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Horny Goat Weed Review 

Horny Goat Weed is used in many popular sports supplements and “penis pills” as everything from a testosterone booster to phyto-androgen to ED ingredient. Does the literature support its use for these purposes or are these clams all bunk?

Horny Goat Weed is often claimed to boost testosterone, but when you search the literature, there is conflicting research on whether Epimedium boosts testosterone. In rats, Epimedium (horny goat weed) did not show in increase in testosterone levels. This paper makes it appear to not be good at boosting testosterone (1) however in another study, Horny Goat Weed is claimed to boost testosterone (7). This study is suspect, because it also shows a phyto-androgen effect in addition to boosting testosterone which doesn’t happen.

Icariin is often sold as a phyto-androgen however, there is very little data on it. That isn’t a bad thing, just makes it unproven. It doesn’t appear to be harmful, since it doesn’t seem to be an estrogenic herb to any significant level (2). Horny Goat Weed and more specifically, icariin does however show some suppression of the androgen receptor, meaning it will make the androgen receptor less sensitive to your body’s own testosterone (3). This is not desirable since a reduction in androgen receptor sensitivity isn’t something you want as a bodybuilder. Typically, bodybuilders will want to increase sensitivity with things like sodium caprylate and carnitine tartrate. There is one paper showing icariin to be a natural phytoandrogen, so it is possible that it can build muscle through this pathway, but it is a fairly low quality article (7).

Epimedium like many herbal “sexual stimulants” probably got its historical use as a “fertility herb” and testosterone booster because it increases nitric oxide levels, which would increase erection quality (4,5,6). This upregulation of Nitric Oxide is useful and healthy, but it isn’t a huge muscle building pathway. N.O. levels do control erections, so it would be good to include in ED products. The main component icariin seems to be responsible for this NO boosting effect (5). There is one paper showing an increased testosterone effect in castrated rats, which is something but it is not a great paper since it shows both a phyto-androgen effect and a testosterone boosting effect (7).

As a fertility aid, we couldn’t find anything on Epimedium (Horny Goat Weed) or icariin increasing sperm quality or sperm count, so this seems to be more myth based on increased NO levels providing better quality erections.

1. Zhong Xi Yi Jie He Za Zhi. 1989 Dec;9(12):737-8, 710. [Effects of yang-restoring herb medicines on the levels of plasma corticosterone, testosterone and triiodothyronine].

2. J Sex Med. 2010 Apr;7(4 Pt 1):1518-28. Epub 2010 Feb 5. Erectogenic and neurotrophic effects of icariin, a purified extract of horny goat weed (Epimedium spp.) in vitro and in vivo. Shindel AW, Xin ZC, Lin G, Fandel TM, Huang YC, Banie L, Breyer BN, Garcia MM, Lin CS, Lue TF.

3. Int J Oncol. 2002 Apr;20(4):681-9. Effects of herbal preparation Equiguard on hormone-responsive and hormone-refractory prostate carcinoma cells: mechanistic studies. Hsieh TC, Lu X, Guo J, Xiong W, Kunicki J, Darzynkiewicz Z, Wu JM.

4. Urology. 2006 Mar;67(3):631-5. Effect of Epimedium brevicornum Maxim extract on elicitation of penile erection in the rat. Chen KK, Chiu JH.

5. J Sex Med. 2010 Apr;7(4 Pt 1):1518-28. Epub 2010 Feb 5. Erectogenic and neurotrophic effects of icariin, a purified extract of horny goat weed (Epimedium spp.) in vitro and in vivo. Shindel AW, Xin ZC, Lin G, Fandel TM, Huang YC, Banie L, Breyer BN, Garcia MM, Lin CS, Lue TF.

6. Int J Impot Res. 2006 Jul-Aug;18(4):335-42. Epub 2006 Jan 5. Epimedium brevicornum Maxim extract relaxes rabbit corpus cavernosum through multitargets on nitric oxide/cyclic guanosine monophosphate signaling pathway. Chiu JH, Chen KK, Chien TM, Chiou WF, Chen CC, Wang JY, Lui WY, Wu CW.

7. Asian J Androl. 2006 Sep;8(5):601-5. Epub 2006 Jun 5. The testosterone mimetic properties of icariin. Zhang ZB, Yang QT. Department of Urology, Second Affiliated Hospital, Shantou University Medical College, Shantou 515041, China.

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