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. Numerous epidemiologic studies have established cardioprotective effects of tree nuts and the legume peanuts. Many clinical studies have been conducted to evaluate the effects of nut consumption on multiple risk factors for cardiovascular disease (CVD), and our research team has considerable experience in studying the effects of nuts on markers of cardiovascular risk (Kris-Etherton, Pearson et al. 1999; Kris-Etherton, Yu-Poth et al. 1999; West, Likos et al. 2002; Zhao, Etherton et al. 2004, under review). In the current medical literature, almonds and walnuts have been studied the most intensively. In contrast, less is known about other nuts, including pistachios. Pistachios are of particular interest because, compared to the other nuts, they have a unique nutrient and fatty acid profile. In particular, they are a good source of plant sterols, which have cholesterol lowering effects, and numerous antioxidants including vitamins E, beta-carotene and lutein, as well as selenium. They also are low in saturated fat and high in unsaturated fats. Because of this nutrient "package", it is likely pistachio consumption can significantly reduce multiple CVD risk factors. For example, dietary antioxidants are known to improve vascular reactivity, an important new marker of endothelial health (West 2001). Because of the increased level of plant sterols in pistachios, their cholesterol-lowering effect would be greater than predicted from the fatty acid profile alone. Taken together, the nutrients present in pistachios have previously been shown to have independent beneficial effects on lipid metabolism and vascular function. Our study would be the first to document that these effects occur with pistachios as a whole food source of phytosterols, antioxidants, and unsaturated fatty acids. This study is designed as a 3 period, randomized crossover with a run-in stabilizing diet period (2 weeks). Participants will be given all of their food for the diet periods and endpoints will be assessed at the end of each period (lipids, markers of inflammation and oxidative stress, vascular health, genetic profile for genes dealing with obesity, heart disease, fat metabolism). Data will be compared for each diet period to the end-of run-in values as well as between groups at end of diet period.