Does ashwagandha work for stress and strength?

Ashwagandha (Withania somnifera) is one of the most studied herbal supplements, and two questions are worth separating: stress and physical performance.

The evidence is strongest for stress. A systematic review and meta-analysis by Akhgarjand and colleagues pooled twelve randomized trials with just over a thousand participants and found that ashwagandha lowered both self-rated stress and anxiety compared with placebo. At the same time the variation between studies was very large, and the authors judged the certainty of the evidence to be low and called for more high-quality trials. A typical single study looks like Salve's eight-week trial in stressed adults, where a root extract reduced stress scores and cortisol and improved sleep at 250 and 600 mg per day. The effects recur, but they are measured over the short term and with questionnaires that are sensitive to expectation.

For strength and performance the support is weaker. A Bayesian meta-analysis by Bonilla and colleagues reviewed thirteen trials and concluded that ashwagandha performed somewhat better than placebo on strength, fitness and recovery in healthy people. But the studies were small, their quality mixed, and several of the researchers had ties to companies that sell the product. Their own conclusion was that more comparable studies are needed before the effect can be called certain.

Taken together: a plausible short-term effect on stress markers, weaker and less certain support for strength, and thin long-term and safety data.

A supplement always has someone who profits from every bottle, and ashwagandha is sold as a shortcut to calm. The word adaptogen sounds scientific but isn't a regulated term, which makes it easy to promise a lot while promising nothing specific. Much of the research is also funded by or tied to the manufacturers, and stress is usually measured with questionnaires that are especially sensitive to expectation: someone who bought something to feel better tends to rate themselves better. Add a fast wellness trend where personal testimonials outweigh confidence intervals, and a modest, low-certainty finding turns into a confident promise.

If you want to try it, the effect is modest and short-term at best, mainly on perceived stress and sleep. Trials usually use a standardized root extract of around 300–600 mg per day. Don't expect it to do the work that sleep, food and training do, and don't count on any noticeable strength effect. If stress or anxiety persists over time, that's a matter for healthcare rather than for a supplement.