Genetic audit uncovers hidden ingredients of Chinese medicine. DNA sequencing tests on 15 popular traditional Chinese medicines seized by Australian border officials reveals a variety of potential toxins, allergens — and even traces of endangered animals.
For desperate people suffering from diseases that are debilitating or still incurable, traditional Chinese medicines are often the “courts of last resort.” Hundreds of thousands of people afflicted with cancers, spinal cord injuries, Lou Gehrig’s disease, multiple sclerosis, diabetes, HIV/AIDS and other diseases turn to these medicines to ease pain or improve the quality of life.
And it’s no wonder, as traditional Chinese medicine (TCMs) have been used for 3,000 years and are an integral part of Chinese culture. In recent decades, the practice has spread across the world and gained popularity, spawning a multimillion-dollar global industry.
But are these medicines safe?
Health practitioners are by no means against TCMs. In fact, the World Health Organization backed traditional Chinese meds in 2008, endorsing an international agreement that promised to give these meds a foothold in health systems around the world.
The “Beijing Declaration” was inked at the first Congress on Traditional Medicine in Beijing in November 2008. The WHO-drafted document called on United Nations members to create policies ensuring the safe and effective use of traditional medicines and systems for licensing practitioners, as well as encourage communication between Western and traditional practitioners.
In the United States, such “complementary and alternative medicine (CAM)” techniques — which include TCM — are accepted even by national health authorities like the National Cancer Institute. Defined as “a group of different medical and health care systems, practices and products that are not presently considered part of conventional medicine,” CAMs are often combined with conventional medicine for an integrative medicine approach to the treatment of cancer, HIV/AIDS and other conditions. There’s even a National Center for Complementary and Alternative Medicine (NCCAM) that’s in charge of checking that these CAMs are safe and effective.
Are traditional Chinese meds regulated?
Still, despite this openness– and the billions of dollars in worldwide sales racked up by traditional Chinese meds — only a small number of TCM products have been validated in scientific trials and the booming TCM industry isn’t well regulated.
Again and again, scientists — including some from the Food and Drug Administration — have found a number of traditional Chinese medicines to be adulterated with pharmacological drugs, in a bid to increase their effectiveness.
What’s more, researchers are finding it hard to pin down and standardize the active ingredients of TCMs, since these are often found in plant extracts that have regional or seasonal variations. Often, because their ingredients are not explicitly detailed, TCMs slip under the radar of regulatory agencies in the U.S., Europe, Canada and Australia. Meanwhile, it’s proven difficult even to just find out what TCMs are made of.
That’s why — despite a growing number of cases detailing adverse reactions — concerns about the efficacy, legality and safety of TCMs have remained unaddressed mainly because there was no solid method to determine their ingredients. That is, until now.
In the past, researchers run assays for toxic compounds and used DNA tests to find out whether a specific plant or animal was present in traditional Chinese meds. But because mislabeling is rampant, researchers don’t always know where to start — what to look for. Conventional approaches will miss many of the species that are present, says Dr. Mike Bunce, a geneticist at Murdoch University near Perth, Australia, who led a new study on TCMs.
Now Dr. Bunce’s team of Australian researchers has turned to a technique that can rapidly read thousands of DNA strands — next-generation DNA sequencers.
When the meds are “sequenced,” researchers can then check the genetic sequences against databases to learn which plants or animals they come from. This ‘deep sequencing’ technique is very effective — it’s been used to characterize mixtures of microbes living in environments as diverse as animal guts and oceans.
What the Australian researchers discovered was that Chinese herbal medicines contain ingredients derived from toxic plants, livestock — and even endangered animals. Worse, few of these ingredients were actually listed on the packaging. Their findings are published in the April 12 issue of PLoS Genetics.
“There’s absolutely no honesty in the labeling of these products. What they declare is completely at odds with what’s in there,” says Dr. Bunce.
Over all, the researchers found that 78 percent of the samples contained animal DNA that was not labeled in Chinese or English on the packaging.
“A product labeled as 100 percent Saiga antelope contained considerable quantities of goat and sheep DNA,” Dr. Bunce reveals. “Another product, Mongnan Tianbao pills, contained deer and cow DNA, the latter of which may violate some religious or cultural strictures,” he tells Medical Daily.
