From The May 2001 Issue of Nutrition Science News

N-acetylcysteine Improves Blood Vessels

N-acetylcysteine (NAC), a relative newcomer to the supplement scene, might be recommended for atherosclerotic patients in light of new research conducted at the National Heart, Lung and Blood Institute, one of the National Institutes of Health in Bethesda, Md.

Researchers studied 16 patients whose average age was 50; nine were men. Seven of the patients had coronary atherosclerosis. Nine did not but were undergoing diagnostic cardiac catheterization for other reasons. All patients had coronary angiography performed after coronary artery blood-flow velocity was measured. The researchers determined coronary vascular resistance and blood flow from blood flow velocity, diameter, and arterial pressure. By testing both before and after the artery was infused with NAC, the researchers determined how the blood vessel responded to acetylcholine, nitroglycerine, and other compounds that produce vascular dilation.

In both normal and atherosclerotic heart vessels, NAC improved the ability of the blood vessels to relax, and increased the effectiveness of acetylcholine, which works by relaxing the lining, or endothelium, of blood vessels. NAC did not dilate blood vessels by itself or increase the response to substances such as nitroglycerine, which cause vasodilation by means other than endothelial response. Thus, the researchers found NAC improved the ability of the inside arterial layer to respond to environmental conditions by constricting or dilating.

Researchers suspect this is because NAC enhances the bioavailability of the relaxing substance nitric oxide, but because nitric oxide has a short half-life and cannot be measured by current methodology, they were unable to determine this directly. In addition, NAC may act as an antioxidant that protects nitric oxide destruction. The authors suggest NAC may be beneficial in treating acute and chronic atherosclerotic manifestations.

—The Journal of the American College of Cardiology 2001;37:117-23.