Ecdysterone, also called 20-hydroxyecdysone (20E) or beta-ecdysterone, is a plant steroid sold in supplements as a “natural anabolic.” The same molecule works as a molting hormone in insects and other arthropods. Plants such as spinach and quinoa contain it, and supplements are usually made from plant extracts.
The human evidence is small and mixed. One 10-week trial in 46 young men reported more muscle and bench-press gains with ecdysterone. Other training trials found no added effect, and analyses of commercial products have repeatedly found far less ecdysterone than the label states. A purified drug form, BIO101, has been tested in sarcopenia and COVID-19 trials but is not an approved medicine. WADA does not prohibit ecdysterone, but it has kept it on its Monitoring Program since 2020.
This page summarizes what clinical trials, analytical studies and anti-doping documents report. It is for education only and is not medical advice.
| Property | Detail |
|---|---|
| Class | Phytoecdysteroid (plant-derived ecdysteroid) |
| Other names | 20-hydroxyecdysone (20E), β-ecdysterone, crustecdysone; BIO101 (investigational drug form) |
| Formula | C₂₇H₄₄O₇, 480.6 g/mol (PubChem) |
| Route | Oral (supplements; BIO101 capsules in trials) |
| Doses in human trials | ≈12–48 mg/day (measured content, training trial); 175–350 mg twice daily (BIO101 phase 2/3); single doses up to 1400 mg (phase 1) |
| Half-life | 2.4–4.9 h in plasma (BIO101 phase 1); ≈3 h urinary elimination half-life |
| Mechanism | Not an androgen; proposed routes are estrogen receptor beta (cell and rat studies) and the MAS receptor (BIO101 developer) |
| US status | Sold in dietary supplements; not an approved drug; not a scheduled controlled substance |
| WADA status | Not on the 2026 Prohibited List; on the 2026 Monitoring Program (anabolic agents, in and out of competition) |
What it is
Ecdysteroids are steroid hormones that control development and reproduction in arthropods (Dioh et al., J Cachexia Sarcopenia Muscle 2023). Many plants make identical or closely related molecules, called phytoecdysteroids (Gorelick-Feldman et al., J Agric Food Chem 2008). Ecdysterone is the most common of them.
Chemically, ecdysterone is a 27-carbon steroid with six hydroxyl (OH) groups and a ketone at position 6 (PubChem CID 5459840). It is not a testosterone derivative. Its structure and its multiple hydroxyl groups make it very different from anabolic-androgenic steroids.
Turkesterone, sold in similar supplements, is a closely related ecdysteroid. It carries one extra hydroxyl group at carbon 11 (formula C₂₇H₄₄O₈) (PubChem CID 14376672). The two are often marketed together, but the human trials summarized below tested ecdysterone, not turkesterone.
| Ecdysteroid | Formula | Molecular weight | Key structural difference |
|---|---|---|---|
| Ecdysterone (20E) | C₂₇H₄₄O₇ | 480.6 g/mol | Reference compound |
| Turkesterone | C₂₇H₄₄O₈ | 496.6 g/mol | Additional 11α-hydroxyl group |
Proposed mechanism
Ecdysterone does not work through the androgen receptor in the way testosterone does. Two different mechanisms have been proposed, and neither is settled:
- Estrogen receptor beta (ERβ). In mouse muscle cells (C2C12 myotubes), ecdysterone caused hypertrophy that was blocked by an antiestrogen and an ERβ-selective antagonist, but not by an antiandrogen (Parr et al., Mol Nutr Food Res 2014). By contrast, an earlier rat study found that ecdysterone did not bind estrogen receptors in an extract from pig uterus and had no estrogenic effects in ovariectomized rats (Seidlova-Wuttke et al., Phytomedicine 2010).
- MAS receptor. The developer of BIO101 describes it as an activator of the MAS receptor, part of the renin-angiotensin system (Fielding et al., J Cachexia Sarcopenia Muscle 2025).
