Pistachio nuts (Pistacia vera L.) are a nutrient- and energy-dense food, and are a significant source of 15 different micronutrients. In addition to an excellent micronutrient profile, pistachios are a good source of monounsaturated and polyunsaturated fats (linoleic acid, oleic acid, and plant sterols). Pistachios have the lowest amount of total fat, and the highest protein, fiber, and phytosterol content compared to other nuts. They possess a high antioxidant content. Specifically, pistachios have high amounts of lutein, zeaxanthin, and phenolic compounds (e.g., anthocyanins, flavonoids, and proanthocyanidins). These aforementioned compounds are known for their anti-inflammatory effects. Pistachios also have been shown to reduce the risk of cardiovascular disease, metabolic syndrome, and all-cause mortality. The purpose of this study will be to determine the effects of consuming 1.5 ounces of pistachios per day compared to consuming no pistachios per day on inflammatory markers (creatine kinase, C-reactive protein, cortisol, Interleukin-8, tumor necrosis factor-alpha, copper-zinc superoxide dismutase, and glutathione peroxidase concentrations) and lean body mass in women and men, 40 to 60 years of age, who have been recreationally active for at least six months (exercising three to five days per week). It is hypothesized that pistachio consumption will significantly lower inflammatory response and significantly increase lean body mass. This will be a randomized study where participants will first complete a two-week baseline run-in period during which they will consume their typical diet. Following this, participants will be randomized to one of two groups for six months: consuming 1.5 ounces of pistachios per day or a control group (consuming no pistachios). Those consuming pistachios will be in addition to their usual diet. The overall goal of this study is to evaluate the effects of pistachio consumption on inflammatory markers and lean body mass in women and men, 40 to 60 years of age, who exercise three to five days per week. This study could provide a simple, healthy way for recreationally active individuals to decrease inflammation and improve body composition.