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Horny goat weed is a perennial herb. Its scientific name is epimedium grandiflorum. This plant is from the Berberidaceae family and is found in the high elevations of Asia. There are approximately 50 species in this plant family, and most possess similar qualities.
Horny goat weed is also known as Yin-Yang-Huo, bishop’s hat, fairy wings, and arrow-leaf barrenwort. This herb has historically been used as an aphrodisiac and to treat impotence and premature ejaculation in men
The substance known as icariin is thought to be the active ingredient in horny goat weed. Icariin is a flavonoid and possesses antioxidant properties. It has also been used in China, Japan and Korea to support the kidneys and improve circulation.
History of Horny Goat Weed
Horny goat weed received its name from a Chinese goat herder. The goats would become sexually excited “horny” during certain times of the year. After closely monitoring the goats, the herder discovered the behaviour occurred while the goats were feeding on a particular type of flowering plant. This plant later became known as horny goat weed.
Horny Goat Weed Uses
Treatment of Erectile Dysfunction (ED) and Improvement of Libido
Icariin has shown weak phosphodiesterase 5 (PDE-5) inhibitor effects in vitro (outside of the body). This is the mechanism of action of the prescription drug sildenafil (Viagra) for treating ED.
It should be noted that Viagra is approximately 80 times more potent than icariin as a PDE-5 inhibitor and has FDA approval for erectile dysfunction.
Icariin can increase levels of testosterone in the bloodstream.3
Increased levels of testosterone increase sexual desire in both men and women as they age, so horny goat weed could help with diminished libido when used as a supplement.
Atherosclerosis (Hardening of the Arteries)
Atherosclerosis is the buildup of fatty deposits (plaque) adhering to the walls of the arteries. This plaque can reduce blood flow through the vessels of the body. This plaque hardens over time. Pieces of the plaque may break off, causing a stroke or a pulmonary embolus.
In a study published in 2017, Fang et al. concluded icariin possesses antioxidant, anti-inflammatory, and lipid modulating effects. These properties may prove useful in the treatment of atherosclerosis in the future. 4
Possible Adjunct in the Treatment of Cancer
Icariin has been shown to enhance the antitumor activity of gemcitabine in gallbladder cancer. The combination of gemcitabine and icariin resulted in significantly smaller tumor size in mice than either drug used alone.6
Icariin inhibited cell growth and induced apoptosis in Burkitt lymphoma cells. More research is needed to ascertain the exact mechanism by which this effect can be explained.7
Icariin may also be beneficial when added to arsenic trioxide in the treatment of hepatocellular carcinoma. This cancer type is aggressive and arsenic trioxide has a very narrow therapeutic window which reduces its benefit.8
Treatment of Osteoporosis
Osteoporosis is a disease characterized by weak bones. Progressive bone loss leads to fractures. This is most common in the elderly population and patients receiving chronic steroid therapy. Icariin has been used in traditional Chinese medicine for centuries in the treatment of bone fractures.
In an article published in 2018, Wang et al. concluded icariin may be used as a future treatment for postmenopausal osteoporosis. This is based on its bone-promoting activity.9
Icariin also appears to inhibit osteoclasts, which are bone cells that break down bone tissue. This action would also be a positive attribute in the treatment of osteoporosis.10
Effects on Alzheimer's Disease and Dementia
Dementia is a failure of the brain. Patients with dementia lose the ability to remember things, become progressively confused and eventually will be dependent on others for their total care.
Although the exact cause of dementia is unknown, we know that stroke can lead to vascular dementia. Protein deposits cause Lewy body dementia in the brain.
The most common form of dementia, Alzheimer’s disease, is thought to be at least partially caused by beta-amyloid plaque formation in brain tissue.
Icariin has been reported to have significant effects on Alzheimer’s disease. This may be accomplished by regulating calcium homeostasis, inhibiting hyperphosphorylation of tau protein and anti-inflammatory effects.11
Icariin has been shown to promote estrogen biosynthesis in vitro, which may explain its positive effect on postmenopausal woman.12
In a study by Yan, et al. published in 2008, icariin was found to lower total cholesterol and triglyceride levels. It was also found to significantly increase estradiol levels leading to the conclusion that icariin may benefit post-menopausal woman.
Horny Goat Weed Side Effects
Breathing problems may result if high doses of horny goat weed are ingested. If you experience any trouble breathing, stop taking the supplement and consult a physician
As with any drug or supplement, allergic reactions are possible. The allergy may be due to the active ingredient or any substances used in the production process. If you experience hives, itching, a rash or breathing problems, stop the supplement. If these symptoms are severe, consult a physician.
Stomach upset, or vomiting may occur. These effects may be transitory, but if they persist or are problematic, the supplement should be discontinued.
Dry mouth and excessive thirst may be experienced, especially at high doses. These side effects are generally mild.
Changes in mood, sweating, racing heartbeat and hypotension are listed as side effects to horny goat weed in some references.
Reliable information regarding drug interactions with horny goat weed is lacking. If you are taking prescription medications, always consult a doctor or pharmacist before starting any dietary supplement.
Horny goat weed contains icariin, which is a flavanol glycoside compound. This substance has been studied for multiple medical conditions.
It appears to be useful as an erectile dysfunction agent. It is less potent than prescription drugs used to treat ED. Icariin may build up over time, so it may be more effective if used chronically.
Icariin also shows promise for the treatment of some cardiac disorders, osteoporosis and dementia. It may also be useful as an adjunct combined with chemotherapeutic agents in some types of cancer.
Horny goat weed is well tolerated. I have personally used this substance and have suffered no adverse effects. I am most interested in its use as a cognitive enhancer and its possible impact on dementia. I do offer this supplement in the Sunshine Store if you would like to give it a try.
Michael J. Brown, RPh. BCPS, BCPP
Mr. Brown is a Clinical Pharmacist specializing in pharmacotherapy and psychiatry.
Read Michael’s story here. Feel free to send Michael a message using this link