Ashwagandha has been used in Ayurvedic medicine for over 3,000 years, primarily as an adaptogen — a substance that helps the body adapt to stress. What's changed recently is that we now have rigorous clinical trials to evaluate whether those traditional claims hold up. The short answer: they do, with some important nuances.
What Is an Adaptogen?
Adaptogens are compounds that work on the body's stress response system — the hypothalamic-pituitary-adrenal (HPA) axis — to normalize the production and response to stress hormones, particularly cortisol. They don't block stress or suppress it; they help regulate the stress response so it's more proportionate and doesn't stay elevated chronically.
Chronically elevated cortisol is associated with weight gain (particularly abdominal fat), poor sleep, suppressed immune function, hormonal imbalances, and accelerated cognitive decline.
What the Clinical Trials Found
A 2019 randomized, double-blind, placebo-controlled study published in Medicine found that adults taking 240mg of ashwagandha extract daily for 60 days showed:
- 23% reduction in serum cortisol compared to placebo
- Significant improvement in sleep quality and onset time
- Reduced perceived stress on validated stress scales
A separate study from the Indian Journal of Psychological Medicine using 300mg twice daily (KSM-66 extract) found a 27.9% reduction in cortisol after 60 days, along with improvements in all stress and anxiety measures used.
💡 The cortisol-lowering effect of ashwagandha is most pronounced in people who are genuinely under chronic stress. People with already-normal cortisol levels see smaller effects.
Beyond Cortisol: Other Studied Benefits
Testosterone and Male Hormones
Several studies in men under stress have found ashwagandha supplementation associated with modestly increased testosterone levels — believed to be a secondary effect of lower cortisol (which suppresses testosterone production). Effect sizes are modest but consistent.
Physical Performance
A study in the Journal of the International Society of Sports Nutrition found that subjects taking KSM-66 ashwagandha had significantly greater gains in muscle strength and recovery compared to placebo over 8 weeks of resistance training.
Thyroid Function
Early research suggests ashwagandha may support thyroid hormone levels, though evidence is preliminary. People with thyroid conditions should consult their doctor.
Which Form and Dose
KSM-66 and Sensoril are the two most studied, patented extracts with the most clinical backing. Generic "ashwagandha root" supplements exist at lower price points but have less standardization.
The research-supported range is 300–600mg of a standardized extract daily. Most studies use two 300mg doses split morning and evening.
Results typically begin appearing at 4–6 weeks, with full effects at 8–12 weeks of consistent use.
⚠️ Ashwagandha is generally well tolerated but should be avoided during pregnancy. Some people experience mild digestive upset — take with food. People with autoimmune conditions should consult their doctor, as adaptogens can stimulate immune activity.
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Shop Ashwagandha on iHerb →⚠️ This article is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting any supplement, especially if you take prescription medications or have an existing health condition.