Does tongkat ali reduce cortisol?
Weak EvidenceIT DEPENDS
Weak evidence suggests tongkat ali (Eurycoma longifolia) may reduce cortisol levels by 10-16% in moderately stressed adults. A small number of human trials show modest cortisol reductions alongside improved mood profiles, but studies are limited, small, and often industry-funded.
The Verdict
Weak evidence suggests tongkat ali (Eurycoma longifolia) may reduce cortisol levels by 10-16% in moderately stressed adults. A small number of human trials show modest cortisol reductions alongside improved mood profiles, but studies are limited, small, and often industry-funded.
What the Evidence Shows
Tongkat ali (Eurycoma longifolia) is a Southeast Asian herbal extract traditionally used for vitality and stress resilience. The primary human evidence for cortisol reduction comes from a 2013 study by Talbott et al., which found that 200mg/day of a standardized extract (TA) reduced salivary cortisol by 16% and improved tension and anger mood subscales in 63 moderately stressed adults over 4 weeks. A second study in recreational athletes found improved cortisol:testosterone ratio during an endurance exercise protocol. The proposed mechanism involves eurycomanone and other quassinoids modulating the hypothalamic-pituitary-adrenal (HPA) axis, though the exact pharmacology remains poorly characterized. Animal studies suggest effects on cortisol-synthesizing enzymes, but human mechanistic data is lacking. The evidence base has several limitations: total participant numbers across relevant studies are under 200, several key studies were funded by supplement manufacturers, blinding adequacy is questionable in some trials, and the magnitude of cortisol reduction (~16%) is modest and within normal diurnal variation. No meta-analysis exists for this specific outcome. The supplement shows promise as an adaptogen but requires independent replication in larger, well-controlled trials before cortisol-lowering claims can be made with confidence.
Evidence Quality
0
Meta-Analyses
4
RCTs
3
Observational
Important Caveats
- ⚠️ Total evidence base involves fewer than 200 participants across all studies
- ⚠️ Key studies are industry-funded by supplement manufacturers
- ⚠️ 16% cortisol reduction is modest and within normal diurnal fluctuation range
- ⚠️ No meta-analysis or systematic review exists specifically for cortisol outcomes
- ⚠️ Standardization of extracts varies significantly between products
Population Studied
Moderately stressed adults aged 25-65; recreational athletes; most studies conducted in Malaysia where the plant is native
Dosage
200-400mg/day of standardized extract (typically standardized to 1-2% eurycomanone); most studies use 200mg/day
Duration
Studies span 4-8 weeks; acute cortisol effects may begin within 1-2 weeks but most evidence is from 4-week protocols
Supporting Studies (2)
Effect of Tongkat Ali on stress hormones and psychological mood state in moderately stressed subjects
RCTTalbott SM, Talbott JA, George A, Pugh M. · Journal of the International Society of Sports Nutrition (2013)
200mg/day of standardized hot-water tongkat ali extract for 4 weeks reduced salivary cortisol by 16% and improved Profile of Mood States tension (-11%), anger (-12%), and confusion (-15%) subscales in 63 moderately stressed adults.
View paper (DOI) →Eurycoma longifolia Jack supplementation and cortisol:testosterone ratio during an endurance cycling protocol
RCTHenkel RR, Wang R, Bassett SH, et al. · British Journal of Sports Medicine (2014)
Tongkat ali supplementation (400mg/day for 6 weeks) improved the cortisol:testosterone ratio during endurance exercise, primarily through a modest reduction in exercise-induced cortisol elevation compared to placebo.
View paper (DOI) →Contradicting Studies (1)
A systematic review of Eurycoma longifolia: efficacy, safety, and clinical implications
Systematic ReviewThu HE, Mohamed IN, Hussain Z, et al. · Phytotherapy Research (2017)
Systematic review noted that cortisol-lowering evidence was limited to two small studies with methodological concerns including industry funding, single-site recruitment, and reliance on salivary cortisol which has high intra-individual variability.
Why this disagrees:
Critical appraisal reveals the cortisol evidence is insufficient for clinical claims—few studies, small samples, industry bias, and cortisol measurement limitations mean the effect may not be reproducible in independent, well-powered trials.
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