Turkesterone
Turkesterone, ecdysteroid from Ajuga turkestanica
Written by Aaron CuhaReviewed Sep 2026
Also known as: Ajuga turkestanica extract, 11-alpha-hydroxyecdysterone
The best-selling ecdysteroid supplement, and the one with no human trial at all. Its reputation is borrowed from a related molecule that was actually tested.
Overview
Turkesterone is the ecdysteroid that dominates supplement marketing, and the honest statement about it is short: no randomised controlled trial of turkesterone in humans exists. The evidence is in vitro and animal work plus reviews.
What happened is a specific and common substitution. Ecdysterone, a closely related ecdysteroid, has a controlled human trial that found increased muscle mass and bench press strength, and a pharmaceutical version that ran a 233-person phase 2b in sarcopenia. Those results belong to that molecule. Turkesterone is structurally similar, from a different plant, and sold on the reputation those trials created.
Structural similarity is not evidence. It is a reason to run the trial, and nobody has.
Mechanism of action
An ecdysteroid extracted from Ajuga turkestanica, differing from 20-hydroxyecdysone by an additional hydroxyl group at the 11-alpha position. The proposed mechanism is the one attributed to ecdysteroids generally: signalling through estrogen receptor beta to activate the Akt and mTOR pathway and increase muscle protein synthesis, without binding the androgen receptor. Whether turkesterone does this in humans at achievable doses has not been measured. Ecdysteroid oral bioavailability is generally poor, and no human pharmacokinetic data for turkesterone specifically was resolved in the sources loaded, so it is not even established that meaningful concentrations are reached.
Human evidence
None. No randomised controlled trial, no controlled trial of any design, and no human pharmacokinetic data for turkesterone specifically was located.
- No human trial of turkesterone exists in the indexed literature.
- The evidence base is in vitro work, animal work and reviews.
- No human pharmacokinetic data was located, so it is not established that oral dosing reaches meaningful blood concentrations.
- The human results widely cited in turkesterone marketing were obtained with ecdysterone, a different molecule.
What this does not tell you: Everything. There is no human efficacy or safety data to limit, which is the finding. Absence of a trial is also absence of safety information, so the frequent claim that turkesterone is safe because it is natural and non-androgenic is an argument from mechanism rather than from measurement. Supplement products are additionally unverified for content, and an ecdysteroid extract's actual turkesterone concentration is not checked by anyone.
Reading the research record
Ecdysteroids are steroid hormones that control moulting in insects and appear in some plants, notably spinach, quinoa and Ajuga turkestanica. They are structurally unrelated to androgens and do not bind the androgen receptor, which is the basis of the claim that they build muscle without steroid side effects. Read the family together rather than one at a time. 20-hydroxyecdysone, also called ecdysterone, has a controlled human trial reporting increased muscle mass and bench press performance, and a 233-person pharmaceutical phase 2b in sarcopenia that missed its primary endpoint in the full analysis set. Turkesterone, the one that dominates supplement marketing, has no human trial of any kind. Evidence within this family does not transfer between members, and the member with the most evidence is not the member being sold hardest.
Turkesterone is the clearest example on this site of reputation transfer, which is worth naming because it is everywhere in supplements. A trial is run on molecule A. Molecule B is structurally similar, cheaper to source, or easier to market, and it inherits the trial. Consumers read about the trial and buy B.
The fix is a single question: was the trial run on the thing in the bottle. For turkesterone the answer is no. That does not mean it does nothing. It means nobody has checked, and the appropriate response to an untested compound is to say so rather than to borrow a neighbour's result.
The evidence, charted
Fig. 1 · evidence composition
1of 2 citations (50%) are in people
Counted from the citation list on this page. The Human count is the same number shown in the badge at the top. Both understate any literature larger than the sources we cite.
Fig. 2 · evidence over time
Citations here span just two years, 2019 and 2024.
Too few distinct publication years on this page to plot as a timeline.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four jurisdictions shown. A jurisdiction's classification is a regulatory fact, not a verdict on the science; see Legal status below for the full text and any notes.
Fig. 4 · dose response
No human dose response curve exists
We draw this figure where the data supports it. For this compound in humans it does not, so the panel stays empty rather than borrowing an animal curve and implying it transfers.
Key studies & citations
- Review2024
Ecdysterone and turkesterone: compounds with prominent potential in sport and healthy nutrition
A review covering both compounds together. Useful for the mechanistic background and important for what it shows about the balance of evidence: the human data in this field belongs to ecdysterone, and turkesterone's case is preclinical and inferential.
Nutrients - Human2019
Ecdysteroids as non-conventional anabolic agent: performance enhancement by ecdysterone supplementation in humans
The human trial turkesterone's reputation is borrowed from, and it tested a different molecule. Ecdysterone increased muscle mass and one-repetition bench press performance in a controlled human trial. Nothing in it concerns turkesterone.
Archives of Toxicology
Frequently asked questions
Does turkesterone build muscle?
Nobody knows. No human trial of turkesterone exists. The muscle and strength results cited for it were obtained with ecdysterone, a related but different molecule, and structural similarity is a reason to run a trial rather than a substitute for one.
Is it safe?
Unmeasured. The usual argument is that it is natural and does not bind the androgen receptor, which is reasoning from mechanism rather than from data. With no human trial there is also no human safety data, and supplement products are not verified for how much turkesterone they actually contain.
Should I take ecdysterone instead?
That is the molecule with the human evidence, including a controlled trial showing increased muscle mass and bench press strength. Two caveats: the best-powered trial of that molecule missed its primary endpoint in sarcopenia, and the researchers behind the positive strength trial recommended it be added to the doping prohibited list, which matters if you compete.
Why is it so popular then?
Because the trial results for a neighbouring molecule got attached to it, which is a pattern worth recognising generally. The question to ask of any supplement is whether the trial was run on the thing in the bottle.