CLINICAL TRIAL: POTENTIAL HEALTH BENEFITS OF DIETARY ANTIOXIDANTS FROM SUPPLEMEN

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. BACKGROUND: A number of observational and experimental studies have shown that the recognized risk factors for atherosclerosis promote an inflammatory oxidative environment in the vasculature that is conducive to pathologic changes in the endothelium. Considerable evidence now exists that endothelial dysfunction both precedes and accelerates atherosclerosis. Antioxidant nutrients, including vitamin C, carotenoids, tocopherols and selenium, may therefore be presumed likely to contribute to a decrease of endothelial dysfunction and to diminish the incidence of cardiovascular events. However, the previous use of antioxidant supplements in clinical trials has yielded disappointing and controversial results. Despite the null trial findings, the use of dietary antioxidant vitamins continues to grow in the U.S. OBJECTIVE: In this revised application, our objective is to determine the short-term efficacy of foods naturally rich in antioxidants vs. supplemental pill antioxidants on markers of inflammation in generally healthy subjects at risk of atherosclerosis. DESIGN: This is a randomized, single-blind (diets)/double blind (supplements), parallel, feasibility study. Ninety adults with elevated risk factors for atherosclerosis and heart disease will be randomly assigned to either: 1) continue their usual diet and receive placebo pills (n=30 Usual/Plac), 2) continue their usual diet and receive antioxidant supplement pills (n=30 Usual/Supp), or 3) increase their consumption of antioxidant rich foods closely matched to antioxidant content of the supplement pills (n=30 Antiox-Food) for eight weeks. Data will be collected at baseline, four, and eight weeks. Primary study outcomes are markers of inflammation including C-reactive protein, fibrinogen, IL-6, TNF-alpha and soluble ICAM-1. Secondary outcomes include urinary isoprostanes. IMPLICATIONS: This study is designed to evaluate the responsiveness of novel markers of atherosclerosis to antioxidant interventions. Tests of inflammatory markers and endothelial function may provide a rapid and reliable methodology to assess the clinical outcome of antioxidant interventions at low cost and allow for fine tuning the choice of optimal combinations, sources and doses of antioxidants for future longer term and larger scale studies.