Teasing out DNA sequences
Traditional Chinese medicine often contains a number of animal and plant components that are meant to act synergistically to treat a particular ailment. What Dr. Bunce’s team did was to sequence DNA from 15 traditional Chinese medicine preparations — including tablets, powders and teas — that had been seized by Australian customs. Focusing on DNA from chloroplasts and mitochondria — the energy-producing cell structures that have their own genomes — the researchers produced 49,000 genetic sequences.
According to a New York Times report on the study, “Figuring out which vertebrates were present was relatively straightforward” but “plants were trickier to pin down.”
“For the researchers to identify what species their sample reads correspond with, they must have something for comparison in a database. Many plant species have yet to be sequenced, though bar code of life initiatives are improving the situation,” the Times says.
“Significantly more money has been invested in animal DNA bar-coding,” Damon P. Little, the assistant curator of bioinformatics at the New York Botanical Garden, tells the Times. “Plant DNA bar-coding efforts will need a similar investment before the reference database will be of comparable depth,” he explains. Damon wasn’t involved in the study.
And what exactly did the researchers find in the TCMs?
• Goat, sheep, deer, buffalo, cow and toad DNA.
• Endangered Saiga antelope and vulnerable Asiatic black bear– two species protected under the Convention on International Trade in Endangered Species that is signed by China and 175 other countries.
• 68 families of plants.
• The most common plant found was mint — often used to treat gastrointestinal upset and gallbladder problems.
• Another common plant was liquorice root –classified as one of the Chinese 50 fundamental herbs but also threatened with species extirpation in some Chinese provinces because of over-harvesting.
• Ephedra, a poisonous herb banned in the U.S., was found in a product labeled as laryngitis medicine
• Aristolochic acid from aristolochia — a known nephrotoxin, hepatotoxin and carcinogen — was also found in this medicine for laryngitis.
“Aristolochic acid is seriously toxic, it has killed people who have taken the wrong dose,” Dr. Bunce warns. “I’d rather have laryngitis than take that material.”
Typically, the packaging of Chinese traditional meds don’t include labels with dosage information — describing how much of a particular ingredient is found in each serving, what dosage people should take or how often they should do so.
And that’s a big problem. It could lead to overdose, drug interactions and allergic reaction.
“People need to be aware of the safety and legality issues surrounding traditional Chinese medicines before adopting them as a treatment option,” the researchers write in PLoS Genetics. Aside from raising consumer awareness, they hope their method can also help regulatory authorities like the FDA and the Australian counterpart develop regulations for traditional Chinese medicine.
“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, United Kingdom.
The new sequencing technique
The new research shows that second-generation, high throughput sequencing is an efficient and cost-effective way to identify the species composition, says Dr. Bunce’s colleague, PhD student Megan Coghlan, who is studying the application of DNA techniques in wildlife forensic applications. “The approach has the ability to unravel complex mixtures of plant and animal products,” she says.
The technique can also make it easier for customs officials to identify the trade of endangered species — which is driven largely by the rising popularity of traditional Chinese meds.
“We found multiple samples that contained DNA from animals listed as trade-restricted according to the CITES. Put simply, these TCMs are not legal,” Coghlan notes.
Dr. Bunce, in fact, thinks 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.
Right now, each sample cost US$35 to test, excluding labor, the researchers estimate, but the cost is expected to fall as DNA sequencing technology becomes cheaper.
British complementary medicine researcher Dr. Ernst agrees. “Screening might be a way forward,” he tells Nature magazine.
Even the UK’s National Health Service praises the study for “develop(ing) a technique that may help to monitor the contents of traditional Chinese medicines or other similar products.”
The NHS also says the Australian research “does raise an important point, which is that some traditional Chinese medicines may not list all of their ingredients on the packaging.”
“This is a problem that the UK’s Medicines and Healthcare products Regulatory Authority (MHRA) has reported in the UK, including cases where banned medications have been found in supposedly ‘natural’ products,” the NHS warns.
Meanwhile, the MHRA also warns that, “The public should be aware that there are some traditional Chinese medicine (TCM) products on the UK market that may be manufactured to low quality standards and may be deliberately adulterated or accidentally contaminated with toxic or illegal ingredients.”
“These products do pose a direct risk to public health and it is not currently possible to distinguish between these products and TCMs that are made to acceptable safety and quality standards,” it cautions.