What Ashwagandha Trials Actually Measured
A 2025 meta-analysis found this herb reliably lowers a stress hormone in the blood — but didn't reliably make people feel less stressed.
Ashwagandha's withanolide compounds appear to modulate the hypothalamic-pituitary-adrenal (HPA) axis, the system governing cortisol release, and may increase serotonin and acetylcholine activity.
Key Findings
- A 2025 review of 15 RCTs (873 people) found ashwagandha measurably reduced cortisol
- A separate review found no matching drop in perceived stress ratings
- A real gap between the biomarker and how people felt
- Trials in diagnosed anxiety patients did show both measures improving together
The cortisol evidence
A 2025 systematic review and meta-analysis of 15 RCTs (873 participants) found ashwagandha supplementation measurably reduced cortisol levels in the blood.1
The gap between biomarker and feeling
A separate meta-analysis of 8 RCTs (488 adults) found ashwagandha reduced cortisol without a corresponding reduction in perceived stress ratings — a real gap between the biomarker and how people said they felt.2 Other individual trials, including one in adults specifically diagnosed with generalized anxiety disorder, found significant improvements in both subjective and objective stress measures, plus better sleep quality.
Why results vary so much
The evidence is real but inconsistent between "lowers your cortisol" and "makes you feel less stressed" — those aren't automatically the same thing, and trial results vary by population, dose, and the specific extract used.
The practical takeaway
- A cortisol drop on a lab test doesn't guarantee you'll feel less stressed day to day
- Results appear stronger in people with diagnosed anxiety than in general "stressed adult" populations
- Talk to a doctor before adding ashwagandha, especially if you're on thyroid, sedative, or immunosuppressant medication
Sources
- "Ashwagandha cortisol/stress meta-analysis." PMC, 2025. ncbi.nlm.nih.gov
- "Standardized Ashwagandha Extract and Markers of Stress in GAD." Natural Health Research. naturalhealthresearch.org
