Ashwagandha

Men’s health: more strength from training is possible but not guaranteed. A maker-supplied trial in 57 men found larger bench press gains than placebo (Wankhede et al., Journal of the International Society of Sports Nutrition, 2015); a later trial found more strength but no extra lean mass on a body scan (Ziegenfuss et al., Nutrients, 2018).

Male fertility: better sperm quality is possible but not guaranteed. A review of four studies in men with fertility problems, one of them randomized, found higher sperm concentration and testosterone and called its data "too limited" (Durg et al., Phytomedicine, 2018). Harvard Health says "its impact on fertility was uncertain".

Stress: lower stress is possible but not guaranteed. Harvard Health Publishing (2026) says research studies support its traditional use for "stress management and better sleep". Pooled trials found lower stress scores at low certainty (Akhgarjand et al., Phytotherapy Research, 2022), and a 120-person trial found no difference from placebo (Smith et al., Journal of Psychopharmacology, 2023).

Sleep: better sleep is possible but not guaranteed. A company-funded trial in 150 healthy adults with unrefreshing sleep found better sleep quality than placebo after six weeks (Deshpande et al., Sleep Medicine, 2020).

Safety: a case series described 5 people who developed jaundice after starting it (Björnsson et al., Liver International, 2020), the US National Institutes of Health LiverTox database rates it a likely cause of liver injury, and Harvard Health lists prostate cancer and thyroid conditions among the reasons not to take it.