Ecdysteroids are naturally occurring steroid hormones primarily found in arthropods, such as insects, and in certain plants. These compounds share a similar chemical structure to androgens, which are male sex hormones, but they operate through distinct biological pathways.
Natural Occurrence and Biological Function
Ecdysteroids are widely recognized for their role in insects, where they function as molting hormones, regulating growth, development, and reproduction. These compounds are synthesized in arthropods from dietary cholesterol.
Beyond insects, ecdysteroids are also found in numerous plant species, where they are known as phytoecdysteroids. In plants, these compounds often act as defensive mechanisms against herbivorous insects, serving as toxins or antifeedants. Common plant sources include spinach (Spinacia oleracea L.) and quinoa (Chenopodium quinoa Willd.), along with medicinal plants like Ajuga turkestanica and Serratula coronata. The concentration of ecdysteroids in some plants can be significantly higher than in arthropods.
Investigating Human Applications
Human interest in ecdysteroids primarily centers on their potential to influence muscle protein synthesis and enhance athletic performance, including strength and endurance. Ecdysteroids are widely marketed in dietary supplements with claims of increasing muscle mass and strength during resistance training, reducing fatigue, and aiding recovery. For instance, one prominent ecdysteroid, 20-hydroxyecdysone (also called ecdysterone), has been extensively studied for its potential hypertrophic effects in mammals.
Research in rats has indicated that ecdysterone can increase muscle hypertrophy at levels comparable to, or even exceeding, certain anabolic androgenic steroids and selective androgen receptor modulators (SARMs). A 10-week human intervention study involving strength training showed significantly greater increases in muscle mass and one-repetition bench press performance in participants who received ecdysterone supplementation.
Ecdysteroids are also being explored for adaptogenic properties, which refer to their ability to help the body adapt to stress. Some studies suggest a wide range of beneficial pharmacological effects in mammals, including antioxidant, anti-inflammatory, and hepatoprotective activities. However, despite promising animal studies and some human research, more extensive and robust human clinical trials are generally needed to draw definitive conclusions about the full spectrum of their effects and optimal applications in humans.
Mechanisms of Action
Ecdysteroids are believed to exert their effects in mammalian systems through distinct biological pathways, unlike traditional anabolic steroids. Unlike anabolic androgenic steroids (AAS) that primarily bind to androgen receptors (AR) to promote muscle growth, ecdysteroids do not show significant binding to AR. Instead, recent research suggests that the anabolic effects of ecdysterone are mediated by its interaction with estrogen receptors, particularly the estrogen receptor beta (ERβ).
This interaction with ERβ is thought to promote protein synthesis, contributing to muscle hypertrophy. Studies have shown that ecdysterone can stimulate protein synthesis in skeletal muscle cells, potentially through direct or indirect activation of the PI3K/Akt signaling pathway. The binding of ecdysterone to human ERβ has been demonstrated in cell culture experiments, further supporting this non-androgenic mechanism of action.
Safety Profile and Usage Considerations
Ecdysteroids generally have low toxicity in mammals. No increases in biomarkers for liver or kidney toxicity were observed in some human studies. However, comprehensive long-term safety data for human consumption remains limited.
Consult healthcare professionals before beginning any new supplement regimen, including ecdysteroids. The quality and purity of dietary supplements can vary, and some ecdysterone-containing supplements have been found to contain lower amounts of the active ingredient than labeled, with some even containing prohibited substances.
Regarding their regulatory status in sports, ecdysteroids are not currently classified as controlled substances in many regions. However, the World Anti-Doping Agency (WADA) has placed ecdysteroids, such as ecdysterone, on its Monitoring List to assess whether they should be added to the Prohibited List due to their potential performance-enhancing effects. This indicates an ongoing evaluation of their use in competitive sports.