Turkesterone

Turkesterone is an ecdysteroid — a plant/insect steroid, not a peptide and not a SARM — sold as a dietary supplement and marketed as a “natural anabolic” alternative to steroids. The honest picture is that turkesterone as an isolated compound has essentially no rigorous human evidence behind its muscle and strength claims; what little supportive science exists is mostly about a chemically related compound, 20-hydroxyecdysone, and even that body of work is weak and mixed.

What it is

Turkesterone is an ecdysteroid (phytoecdysteroid): a polyhydroxylated steroid produced by plants and insects. It is structurally a hydroxylated analogue of 20-hydroxyecdysone (20E, “ecdysterone”), carrying an extra hydroxyl group relative to 20E. It is not a peptide and not a SARM. Commercial material is isolated mainly from Ajuga turkestanica and related plants.

The proposed mechanism is extrapolated largely from cell and animal work on the broader ecdysteroid class — not from turkesterone specifically. Notably, ecdysteroids do not bind the human androgen receptor; suggested pathways instead include estrogen receptor beta (ERβ) signaling and downstream PI3K/Akt-mediated protein synthesis. These remain hypotheses. The precise mechanism of turkesterone in humans is not established.

The claims

Marketers and users describe turkesterone as a “natural anabolic” for muscle growth, strength, and recovery — promising faster lean-mass gains allegedly without androgenic side effects, without testosterone suppression, and without any need for post-cycle therapy. It is positioned as a “legal, natural alternative to anabolic steroids and SARMs.”

These claims are largely unsupported by direct human evidence on turkesterone.

What the evidence actually shows

• Turkesterone specifically: essentially no rigorous human evidence. There are no well-powered, peer-reviewed, placebo-controlled human trials showing that turkesterone increases muscle or strength. A 2024 review in Nutrients notes that human data for turkesterone as an isolated compound is minimal to absent, and that body-composition and strength claims rest on extrapolation from 20-hydroxyecdysone and on animal work.
• 20-hydroxyecdysone (the related, better-studied compound):
  • Isenmann et al. (2019, Archives of Toxicology) ran a 10-week resistance-training trial (n≈46 young men) of ecdysterone-containing supplementation and reported significantly greater increases in muscle mass and one-rep-max bench press, with no rise in liver or kidney toxicity biomarkers. This is the single most-cited human study supporting an anabolic effect. Caveats: modest sample size, and analytical work has found that the actual ecdysterone content of marketed products can differ substantially from labels, complicating dose interpretation.
  • Parr et al. (2015, Biology of Sport, “Ecdysteroids: A novel class of anabolic agents?”) is a review framing the anabolic hypothesis, including ERβ-mediated activity, and flagging that potency, bioavailability, and metabolism in mammals are major limitations.
  • Preclinical/animal: rodent studies report stimulation of protein synthesis, often without endocrine disruption, plus in-vitro ERβ-mediated activity in C2C12 myotubes. These do not establish human efficacy.

Bottom line on evidence: the science for the broader ecdysteroid class is weak and mixed, and the evidence for turkesterone itself in humans is effectively absent. Oral bioavailability in mammals is generally considered low — a recurring caveat across the literature.

Legal and regulatory status

• FDA: Turkesterone is not an FDA-approved drug. Ecdysteroids are sold as dietary-supplement ingredients. There is no known FDA enforcement action specifically declaring turkesterone or ecdysterone an unlawful dietary ingredient. (For contrast, the FDA has publicly stated that SARMs are not lawful dietary-supplement ingredients — but SARMs are a different drug class with different chemistry.)
• DEA: Ecdysteroids are not controlled substances and are not anabolic steroids under the Anabolic Steroid Control Act, which covers testosterone-derived androgens — again, a different compound class. No DEA scheduling of turkesterone is known.
• Anti-doping (WADA): Ecdysterone (20-hydroxyecdysone) is not on the WADA Prohibited List. It has been on the WADA Monitoring Program since 2020 and remains on the 2026 Monitoring Program — monitored substances are not prohibited. Turkesterone is not separately listed as prohibited. (For contrast, SARMs fall under S1.2 anabolic agents and GW-501516/SR9009 under S4.5 — genuinely banned, but unrelated to turkesterone.)

The main practical regulatory issue is label accuracy: independent analyses have repeatedly found ecdysteroid products mislabeled for content and purity.

Safety

No reliable human safety dataset for turkesterone exists. Long-term safety in humans is unknown and unstudied. Available animal and short-term human data on ecdysteroids generally do not show androgenic effects, testosterone suppression, or overt toxicity — but that is reassuring only for short exposures and mostly for 20E, not a clean bill of health for turkesterone.

The clearest documented hazards are about product quality, not intrinsic pharmacology: mislabeling, underdosing, and possible adulteration or contamination of supplements. Hepatotoxicity case reports tied to “turkesterone” products plausibly reflect adulterants or other ingredients rather than the molecule itself — causality is unproven.

Crucially, the dramatic harms associated with other compounds do not belong to turkesterone: testosterone suppression, HDL-lowering, and liver-enzyme elevation are documented with SARMs; vision and light-perception disturbances with andarine (S-4); and GW-501516 (cardarine) development was halted after rodent carcinogenicity (multi-organ tumors). None of these are established turkesterone effects.

Bottom line

Turkesterone is an ecdysteroid with an appealing “natural anabolic” marketing story but little-to-no direct human evidence behind its muscle and strength claims. The supporting science is mostly about the related compound 20-hydroxyecdysone and is itself weak and mixed. Turkesterone is not FDA-approved, not DEA-controlled, not an anabolic steroid under US law, and not WADA-prohibited (ecdysterone is merely monitored). The clearest documented risk is supplement quality and mislabeling, and long-term human safety is unknown.

Evidence grade: No credible evidence.

Sources

• Parr MK et al. “Ecdysteroids: A novel class of anabolic agents?” Biology of Sport 2015;32(2):169–173 (PMID 26060342)
• Isenmann E et al. “Ecdysteroids as non-conventional anabolic agent: performance enhancement by ecdysterone supplementation in humans.” Archives of Toxicology 2019;93(7):1807–1816
• Todorova V et al. “Ecdysterone and Turkesterone—Compounds with Prominent Potential in Sport and Healthy Nutrition.” Nutrients 2024 (PMC11085066)
• WADA 2026 Monitoring Program
• WADA: “WADA’s 2026 Prohibited List now in force”
• FDA: New Dietary Ingredient (NDI) Notification Process