Oral folate enhances endothelial function in hyperhomocysteinaemic subjects

Background Elevated plasma homocysteine (Hcy) is a risk factor for vascular disease. A postulated mechanism is vascular endothelial damage by homocyst eine. Hcy levels are inversely related to blood concentrations of folate an d can be lowered by folate supplements. The effect of oral folic acid on en dothelial function was investigated in healthy adults with mild hyperhomocy steinaemia. Patients and methods Eighteen healthy subjects (Hcy > 13 mu mol L-1 at entr y), from a screening population of 890 volunteers, were entered into a rand omised double-blind placebo-controlled crossover study of oral folic acid ( 5 mg daily for six weeks) with a six week interval between treatments. Flow -mediated (endothelium-dependent) and (endothelial-independent) glyceryl tr initrate (GTN)-mediated brachial artery dilatation were measured by high re solution wall tracking. Results Folate supplementation enhanced endothelium-dependent responses (+0 .08 +/- 0.05 vs. +0.04 +/- 0.04 mm, P = 0.015) but endothelium-independent responses (GTN) were unchanged. Folate reduced Hey (8.7 +/- 2.5 vs. 12.1 +/ - 3.6 mu mol L-1). Conclusion High dose folic acid supplementation enhances endothelium-depend ent vascular function and lowers plasma Hcy. This provides preliminary evid ence that folate may have beneficial cardiovascular effects in adults with mild hyperhomocysteinaemia.