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Improved vascular endothelial function after oral B vitamins: An effect mediated through reduced concentrations of free plasma homocysteine.

Abstract：

BACKGROUND:Hyperhomocysteinemia is an independent risk factor for coronary heart disease (CHD). Dietary supplementation with B vitamins lowers plasma homocysteine by up to 30%. However, little is known about the potential beneficial effects of homocysteine lowering on vascular function in patients with CHD. METHODS AND RESULTS:We investigated 89 men with CHD (aged 56 [range 39 to 67] years). Brachial artery flow-mediated dilatation (endothelium dependent) and nitroglycerin-induced dilatation (endothelium independent) were measured before and 8 weeks after treatment with either (1) folic acid (5 mg) and vitamin B(12) (1 mg) daily (n=59) or (2) placebo (n=30). Total, protein-bound, and free plasma homocysteine, serum folate, and vitamin B(12) were measured at baseline and at 8 weeks. Flow-mediated dilatation improved after treatment with B vitamins (2.5+/-3.2% to 4.0+/-3.7%, P:=0.002) but not placebo (2.3+/-2.6% to 1.9+/-2.6%, P:=0.5). Vitamin therapy lowered plasma concentrations of total homocysteine (from 13.0+/-3.4 to 9.3+/-1.9 micromol/L, P:<0.001), protein-bound homocysteine (from 8.7+/-2.8 to 6.2+/-1.4 micromol/L, P:<0.001), and free homocysteine (from 4.3+/-1.2 to 3.0+/-0.6 micromol/L, P:<0.001) and raised concentrations of serum folate (from 10.3+/-4.3 to 31.2+/-10.8 ng/mL, P:<0.001) and vitamin B(12) (from 314+/-102 to 661+/-297 pg/mL, P:<0.001). In regression analysis, improved flow-mediated dilatation correlated closely with the reduction in free plasma homocysteine (r=-0.26, P:=0.001), independent of changes in protein-bound homocysteine, folate, and vitamin B(12). Nitroglycerin-induced dilatation was unchanged after both B vitamins and placebo. CONCLUSIONS:Folic acid and vitamin B(12) supplementation improves vascular endothelial function in patients with CHD, and this effect is likely to be mediated through reduced concentrations of free plasma homocysteine concentrations. Our data support the view that lowering homocysteine, through B vitamin supplementation, may reduce cardiovascular risk.

journal_name

Circulation

journal_title

Circulation

authors

Chambers JC,Ueland PM,Obeid OA,Wrigley J,Refsum H,Kooner JS

doi

10.1161/01.cir.102.20.2479

subject

Has Abstract

pub_date

2000-11-14 00:00:00

pages

2479-83

issue

eissn

0009-7322

issn

1524-4539

journal_volume

102

pub_type

临床试验,杂志文章,随机对照试验

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Improved vascular endothelial function after oral B vitamins: An effect mediated through reduced concentrations of free plasma homocysteine.