Ashwagandha (Withania somnifera) — intervention evidence review

Regulatory status: dietary supplement

• **Perceived stress and anxiety** (PSS, HAM-A, DASS, GHQ-28).
• **Serum / morning cortisol** (and sometimes DHEA-S) as a stress-axis marker.
• **Sleep quantity and quality** (actigraphy SOL/TST/SE/WASO; PSQI; sleep-quality scales) — the 600 mg sleep claim.
• **Male testosterone and fertility** (total T, LH, sperm count / volume / motility).
• **Strength, muscle size, and body composition** as an adjunct to resistance training.
• **Thyroid indices** in subclinical hypothyroidism (TSH down, T3/T4 up).
• **Cognition** (memory, attention, executive function) in MCI, bipolar disorder, or self-reported cognitive complaints.

Ashwagandha root extract at **~600 mg/day of a standardised preparation (most often KSM-66 300 mg BID, 8–12 weeks)** has **replicated, if industry-flavoured, human RCT support** for lower perceived stress, lower cortisol, and modestly better sleep (actigraphy + PSQI), with a smaller, still-positive file for novice strength gains, male semen parameters, and MCI-range memory. **Confidence: weak-to-moderate** for stress-axis and sleep at that dose and duration; **weak-to-moderate** for testosterone/fertility and strength; **weak** for cognition and for treating subclinical hypothyroidism (one pilot). It does **not** have adequate evidence as a 120 mg add-on in a rhodiola combo, as a COVID drug, as a female-fertility agent, or as a long-term daily tonic. The safety story is no longer “Ayurvedic and therefore gentle.” **LiverTox B**, a growing HILI case series (including ACLF deaths in cirrhotics and at least one transplant), **thyroid hormone up-shift**, and a **pregnancy contraindication** are the items that should change a use-decision. Denmark has banned it in supplements; several EU agencies advise vulnerable groups off it. That is a real regulatory split, not a blog scare.