Improved Vascular Endothelial Function After Oral B Vitamins

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 (nϭ59) or (2) 001).In regression analysis, improved flow-mediated dilatation correlated closely with the reduction in free plasma homocysteine (rϭϪ0.26, Pϭ0.001), 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.

Folic acid improves endothelial dysfunction in type 2 diabetes - an effect independent of homocysteine-lowering

“…While previous studies have suggested that the benefits of folic acid on FMD are partly dependent on its homocysteine-lowering effect, 7,8 our present study suggests the effects are independent of homocysteine-lowering, confirming the findings of the other recent diabetic studies. 25,26 It has been realized that the oxidative stress of diabetes may lead to oxidation of tetrahydrobiopterin, an essential co-factor of eNOS, resulting in the uncoupling of the eNOS enzyme and a loss of NO availability.…”

“…Our FMD results demonstrate considerable inter-patient variation of FMD with a wide range of values noted with folic acid and placebo, which is similar to that seen in other studies which have used similar methodology. 7,8,21,23,25,[28][29][30] Despite this variability, our study was sufficiently powered to demonstrate the absolute 2.6% increase in FMD with as few as 18 patients in this cross-over design. 31,32 On the other hand, as our study was only powered according to the effect on FMD, this small sample size may have been insufficient to demonstrate a significant secondary effect on the inflammatory markers.…”

“…[7][8][9][10] However, when we started our study, there was limited information in subjects with diabetes mellitus. Using forearm plethysmography, van Etten et al 17 demonstrated that subjects with type 2 diabetes have impaired endothelium-dependent, serotonin-induced vasodilation and mildly reduced endotheliumindependent vasodilation in response to sodium nitroprusside.…”

“…[1][2][3]6 We and others have demonstrated that folic acid can significantly improve endothelium-dependent vasodilation in patients with coronary artery disease, [7][8][9][10] asymptomatic hyperhomocysteinemia, 11,12 and asymptomatic familial hypercholesterolemia. 13,14 While this benefit may in part be related to homocysteinelowering, 7,8 other studies suggest that the restoration of endothelial function by folates may be independent of its homocysteine-lowering effect. 10,14 In fact, 5-methyltetrahydrofolate, the active metabolite of folic acid, may have direct effects on uncoupled eNOS, which results in increased release of NO and decreased release of superoxide anion.…”

A növényi alapú étrendről

“…Nyolc héttel később megmérték a résztvevők teljes, a fehérjéhez kötött és a plazma homociszteinszintjeit, amelyek szignifikánsan csökkentek. Mindemellett javult a vizsgált egyének ereinek endothelfunkciója is [31].…”