Animal study suggests: low doses of ecdysteroids promote muscle building
The amounts of ecdysteroids in bodybuilding supplements are probably sufficient to stimulate growth of muscle mass, write endocrinologists at the University of Goettingen, Germany, in an article in the Journal of Steroid Biochemistry and Molecular Biology. In animal studies, modest doses of the ecdysteroid 20-hydroxy-ecdysone [structural formula shown below] increased the muscle mass of rats and also reduced the amount of body fat.
We have written about Dana Seidlova-Wuttke's research project before. Seidlova-Wuttke is a gynaecologist by training who specialises in the use of medicinal herbs. Her current research in Germany is on whether ecdysteroids are of use to post-menopausal women. She already publish the results of a study that showed that ecdysterone strengthens the bones and joints of female rats. The animals Seidlova-Wuttke uses for her experiments have had their ovaries removed, so they produce very low levels of sex hormones.
In the study that has been published in the Journal of Steroid Biochemistry and Molecular Biology, the researchers gave rats 18, 56 or 116 mg ecdysterone orally every day. Control groups were given ordinary feed [ovx,sf] or feed containing a small amount of synthetic estradiol [ovx+E2].
The figures below show that the ovx+E2 rats had gained hardly any fat at all after 3 months. The ovx,sf rats had got fatter, but the rats that had been given ecdysteroids had gained less fat than the ovx,sf rats.
The fat on the shinbone is called paratibial fat. This is a marker for subcutaneous fat, which is the fat that lies under the skin. The higher doses of ecdysteroids inhibited the growth of the paratibial fat. And all doses inhibited the growth of visceral fat [intra-abdominal fat]. This is the fat that surrounds the organs in the abdominal cavity, which increases the risk of cardiovascular disease.
The figure below shows what happened to the lab animals' muscle mass. The ecdysteroids had an anabolic effect.
The researchers concluded that the ecdysteroids did not have an estrogenic effect: they had no effect on the uterus of the rats. But estradiol did have an estrogenic effect. Of course.
For athletes the most interesting passages in the article concern the dose-effect relation of ecdysteroids. "A pharmacologic rule says that on the basis of per kg body weight rodents require approximately 10–15-fold higher doses of compounds in order to achieve the same effects as in humans", the researchers write. "Augmentations of muscle mass in the humans were described under a daily intake of 200 mg/person and bodybuilders consume gram-quantities of ecdysteroids. On the basis of these considerations our lowest dose corresponded to doses suggested for normal consumers whereas the highest dose corresponded to quantities taken by bodybuilders. Hence, doses used in the present study are relevant values for the human."
So a daily dose of several hundred milligrams of ecdysteroids should be enough to encourage muscle growth, according to this article. And perhaps ecdysteroids are also effective at even smaller doses.
"It was interesting to note that ecdysteroids at the tested doses resulted seldomly in a dose related response", the Germans write. "This may point to a bell-shaped dose–response curve which would mean that all 3 doses were in the peak range of the bell and that theoretically even lower doses could be effective on several parameters."
J Steroid Biochem Mol Biol. 2010 Apr;119(3-5):121-6.
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Ecdysteroids curb growth of fat tissue in animal study 24.01.2009
Ecdysterone gives rat mega-muscles 27.08.2008