Ashwagandha
adaptogen
Key Takeaways
- Meta-analysis of 12 RCTs shows significant reductions in anxiety and stress levels (pmid:36017529)
- 300 mg twice daily improved sleep quality in both healthy and insomnia subjects (pmid:32818573)
- Associated with increased muscle strength and testosterone in resistance-trained men (pmid:26609282)
- Rare cases of liver injury have been reported, especially in those with pre-existing liver disease (pmid:37756041)
- No established RDA or FDA daily value; classified as a dietary supplement, not an essential nutrient
13
Studies Reviewed
Role in the Body
Ashwagandha (Withania somnifera) is an evergreen shrub used in Ayurvedic medicine as an adaptogen, a compound that may increase resilience to biological, physical, or chemical stressors. Its root is rich in steroidal lactones called withanolides and alkaloids, which are believed to mediate many of its proposed effects, though other unidentified active compounds may also contribute. The herb appears to modulate the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic-adrenal-medullary system, as well as GABAergic and serotonergic pathways. These mechanisms may underlie its observed effects on stress, anxiety, sleep, and cognitive function. Additionally, ashwagandha has demonstrated anti-inflammatory and antioxidant properties in preclinical models, and may influence testosterone levels and exercise recovery in certain populations.
- Adaptogenic stress response modulation via HPA axis
- GABAergic and serotonergic pathway modulation (sleep and mood)
- Antioxidant and anti-inflammatory activity
- Potential modulation of testosterone and exercise recovery
Supplement Forms
Root extract (standardized to withanolides)
RecommendedBioavailability: 0%
Most clinical trials use root extract; 300-600 mg/day typical doses
Root and leaf extract
Bioavailability: 0%
Chemical composition differs between plant parts
Liposomal ashwagandha
Bioavailability: 0%
One study used 225 mg liposomal form (pmid:38931168); limited data
Deficiency
Prevalence: Not applicable; ashwagandha is not an essential nutrient.
Safety & Interactions
Possible Side Effects:
- • Generally well tolerated at 300 mg twice daily for 8 weeks (pmid:33338583)
- • Rare cholestatic liver injury, including fatalities in patients with pre-existing liver disease (pmid:37756041)
- • Gastrointestinal discomfort in some studies
Drug Interactions:
- • Potential interactions with thyroid medications
- • Possible additive effects with sedatives/anxiolytics
- • Herb-drug interactions not well characterized
Contraindications:
- • Pre-existing liver disease
- • Pregnancy (insufficient safety data)
- • Autoimmune conditions
Frequently Asked Questions
Does ashwagandha actually reduce stress and anxiety?
A meta-analysis of 12 RCTs found significant reductions in both anxiety and stress, though evidence certainty was rated low. Doses of 300-600 mg/day were most commonly studied.
Is ashwagandha safe for long-term use?
Short-term use (8-12 weeks) appears safe in healthy adults. Rare liver injury cases have been reported. Long-term safety data are limited.
What is the best form of ashwagandha to take?
Root extract standardized to withanolide content at 300-600 mg/day has the most clinical support.
Research Sources
14 peer-reviewed studies analyzed from PubMed. 8 directly cited in this review.