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Introducing Epimedium

Epimedium is a genus of plants comprising some 50 or more species. Two species are found around the mediterranean, where they are known by names such as Bishop’s Hat, Fairy Wings or, less poetically, Barrenwort. The genus is far more abundant in Asia, where the majority of the species are found. In China, Epimedium was long ago given the name Horny Goat Weed (Yin Yang Hao). As the legend has it, a goatherd noticed that eating the plant caused his male goats to become very excitable; Epimedium entered the Chinese pharmacopeia as a male libido enhancer, and remains popular as such to this day.

What’s in a name?

The difference in nomenclature on the two continents, Barrenwort in Europe or Horny Goat Weed in Asia, is intruiguing. Dioscorides the Greek wrote about Epimedium in the 1st century AD. His recommended use for it was as a contraceptive; there was not even a hint in his writings that it could be used as a male libido enhancer. In 1597, Gerard of London recorded it as ‘Barren Woort’ because ‘as some authors affyrme, being drunke it is an enemie to conception.’ (1). So why the difference in names? Perhaps the species endemic to each continent have different properties. In China, Epimedium is used as an aid to fertility, but perhaps in Europe, the species that grow there do not have the same effect. Let’s look at that.

Pharmacological studies can offer some answers. Horny Goat Weed makes males ‘strong’, as a traditional Chinese medicine practioner would say; a euphemism, if ever I have heard one, for curing erectile dysfunction. It turns out that Horny Goat Weed does in fact contain a compound whose mechanism of action is very much like Viagra. The compound, icariin, inhibits PDE-5 activity, which regulates blood flow in the penis, and increases the production of nitric oxide. It’s the most likely primary active component of Epimedium extracts.





Dioscorides and the Chinese Materia Medica were talking about different species of Epimedium, although this distinction has become lost by contemporary writers. Commonly, the species that is known as Horny Goat Weed is the Asian Epimedium grandiflorum, a species for which taxonomic databases list the name ‘barrenwort’ as a synonym. However, the common European species is Epimedium alpinum, named in 1793 by Linnaeus, and this is the species that is more deserving of the name ‘barrenwort’. The use of the synonym for E. grandiflorum is historically incorrect.

So does the species matter? The tumescing compound icariin has been identified in E. pubescens, E. wushanense, E. myrianthum, E. sagittatum, E. koreanum and E. brevicornu (1), as well as in E. grandiflorum. All of these species of Epimedium are found in Asia, where much of the research has been carried out. The European E. alpinum, on the other hand, has not been studied for the presence of icariin, perhaps a consequence both of it being on the wrong continent for this kind of research, and it not being traditionally used as an aphrodisiac.

Which begs the next question: was it not used as an aphrodisiac because nobody knew it had male enhancement properties, or was it not used as such because it didn’t have that effect? Its use in China, so the legend tells, took the serendipitious coming together of a flock of goats, an observant goat herder and a sufficient abundance of the plant that it could form a noticeable part of the goat’s diet. In the absence of these three conditions, would anyone in Europe have noticed?

Dioscorides had noticed something about Epimedium, but it wasn’t that it enhanced virility. Rather, as he wrote, “The root causes barrenness. Three teaspoonfuls of the leaves pounded into small pieces, and taken as a drink in wine for three days after the menstrual flow purgation, keeps women from conception.” This useage of Epimedium is the one that persisted in Europe, although no legend accompanies to tell the origins of this use.

A contraceptive and a libido enhancer?

The contraceptive properties of Epimedium have been subjected to little investigation, compared to it’s sexual enhancement properties. Intriguingly, however, icariin has been found to also have estrogen-like (phytoestrogenic) effects. The phytoestrogen flavonoids icariin, genistein and daidzein, all derived from Epimedium, have been investigated for their potential to regulate hormone-induced osteoporisis, a use for which they have shown some promise. It’s certainly possible, alhtough not at all proven, that E. alpinum may be sufficiently hormonally disruptive to interfere with a woman’s cycle, thus earning it the name ‘barrenwort’.

Two continents apart, Epimedium came to be known for two very different uses. If not for a legendary flock of goats, it’s PDE-5 inhibiting properties may have never been discovered. If not for a scrupulous Greek named Dioscorides, it’s supposed role in preventing conception never recorded. But looking back, it is the traditional Chinese usage that has stood the test of time.

Postscript

Stearn’s monograph on Epimedium (3) discussed whether the plant that Dioscorides described, was the same plant that we now call Epimedium. I think that the phytoestrogenic potential identified in extracts of Epimedium grandiflorum make it more likely that the identification is correct; even notwithstanding that there has been very little research into the contraceptive properties of the plant.

(1) 1597 Gerard, London

(2) http://www.plantsystematics.com/qikan/manage/wenzhang/aps06172.pdf

(3) The Genus Epimedium and Other Herbaceous Berberidaceae By William Thomas Stearn, Julian Shaw, Peter Shaw Green, Brian Matthew. 2002.