MikroScore
Science-backed ingredient evidence
Moderate Evidenz Safety: Likely safe Study dose: 600 mg/day

Ashwagandha (Withania somnifera)

Also known as: Indian ginseng, Winter cherry, Withania somnifera, KSM-66, Sensoril

Summary Moderate Evidenz

Ashwagandha is an Ayurvedic adaptogen backed by multiple RCTs for stress and cortisol reduction. Sleep and testosterone effects are promising but come from small studies.

EU Health Claims: No approved claims

No health claims for ashwagandha have been approved by EFSA. In Germany it is legal as a botanical food supplement but may not carry health claims. BfR notes hepatotoxicity risk at high doses.

AI Summary

Quick verdict

Ashwagandha is an Ayurvedic adaptogen backed by multiple RCTs for stress and cortisol reduction. Sleep and testosterone effects are promising but come from small studies.

What the evidence supports

Multiple RCTs show consistent cortisol reduction (–14–27%) and improvements in perceived stress scores. Evidence for sleep and testosterone is available but from small trials.

What is NOT supported

Long-term safety and rare adverse effects in humans remain insufficiently studied.

EU/EFSA status

Not approved. No health claims for ashwagandha have been approved by EFSA. In Germany it is legal as a botanica…

Safety

Likely safe

This AI summary is generated from the structured data on this page.

What is Ashwagandha?

Ashwagandha (Withania somnifera) is a root plant used in traditional Ayurvedic medicine and is classified as an adaptogen — a term for substances thought to modulate physiological stress responses. The name derives from Sanskrit and roughly means “smell of horse” (withanolides, the primary active compounds, have a characteristic odour). The plant has been used for over 3,000 years.

In the modern supplement context, ashwagandha is primarily studied for stress reduction. Two proprietary extracts dominate the research: KSM-66 (root extract, standardised to ≥5% withanolides) and Sensoril (root/leaf extract, standardised to ≥10% withanolides). Nearly all cited RCTs use one of these extracts — generic root powder without standardisation has no comparable evidence base.

Mechanism of Action

Primary proposed mechanisms:

  • HPA-axis modulation: Ashwagandha appears to modulate the hypothalamic-pituitary-adrenal axis, resulting in lower cortisol levels. The exact mechanism (direct glucocorticoid receptor interaction? CRH suppression?) is not fully established.
  • GABA-mimetic activity: Withanolides have GABA-A receptor-modulating properties, which may explain anxiolytic effects.
  • Antioxidant effects: NF-κB inhibition and reduction of oxidative stress in cell studies.
  • Androgen pathway: Influence on testosterone levels in studies with young men (mechanism unclear).

What Do the Studies Show?

Clearly supported: stress reduction

The strongest evidence domain. The Chandrasekhar et al. RCT (n=64, 60 days): serum cortisol –27.9%, PSS score significantly improved. Other KSM-66 studies consistently show 14–27% cortisol reduction vs. placebo over 8–12 weeks. Important: these studies enrolled adults with chronic stress — not healthy, non-stressed individuals.

Multiple systematic reviews (2021–2023) confirm significant reductions in stress and anxiety with standardised ashwagandha extracts. Effect sizes are moderate (SMD ~0.5–0.8 for stress scores).

Sleep

RCT Langade et al. (n=60, 10 weeks, 300 mg twice daily): PSQI score improved, sleep latency reduced by approximately 22 minutes, sleep duration extended. Effects replicated in a second RCT (Langade 2021). Evidence is solid but studies are relatively small.

Testosterone and muscle strength

Wankhede et al. (n=57, resistance-trained men): +18 kg bench press (vs. +6 kg placebo), testosterone significantly increased. Caveat: small study, baseline group differences unclear, replication inconsistent in other trials. No EFSA claim.

Cognition

Choudhary et al. (n=50, 8 weeks): improvement in memory, attention, and information-processing speed on standardised tests. Plausible via stress reduction (cortisol impairs cognition), but a direct nootropic effect is not sufficiently established.

