How we rate
“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.
Ashwagandha
An adaptogenic herb from Ayurvedic medicine, studied for stress management, sleep, and recovery.
Benefits
- Reduces stress and anxiety compared to placebo (meta-analysis of 12 randomized trials, 1,002 participants); the effect on stress is concentrated between 300 and 600 mg per day
- Improves sleep quality and morning alertness in 65-80 year olds at 600 mg per day for 12 weeks (placebo-controlled trial)
- Combined with weight training, increases bench press strength more over 8 weeks: +46 kg compared to +26.4 kg under placebo, with better muscle recovery
Precautions
Not recommended in case of pregnancy, breastfeeding, autoimmune disease, or thyroid disorder. Possible interactions with sedatives. Liver damage has been reported: five cases in Iceland and the United States, with jaundice appearing after 2 to 12 weeks of use and liver tests returning to normal within 1 to 5 months in four of them; in India, three deaths in patients who already had chronic liver disease. If you have a liver disease, this is the most serious known risk; jaundice or itching while taking it should cause you to stop and consult a doctor. The authors of the meta-analysis on stress and anxiety themselves judge the certainty of the evidence to be low, and a trial with another extract (200 mg twice a day) did not reduce perceived stress compared to placebo.
Recommended dosage
300 to 600 mg of standardized root extract per day
How to take it
- For stress: 300 to 600 mg of extract per day. This is the range where the meta-analysis of 12 trials locates the favorable effect on stress.
- For sleep: 600 mg of root extract per day, in a trial conducted in people aged 65 to 80.
- For strength, with weight training: 300 mg twice a day for 8 weeks in one trial, 500 mg per day of an aqueous extract in another.
- For endurance: 500 to 600 mg of extract per day, the best-supported dose according to the 2026 meta-analysis on physical performance.
- For memory and attention: 225 to 400 mg of extract per day for 30 days, in stressed adults.
- How long: allow several weeks. Trials last from 30 days to 8 weeks; in just 8 days, handball players only gained grip strength.
- In one or two doses: the strength trial split the dose in two (300 mg twice a day). No study in this file compares one dose to two, morning to evening, or during versus outside of meals.
- The extract matters: each trial uses a specific standardized extract, and what is observed with one does not necessarily apply to another.
- Long-term: data is lacking. The 2024 meta-analysis on stress estimates that the safety of prolonged intake still needs to be studied.
Did you know?
A low dose of Ashwagandha (30 mg/day), derived from an optimised root extract, has been shown to significantly improve cardiorespiratory fitness and delay the onset of fatigue in healthy adults.
What the studies say
This meta-analysis summarised the evidence on the effects of oral ashwagandha supplementation on physical performance. The findings suggest that ashwagandha may improve overall physical performance, particularly aerobic endurance, although the benefits are not consistent. A dose of 500 to 600 mg of extract per day is the one most strongly supported by the evidence.
Li X, Li H, Yao S, Hou Y, Chi A. — Nutrients (2026) — View the source study
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more