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 homocysteine. Hcy levels are inversely related to blood concentrations of folate and can be lowered by folate supplements. The effect of oral folic acid on endothelial function was investigated in healthy adults with mild hyperhomocysteinaemia.


METHODS
Eighteen healthy subjects (Hcy > 13 micromol L-1 at entry), from a screening population of 890 volunteers, were entered into a randomised 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 trinitrate (GTN)-mediated brachial artery dilatation were measured by high resolution 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 Hcy (8.7 +/- 2.5 vs. 12.1 +/- 3.6 micromol L-1).


CONCLUSIONS
High dose folic acid supplementation enhances endothelium-dependent vascular function and lowers plasma Hcy. This provides preliminary evidence that folate may have beneficial cardiovascular effects in adults with mild hyperhomocysteinaemia.
Bellamy
M F
MF
Cardiovascular Sciences Research Group, Wales Heart Research Institute, University of Wales College of Medicine, Cardiff, UK.
McDowell
I F
IF
Ramsey
M W
MW
Brownlee
M
M
Newcombe
R G
RG
Lewis
M J
MJ
D000284:Administration, Oral; D000328:Adult; D001783:Blood Flow Velocity / Q000187:drug effects; D001916:Brachial Artery / Q000187:drug effects / Q000502:physiology; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology*; D005492:Folic Acid / Q000008:administration & dosage*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D012307:Risk Factors; D014652:Vascular Diseases / Q000209:etiology / Q000517:prevention & control; D014664:Vasodilation / Q000187:drug effects
D006710:Homocysteine; D005492:Folic Acid