Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| Ashwagandha (KSM-66) | Tongkat Ali (Eurycoma longifolia) | |
|---|---|---|
| Category | Adaptogens | Adaptogens |
| Standard Dose | 600mg KSM-66 daily (300mg 2x/day) | 200-400mg daily (standardized to 2% eurycomanone or 22-40% bioactive content) |
| Timing | Morning and evening with meals. Evening dose supports sleep quality via cortisol reduction. | Morning with or without food. Can split AM/PM. |
| Cycle Duration | Cycle 8-12 weeks on, 2-4 weeks off (to prevent adaptogenic tolerance) | Cycle 8 weeks on, 2 weeks off (or 5 days on, 2 off) |
| Evidence Level | strong_human | moderate_human |
Ashwagandha's primary bioactives are withanolides (particularly withaferin A and withanolide D). KSM-66 is a full-spectrum root extract standardized to >5% withanolides. It modulates the HPA axis by reducing cortisol output (20-30% reduction in trials), likely through GABAergic activity (withanolides are GABA-mimetic at GABA-A receptors) and by normalizing cortisol receptor (GR) sensitivity. It also inhibits the NMDA-induced neurotoxicity pathway, enhances DHEA-S production, promotes thyroid function (increases T4 to T3 conversion), upregulates antioxidant enzymes (SOD, catalase, glutathione peroxidase), and has demonstrated sirtuin-activating properties.
600mg KSM-66 daily (300mg 2x/day)
Morning and evening with meals. Evening dose supports sleep quality via cortisol reduction.
Cycle 8-12 weeks on, 2-4 weeks off (to prevent adaptogenic tolerance)
Tongkat Ali contains quassinoids (eurycomanone, eurycomanol) and bioactive peptides (eurypeptides). Primary mechanisms: reduces SHBG binding, freeing testosterone; inhibits aromatase (CYP19A1), reducing estrogen conversion; modulates the HPA axis reducing cortisol; stimulates Leydig cell steroidogenesis via cAMP pathway activation; and may inhibit phosphodiesterase (PDE) enzymes. The net effect is increased free testosterone, improved testosterone:cortisol ratio, and enhanced libido via dopaminergic and NO-mediated pathways in erectile tissue.
200-400mg daily (standardized to 2% eurycomanone or 22-40% bioactive content)
Morning with or without food. Can split AM/PM.
Cycle 8 weeks on, 2 weeks off (or 5 days on, 2 off)
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