Dual impact of Ashwagandha: Significant cortisol reduction but no effects on perceived stress - A systematic review and meta-analysis

Albalawi A, et al.

Published in Nutrition and Health

Methodology

Systematic review and meta-analysis of randomised placebo-controlled trials of Withania somnifera reporting serum cortisol and validated perceived stress outcomes, with pooled standardised mean differences.

Key Findings

Meta-analysis of randomised trials (488 participants) found ashwagandha supplementation significantly reduced serum cortisol compared with placebo, but produced no statistically significant improvement in perceived stress scale scores, revealing a dissociation between the biochemical and subjective outcomes.

Conclusions

Ashwagandha reliably lowers cortisol but that biochemical change did not translate into reduced perceived stress in pooled trial data, tempering common marketing claims.

Limitations

Small pooled sample across heterogeneous extracts, doses and durations; several included trials industry-funded and at risk of bias; perceived stress instruments vary; short intervention periods of typically 8 weeks.