Academic journal article Bulletin of the World Health Organization

Herbs for Health, but How Safe Are They?

Academic journal article Bulletin of the World Health Organization

Herbs for Health, but How Safe Are They?

Article excerpt

Herbal medicines are popular. They are extensively used in the developing world, where in many places they offer a more widely available and more affordable alternative to pharmaceutical drugs. In Africa, for example, up to 80% of the population depends on them, according to WHO estimates. A recent study by the Roll Back Malaria Initiative found that in Ghana, Mali, Nigeria and Zambia, herbal medicine is the first choice for home treatment of nearly two thirds of children with high fever. In India, where the traditional Ayurvedic medicine employs over 1200 different herbs, herbal medicine is regularly used by about 65% of the population.

Herbal medicines are also popular in developed countries -- the same WHO estimates state that 50% of Canadians and 75% of people in France have tried complementary or alternative medicine, which often includes herbal remedies. And in Japan, 85% of doctors prescribe not only modern medicine but also the traditional herbal medicine (called Kampo), which is covered by health insurance.

Herbal medicines are also profitable. Worldwide, they represent a market value of about US$ 43 billion a year, according to WHO. In the US, alone, over 1500 herbal medicines are sold annually for a total of nearly US$ 5 billion and now constitute the fastest growing sector of the US pharmaceutical market, according to the US president's commission on dietary supplements.

The growing popularity of these remedies is fuelling -- and is to some extent fuelled -- by increasing scientific interest in herbal medicine. WHO estimates that of the 35 000-70 000 species of plants that are used for medicinal purposes around the world, some 5000 have been submitted to biomedical scrutiny. Scientific evidence of efficacy is beginning to emerge from randomized controlled trials in which herbs compare favourably with placebo. Examples include St John's wort for mild depression, ginkgo biloba for some forms of dementia, saw palmetto for benign prostatic hyperplasia, and horse chestnut seeds for chronic venous insufficiency, to mention only four. And, of course, a number of commonly used pharmaceutical products are of botanical origin -- aspirin, digitoxin, and quinine are three well-known examples.

Another reason for the growing popularity of herbal medicines is that many people believe they are safer, "more natural," than pharmaceuticals. But as Dr Saul Green, a biochemist and board member of the nonprofit US National Council Against Health Fraud, notes: "Natural doesn't mean safe. You can find a dozen or more poisons that are totally natural."

Herbal medicines, however natural, can cause serious illnesses, from allergy to liver or kidney malfunction, to cancer, and even death. In terms of carcinogenicity, for example, the toxicological potential of natural plant chemicals is roughly the same as that of synthetic chemicals, according to US toxicologist Dr Lois Gold, head of the carcinogenic potency project at the University of California at Berkeley. And the fact that herbal products tend to be taken for long periods at doses close to their toxic range doesn't help, she notes.

Blindness, too, has been attributed to the use of herbal medicines. A study published in the Journal of Tropical Medicine and Hygiene in 1994 reported that 25% of corneal ulcers in the United Republic of Tanzania were linked to the use of traditional eye medicines, of which many are based on herb extracts. Another study, published in the British Journal of Ophthalmology in 1976, found that they were associated with 26% of childhood blindness cases in Malawi. A lack of proper sterilization, along with inclusion of urine, saliva, or breast milk in some of these medicines, gives pathogens ample opportunity to thrive in eyes already hard hit by injury or infection.

Perhaps the biggest problems with herbal medicines are a lack of standardization and of safety regulations. Standardization of a herbal medicine that may contain hundreds of chemical constituents, with little or no evidence indicating which might be responsible for the presumed or proven therapeutic effect, is a particularly thorny issue. …

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