Ashwagandha (Withania somnifera) for the treatment and enhancement of mental and physical conditions: A systematic review of human trials

Abstract Ashwagandha is a medicinal plant that has been used in Ayurvedic and indigenous medicine for over 3,000 years. Because interest and the popularity of ashwagandha has increased in several Western countries, there are an increasing number of human trials evaluating its efficacy across a range of conditions. Based on the PRISMA guidelines, human trials assessing the effects of ashwagandha on mental and/or physical conditions, and/or human performance, used as a stand-alone or adjunct intervention, and delivered as a single ingredient, were eligible for inclusion in this systematic review. Forty-one studies were identified examining the effects of ashwagandha on stress and anxiety, sexual function and fertility, athletic performance, cognitive performance, pain, fatigue, thyroid function, schizophrenia, diabetes, obsessive-compulsive disorder, insomnia, hypercholesterolemia, and tuberculosis. Results from most of these studies indicated positive effects from ashwagandha intake, although treatment dose, duration, and extract types varied significantly. Moreover, trials often comprised of small sample sizes and were primarily conducted in India (32 studies). Overall, the strongest evidence for therapeutic efficacy of ashwagandha is the alleviation of stress and anxiety symptoms. The results from this systematic review suggest ashwagandha has a potentially large array of therapeutic applications. However, while promising, the significant heterogeneity across studies and the limited number of investigations means further research utilising robust and adequately-powered study designs are required.