Herbalism
<p ><b>Herbal medicine</b> (or <b>"herbalism"</b>) is the study and use of medicinal properties of <a href="http://en.wikipedia.org/wiki/Plant" title="Plant" >plants</a>.<sup id="cite_ref-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Herbalism#cite_note-0" >[1]</a></sup>
</p>
<div class="thumb tright" >
<div class="thumbinner" ><a href="http://en.wikipedia.org/wiki/File:Salix_alba_004.jpg" class="image" ><img src="/e6d3058d-5f32-5f77-9aa5-20fbcd0a281d.jpg"/></a>
<div class="thumbcaption" >
<div class="magnify" ><a href="http://en.wikipedia.org/wiki/File:Salix_alba_004.jpg" class="internal" title="Enlarge" ><img src="/259f25f6-f40f-53fa-9b23-acdac51d969c.png"/></a></div>
The bark of <a href="http://en.wikipedia.org/wiki/Willow" title="Willow" >willow</a> trees contains large amounts of <a href="http://en.wikipedia.org/wiki/Salicylic_acid" title="Salicylic acid" >salicylic acid</a>, which is the <a href="http://en.wikipedia.org/wiki/Active_metabolite" title="Active metabolite" >active metabolite</a> of <a href="http://en.wikipedia.org/wiki/Aspirin" title="Aspirin" >aspirin</a>. Willow bark has been used for millennia as an effective <a href="http://en.wikipedia.org/wiki/Pain_reliever" title="Pain reliever" class="mw-redirect" >pain reliever</a> and <a href="http://en.wikipedia.org/wiki/Fever" title="Fever" >fever</a> reducer.<sup id="cite_ref-1" class="reference" ><a href="http://en.wikipedia.org/wiki/Herbalism#cite_note-1" >[2]</a></sup></div>
</div>
</div>
<p >Plants have the ability to synthesize a wide variety of chemical compounds that are used to perform important biological functions, and to defend against attack from predators such as insects, fungi and herbivorous mammals. </p>
<p>
Many of these <a href="http://en.wikipedia.org/wiki/Phytochemicals" title="Phytochemicals" class="mw-redirect" >phytochemicals</a> have beneficial effects on long-term health when consumed by humans, and can be used to effectively treat human diseases. </p>
<p>
At least 12,000 such compounds have been isolated so far; a number estimated to be less than 10% of the total.<sup id="cite_ref-tapsell_2-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Herbalism#cite_note-tapsell-2" >[3]</a></sup><sup id="cite_ref-lai_3-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Herbalism#cite_note-lai-3" >[4]</a></sup> </p>
<p>
Chemical compounds in plants mediate their effects on the human body through processes identical to those already well understood for the chemical compounds in conventional drugs; thus herbal medicines do not differ greatly from conventional drugs in terms of how they work. </p>
<p>
This enables herbal medicines to be as effective as conventional medicines, but also gives them the same potential to cause harmful side effects.<sup id="cite_ref-tapsell_2-1" class="reference" ><a href="http://en.wikipedia.org/wiki/Herbalism#cite_note-tapsell-2" >[3]</a></sup><sup id="cite_ref-lai_3-1" class="reference" ><a href="http://en.wikipedia.org/wiki/Herbalism#cite_note-lai-3" >[4]</a></sup></p>
<p>
The use of plants as medicines predates written human history. </p>
<p>
<a href="http://en.wikipedia.org/wiki/Ethnobotany" title="Ethnobotany" >Ethnobotany</a> (the study of traditional human uses of plants) is recognized as an effective way to discover future medicines. In 2001, researchers identified 122 compounds used in modern medicine which were derived from "ethnomedical" plant sources; 80% of these have had an ethnomedical use identical or related to the current use of the active elements of the plant.<sup id="cite_ref-Fabricant2001_4-0" class="reference" ><a href="http://en.wikipedia.org/wiki/Herbalism#cite_note-Fabricant2001-4" >[5]</a></sup> </p>
<p>
Many of the <a href="http://en.wikipedia.org/wiki/Pharmaceuticals" title="Pharmaceuticals" class="mw-redirect" >pharmaceuticals</a> currently available to physicians have a long history of use as herbal remedies, including <a href="http://en.wikipedia.org/wiki/Aspirin" title="Aspirin" >aspirin</a>, <a href="http://en.wikipedia.org/wiki/Digitalis" title="Digitalis" >digitalis</a>, and <a href="http://en.wikipedia.org/wiki/Quinine" title="Quinine" >quinine</a>, <a href="http://en.wikipedia.org/wiki/Opium" title="Opium" >opium</a>.</p>
<p>
The use of <a href="http://en.wikipedia.org/wiki/Herb" title="Herb" >herbs</a> to treat <a href="http://en.wikipedia.org/wiki/Disease" title="Disease" >disease</a> is almost universal among non-industrialized societies, and is often more affordable than purchasing expensive modern pharmaceuticals. </p>
<p>
The <a href="http://en.wikipedia.org/wiki/World_Health_Organization" title="World Health Organization" >World Health Organization</a> (WHO) estimates that 80 percent of the population of some Asian and African countries presently use herbal medicine for some aspect of primary health care. Studies in the United States and Europe have shown that their use is less common in clinical settings, but has become increasingly more in recent years as scientific evidence about the effectiveness of herbal medicine has become more widely available.</p>