate, or total B-6. Multivariat e analysis reveals that an elevated homocysteine level is a risk facto r for CAD in French Canadian men and women and that reduced levels of pyridoxal phosphate, folate, and vitamin B-12 contribute to elevated p lasma homocysteine levels. We conclude that in our subjects of French Canadian descent, plasma levels of homocysteine are influenced by leve ls of folate, vitamin B-12, and pyridoxal phosphate. In healthy men, m ean homocysteine levels are higher than in healthy women. Men and wome n with CAD had significantly higher homocysteine levels than controls and this elevation is independent of traditional risk factors. Prospec tive studies are needed to determine the role of homocysteine in CAD. The influence of treatment of elevated homocysteine levels on cardiova scular morbidity and mortality must be assessed.