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Ashwagandha: what the evidence actually shows

surging  ashwagandha — attention is ahead of the evidence

Reviewed by Substrate editorial, Independent research collective ·

⚠ Safety in context

Evidence by outcome

strengthgrade Bmoderate certainty— Ashwagandha supplementation was more efficacious than placebo for improving strength/power variables in healthy individuals.
energy / fatiguegrade Bmoderate certainty— Ashwagandha supplementation was more efficacious than placebo for improving fatigue/recovery variables in healthy individuals.
moodgrade Bmoderate certainty— Meta-analysis of 22 studies: ashwagandha supplementation significantly reduced stress, depression, and anxiety scores versus control, with a dose-response relationship observed for stress. One of the more consistent mental-health signals in the ashwagandha literature, though study quality and dosing vary.
sleepgrade Clow certainty— small, early-stage effect on sleep
stressgrade Clow certainty— small reduction in perceived stress in short trials
cognitiongrade Clow certainty— preliminary improvements in memory/executive function; small trials
strengthgrade Clow certainty— A single 8-week randomized controlled trial in men doing resistance training found greater gains in muscle strength and size, and better recovery, with ashwagandha versus placebo. One small trial cannot anchor a strong grade; independent replication is needed.
blood sugargrade Clow certainty— Systematic review and meta-analysis of Withania somnifera (ashwagandha) in diabetes: pooled data suggest a possible glucose-lowering effect, but the authors conclude the anti-diabetic profile is not yet established and call for larger, longer randomized trials measuring blood glucose, HbA1c and insulin. Signal, not confirmation.
testosterone / hormone levelsgrade Dvery-low certainty— Systematic review of 4 trials (only 1 RCT, mostly uncontrolled before-after): testosterone up 17%, LH up 34%, semen concentration +13.57 million/ml; authors call their own evidence "too limited to provide sufficiently robust evidence".
immune functiongrade Dvery-low certainty— Review: ashwagandha shows immunomodulatory effects in mechanistic and early studies, but clinical evidence that it meaningfully improves immune outcomes in people is preliminary.

People say · Evidence shows

“Ashwagandha balances cortisol”

aheadlargemechanistic speculation

What it probably doesn't do

Grade history

Re-review cadence: every 12 months (Grade A/B) · next scheduled by · methodology v1.

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sources: PMID:33670194 · PMID:41644067 · PMID:31728244 · PMID:25405876 · PMID:42199854 · PMID:26609282 · PMID:31975514 · PMID:30466985 · PMID:36909188

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Plain-text citation
Substrate. Ashwagandha: what the evidence actually shows. https://evidencebased.info/interventions/ashwagandha. Updated 2026-07-16.
BibTeX
@misc{substrate_rventionsashwagandha,
  author = {Substrate editorial},
  title  = {Ashwagandha: what the evidence actually shows},
  year   = {2026},
  url    = {https://evidencebased.info/interventions/ashwagandha},
  note   = {evidencebased.info}
}