Folic acid and vitamin B12 are more effective than vitamin B6 in lowering fasting plasma homocysteine concentration in patients with coronary artery disease.

Abstract

To investigate whether vitamin B(6) supplementation had a beneficial effect on lowering fasting plasma homocysteine concentrations in coronary artery disease (CAD) patients. A single-blind intervention study. The study was performed at the Taichung Veterans General Hospital, the central part of Taiwan. A total of 50 subjects were identified by cardiac catheterization to have at least 70% stenosis of one major coronary artery. In all, 42 patients successfully completed this study. Patients were randomly assigned to one of five groups and treated with a daily dose of placebo (n=8), 5 mg vitamin B(6) (n=8), 10 mg vitamin B(6) (n=8), 50 mg vitamin B(6) (n=9), or 5 mg folic acid combined with 0.25 mg vitamin B(12) (n=9) for 12 weeks. Nutrient intakes were recorded by using 24-h diet recalls when patients returned to the cardiology clinic before the intervention (week 0) and at week 12. Vitamin B(6) status was assessed by direct measures (plasma pyridoxal 5'-phosphate) and indirect measures (erythrocyte alanine and aspartate aminotransaminase activity coefficient). Fasting plasma homocysteine, serum folic acid, and vitamin B(12) were measured. Fasting plasma homocysteine concentration did not respond to high or low doses of vitamin B(6) when compared with a placebo treatment after 12 weeks of supplementation. The mean fasting plasma homocysteine concentration, however, decreased significantly after 12 weeks of folic acid combined with vitamin B(12) supplementation (P=0.047). Further, within group, mean fasting plasma homocysteine concentration was nonsignificantly increased by 25.5, 16.2, and 18.3% in placebo, 10 mg/day and 50 mg/day vitamin B(6) supplemented groups, respectively; whereas folic acid combined with vitamin B(12) supplementation significantly reduced fasting plasma homocysteine concentration by 32% (P<0.001). Our results indicate that vitamin B(6) supplementation alone is less effective than folic acid combined with vitamin B(12) in lowering plasma homocysteine concentrations in CAD patients. This study was supported by the National Science Council, Taiwan, Republic of China (NSC-91-2320-B-040-023).