Ashwagandha
Preliminary· human dataAlso known as: Withania somnifera
An adaptogen with early human data for stress and, more tentatively, strength.
What it is
Ashwagandha (Withania somnifera) is a herb used in traditional Ayurvedic medicine, marketed today as an "adaptogen" — something claimed to help the body resist stress. Standardised root extracts are the common supplement form.
What the evidence shows
Stress and cortisol. Preliminary· human data This is the best-studied claim: several small randomised trials report reduced perceived stress and lower cortisol over about eight weeks. The trials are small and often industry-funded, so treat it as promising rather than established.
Sleep. Preliminary· human data Some evidence for modest improvements in sleep quality, again from limited studies.
Strength, muscle and testosterone. Preliminary· human data A handful of small studies suggest modest gains in strength or recovery, and some report small testosterone changes. The base is thin and not convincing on its own — nowhere near creatine's evidence.
Broad "hormone-optimising" claims. Marketing claim Sweeping claims about transforming hormones or performance run well ahead of the data.
Who it suits
People mainly interested in the stress/sleep angle who understand the evidence is early — and who have checked the safety points above, which are the real consideration here.
Practical notes
Study effects built over roughly 8 weeks of daily use, so it isn't an acute aid. As a herbal product, potency and purity vary between brands. If you're tracking recovery, the recovery readiness index is a more direct signal than any supplement.
Sources
Frequently asked questions
- Does ashwagandha reduce stress?
- Several small randomised trials report reductions in stress and cortisol, which is the most-studied claim. The trials are small and often industry-funded, so treat it as promising rather than proven.
- Does it build muscle or strength?
- A few small studies suggest modest gains in strength and recovery alongside training, but the evidence base is thin and not yet convincing on its own. It is not in the league of creatine.
- Who should avoid it?
- People who are pregnant, have thyroid conditions or autoimmune disease, or take sedatives or thyroid medication should be cautious and seek medical advice — there are rare reports of liver issues too.
- How long to see effects?
- Most stress studies ran for around 8 weeks of daily use, so any effect builds over time rather than acutely.
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Written and reviewed by Mathew Beale — MSc Biotechnology, University of Reading.
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