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Long-term effect of combined vitamins E and C on coronary and peripheral endothelial function
Scott Kinlay1, Dominik Behrendt, James C Fang
1Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA. skinlay@partners.org
Objectives:
We tested whether long-term administration of antioxidant vitamins C and E improves coronary and brachial artery endothelial function in patients with coronary artery disease (CAD).
Background:
Endothelial function is a sensitive indicator of vascular health. Oxidant stress and oxidized low-density lipoprotein (LDL) impair endothelial function by reducing nitric oxide bioavailability in the artery wall.
Methods:
We randomly assigned 30 subjects with CAD to combined vitamin E (800 IU per day) and C (1000 mg per day) or to placebos in a double-blind trial. Coronary artery endothelial function was measured as the change in coronary artery diameter to acetylcholine infusions (n = 18 patients), and brachial artery endothelial function was assessed by flow-mediated dilation (n = 25 patients) at baseline and six months. Plasma markers of oxidant stress (oxidized LDL and autoantibodies) were also measured.
Results:
Plasma alpha-tocopherol (p < 0.001) and ascorbic acid (p < 0.02) increased with active therapy. Compared to placebo, there was no improvement in coronary and brachial endothelial vasomotor function over six months. Although vitamins C and E tended to reduce F2-isoprostanes (p = 0.065), they failed to alter oxidized LDL or autoantibodies to oxidized LDL.
Conclusions:
Long-term oral vitamins C and E do not improve key mechanisms in the biology of atherosclerosis or endothelial dysfunction, or reduce LDL oxidation in vivo.