Taking ephedra is 200 times more risky than taking many other commonly used herbs, according to a study which has pitted the reported side effects of controversial weight-loss supplement against those of herbs such as gingko biloba.
The study calls into question the position of the herb, which is currently an unrestricted dietary supplement in the US and several other markets.
Researchers found that products containing ephedra accounted for less than 1 per cent of the herbal supplement sales in the United States in 2001. These products, however, were responsible for 62 per cent of all herbal-related reports made to poison control centers nationwide that year, according to the team at the San Francisco VA Medical Center (SFVAMC).
"The argument has always been that ephedra is safe because it is natural and has been used for thousands of years. Our study shows that ephedra is hundreds of times riskier than other commonly used herbs," said the study's lead author, Dr Stephen Bent, staff physician at SFVAMC and an assistant professor of medicine at UCSF.
The study, which will appear in the 18 March issue of the Annals of Internal Medicine, has prompted its authors to call for more stringent regulation or banning of the substance by the US Food and Drug Administration.
Products containing ephedra, also known as ma-huang, often claim to promote weight-loss and boost energy. However, the herb and its extract are known to cause certain side effects including anxiety, insomnia, increases in blood pressure and heart rate, and have been associated with many more serious reactions, including heart attacks and strokes that can lead to death.
In the current study, researchers used data gathered by the American Association of Poison Control Centers and published in its "Toxic Event Surveillance System Database Annual Report 2001." An estimated 80 per cent of the calls received by poison control centres come from the general public, as opposed to health care providers.
The researchers used the call data in conducting a statistical analysis commonly employed to monitor the relative safety of prescription drugs. "We looked at the number of adverse events among ephedra users versus the number of adverse events among users of other herbs," said Bent, also a researcher with UCSF's Osher Center for Integrative Medicine.
Taking into account the volume of sales for each product, the researchers calculated that the use of ephedra poses a risk 200 times greater than the risks posed by all other herbal supplements combined. Individual comparisons ranged from a relative risk compared to kava of 100 times greater to 720 times greater when compared to Ginkgo biloba.
"The markedly elevated relative risks observed with ephedra-containing products were stable over a wide range of estimates of ephedra sales," Bent said.
The study's senior author, Dr Michael Shlipak, said ephedra has stimulant properties that have been well described. "Our study shows that ephedra is unsafe for routine and unsupervised use," said Shlipak, a SFVAMC researcher and an assistant professor of medicine and epidemiology and biostatistics at UCSF.
He added: "The regulation of ephedra is an important issue that currently has the attention of the US Congress and the Bush administration, and we hope that our study will inform that decision."
Just last week an industry body, the Ephedra Education Council, said it had sent a letter to the US Department of Health, with backing from medical professionals, demonstrating the benefits of the herb when used safely. It is hoping that the government will bring in stricter legislation and labelling standards rather than banning the herb. However, many suppliers are already launching alternatives, or stopping supplies, in anticipation of a drop in the market for ephedra-containing products.
In the UK, ephedra products containing less than 1,800 milligrams can only be sold following a consultation with a herbal medicine practitioner. Products containing higher doses of ephedra must be sold in pharmacies, according to a BBC Online report.