1. Dietary supplementation with vitamin E reduces ischaemic events in patients with established coronary artery disease and improves endothelial function in cholesterol-fed rabbits. We examined whether such dietary supplementation with vitamin E improves endothelial function in patients with mild hypercholesterolaemia and coronary artery disease.
2. Twenty patients (total cholesterol 6.8 ± 1.1 mmol/l, mean ± SD) with angiographically documented coronary artery disease were randomly allocated to receive placebo (n = 10) or vitamin E, 400 i.u. daily, (n = 10) for 8 weeks. Endothelium-dependent and independent vasodilatation within forearm vasculature was assessed by brachial artery infusion of acetylcholine (co-infused with saline vehicle and l-arginine) and nitroprusside before and after supplementation.
3. Plasma concentrations of vitamin E increased from 32.9 ± 3.8 to 69.1 ± 11.8 μmol/l (means ± SE) in the vitamin E-supplemented group (P < 0.01) but did not change significantly in the placebo group. Lipid profiles remained similar before and after supplementation in both groups. Forearm blood flow responses to acetylcholine (7.5 and 15 μg/min) and nitroprusside (3 and 10 μg/min) were similar before and after supplementation in both groups. Acute intra-arterial administration of l-arginine (10 mg/min) augmented the response to acetylcholine (15 μg/min) in both groups before and after supplementation to a similar degree (mean augmentation: 60 ± 18%, P < 0.01).
4. Acute administration of l-arginine reverses endothelial dysfunction in forearm vasculature of patients with mild hypercholesterolaemia and coronary artery disease but supplementation with vitamin E (400 i.u. daily) for 8 weeks does not reverse l-arginine-responsive endothelial dysfunction.