Independent supplement ratingsUS and Canada · Updated weekly
A ratings desk for a category that has spent thirty years grading its own homework.
A ratings desk for a category that has spent thirty years grading its own homework.
Ashwagandha is one of the few supplements with genuine randomised-trial support — specifically for reducing stress and cortisol. KSM-66 is the branded, standardized root extract used in much of that research, at roughly 300–600 mg a day over several weeks.
The detail that decides it is form: the trials run on standardized extracts like KSM-66, not raw root powder. A bigger milligram number of plain root is not the same thing, which is why our ranking scores named extracts above powder regardless of the label figure.
Well tolerated short-term in the studies, but not for everyone — it can interact with thyroid medication and isn't advised in pregnancy. Research on PubMed →
Yes, and the difference decides whether the research applies to what you bought. KSM-66 is a standardized root extract, concentrated so the active fraction is a known quantity. Raw root powder is milled plant. A label boasting 1,000 mg of powder is not beating 300 mg of extract — it is describing something else. Our ranking scores named extracts above powder for that reason.
300–600 mg a day, which is the range the stress and cortisol trials used, taken daily over several weeks rather than as needed. The studies ran for weeks before measuring anything.
It can interact with thyroid medication, and it is not advised in pregnancy. Short-term use was well tolerated in the trials, which says nothing about years of it. Anyone on prescription medication should raise it with a clinician first — this page is not medical advice.
Both are standardized ashwagandha extracts, made from different parts of the plant and studied at different doses. KSM-66 is a root extract and carries most of the modern stress research behind it. The comparison is in KSM-66 vs Sensoril.
Reviewed by the NFS editorial team · Educational only — not medical advice.