What is NOT supported

  • Direct anti-ageing effects in humans
  • Telomere protection or senolytic effects
  • Long-term effects beyond 12 weeks — most RCTs run 8–12 weeks
  • Effects in non-stressed individuals (most studies enrolled stressed adults)

EFSA and BfR Status

EFSA has not approved any health claims for ashwagandha.

Germany’s BfR (Federal Institute for Risk Assessment) issued a safety assessment in 2023 warning that high doses (>1,000 mg/day of extract) combined with prolonged use may increase the risk of liver toxicity, based on case reports from Europe. At recommended doses (300–600 mg/day) the risk is considered low, but long-term data are lacking.

Dosage and Product Selection

  • Typical RCT dose: 300–600 mg KSM-66 or Sensoril per day, often split into 2 servings
  • For sleep: 300–600 mg in the evening, with a light meal
  • Duration: 8–12 weeks, then reassess — long-term data beyond 3 months are scarce
  • Quality marker: extract with known withanolide content (≥5% for KSM-66)

Safety

At standard doses (300–600 mg/day, 8–12 weeks) ashwagandha is considered likely safe. Controlled studies have not shown liver function abnormalities. Case reports of hepatotoxicity (cholestasis, hepatocellular damage) exist, often at higher doses, with non-standardised products, or after prolonged use.

Contraindications and warnings:

  • Pregnancy: Contraindicated — ashwagandha has uterine-stimulating effects (historically used as an abortifacient)
  • Liver disease: Avoid, or use only under medical supervision
  • Hyperthyroidism: Ashwagandha may influence T3/T4 — clarify with a doctor if you have thyroid issues
  • Immunosuppressants: Possible additive immunostimulating effects
  • High dose (>1,000 mg/day): Increased hepatotoxicity risk per BfR

Honest Limitations

  • Most positive studies used proprietary extracts often funded by manufacturers — conflicts of interest cannot be excluded
  • Nearly all studies include fewer than 100 participants and run fewer than 12 weeks — long-term effects and safety with prolonged supplementation are unknown
  • Stress scores and subjective sleep quality are susceptible to placebo effects; double-blinding is difficult because ashwagandha has a distinctive odour
  • For non-stressed, well-sleeping individuals without a training context, the added benefit is unclear
  • No approved health claims in the EU

Key Studies

A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root in reducing stress and anxiety in adults

Chandrasekhar K et al. (2012)

RCT, n=64, 300 mg KSM-66 twice daily, 60 days: serum cortisol –27.9%, Perceived Stress Scale significantly improved, anxiety scores reduced vs. placebo. Methodologically sound.

PubMed PMID 23439798

Efficacy and Safety of Ashwagandha Root Extract in Insomnia and Anxiety

Langade D et al. (2019)

RCT, n=60, 300 mg twice daily, 10 weeks: sleep quality (PSQI) significantly improved, sleep latency –22 min vs. placebo, anxiety scores reduced.

PubMed PMID 31728244

Examining the effect of Withania somnifera supplementation on muscle strength and recovery

Wankhede S et al. (2015)

RCT, n=57 young men, resistance training: bench press +18 kg (ashwagandha) vs. +6 kg (placebo). Testosterone significantly increased. Study is small; results need replication.

PubMed PMID 26609282

Safety and tolerability of ashwagandha root extract: A systematic review and meta-analysis

Pratte MA et al. (2014)

Systematic review: ashwagandha is safe at recommended doses (300–600 mg/day). Liver values unremarkable in controlled studies. Low adverse-event rate.

PubMed PMID 25552213

Efficacy and Safety of Ashwagandha Root Extract in Improving Memory and Cognitive Functions

Choudhary D et al. (2017)

RCT, n=50, 300 mg KSM-66 twice daily, 8 weeks: improvement in memory (Wechsler Memory Scale), attention, and information-processing speed vs. placebo.

PubMed PMID 28471731
Editorial notice: For most ingredients described here, no health claims are approved in the EU (Regulation (EC) 1924/2006). Evidence levels are editorial assessments of research quality — not health promises. This content is not a substitute for medical advice and does not constitute a recommendation to treat, alleviate, or prevent any disease.