Reuters
Health
Monday, February 9, 2004
LONDON (Reuters)
- The amount of active ingredients vary in supplements of St John's wort, a
herbal remedy used to treat mild depression, scientists said on Monday.
A study by scientists
at the National Chung-Sing University in Taiwan raises concerns about dosages
people may be taking of the over-the-counter remedy and how it can react with
other drugs.
Hypericin and
pseudopericin are the components that are reported to have antidepressant and
antiviral effects. But amounts listed on the label are not always accurate, the
scientists found.
"Our
results showed that the actual contents of hypericin in these products ranged
from 1.7 to 38.5 percent of the claimed amounts," Professor Miao-Lin Hu
said in a report in the Journal of the Science and Food Agriculture.
Although
pseudohypericin was not listed on the labels of the five brands of St John's
wort supplements that the scientists analysed, it was present in much higher
quantities than hypericin.
The five
products used in the study were purchased in California health food stores.
Scientists have
called for stricter control of herbal supplements, which are not regulated by
the U.S. Food and Drug Administration (FDA) or similar agencies in other
countries.
"Inaccurate
labelling has at least one of two effects. The first is potentially to lead to
incorrect dose when the label information is complied with," Jonathan
Berman of Britain's Society of Chemical Industry said in a statement.
"The second
is the potential to degrade the perceived significance of the label information
amongst either dispensing practitioners, or the patients. This perception could
then carry over to more significant drugs," he added.
Research into St
John's wort has shown it can interfere with cancer chemotherapy drugs. It
stimulates an enzyme that is involved in metabolism of about half of all drugs,
including chemotherapy agents.
It has also been
shown to counteract the effect of oral contraceptives and has resulted in at
least two unwanted pregnancies in Sweden.
Sweden's drug
agency said the effect of the herb, which has been used for centuries in folk
and herbal remedies, may last for two weeks after use. It recommended that
people taking it at the same time as a drug should consult their doctors.