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28.06.2014

Diosgenin, the plant steroid in Smilax and Yam

Twenty or thirty years ago, thousands of bodybuilders took extracts from plants such as Smilax officinalis [sarsaparilla] and Dioscorea esculenta [wild yam]. These contained the steroid-like diosgenin [structural formula shown here]. And lo: a Japanese animal study published in the Journal of Steroid Biochemistry and Molecular Biology suggests that diosgenin does indeed have an anabolic effect.

Smilax
Supplements containing Smilax would boost your testosterone levels, announced supplement manufacturers thirty years ago. Unlikely, as anyone with a bit of biochemistry knew.

Nevertheless, recent, reliable studies suggest that diosgenin does indeed initiate anabolic processes in cells. And, according to the animal study that researchers at Ritsumeikan University in Japan published in the Journal of Steroid Biochemistry and Molecular Biology, diosgenin might be interesting for athletes who want to build muscle mass.

Study
The Japanese wondered whether diosgenin, which resembles DHEA, boosts muscle cells' glucose uptake as DHEA does. They injected diosgenin into the small intestine of diabetic rats. If the rats had been adult humans who were given capsules by mouth, they would have received about 200 mg. [DIO]

Results
The diosgenin caused the rats' glucose level to go down. This did not happen in the animals that had been given no active ingredients [CON], nor did it happen in the animals that were given diosgenin together with an inhibitor of the enzyme 5-alpha-reductase [DIO-In].

5-Alpha-reductase converts DHEA and testosterone into DHT. This conversion is crucial for the anti-diabetic effect of DHEA, and apparently also for that of diosgenin.

Diosgenin boosted the concentration of DHEA and DHT in the muscles, and also in the animals' blood. This increase in concentration of DHT in the muscles didn't happen in the rats that were also given the 5-alpha-reductase inhibitor.

Diosgenin activated the anabolic switches Akt and protein kinase C in the muscles, thus boosting the manufacture of the glucose transporter GLUT4 in the muscles. Diosgenin also stimulated GLUT4 to make its way to the muscle cells' membrane and from there to absorb glucose from the bloodstream.

The Japanese also did the same experiments but using yam powder. The results were almost identical.

The researchers don't know how diosgenin boosts the concentrations of DHEA and DHT. Is it that diosgenin then converts into DHEA? Or does diosgenin do something to the enzymes that are involved in the steroid production?

Sponsor
The study was financed by the Japanese government.

Source:
J Steroid Biochem Mol Biol. 2014 Sep;143:152-9.

More:
Dioscorea esculenta supplement boosts DHT in athletes 10.10.2020
Dioscorea esculenta increases the concentration of DHT in muscles 09.10.2020

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