In cell culture, phytoecdysteroids increased protein synthesis by up to 20% in mouse and human muscle cells, an effect blocked by a PI3K inhibitor (Gorelick-Feldman et al., J Agric Food Chem 2008).
“Stronger than Dianabol”? This claim comes from a rat study. At 5 mg/kg for 21 days, ecdysterone increased soleus muscle fiber size more than metandienone (Dianabol), estradienedione and SARM S-1 given at the same dose (Parr et al., Biol Sport 2015). This was a fiber-size measurement in rats, not a test of strength or muscle mass in people, and it cannot be read as a human potency comparison.
How it works in the body
The best human pharmacokinetic data come from the phase 1 study of BIO101, a purified (≥97%) 20E drug candidate. Healthy young adults took single doses of 100–1400 mg, and older adults took repeated doses for 14 days (Dioh et al., J Cachexia Sarcopenia Muscle 2023):
| Parameter | Finding |
|---|---|
| Time to peak (median) | About 2–3.5 h |
| Plasma half-life (mean) | 2.4–4.9 h across single doses |
| Dose proportionality | Peak level and exposure rose less than proportionally from 100 to 1400 mg |
| Oral bioavailability | Described as low; absorption appeared to saturate at higher doses |
| Urinary recovery of 20E, 0–24 h (700 mg) | 1.61% fasted, 2.31% fed |
| Age | Exposure 13–22% lower in adults aged 65 or older; half-life unchanged |
| Repeated dosing | Slight accumulation with twice-daily dosing (ratio 1.31) |
| Main metabolites | 14-deoxy-20-hydroxyecdysone and 14-deoxypoststerone |
A separate study gave 12 volunteers a single 50 mg dose of pure ecdysterone (Ambrosio et al., Metabolites 2021). Ecdysterone was detected in urine for more than 2 days. Its urinary elimination half-life was about 3 hours, and about 18% of the dose was recovered in urine as unchanged ecdysterone.
Food sources
Spinach and quinoa contain ecdysterone, but very little of it appears to be absorbed:
- In 8 volunteers who ate about 950 g of sautéed spinach or 912 g as a smoothie, only about 1.4% of the ecdysterone was recovered in urine as the parent compound plus metabolites (Yuliandra et al., Mol Nutr Food Res 2023).
- After about 368 g of cooked quinoa, the recovered amount was 2.61%. The authors concluded that quinoa and spinach are poor sources of ecdysterone in terms of bioavailability (Isenmann et al., Arch Pharm 2024).
Regulatory status
Anti-doping (WADA)
Ecdysterone is not named in the WADA 2026 Prohibited List. Instead, WADA lists it first on the 2026 Monitoring Program, under “Anabolic Agents,” monitored both in and out of competition.
The Monitoring Program covers substances that are not on the Prohibited List but that WADA wants to track “to detect potential patterns of misuse in sport,” as quoted in the 2026 document. Ecdysterone has been on the program since 2020 (Ambrosio et al., Metabolites 2021; Isenmann et al., Arch Pharm 2024). The authors of the 2019 human training trial recommended adding it to the Prohibited List under S1.2, “other anabolic agents” (Isenmann et al., Arch Toxicol 2019).
Monitoring data show it is common in athletes’ samples. The Polish anti-doping laboratory confirmed ecdysterone in 507 of 11,191 samples tested over 2.5 years, at concentrations from 1 ng/mL to over 2000 ng/mL (Kwiatkowska et al., Drug Test Anal 2024). In the same study, the highest urine level after volunteers used spinach preparations, Rhaponticum tea or a plant-based cream was 691 ng/mL. Telling dietary intake apart from supplement use from urine levels alone may be difficult (Yuliandra et al., Mol Nutr Food Res 2023).
