How do ashwagandha extracts differ?

What the evidence shows

A finding for one studied preparation does not establish the same effect for every ashwagandha product. This summary does not rank extracts or establish that one brand is superior to another.^[1]

What the cited evidence shows

Ashwagandha (Withania somnifera) is an evergreen shrub used in traditional Ayurvedic medicine. Supplements may contain extracts of its root, leaf, or both.^[1]

Clinical trials of ashwagandha have used a variety of preparations, and many have had small sample sizes. A finding for one studied preparation does not establish the same effect for every ashwagandha product. This summary does not rank extracts or establish that one brand is superior to another.^[1]

Named extracts in selected trials

The 2024 resistance-training trial studied KSM-66 ashwagandha root extract standardized to more than 5% total withanolides, at 300 mg twice daily for eight weeks in 80 active adults aged 18–45, with 73 included in efficacy analysis. This is the formulation and regimen of one training trial, not a general product recommendation, proof of strength improvement or evidence that all products labeled KSM-66 are equivalent.^[2]

The 2025 postmenopause trial studied Sensoril aqueous ashwagandha extract from roots and aerial parts at 250 or 500 mg/day, divided morning and evening after meals for 24 weeks. The selected postmenopausal population and small groups do not establish a dose for other goals, equivalence to other preparations or safety over many months or years.^[3]

The 2019 stress trial described Shoden as a standardized ashwagandha root extract, prepared using ethanol and water and containing 35% withanolide glycosides; 60 adults with mild stress took 240 mg once daily after dinner for 60 days. This describes the formulation in that paper, whose root-extract wording should not be assumed to identify the plant parts of every current Shoden product. Its milligrams and withanolide-glycoside percentage do not establish equivalence or superiority to differently standardized extracts.^[4]

No head-to-head winner from these trials

The selected KSM-66, Sensoril and Shoden trials compared each studied formulation with placebo in different populations and protocols; they did not directly compare these three extracts with each other. The papers describe different plant-part preparations and standardization information, including total withanolides in KSM-66 and withanolide glycosides in Shoden. A higher printed percentage or a lower extract-milligram dose does not establish superior clinical results from these trials. Their findings cannot be transferred to an unstudied powder, tea, gummy or combination product.^{[2], [3], [4]}

Safety belongs in the decision

NIH guidance describes short-term tolerability observations for ashwagandha over about three months, while safety over longer periods remains unknown. Short studies cannot establish safety for every person, preparation, or duration of use.^[1]

Read the supporting evidence summaries

The linked research pages provide study populations, formulations, doses, outcomes, and limitations in greater detail.

• KSM-66, Sensoril and Shoden: Extract Evidence →
• Ashwagandha Safety and Tolerability →

Related questions

• What are the safety cautions for ashwagandha?

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