The use of herbs to treat disease is almost universal among non-industrialized societies. A number of traditions have come to dominate the practise of herbal medicine in the west at the end of the twentieth century:-
- The Western, based on Greek and Roman sources,
- The Ayurvedic from India, and
- Chinese herbal medicine.
Many of the pharmaceuticals currently available to Western physicians have a long history of use as herbal remedies, including opium, aspirin, digitalis, and quinine.
All plants produce chemical compounds as part of their normal metabolic activities. These can be split into two categories - primary metabolites, such as sugars and fats, found in all plants; and secondary metabolites found in a smaller range of plants, some only in a particular genus or species. The autologous functions of secondary metabolites are varied; for example as toxins to deter predation, or to attract insects for pollination. It is these secondary metabolites which can have therapeutic actions in humans, and which can be refined to produce drugs. Some examples are inulin from the roots of dahlias, quinine from the cinchona, morphine and codeine from the poppy, and digoxin from the foxglove.
As of 2004, the National Center for Complementary and Alternative Medicine started to fund clinical trials into the effectiveness of herbal medicine .
Some surveys of scientific herbal medicine can be found in: Evidence-based herbal medicine edited by Michael Rotblatt, Irwin Ziment; Philadelphia: Hanley & Belfus, 2002; and Herbal and traditional medicine: molecular aspects of health, edited by Lester Packer, Choon Nam Ong, Barry Halliwell; New York: Marcel Dekker, 2004
A survey released in May 2004 by the National Center for Complementary and Alternative Medicine focused on who used complementary and alternative medicines (CAM), what was used, and why it was used. The survey was limited to adults age 18 years and over during 2002 living in the United States. According to this recent survey, herbal therapy, or use of natural products other than vitamins and minerals, was the most commonly used CAM therapy (18.9%) ( table 1 on page 8) when all use of prayer was excluded.
Examples of some commonly used herbal medicines:
- Artichoke and several other plants have been associated with reduced total serum cholesterol levels in preliminary studies .
- Black cohosh and other plants that contain phytoestrogens (plant molecules with estrogen activity) have been found to have some benefits for treatment of symptoms resulting from menopause .
- Echinacea extracts have been shown to limit the length of colds in some clinical trials, although some studies have found it to have no effect. .
- Garlic has been found to lower total cholesterol levels, mildly reduce blood pressure, reduces platelet aggregation, and has antibacterial properties .
- St John's wort has been found to be more effective than placebo for the treatment of mild to moderate depression in some clinical trials .
In pop culture
'Herblore' is a skill in the MMORPG RuneScape, which mainly involves the player combining various type of herbs found in the game into various potions. 'Herbalism', in the MMORPG World of Warcraft allows the player to collect plants for use as reagents for the skill 'Alchemy'.
A common misconception about herbalism and the use of 'natural' products in general, is that 'natural' equals safe. Nature however is not benign and many plants have chemical defence mechanisms against predators that can have adverse effects on humans. Examples are hemlock and nightshade, which can be deadly to humans. Herbs can also have undesirable side-effects just as pharmaceutical products can, exacerbated by lack of control over dosage and purity.
The common names of herbs may be shared with others with different effects. For example, in one case in Belgium in a TCM-remedy for losing weight, one herb was swapped for another that caused kidney damage. One varietie of the herb causes elevated blood pressure and increased heart rate, versus another variety for the weight-loss remedy, the varieties are differentiated by the suffix in the Latin names.
The legal status of a herbal ingredient may vary from one country to another. For example, Ayurvedic herbal products often contain levels of heavy metals that would be considered unsafe in the US. However, heavy metals are considered to have therapeutical benefits in Ayurvedic medicine.
It is often advised that those wishing to use herbal remedies first consult with a physician, as some have the potential to cause adverse drug interactions when used in combination with various prescription and over-the-counter pharmaceuticals. For example, dangerously low blood pressure may result from the combination of an herbal remedy that lowers blood pressure together with prescription medicine that does the same thing. However, please be aware that most physicians have no knowledge of herbal medicine, so may not be the best sources of information. Also, there is little known about interactions of herbal remedies with pharmaceuticals, since contrary to pharmaceutical medicine, there is no system in place to report and publish any (adverse) interactions, so even herbalists may not be aware of adverse interactions.
To put the safety issue in perspective, an editorial in the British Medical Journal pointed out, "Even though herbal medicines are not devoid of risk, they could still be safer than synthetic drugs. Between 1968 and 1997, the World Health Organization's monitoring centre collected 8985 reports of adverse events associated with herbal medicines from 55 countries. Although this number may seem impressively high, it amounts to only a tiny fraction of adverse events associated with conventional drugs held in the same database." (BMJ, October 18, 2003; 327:881-882).
A meta-analysis published in the Journal of the American Medical Association (JAMA) reported the following: "The overall incidence of serious adverse drug reactions (ADRs) was 6.7% (95% confidence interval [CI], 5.2%-8.2%) and of fatal ADRs was 0.32% (95% CI, 0.23%-0.41%) of hospitalized patients. We estimated that in 1994 overall 2,216,000 (1,721,000-2,711,000) hospitalized patients had serious ADRs and 106,000 (76,000-137,000) had fatal ADRs, making these reactions between the fourth and sixth leading cause of death." (JAMA. 1998;279:1200-1205)
Finally, research posted by Ron Law shows a United States death rate of 0.0001% from dietary supplements versus 2.4% from "preventable medical misadventures" and 5.18% from properly prescribed and used drugs (http://www.laleva.cc/petizione/english/ronlaw_eng.html).