A SPRINKLING OF HERBS

The medicinal plants (or botanicals) that were the basis of nineteenth century drugs have today been largely superseded by synthetic chemicals. Some botanicals, such as digitalis, used in the treatment of heart conditions, remain in wide use, but they are heavily outnumbered by formulations that,  while  they  may  be  modelled  after older herbal  concoctions,  differ from  them  in  both their  molecular form and their method of preparation.

Not everyone, however, has welcomed this change. Many modern drugs, especially those for chronic disorders, have both variable success rates and a high incidence of unpleasant, even dangerous, side-effects. And man-made drugs tend to be more expensive. Unlike time honoured plant preparations, they are new when they are introduced, so can be patented. Drug companies charge high prices in order to recoup their research and development costs and reap their profits. The reaction in some western countries, where conventional medicine has tended to dismiss botanicals, has been a renewed interest in plants with therapeutic properties.

There is evidence that garlic can (in sufficient concentration and properly coated to ensure that enzymes in the stomach do not digest it before it is absorbed) significantly lower cholesterol; that valerian root helps people to sleep; that a tincture made from the above ground parts of the purple-coneflower plant does as much as its synthetic competitors to relieve cold and influenza symptoms; and that migraine sufferers derive as much benefit from dried feverfew leaves as from standard headache drugs. And the botanicals have minimal side-effects. Why, then, have botanicals had to struggle to gain the respect of much - some would say most - of the medical establishment?

One reason is that in many countries medical schools teach very little about drugs, whether synthetic or botanical. Similarly, the professional journals that tend to carry the most weight with doctors (because of their large international circulations) rarely report on plant-based therapies. An unusual break in the silence was a recent study reported in a journal that confirmed the efficacy of cranberry juice for bladder infections, long claimed by its advocates outside the medical profession. But for every such favourable report there are other, negative ones. Another study drew its readers' attention to an epidemic of irreversible kidney failure among women in Belgium who had used a slimming formula containing a toxic Chinese herb.

Herbalists can counter negative reports with corresponding stones of the mischief done by synthetic drugs. In America during the 1930s, for example, a drug, dinitrophenol, was popular for slimming - until it was found that many of its users developed cataracts. More recently, Oraflex, an arthritis drug, (called Opren in Europe) was taken off the market after a spate of deaths following its introduction in 1982. It is, in fact, precisely such episodes that make some health officials mistrustful of ail drugs, and thus reluctant to give herbal medicines the benefit of the doubt on safety.

Among these experts is Robert Temple, who runs the Office of Drug Evaluation and Research at America's Food and Drug Administration. At a recent conference in Washington, DC, where it was argued that many herbal preparations have been used since antiquity and so can be assumed to be harmless, Dr. Temple disagreed. If nothing else makes the premise questionable, he noted, it is that the toxicity of tobacco went unrecognised for centuries. Besides, he added, people are living longer than they used to, and thus are at greater risk than in the past from any medicine - natural or synthetic -that seems safe in the short run but that has not been sufficiently studied to detect delayed adverse effects.

The World Health Organisation, a regulatory arm of the United Nations has, by contrast, proposed to permit ready access to virtually every botanical with a track record unless modern scientific data exists that casts doubt on its safety. Given that three - quarters of the world's population are believed to use botanicals, the approach seems reasonable, perhaps even wise.

On the other hand, a passive policy has drawbacks. Almost inevitably, it would discourage investment in research aimed at pushing knowledge about 'natural' remedies - their efficacy, as well as their safety - beyond the limited information now available. There is a lot left to lear.