相关链接：PDF全文 Øyvind Bleie， Helga Refsum， Per Magne Ueland， Stein Emil Vollset， Anne Berit Guttormsen， Ebba Nexo， Jørn Schneede，Jan Erik Nordrehaug， and Ottar Nygård

Background: Vitamin B-6 is necessary for the metabolism of homocysteine and is often used in combination with folic acid and vitamin B-12 in clinical trials that investigate whether the lowering of plasma total homocysteine (tHcy) can prevent vascular disease.

Objective: We compared the effects of vitamin B-6 with the effects of folic acid and vitamin B-12， as used in the Western Norway B-vitamin Intervention Trial (WENBIT)， on basal and postmethionine load (PML) tHcy and cystathionine concentrations.

Design: Ninety patients with suspected coronary artery disease were randomly assigned to 1 of 4 groups to receive daily oral treatment with 1) 0.8 mg folic acid， 0.4 mg vitamin B-12， and 40 mg vitamin B-6 (group A); 2) 0.8 mg folic acid and 0.4 mg vitamin B-12 (group B); 3) 40 mg vitamin B-6 (group C); or 4) placebo (group D). For the first 2 wk， groups A and B received additional folic acid (5 mg/d). A methionine-loading test was performed at baseline and after 3 mo.

Results: Treatment with folic acid and vitamin B-12 caused a rapid and significant lowering of basal (31%) and PML tHcy concentrations (22%)， with no effect on cystathionine. Vitamin B-6 did not change basal tHcy and had a significant but limited effect on PML tHcy concentrations. However， vitamin B-6 treatment markedly lowered basal and PML cystathionine by 31% and 42%， respectively.

Conclusion: The folic acid and vitamin B-12 combination applied in WENBIT provides rapid， substantial， and long-term tHcylowering effects， whereas the effect of vitamin B-6 on tHcy was relatively small and confined to PML tHcy. However， vitamin B-6 treatment caused a marked reduction in plasma cystathionine. Cystathionine could be a useful marker for assessment of the vitamin B-6 effect and should， together with tHcy， be related to clinical outcome in ongoing trials. Am J Clin Nutr 2004;80:641– 8. KEY WORDS Homocysteine， cystathionine， folate， vitamin B-6， vitamin B-12， vascular disease， methionine loading