Drug and supplement status
Ecdysterone is not an approved drug. BIO101 remains investigational; after its phase 2b sarcopenia trial, the sponsor described plans to continue development (Fielding et al., J Cachexia Sarcopenia Muscle 2025). Ecdysterone is sold in dietary supplements (Ambrosio et al., J Pharm Biomed Anal 2020). It is not named among the anabolic steroids in the US Schedule III list (21 CFR 1308.13).
What the research shows
Resistance training in healthy men
Four controlled training trials have tested ecdysterone-containing products. Their results disagree, and product content is a recurring problem.
| Trial | Participants | Product and dose | Duration | Result vs placebo |
|---|---|---|---|---|
| Wilborn et al. 2006 | 45 resistance-trained men (four arms, including placebo) | Extract standardized for 30 mg/day 20E; content not verified | 8 weeks | No difference in fat-free mass, body fat, bench or leg press 1RM, or sprint power |
| Isenmann et al. 2019 | 46 young men | Ecdysterone supplement at two doses; measured ≈12 or 48 mg/day | 10 weeks | Significantly greater gains in muscle mass and one-repetition bench press |
| Dissemond et al. 2025 | 28 resistance-trained men randomized, 24 completed | Commercial 20E plus diosgenin product, taken as labeled | 12 weeks | No difference in strength, fat-free mass, muscle mass or muscle thickness |
| Sripinyowanich et al. 2025 | 20 young men | 30 mg/day 20E from asparagus extract | 12 weeks | Greater arm fat loss and fat oxidation at 40% of peak VO₂; lower fasting insulin within the 20E group |
A few details matter for interpreting these trials:
- Isenmann et al. 2019 is the main positive trial. The supplement was screened for anabolic steroid contamination before use, and participants were tested for prohibited substances. A later analysis by the same research group reported that the capsules held about 6 mg of 20E each, for 12 mg/day in the low-dose group and 48 mg/day in the high-dose group, well below the labeled amount (Dissemond et al., J Int Soc Sports Nutr 2025).
- Dissemond et al. 2025 found that its commercial product contained less than 1% of the claimed 20E and 10.4% of the claimed diosgenin. The negative result therefore says more about the product than about ecdysterone itself.
- Wilborn et al. 2006 did not measure the 20E content of its product, so it is unclear how much the participants actually received.
- Sripinyowanich et al. 2025 focused on fat and glucose measures. Most improvements were within-group changes; only arm fat and fat oxidation at one exercise intensity differed significantly from placebo.
Older adults
In a 12-week trial in adults over 50, a spinach extract (2 g/day) combined with moderate training improved knee strength more than placebo with training (n = 23 vs 22) (Pérez-Piñero et al., Nutrients 2021). The daily 20E dose in this product was about 3.2 mg, and the extract was also high in nitrate. That makes it hard to attribute the effect to ecdysterone (Dissemond et al., J Int Soc Sports Nutr 2025).
Sarcopenia (BIO101)
SARA-INT randomized 233 adults aged 65 or older with sarcopenia and limited mobility to BIO101 175 mg twice daily, 350 mg twice daily, or placebo for 6–9 months (Fielding et al., J Cachexia Sarcopenia Muscle 2025). The COVID-19 pandemic disrupted the trial, and 55% of end-of-treatment efficacy assessments were lost.
| Population (350 mg twice daily vs placebo) | Change in 400 m walking speed | Significance |
|---|---|---|
| Full analysis set | +0.07 m/s | Not significant |
| Per-protocol population | +0.09 m/s | p = 0.008 |
The authors noted that these figures approach the minimal clinically important difference for sarcopenia, 0.1 m/s. The primary analysis did not reach significance, so the result is encouraging but not proof of benefit.
