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

Abstract

Background

The global medicine market is projected to reach US$417 billion by 2033, reflecting rising demand for natural healthcare alternatives. Ashwagandha (Withania somnifera) is widely used in Ayurvedic medicine for stress management, but evidence supporting its efficacy remains inconsistent.

Aim

This systematic review and meta-analysis evaluated Ashwagandha's impact on cortisol levels (a biological stress marker) and perceived stress via Perceived Stress Scale (PSS) scores across randomized controlled trials (RCTs).

Method

PRISMA guidelines were followed. Four databases (PubMed, CINAHL, Google Scholar, and Scopus) were searched for studies from January 2012 to February 2024, yielding seven studies on cortisol and six on perceived stress (n = 488 participants). Inclusion criteria were RCTs longer than or equal to two weeks, oral doses ≥250 mg/day, and reporting cortisol and PSS outcomes. The Cochrane Risk of Bias 2 tool was used to assess the risk of bias.

Results

There was a statistically significant reduction in cortisol levels (−1.16 µg/dL, 95% CI: −1.64 to −0.69, P < 0.001). No significant impact was observed on perceived stress (SMD = −0.355, 95% CI: −1.188 to 0.47; P = 0.40). Heterogeneity was moderate (I² = 50.9%). However, no statistically significant impact was observed on perceived stress (SMD = −0.355, 95% CI: −1.188 to 0.47; P-value = 0.40). The heterogeneity among studies was moderate (I² = 50.9%). Risk of bias was generally moderate; most studies reported adequate randomization, but some lacked allocation concealment. No publication bias was detected.

Conclusion

Findings support Ashwagandha's role in lowering cortisol, but gaps remain regarding long-term safety, dosing, and effectiveness across diverse populations. The disconnect between cortisol and PSS outcomes highlights the need for longer treatment duration and broader demographic inclusion. Longitudinal research is recommended to validate Ashwagandha as a holistic stress management tool.