Horny Goat Weed (Epimedium)  

Description:
Epimedium is a genus of twenty-one related plant species. The Chinese refer to epimedium as "yin yang huo", which has been loosely translated by some as "licentious goat plant" and explains why Western supplement companies have adopted the titillating name by which it is known in the U.S: (horny goat weed). Epimedium is grown as an ornamental herb in Asia and the Mediterranean region, and various species are used for medicinal purposes, including Epimedium sagittatum, Epimedium brevicornum, Epimedium wushanense, Epimedium koreanum, and Epimedium pubescens.

Claims:
Because of the traditional use of epimedium for treating fatigue and boosting sex drive, the majority of the claims for Western dietary supplements center around sex drive: Boosts libido (sex drive) Increases energy levels Enhances recovery from exercise (via cortisol-control) Makes you more sexy (not really, but this is what the ads would suggest)

Theory:
The use of epimedium as a medicinal herb dates back to at least 400 A.D., where it has been used as a tonic for the reproductive system (boosting libido and treating impotence) and as a rejuvenating tonic (to relieve fatigue). Epimedium is thought to work via modulation of cortisol levels (the primary stress hormone). Under conditions of high stress, the increased cortisol levels are known to cause fatigue and depress sex drive - so bringing cortisol levels back into normal ranges is also thought to help restore normal metabolism, energy levels and libido.

Scientific Support:
Animal studies have shown that epimedium may function a bit like an adaptogen (such as cordyceps, rhodiola, ashwagandha, and ginseng) by increasing levels of epinephrine, norepinephrine, serotonin, and dopamine when they are low (an energy-promoting effect), but reducing cortisol levels when they are elevated (an anti-stress effect). There is also evidence that epimedium can restore low levels of both testosterone and thyroid hormone (bringing low levels back to their normal levels) - which may account for some of the benefits of epimedium in improving libido (sex drive). Animal studies using epimedium have shown a reduction in bone breakdown, an increase in muscle mass, and a loss of body fat-each of which may be linked to the observed return of abnormal cortisol levels back to normal values (and rhythm). In a series of studies conducted in humans and animals by Chinese researchers, immune-system function was directly suppressed and bone loss was accelerated, by using high-dose synthetic cortisol (glucocorticoid drugs). Subsequent administration of epimedium extract reduced blood levels of cortisol and improved immune immune-system function (in the humans) and slowed bone loss and strengthened bones (in the animals).

Safety:
It is interesting to note that although at least 15 fifteen active compounds have been identified in epimedium extracts, (luteolin, icariin, quercetin, and various epimedins), many supplement companies currently use alcohol extracts standardized only for high levels of icariin. The traditional use of epimedium, however, is as a hot-water decoction (tea), which would result in a very different profile of active constituents when compared to the high-icariin alcohol extracts that are more commonly used in commercial products. Although at least one test test-tube study has shown icariin to protect liver cells from damage with by various toxic compounds, other feeding studies (in rodents) have suggested that high-dose icariin may be associated with kidney and liver toxicity. There have been no reports of adverse side effects associated with the traditional preparation of epimedium (water-extracted) at the suggested dosage (250 to 1,000mg per day).

Dosage: Because all of the existing scientific evidence for the anti-stress and cortisol-controlling effect of epimedium has been demonstrated for water-extracted epimedium (that is, as a tea), and because this form of extraction may result in a safer form of epimedium (compared to the high-icariin alcohol extract), it may be prudent to select supplements that specifically use a more traditional formulation. There have been no reports of adverse side effects associated with the traditional preparation of epimedium (water-extracted) at the suggested dosage (250-1,000mg/day in 2-3 divided doses).

References:
1. Cai D, Shen S, Chen X. Clinical and experimental research of Epimedium brevicornum in relieving neuroendocrino-immunological effect inhibited by exogenous glucocorticoid. Zhongguo Zhong Xi Yi Jie He Za Zhi. 1998 Jan;18(1):4-7.
2. Chen MD, Kuang AK, Chen JL. Influence of yang-restoring herb medicines upon metabolism of thyroid hormone in normal rats and a drug administration schedule. Zhong Xi Yi Jie He Za Zhi. 1989 Feb;9(2):93-5, 70.
3. Gau S, Fu D, Zhang H. Advances in the study on the treatment of osteoporosis with Epimedium brevicornum and its compound prescription. Zhongguo Zhong Yao Za Zhi. 1999 Apr;24(4):249-51.
4. Gu Y, Meng G. Preparation conditions for decoction of Epimedium grandiflorum Morr. Zhongguo Zhong Yao Za Zhi. 1990 Jul;15(7):412-3, 446.
5. Kuang AK, Chen JL, Chen MD. Effects of yang-restoring herb medicines on the levels of plasma corticosterone, testosterone and triiodothyronine. Zhong Xi Yi Jie He Za Zhi. 1989 Dec;9(12):737-8, 710.
6. Lee MK, Choi YJ, Sung SH, Shin DI, Kim JW, Kim YC. Antihepatotoxic activity of icariin, a major constituent of Epimedium koreanum. Planta Med. 1995 Dec;61(6):523-6.
7. Liang HR, Vuorela P, Vuorela H, Hiltunen R. Isolation and immunomodulatory effect of flavonol glycosides from Epimedium hunanense. Planta Med. 1997 Aug;63(4):316-9.
8. Liu ZY, Yang YG, Zheng B. Effect of improving memory and inhibiting acetylcholinesterase activity by invigorating-qi and warming-yang recipe. Zhongguo Zhong Xi Yi Jie He Za Zhi. 1993 Nov;13(11):675-6, 646.
9. Peng G, Fu M, Zhang D. The experimental study about the relations between Chinese herb-epimedium leptorrhizum stearn (CH-ELS) and endogenous cAMP in alveolar bone of orthodontic tooth in rats. Zhonghua Kou Qiang Yi Xue Za Zhi. 1997 Jan;32(1):40-2.
10. Wu T, Cui L, Zhang Z, Chen Z, Li Q, Liao J, Huang L. Experimental study on antagonizing action of herba Epimedii on side effects induced by glucocorticoids. Zhongguo Zhong Yao Za Zhi. 1996 Dec;21(12):748-51, 763.
11. Yu S, Chen K, Li S, Zhang K. In vitro and in vivo studies of the effect of a Chinese herb medicine on osteoclastic bone resorption. Chin J Dent Res. 1999 Feb;2(1):7-11.

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