By Ewen Callaway of Nature magazine
Chinese herbal medicines contain ingredients derived from endangered animals, toxic plants and livestock, a genetic audit has discovered. Few of these ingredients were listed on the packaging.
"There's absolutely no honesty in the labeling of these products. What they declare is completely at odds with what's in there," says Mike Bunce, a geneticist at Murdoch University near Perth, Australia, who led the study. The results are published today in PLoS Genetics.
Traditional Chinese medicines rack up billions of dollars in worldwide sales each year, and exports to Western countries are on the rise. However, most of the medicines have not been proved to be effective, and industry regulation is scant.
When the medicines have been ground up, it is very difficult to tell what they are made of. In the past, researchers have examined herbal medicines by running assays for toxic compounds and using DNA tests to determine whether a specific plant or animal is present.
But mislabeling is rampant, so researchers do not always know what to look for and conventional approaches will miss many of the species that are present, says Bunce.
His team turned instead to next-generation DNA sequencers, which can rapidly read thousands of DNA strands. The researchers can then check the genetic sequences against databases to learn which plants or animals they come from. This 'deep sequencing' technique has been used to characterize mixtures of microbes living in environments such as oceans and animal guts.
More harm than good
Bunce's team sequenced DNA from 15 traditional Chinese medicine preparations that had been seized by Australian customs, including powders, tablets and teas. Focusing on DNA from chloroplasts and mitochondria -- energy-producing structures in cells that have their own genomes -- the researchers produced 49,000 genetic sequences.
They identified 68 families of plants, including a poisonous herb called Ephedra and the woody vine Aristolochia. Sometimes known as birthwort, Aristolochia contains aristolochic acid, which can cause kidney and liver damage and bladder cancer. Medicinal use of the herb probably explains high rates of bladder cancer in Taiwan, according to a paper published this week in Proceedings of the National Academy of Sciences.
At least one of the four medicines that contained Aristolochia DNA also contained aristolochic acid. Other medicines contained DNA from plants in the same family as ginseng -- the root of which is illegal to trade internationally -- as well as soya and nut-bearing plants, which can cause severe allergic reactions. But many plant DNA sequences could not be pinned to individual species, because plant genetic databases are incomplete.
Mix and match
The researchers also found DNA from eight genera of vertebrate animals. Genetic material from the critically endangered Saiga antelope (Saiga tatarica) was present in one powder; and boxes marked as bear-bile powder or decorated with the outline of a bear contained traces of DNA from the Asian black bear (Ursus thibetanus), which is classed as vulnerable.
Nearly half of the medicine samples tested for animal DNA contained genetic material from multiple animals, and more than three-quarters included DNA from animals not listed on the packaging, such as water buffalo, domestic cows and goats.
"Many of those traditional Chinese medicine supplements are such adventurous mixtures of multiple ingredients that, quite frankly, nothing surprises me about them," says Edzard Ernst, chair in complementary medicine at Peninsula Medical School in Exeter, UK.
Bunce thinks that food and drug regulatory agencies should consider adopting deep-sequencing techniques to screen herbal medicines; his team has applied for a grant to test its methods on supplements that are on the market in Australia. The researchers estimate that in their study, each sample cost US$35, excluding labor, to test, but the cost will fall as DNA sequencing technology becomes cheaper.
"Screening might be a way forward," says Ernst. "It would be surprising if, among these thousands of ingredients, there were not a few that have the potential to do more good than harm. However, my impression is that we are a very long way from instilling proper science into this area such that patients are not at risk of either direct harm or the indirect harm of treating serious conditions with useless supplements."
This article is reproduced with permission from the magazine Nature. The article was first published on April 12, 2012.
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3 Comments
Add CommentSo do we give up all of our vitamins from Walmart and Sam's Club, or is there a list of products we should avoid?
Reply | Report Abuse | Link to thisWhile agree that there are some significant problems with some of the patent remedies produced in China, this article is a bit sensationalist. One example is the statement that Ephedra is a "poisonous" plant. I guess myself, my family, and all the patients who have consumed it over the last couple thousand years must have a special antibody that protects us. It was banned for use because it was, very unfortunately, used in a way that was wrong and foolish, not adhering to any rationale method that a trained herbalist would do. Also, who is to say that the animal products found in those products came from animals in the wild? I don't believe most animal products should be used, but there is no questioning the data, just putting it out there without honest scientific method. This is a very poorly written paper and Nature and SA should be embarrassed to have it in their publications. The kicker is, of course, to quote Erst, and misrepresent him (he is supposedly retired), who has spent much of his career trying to "prove" herbal medicine doesn't work. Of course, he didn't really get too far since we all know it does work.
Reply | Report Abuse | Link to thisWhile you folks worry about minor side-effects and rare adverse reactions, the drug companies keep pouring billions of dollars into marketing single chemicals (mostly originating from plants) as medicines, while having a disgraceful record when it come to side-effects and adverse reactions, not to mention deaths. When we consider the numbers of people who depend on plants as medicine in the world (about 80%) and how many problems there are associated with that use, and we compare that to far fewer people using drugs, any good statistical analysis clearly shows that herbal medicine is FAR safer than drugs, and there is plenty of both historical data and current research to show this....
It is one thing to point out that Chinese medicine may be adulterated with undeclared ingredients because of poor regulations and lack of methods of detection until now. It is another to paint Chinese medicine as "toxic" or unethical because it contained products from endangered animal species. All medicines are potentially toxic if used at a "toxic" dose.
Reply | Report Abuse | Link to thisChinese medicine should be recognized as a rich resource for western medicine. Ephedra was banned because it was misused, but pseudoephedrine remains a common over-the-counter medicine for common cold. Ursodeoxycholic acid, a bear bile acid, now synthesized, is a frequently used western medicine for patients with liver disease. Artemisinin and its derivatives, now the mainstay of treatment of malaria, came originally from a Chinese herb for malaria. More tools are needed to make producers of Chinese medicine accountable, and more research will increase our understanding of Chinese medicine.