Origin & tradition
Ashwagandha (Withania somnifera) is classified as a Rasayana in Ayurveda — the highest tier of rejuvenating tonics — used for millennia to promote vitality, stamina, and longevity alongside sexual health.
Eastern tradition · Adaptogen Herb
Ashwagandha (KSM-66) 印度人参
Ayurveda's premier Rasayana tonic — now one of the most RCT-backed adaptogens for stress, cortisol, testosterone, and cognitive aging.
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Why longevity buyers care
Key active: Withanolides (botanical extract — KSM-66 / Sensoril standardized).
KSM-66 and Sensoril extracts show consistent HPA-axis regulation in human RCTs: reduced cortisol, improved testosterone, muscle strength, and cognitive performance. Animal studies show healthspan extension and Nrf2/FOXO pathway activation. The withanolide withanone inhibits CDK4/6 and may suppress cellular senescence.
Effect summary
Studied health outcomes
Editorial summary — This table is curated by hand from published research consensus, not automatically calculated from our trial database. Grades reflect our interpretation of the literature. Treat as a starting point, not a definitive verdict. See the Evidence panel below for the underlying trial and paper counts sourced directly from ClinicalTrials.gov and PubMed.
| Health outcome | Effect | Magnitude | Grade |
|---|---|---|---|
| Cortisol / perceived stress | Decreases | Strong | A |
| Testosterone (men) | Increases | Moderate | B |
| Muscle strength & mass | Increases | Moderate | B |
| Sleep quality (PSQI score) | Increases | Moderate | B |
| Anxiety (HAM-A scale) | Decreases | Strong | A |
| Thyroid hormones (T3/T4) | Increases | Minor | C |
| Cardiorespiratory endurance | Increases | Moderate | B |
Grade: A = robust RCTs · B = several RCTs / meta-analysis · C = limited or mixed RCTs · D = observational or early data
Dosage guidance
How Ashwagandha (KSM-66) is typically used
- Typical dose
- 300–600 mg/day (root extract)
- Form
- capsule (KSM-66 or Sensoril standardized extract)
- Timing
- morning or evening; evening preferred if using for sleep
KSM-66 (5% withanolides, root only) has the most RCT data. Sensoril (10% withanolides, root+leaf) is an alternative. Start at 300 mg; most studies use 300–600 mg. Not for use during pregnancy.
Informational only — not a prescription or personalised medical advice. Consult a qualified clinician before starting any supplement or medication.
Evidence summary
What the research actually says
82Evidence confidence
Human RCT evidence57 randomized controlled trials · 45 meta-analyses / systematic reviews
Multiple high-quality RCTs (stress, hormones, cognition, muscle); strong evidence base
KSM-66 and Sensoril extracts show consistent HPA-axis regulation in human RCTs: reduced cortisol, improved testosterone, muscle strength, and cognitive performance. Animal studies show healthspan extension and Nrf2/FOXO pathway activation. The withanolide withanone inhibits CDK4/6 and may suppress cellular senescence.
72registered clinical trials reference this intervention
0selected peer-reviewed papers (longevity / aging angle)
Key active: Withanolides (botanical extract — KSM-66 / Sensoril standardized) — a multi-compound botanical extract, so activity is not reducible to a single molecule.
According to PubMed and ClinicalTrials.gov: trial counts from ClinicalTrials.gov, peer-reviewed literature from PubMed. Counts auto-refresh weekly; last checked 2026-06-12. They include trials across many endpoints, not only longevity.
Informational only — not medical advice, a treatment claim, or a substitute for a qualified clinician. Evidence strength varies; we show mixed and null results on purpose.
Evidence collections
Ashwagandha (KSM-66) appears in
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