A pilot study of 15 subjects will be conducted to confirm an acute effect of grape seed extract on endothelial function. We then will perform a a randomized, double blind, placebo controlled crossover study designed to investigate the benefit of grape seed extract/vitamin C treatment on endothelial function. Participants (n=40) will take a food supplement containing 450 mg of grape seed extract and 1500 mg of vitamin C or matching placebo for four weeks and then cross over to the alternative treatment (active supplement or placebo) for four weeks. We will examine endothelial function before and after each of the two treatment periods. The study will provide information about the vascular effects of these compounds.

Inclusion Criteria:

• Coronary artery disease

Exclusion Criteria:

• Pregnancy
• Clinical history of other major illness including end-stage cancer, renal failure, hepatic failure, gastrointestinal disorders that may impair absorption, or other conditions that in the opinion of the principal investigator make a clinical study inappropriate.
• Treatment with an investigational new drug within the last 30 days.
• History of a psychological illness or condition such as to interfere with the subject's ability to understand the requirements of the study.
• Vitamin E, Vitamin C, and beta carotene, lipoic acid, and other food or herbal supplements within 1 month of enrollment.