Member of the Aristolochia genus. Image: Wikimedia/Bogdan
Cancer-Causing Herbal Remedies | A potent carcinogen lurks within certain traditional Chinese medicines
Plants of the Aristolochia genus have for centuries been used in Chinese herbal remedies, but they contain a naturally carcinogenic compound that causes mutations in the cells of people who consume them, according to two studies published in Science Translational Medicine today (August 7). The papers reveal that the compound, called aristolochic acid, causes more mutations than two of the best-known environmental carcinogens: tobacco smoke and UV light.
“A lot of people in the lay public assume that if something is herbal or natural that it is necessarily healthy,” said Marc Ladanyi, an investigator in the human oncology and pathogenesis program at Memorial Sloan-Kettering Cancer Center in New York who was not involved in the studies. “But this work very clearly shows that this natural plant product is extremely genotoxic and carcinogenic.”
Despite the long history of Aristolochia use in herbal remedies, evidence of the plants’ inherent danger emerged only recently. In the early 1990s, women who had received Aristolochia treatments at a weight loss clinic in Belgium developed kidney problems that progressed to renal failure and, in later years, to abnormal growths in their upper urinary tracts. More recently, Aristolochiacontamination of local wheat crops was determined to be the cause of a high incidence of urothelial carcinomas of the upper urinary tract (UTUC) among rural communities on the banks of the Danube river in Europe. And in Taiwan, where recent prescription records reveal that approximately one-third of the population has taken Aristolochia-containing medicines, the incidence of UTUCs is the highest in the world.
Aristolochic acid has been banned in most countries since 2003. But, said Thomas Rosenquist of Stony Brook University in New York, “there are a lot of countries in Asia, like India, that still use it as part of their traditional herbal medicines. And even though it is banned in places like China, it is still readily available.”
The continued use of the plants might be because “[practitioners] may be slow to accept that they are actually hurting people that they are trying to help,” said Rosenquist. “And there may be a 20- to 30-year lag time between exposure to the carcinogen and [developing cancer], so making the connection might be difficult.”
In addition, many people may simply not know about the risk, said Steve Rozen of the Duke-National University of Singapore Graduate Medical School. “I’m eager to make sure this paper gets public press, because I think it’s important that people really understand the dangers.