Epimedium grandiflorum, also referred to as horny goat weed, or yin wang huo, refers to a Chinese herb derived from 21 related plant species of herbaceous flowering plants in the Berberidaceae family. Horny goat weed products are comprised of one or a combination of the varying horny goat weed plants and have been used in traditional Chinese medicine for a variety of health-promoting purposes for almost 2,000 years. There are no clinical trials confirming the efficacy or safety of horny goat weed however, and you should therefore consult with your health-care practitioner before supplementing with it.
Mechanism of Action
The exact mechanism of action of horny goat weed is unknown, but Memorial Sloan-Kettering Cancer Center, or MSKCC, states that icariin is a major constituent of horny goat weed. Preliminary research suggests that icariin can help to reduce the ability of cancer cells to multiply and proliferate. Horny goat weed also has immune stimulating properties likely due to its ability to increase the production of the important immune supporting substances antibodies and cytokines Horny goat weed also contains flavonoids, which are potent antioxidants found in plants. Preliminary research suggests the flavonoids in the herb help to prevent bone loss in postmenopausal women.
Sexual Tonic and Other Purported Benefits
Horny goat weed contains sterols, which are steroidal hormone-like substances found in plants. When they are consumed by humans, they are thought to alter levels of certain hormones in the body. Horny goat weed is thought to regulate the levels of the sex hormone testosterone and decrease levels of the stress hormone cortisol in the body. Cortisol is associated with depressing the sex drive. As such, MSKCC states, the most popular usage of horny goat weed is for the treatment of sexual dysfunction and the enhancement of sexual performance. According to IronMagazine.com, horny goat weed is used as a reproductive tonic and purported to boost libido and treat impotence. Additional purported uses for the herb include to treat arthritis, reduce fatigue, boost energy, enhance exercise recovery, prevent and treat cancer, promote nerve health and reduce nerve pain. These uses are based primarily on anecdotal and not scientific evidence, however.
Water vs. Alcohol Extracts
Horny goat weed is thought to contain at least 15 active ingredients, and when it is used by traditional Chinese medicine practitioners, it is usually "water extracted," meaning the whole herb is made into a tea. No adverse side effects have been associated from the traditional preparation, however, in North America horny goat weed is commonly sold as an alcohol extract and standardized only to contain high levels of icariin. High levels of icariin may cause liver or kidney toxicity and other unwanted side effects.
Recommended Dose and Precautions
The recommended dose of horny goat weed is 250 mg to 1,000 mg a day, taken in two or three divided doses. An overdose of horny goat weed may cause muscle cramps and spasm, respiratory complications and hyperactivity. In addition, horny goat weed may alter levels of the hormone estrogen in the body, and patients with hormone sensitive cancers, such as breast or ovarian cancer, should use the herb with caution.
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