Toxic plants and animal products found in traditional Chinese medicines

By Dr. Ananya Mandal, MDApr 15 2012

A study has found that some traditional Chinese medicines contain potentially poisonous plants, unlabelled ingredients and bits of endangered animals. This has triggered a bid for routine testing and tighter regulation of complementary medicines.

Researchers analyzed the ingredients in 16 Chinese medicines seized by customs and found three-quarters contained undeclared animal products, including the critically endangered Asiatic black bear. The study comes after the Australian government's decision to register Chinese medical practitioners in the same way as other health professionals.

According to study leader Mike Bunce, some tested medicines contained material from up to 30 plant families, including some known to be highly allergenic, many of which were not labelled. “People have got to be aware of what they are ingesting,” said Dr Bunce, from the Australian Wildlife Forensic Services and Ancient DNA Laboratory within the school of biological sciences and biotechnology at Murdoch University in Murdoch, Australia.

The team used next generation DNA sequencing, the same technology used to read a person's genetic code, to detect the presence of plants and animals based on their DNA profile. “The technology is very powerful at unravelling complicated mixtures,” Dr Bunce explained. Each DNA sequence was compared to databases of known animal and plant DNA sequences. They found several medicines contained DNA from the Asarum family, a group of plants, commonly known as wild ginger, some of which contain the cancer-causing chemical, Aristolochic acid. “One of the products did have this acid in it,” said Dr Bunce, whose findings are published in the journal PloS Genetics.

Dr Bunce said another product, which claimed to contain 100 per cent Saiga Antelope Horn powder, also contained goat and sheep DNA. “Water buffalo, domestic cow and deer species were also not listed on the packaging of samples in which they were genetically identified,” he said.

Chinese medicines are regulated by the Therapeutic Goods Administration as listed complementary medicines. A spokeswoman for the administration said listed medicines were low risk and contained ingredients evaluated as low risk. Of the 181 registered complementary medicines investigated by the administration between June last year to January more than half breached the administration's guidelines. Unregistered medicines may be seized by customs, or investigated by the administration. The medicines tested in the study were confiscated by customs for breaking environment laws and were not registered medicines.

“But I would not be surprised if those products were for sale in Australia,” Dr Bunce said. As DNA profiling cannot detect the active ingredients in Chinese medicine, all products should be screened for DNA and active chemicals. “Controls need to be implemented to ensure consumer safety and to minimize the impacts on protected biota,” he said.

“There is a lot of debate about the efficacy of [Chinese medicines] and other herbal medicines,” Bunce said. “[But] this research is not about efficacy. It is about accurately and honestly labelling products,” he explained. “We would argue that it is manifestly obvious that herbal medicines need to be carefully evaluated for legality, [and] accurate disclosure of ingredients and pharmacologic activities,” Bunce added. Routine DNA testing could go a long way towards putting manufacturers and importers “on notice” to accurately label their products, he suggested.

A respiratory medicine specialist, Associate Professor Hubertus Jersmann, from the University of Adelaide, said Chinese medicines should be standardized and tested to ensure they contain the ingredients labelled. “Citizens in Australia rely on the Therapeutics Goods Administration (TGA) to be rigorous in deciding what is allowed to be a medicine and what's not,” Associate Professor Jersmann, from the University of Adelaide, said. A professor of neurophysiology at Flinders University, Marcello Costa, said both the safety and the efficacy of Chinese medicines needed to thoroughly tested.

Lona Sandon, an assistant professor of clinical nutrition at the University of Texas Southwestern Medical Center at Dallas, suggested that the findings speak to the broader issue of dietary supplement safety in the United States. “First of all, although the traditional Chinese medicine products this study looked at may not be openly sitting on American store shelves, in this day and age you bet you can get them on the Internet,” she cautioned. “So, the argument that it's not an issue in the U.S. is a bad one.” But also, Sandon added, “just like these traditional medicines, dietary supplements that are openly sold in the U.S. are not like drugs. They do not have to undergo the scrutiny of testing for safety, for efficacy or for purity that would show that what the manufacturers say is in the product is truly in the product, and in the amount that they say is in the product,” she pointed out.

“Now, we do have the Council for Responsible Nutrition, which is a supplement industry trade group that is attempting to clean up the image of the supplement industry in the eyes of health and medical professionals,” she noted. “But that's just a voluntary notion that mostly appeals just to the big supplement players who want to keep a good reputation and are interested in being part of this group,” Sandon cautioned. “Lots of smaller companies may not be so ethical. And either way, the practice still has nothing to do with questions of safety or efficacy,” she stressed. “I don't care how many times something is touted as being natural. All the things they found in these traditional Chinese medicines were natural. Ephedra was natural, and it killed people. Natural does not always equal safe,” Sandon stated.

Council for Responsible Nutrition officials would not comment on the findings, suggesting it was inappropriate to confuse traditional Chinese medicines produced under Chinese regulations with dietary supplements manufactured in the United States. That sentiment was shared by Mark Blumenthal, founder and executive director of the American Botanical Council. While acknowledging that some aspects of traditional Chinese medicine formulation are “alarming and distasteful,” Blumenthal concurred that such practices are not representative of the American dietary supplement industry's standards.