In the face of greatly increased consumption of herbal remedies and herbal
supplements, particularly in the United States, a need to make an up-to-date
assessment of the problems they may pose has arisen. In the British Medical
Journal for August 12, Professor Ernst of Exeter university has contributed
an editorial dealing with this question. There is a growing body of evidence
that some herbal remedies are efficacious, he writes. For instance, there has
been increased demand for St John’s wort (Hypericum perforatum) following
publication of a group of reports of randomised trials in 1,757 patients suffering
from mild to moderate depression. Extracts of hypericum proved significantly
more effective than placebo and as effective as conventional antidepressants
in alleviating symptoms.
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Herbal remedies: clockwise from top left, ginkgo, St.
John's wart, horse chesnut
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Ginkgo has been shown to be more effective than placebo in slowing the progress
of dementia. Urological symptoms in benign prostate hyperplasia have been relieved
by saw palmetto, which was as effective as finasteride, with fewer adverse effects.
Horse chestnut seed extracts have proved effective for chronic venous insufficiency.
However, the mode of action of such remedies is not yet understood, and there
may be doubt over which constituent is responsible, as happened over St John’s
wort, where hyperforin was found to be as important as hypericin. The question
of benefit against risk must be answered, particularly since most herbal remedies
may evade full control as food supplements. In these circumstances quality and
safety may not be fully assured. Variations in quality may be wide from batch
to batch.
Then, herb-drug interactions must be considered. For instance, ginseng alone
may have few serious side-effects, but with warfarin it may induce excessive
anticoagulation. Moreover, herbal remedies may prove as expensive as conventional
ones, or more so, so the argument for cheapness does not always hold. Doctors
should think about changing their prevalent attitude of dismissing herbs, and
with pharmacists should be at hand to advise patients who use them. More undergraduate
information should be made available on herbal treatments. Patients should be
questioned about their use of herbal products, so that herb-drug interactions
may be avoided.