Short answer: standardised ashwagandha extract has the most consistent human evidence of any adaptogen for cortisol and perceived stress, with randomised placebo-controlled trials reporting reductions over roughly 60 days. Findings on testosterone and physical performance are real but come from small trials in specific groups, and should be held more loosely than the cortisol data.
What makes a standardised extract different
KSM-66 is a full-spectrum root extract standardised to a minimum of 5% withanolides, the marker compounds used to make a dose reproducible batch to batch. That standardisation is the entire reason a trial result means anything: a generic root powder at an unstated withanolide content is not the intervention that was tested.
The extract is widely used in published trials. We previously stated a specific count of studies; since that figure comes from supplier marketing rather than a source we can verify, we have removed it. See KSM-66 vs Standard Ashwagandha.
Cortisol and perceived stress
The most-cited trial is Chandrasekhar and colleagues (2012) in the Indian Journal of Psychological Medicine: a randomised, double-blind, placebo-controlled study of 64 adults given 300 mg of a high-concentration full-spectrum root extract twice daily for 60 days, reporting a 27.9% reduction in serum cortisol and a substantial fall in Perceived Stress Scale scores.
An earlier version of this page attached that finding to a different paper — a 2021 review in Current Neuropharmacology — while naming the Indian Journal of Psychological Medicine. The finding is real; the citation was wrong, and is now correct.
Supporting it, Lopresti and colleagues (2019) in Medicine gave 240 mg daily of a standardised extract for 60 days and reported reduced morning cortisol alongside improvements in self-reported stress and anxiety measures.
Testosterone and physical performance
This is where the evidence is thinner, and where the category most often overreaches.
Lopresti and colleagues (2019), in the American Journal of Men's Health, ran a randomised, double-blind, placebo-controlled crossover study of ashwagandha extract in ageing, overweight men and reported changes in hormonal and vitality measures, including DHEA-S and testosterone.
Separately, Wankhede and colleagues (2015) in the Journal of the International Society of Sports Nutrition found improvements in muscle strength and recovery measures versus placebo in men undertaking resistance training.
Two caveats worth stating. These are small trials in specific populations — ageing overweight men, and men in a training programme — not evidence of a general hormonal effect in everyone. And the proposed mechanism is indirect: lower cortisol removing an inhibitory influence, rather than direct hormonal stimulation. A previous version of this page cited a paper on chronic kidney disease for the testosterone finding, which was wrong and has been replaced.
How it fits the AE·ORA formulas
Ashwagandha Plus uses KSM-66 at 600 mg standardised to 5% withanolides, within the range used in the trials above. Ashwagandha pairs organic root with black pepper as a simpler two-ingredient option.
For where ashwagandha sits among the other levers on evening cortisol — most of which are free — see How to Lower Cortisol Naturally.
Frequently Asked Questions
Quick answers to the questions readers most often ask.
What are the benefits of KSM-66 ashwagandha?
The best-supported benefit is reduced serum cortisol and perceived stress: randomised placebo-controlled trials report reductions over roughly 60 days, including a frequently cited 27.9% cortisol reduction. Findings on sleep quality, testosterone and strength exist but come from smaller trials in specific populations.
How long does KSM-66 take to work?
The trials reporting cortisol and stress reductions ran for about 60 days of consistent daily use. The effect is cumulative rather than acute, so judge it over weeks rather than days.
Does ashwagandha increase testosterone?
Randomised trials in specific groups — ageing overweight men, and men in resistance training — have reported changes in testosterone and DHEA-S versus placebo. These are small studies, and the proposed mechanism is indirect, via reduced cortisol rather than direct hormonal stimulation. It is not established as a general effect in all men.
Is KSM-66 safe for daily use?
Standardised ashwagandha extract has been used in trials at 240 to 600 mg daily for up to about eight to twelve weeks without significant adverse effects in healthy adults. Anyone pregnant or breastfeeding should avoid it. Anyone with thyroid conditions, autoimmune conditions, or taking sedatives, immunosuppressants or thyroid medication should speak to a clinician first.
What is the difference between KSM-66 and regular ashwagandha?
KSM-66 is a full-spectrum root extract standardised to at least 5% withanolides, so the active content is reproducible batch to batch and matches what was tested in trials. Generic ashwagandha powder has variable withanolide content, which means a trial result does not reliably transfer to it.
References
Every reference below has been verified against PubMed. Populations and doses are stated in the text.
- Chandrasekhar K et al. A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root. Indian J Psychol Med. 2012.
- Wankhede S et al. Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial. J Int Soc Sports Nutr. 2015.
- Lopresti AL et al. A randomized, double-blind, placebo-controlled, crossover study examining the hormonal and vitality effects of ashwagandha in aging, overweight males. Am J Mens Health. 2019.
- Lopresti AL et al. An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract. Medicine (Baltimore). 2019.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.
Related reading