Severe COVID-19 (BIO101)
The COVA phase 2/3 trial randomized 238 adults hospitalized with severe COVID-19 pneumonia to BIO101 350 mg twice daily or placebo for up to 28 days (Lobo et al., EClinicalMedicine 2024). The trial stopped short of its planned 310 patients because of low recruitment.
| Outcome (modified ITT, n = 233) | BIO101 | Placebo | Result |
|---|---|---|---|
| Respiratory failure or early death by day 28 | 13.5% | 24.3% | p = 0.043 |
| Discharged after recovery by day 28 | 80.1% | 70.9% | Not significant (p = 0.059) |
| Time to death over 90 days | — | — | HR 0.55 (95% CI 0.29–1.08), not significant |
Side effects and risks
What trials report
No long-term safety studies exist for ecdysterone supplements. The available short-term data are reassuring but limited:
- Phase 1 (BIO101). Adverse events were mild to moderate, with no serious events. Headache was the most common treatment-related event at 450 mg twice daily (5 of 8 participants), and constipation or diarrhea were most common at 350 mg twice daily (Dioh et al., J Cachexia Sarcopenia Muscle 2023).
- SARA-INT. Treatment-related adverse events occurred in 16.0% on placebo, 13.3% on 175 mg twice daily and 13.5% on 350 mg twice daily (Fielding et al., J Cachexia Sarcopenia Muscle 2025).
- Training trials. The 2019 trial found no rise in liver or kidney biomarkers (Isenmann et al., Arch Toxicol 2019). The 2006 trial found no changes in testosterone, free testosterone or cortisol (Wilborn et al., J Int Soc Sports Nutr 2006).
A 2026 case report described severe exertional rhabdomyolysis (muscle breakdown) in a 23-year-old man after a resistance session of more than 4 hours. He was taking several supplements, including creatine, beta-alanine, citrulline malate and ecdysterone (Chowaniec et al., Cureus 2026). The authors noted that ecdysterone had not previously been linked to rhabdomyolysis, and a single case with several supplements cannot establish cause.
Product quality and contamination
The largest practical risk is the product itself. Analyses of commercial ecdysterone supplements found:
- In 12 products, the actual ecdysterone content was generally much lower than labeled (Ambrosio et al., J Pharm Biomed Anal 2020).
- In 21 products from 10 brands, every sample contained much less ecdysterone than labeled, and 20% contained a WADA-prohibited substance. Content varied from batch to batch (Pálinkás et al., Separations 2023).
- A product used in a 2025 training trial held less than 1% of its claimed 20E (Dissemond et al., J Int Soc Sports Nutr 2025).
For tested athletes, contamination with prohibited anabolic agents is a real risk, separate from ecdysterone’s own Monitoring Program status.
Key takeaways
- A plant steroid, not an androgen. Ecdysterone (20-hydroxyecdysone) is an insect molting hormone also made by plants; proposed mechanisms involve estrogen receptor beta or the MAS receptor rather than the androgen receptor.
- Thin and conflicting human evidence. One 10-week trial in 46 men found greater muscle and bench-press gains; other training trials found no added benefit, often with products that held far less 20E than labeled.
- Short half-life and low absorption. Plasma half-life is about 2.4–4.9 hours, and only a small share of an oral dose, or of the ecdysterone in spinach and quinoa, is recovered in urine.
- Drug development is ongoing but unproven. The purified form BIO101 showed borderline results in sarcopenia and a reduced rate of respiratory failure or death in one COVID-19 trial; it is not approved.
- Monitored, not prohibited, by WADA. It is on the 2026 Monitoring Program under anabolic agents, not the 2026 Prohibited List. In one analysis of 21 supplements, 20% contained a prohibited substance.
Sources
- 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. PubMed.
- 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. PubMed; PMC.
- Dissemond J, Havers T, Held S, et al. How reliable is the labeling of a commercial phytosteroid product? A 12-week randomized double-blind training study. J Int Soc Sports Nutr. 2025;22(1):2540408. PubMed; PMC.
- Sripinyowanich S, Denben B, Satapoomin P, et al. Effects of asparagus-derived 20-hydroxyecdysone supplementation on fat oxidation and insulin sensitivity in resistance-trained males. J Nutr Sci Vitaminol (Tokyo). 2025;71(6):526–536. PubMed.
