Ecdysterone for Athletes: What the Evidence Says
Ecdysterone is a plant steroid marketed as a 'natural anabolic' that builds muscle without hormonal side effects. One much-cited trial put it on anti-doping agencies' radar, but the overall evidence is far thinner than marketing suggests. Our editorial team reviews the research honestly and explains why caution is warranted.
What ecdysterone is
Ecdysterone, also called 20-hydroxyecdysone or beta-ecdysterone, belongs to the ecdysteroids, a class of hormones that control moulting in insects and crustaceans. Many plants also produce them, probably as a defence against insects. Spinach, quinoa and the herb Cyanotis arachnoidea are among the sources.
Despite its steroid structure, ecdysterone does not appear to bind meaningfully to the human androgen receptor. Research suggests it may act through oestrogen receptor beta, which is involved in muscle cell growth, although this mechanism is still being explored.
Interest in ecdysteroids began in the Soviet Union in the 1970s and 1980s, where researchers studied them for physical performance. Much of that early literature is difficult to access and evaluate by modern standards.
In the UK, ecdysterone is sold as a food supplement, typically in capsules containing extracts standardised to a stated percentage. It is not a licensed medicine and has no authorised health claims.
Animal and laboratory research
In rodent studies, ecdysterone increased muscle fibre size and grip strength, and some researchers reported effects comparable to certain anabolic agents at equivalent doses. A study by Parr and colleagues found that ecdysterone increased muscle fibre size in rats more than some reference compounds.
Cell culture experiments showed that ecdysterone increased protein synthesis in muscle cells, an effect that could be blocked by an oestrogen receptor beta antagonist. This supports the proposed mechanism but does not prove it operates the same way in humans.
Translating animal results to people is never straightforward. Doses, metabolism and absorption differ between species, and many compounds that build muscle in rodents fail in human trials.
Laboratory findings, therefore, justify further research rather than serving as proof. Marketing materials often blur this distinction, presenting animal data as if they were established human outcomes.
The human evidence
The most cited human study was published by Isenmann and colleagues in 2019. Forty-six young men undertook a ten-week resistance training programme, with groups receiving ecdysterone-containing supplements or placebo. The ecdysterone groups showed greater increases in muscle mass and bench press performance.
The trial had important limitations: a small sample size, a short duration and an analysis that combined groups taking different doses. Further, independent replication by other groups is lacking, and earlier studies, such as one by Wilborn and colleagues in 2006, found no significant effect on body composition or strength.
Product quality also complicates interpretation. Analyses of commercially available ecdysterone supplements have found that many contained much less, or sometimes none, of the declared amount, while others contained more.
| Study | Design | Main finding |
|---|---|---|
| Wilborn et al., 2006 | 8 weeks, trained men | No significant effect on muscle or strength |
| Isenmann et al., 2019 | 10 weeks, 46 young men | Greater gains in muscle mass and strength |
| Supplement analyses | Label versus content testing | Large discrepancies in declared amounts |
Overall, the evidence that ecdysterone builds muscle in humans is preliminary. One positive trial is a signal worth investigating, not a settled conclusion.
Anti-doping status
Following the 2019 study, the World Anti-Doping Agency added ecdysterone to its Monitoring Program, which tracks substances to assess patterns of misuse in sport. As of the most recent lists, ecdysterone itself is monitored rather than prohibited.
Monitoring status can change. The WADA list is updated annually, and athletes should check the current position through UK Anti-Doping and tools such as Global DRO before using any supplement.
A larger practical risk is contamination. Supplements marketed as natural anabolics have repeatedly been found to contain undeclared anabolic steroids or other prohibited substances. Under strict liability, an athlete who tests positive is responsible regardless of the label.
- Check the current WADA list each year.
- Prefer batch-tested products, for example under Informed Sport.
- Keep records of products and batch numbers you use.
- Be wary of products promising steroid-like results.
Safety and practical considerations
Short-term human studies have not reported serious adverse effects, and ecdysteroids appear to have low acute toxicity in animals. However, long-term safety data in humans are essentially absent.
Because ecdysterone may act on oestrogen receptor beta, theoretical concerns exist for people with hormone-sensitive conditions. Pregnant or breastfeeding women and adolescents should avoid it in the absence of safety data.
Supplement quality is a significant issue. Given documented discrepancies between labels and contents, buyers have little certainty about what they are taking. Products should state the source plant, the extract's standardisation and the amount of ecdysterone per capsule.
For most athletes, investing in proven fundamentals such as progressive overload, sufficient protein, adequate sleep and well-established supplements such as creatine monohydrate provides far more reliable returns.
Editorial conclusions
Ecdysterone is a plant ecdysteroid with interesting laboratory and animal data and one notable positive human trial.
Human evidence remains thin and unreplicated, while supplement quality and label accuracy vary widely.
It is on WADA's Monitoring Program rather than the prohibited list, but contamination risks make batch-tested products essential for competitive athletes.
Our editorial team suggests reading next about creatine monohydrate's evidence base, supplement contamination in sport and turkesterone claims.
References
- Isenmann E, Ambrosio G, Joseph JF, et al. Ecdysteroids as non-conventional anabolic agent: performance enhancement by ecdysterone supplementation in humans. Arch Toxicol. 2019;93(7):1807–1816.
- Parr MK, Zhao P, Haupt O, et al. Estrogen receptor beta is involved in skeletal muscle hypertrophy induced by the phytoecdysteroid ecdysterone. Mol Nutr Food Res. 2014;58(9):1861–1872.
- Wilborn CD, Taylor LW, Campbell BI, et al. Effects of methoxyisoflavone, ecdysterone, and sulfo-polysaccharide supplementation on training adaptations in resistance-trained males. J Int Soc Sports Nutr. 2006;3(2):19–27.
- Dinan L, Lafont R. Effects and applications of arthropod steroid hormones (ecdysteroids) in mammals. J Endocrinol. 2006;191(1):1–8.
- Parr MK, Botrè F, Naß A, et al. Ecdysteroids: a novel class of anabolic agents? Biol Sport. 2015;32(2):169–173.
- Maughan RJ, Burke LM, Dvorak J, et al. IOC consensus statement: dietary supplements and the high-performance athlete. Br J Sports Med. 2018;52(7):439–455.
