Adaptogen
Ashwagandha (KSM-66 / Sensoril)
Withania somnifera
The adaptogen people reach for when stress feels relentless. It's the most studied root for everyday tension — standardized extracts like KSM-66 have, in several trials, eased perceived stress and cortisol against placebo.
Our pick, and why
Choosing a ashwagandha (ksm-66 / sensoril) on iHerb
The trials that produced ashwagandha's stress and cortisol results used specific standardized extracts, not generic powder — so that's what we screen for. Among these three, only the Sports Research complex contains a named, clinically-trialed extract (Shoden®, 120 mg at ~35% withanolide glycosides) at a dose used in studies, which is why it's our pick. The NOW Foods extract at least discloses its standardization (2.5% withanolides, 11 mg), but it's a generic, unbranded extract rather than one with its own trial evidence. The Jarrow extract states no withanolide content at all, so there's no way to confirm it matches what the research tested. One honest caveat: our pick is a blend — if you want the single most-studied option, a dedicated KSM-66 600 mg root extract is the textbook choice.
How we judge these
A named, clinically-trialed standardized extract (KSM-66, Sensoril or Shoden) with the withanolide content stated, dosed in its studied range. Generic, unbranded 'root powder' is not the extract the trials used.
| Product | Product | Named extract | Withanolides | Plant part | Dose / serving | Meets it | Link |
|---|---|---|---|---|---|---|---|
| Our pick Sports Research Ashwagandha Broad-Spectrum Complex | Shoden® | ≈48 mg (Shoden 35% + 1.5% blend) | Root & leaf | 500 mg (120 mg Shoden) | ✓ | iHerb → | |
| NOW Foods Ashwagandha Extract | Generic (unbranded) | 2.5% (11 mg) | Root & leaf | 450 mg | — | iHerb → | |
| Jarrow Formulas Ashwagandha Extract | Generic (unbranded) | Not stated | Root | 300 mg | — | iHerb → |
- Sports Research Ashwagandha Broad-Spectrum ComplexOur pick
- Named extract
- Shoden®
- Withanolides
- ≈48 mg (Shoden 35% + 1.5% blend)
- Plant part
- Root & leaf
- Dose / serving
- 500 mg (120 mg Shoden)
- Meets our criterion
- ✓
- NOW Foods Ashwagandha Extract
- Named extract
- Generic (unbranded)
- Withanolides
- 2.5% (11 mg)
- Plant part
- Root & leaf
- Dose / serving
- 450 mg
- Meets our criterion
- —
- Jarrow Formulas Ashwagandha Extract
- Named extract
- Generic (unbranded)
- Withanolides
- Not stated
- Plant part
- Root
- Dose / serving
- 300 mg
- Meets our criterion
- —
Specs verified against live listings at time of writing and can change — confirm on the product page. Links are affiliate links; details.
Ashwagandha has moved from Ayurvedic tradition to the clinical-trial literature more successfully than almost any other herb. Standardized root extracts have a respectable stack of randomized, placebo-controlled studies behind them showing reductions in perceived stress, anxiety-scale scores, and morning cortisol in chronically stressed adults.
It is, however, a stress herb, not a depression treatment — the research population is “stressed but healthy adults”, and that’s the honest frame for using it.
What to look for
- A named, standardized extract (KSM-66 or Sensoril) with withanolide content listed
- Root extract rather than cheap leaf-and-stem powder
- A consistent 6–8 week trial before judging whether it helps you