- Pérez-Piñero S, Ávila-Gandía V, Rubio Arias JA, et al. A 12-week randomized double-blind placebo-controlled clinical trial, evaluating the effect of supplementation with a spinach extract on skeletal muscle fitness in adults older than 50 years of age. Nutrients. 2021;13(12):4373. PubMed.
- Dioh W, Tourette C, Del Signore S, et al. A Phase 1 study for safety and pharmacokinetics of BIO101 (20-hydroxyecdysone) in healthy young and older adults. J Cachexia Sarcopenia Muscle. 2023;14(3):1259–1273. PubMed; PMC.
- Fielding RA, Dao MM, Cannon K, et al. BIO101 in sarcopenic seniors at risk of mobility disability: results of a double-blind randomised interventional phase 2b trial. J Cachexia Sarcopenia Muscle. 2025;16(2):e13750. PubMed; PMC.
- Lobo SM, Plantefève G, Nair G, et al. Efficacy of oral 20-hydroxyecdysone (BIO101), a MAS receptor activator, in adults with severe COVID-19 (COVA): a randomized, placebo-controlled, phase 2/3 trial. EClinicalMedicine. 2024;68:102383. PubMed.
- Ambrosio G, Yuliandra T, Wuest B, et al. Urinary elimination of ecdysterone and its metabolites following a single-dose administration in humans. Metabolites. 2021;11(6):366. PubMed; PMC.
- Yuliandra T, Touvleliou K, de la Torre X, et al. Urinary excretion of ecdysterone and its metabolites following spinach consumption. Mol Nutr Food Res. 2023;67(14):e2200518. PubMed.
- Isenmann E, Yuliandra T, Touvleliou K, et al. Quinoa as phytopharmaceutical? Urinary elimination of ecdysterone after consumption of quinoa alone and in combination with spinach. Arch Pharm (Weinheim). 2024;357(6):e2300689. PubMed.
- Kwiatkowska D, Grucza K, Chajewska K, et al. Ecdysterone: possible sources of origin in urine. Drug Test Anal. 2024;16(8):777–785. PubMed.
- 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. PubMed.
- Parr MK, Botrè F, Naß A, et al. Ecdysteroids: a novel class of anabolic agents? Biol Sport. 2015;32(2):169–173. PubMed; PMC.
- Gorelick-Feldman J, Maclean D, Ilic N, et al. Phytoecdysteroids increase protein synthesis in skeletal muscle cells. J Agric Food Chem. 2008;56(10):3532–3537. PubMed.
- Seidlova-Wuttke D, Christel D, Kapur P, et al. Beta-ecdysone has bone protective but no estrogenic effects in ovariectomized rats. Phytomedicine. 2010;17(11):884–889. PubMed.
- Ambrosio G, Wirth D, Joseph JF, et al. How reliable is dietary supplement labelling? Experiences from the analysis of ecdysterone supplements. J Pharm Biomed Anal. 2020;177:112877. PubMed.
- Pálinkás Z, Békési D, Utczás M. Quantitation of ecdysterone and targeted analysis of WADA-prohibited anabolic androgen steroids, hormones, and metabolic modulators in ecdysterone-containing dietary supplements. Separations. 2023;10(4):242. DOI.
- Chowaniec P, Miedziaszczyk M, Kucia M, et al. Exercise-induced rhabdomyolysis with supplements (creatine, β-alanine, citrulline malate, and β-ecdysterone). Cureus. 2026;18(3):e104852. PubMed.
- World Anti-Doping Agency. The 2026 Monitoring Program. September 2025. WADA.
- World Anti-Doping Agency. World Anti-Doping Code International Standard: Prohibited List 2026. WADA 2026 Prohibited List.
- National Center for Biotechnology Information. PubChem compound summaries: 20-hydroxyecdysone (CID 5459840) and turkesterone (CID 14376672). PubChem; PubChem.
- Code of Federal Regulations. 21 CFR 1308.13, Schedule III. 21 CFR 1308.13.