Ashwagandha, Withania somnifera, is an adaptogenic herb that belongs to the pepper family. It has an extensive, 4,000-year history of traditional use and is one of the most revered and widely used Ayurvedic herbs. Ashwagandha is believed to increase energy and overall health and longevity. Withanolides are key constituents of this herb and play an important role in ashwagandha's overall ability to promote physical and mental health. In animal studies, ashwagandha has been shown to support the activity of lymphocytes and macrophages, moderate occasional stress, enhance memory and cognitive function, provide neuroprotection by scavenging free radicals, and support thyroid function. A small human clinical trial demonstrated the ability of ashwagandha to support healthy glucose and lipid metabolism. In a double blind, placebo-controlled clinical trial involving 42 volunteers, a formulation including ashwagandha indicated its potential to help promote joint comfort, which may involve modulation of cyclooxygenase enzyme activity. Traditional uses for ashwagandha included support for healthy male sexual function. Ashwagandha should be avoided by pregnant women and by individuals allergic to plants in the nightshade family.