RESEARCH MONOGRAPH · KDC-MN-108

Ashwagandha (Withania somnifera)

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 2 min read

Our opinion on this compound

73/100

The adaptogen with the strongest cortisol RCT base. Withanolide chemistry is the variable

Ashwagandha is the adaptogen with the cleanest human trial story, even if the trial quality varies. The cortisol-lowering effect in chronically stressed adults is replicated across multiple RCTs (Chandrasekhar 2012, Lopresti 2019, Salve 2019, and others), with reasonably consistent magnitudes in the 20-30% reduction range over 8-12 week dosing periods. Thats unusually consistent for an herbal.

The active chemistry is the withanolides, a family of steroidal lactones with KSM-66 (Ixoreal Biomed's standardized extract) and Sensoril being the two most-studied commercial preparations. KSM-66 is standardized to 5% withanolides via HPLC, Sensoril is higher in withanolide content but from a different extraction approach. The trials mostly use one or the other and the results aren't trivially interchangeable.

Mechanistically the cortisol effect is plausibly via HPA axis modulation, the withanolides have demonstrated GABA-A modulatory activity in some assays, and there's emerging data on parts of the molecule hitting NF-kB and inflammation pathways. The "adaptogen" framework is hand-wavy in general but ashwagandha probably has more legitimate convergent mechanisms than most.

The sleep, anxiety, and subjective stress endpoints all move modestly in the trial literature. The testosterone-and-muscle endpoints (Wankhede 2015 and friends) showed signals in untrained men, smaller in trained populations. The thyroid effects (some users see TSH and T4 shifts) are real and worth being aware of from a research safety perspective.

What we like: cleanest RCT base of any traditional adaptogen, identifiable active compound family, two well-standardized commercial preparations with their own published trials. The cortisol effect is probably the most replicated finding.

What we dont like is the autoimmune-and-thyroid edge cases. Ashwagandha can push thyroid function up in some individuals and there are case reports of hepatotoxicity (rare but real, mostly from non-standardized or adulterated preparations). The withanolide profile matters and not all extracts are equivalent.

Sourcing: KSM-66 or Sensoril for the trial-grade preparations, or a generic standardized to specified withanolide content with COA. Avoid root-and-leaf mixed extracts (the leaf withanolide profile differs and the trial base is root-only). Pure withaferin A is also available as a research compound but has a different pharmacology than the full extract.

Most defensible adaptogen at the trial level. Just respect the thyroid signal.

Evidence: 70
Mechanism: 62
Reliability: 70
Safety: 78
Sourcing: 75
Value: 80
Signal: 75
Staying power: 72

Plain-language summary Intrigue 62 / 100

Ashwagandha (Withania somnifera) is an Ayurvedic adaptogenic root used for thousands of years. The withanolides class drives the cortisol-lowering and anxiolytic effects. Studies show modest cortisol reduction and stress benefit. Not stocked by Kodiac. This monograph is provided for research and educational reference.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

Ayurvedic adaptogenic root extract

A root extract from Withania somnifera standardized to withanolides, with documented anxiolytic, cortisol-lowering, and testosterone-supporting effects.

Abstract

Ashwagandha (Withania somnifera) is a small evergreen shrub root used in Ayurvedic medicine for stress, anxiety, fatigue, and physical performance. The active constituents are withanolides (notably withaferin A, withanolide A, and others), with commercial extracts standardized to total withanolide content (typically 5 percent or higher). The KSM-66 (Ixoreal Biomed) and Sensoril (Natreon) extracts are the most extensively studied in clinical trials. Multiple randomized trials demonstrate cortisol reduction, anxiety reduction (DASS-21, Hamilton Anxiety), modest testosterone elevation in men with low baseline, and improvements in muscle strength and endurance. Mechanism is multimodal including GABA-A receptor allosteric modulation, modest serotonergic effects, and HPA axis modulation. Reported research dose ranges in the literature are typically 300 to 600 mg of standardized extract.

Mechanism of action

GABA-A allosteric modulation; HPA axis modulation; modest serotonergic effects. Withanolide constituents.

Reported research dose ranges

300 to 600 mg standardized extract (reported research dose ranges in the literature).

References

Pratte MA, et al. An alternative treatment for anxiety: a systematic review of human trial results reported for the Ayurvedic herb ashwagandha. J Altern Complement Med 2014.

Read the full monograph

The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, reported research dose ranges, sourcing and quality verification, reconstitution and handling, stack interaction considerations, and a curated reference list. Available as a research-use-only PDF download.

KDC-MN-108

The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

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Ashwagandha (Withania somnifera)

Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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