Rare species DNA in Chinese remedies
“DNA testing of traditional Chinese medicines has shown that many contain traces of endangered animals,” The Independent has today reported.
The tests were performed by Australian scientists devising new ways to detect exactly what plant and animal materials are actually contained in traditional Chinese medicines and herbal teas. Knowing exactly what is in some traditional products can often be difficult, and in the past some have been found to contain materials from endangered species, banned medicines and toxic metals. The research was designed to create a new testing procedure rather than assess products on sale legally, and only tested samples of products seized by customs for breaking international endangered species trading rules. Some samples were found to contain DNA from potentially harmful plants, and also from endangered species such as black bears and antelope. Not all of the samples that contained animal DNA had been labelled as containing material from animals.
Given that the samples were all seized products, the results do not necessarily represent products that are imported legally. However, it does raise the important issue that these medicines may not always be labelled appropriately, and that consumers should be aware of this and view these medicines with caution.
The UK’s Medicines and Healthcare products Regulatory Authority states that “there are some traditional Chinese medicine 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”. The agency says these low-quality products pose a “direct risk to public health” and currently it is impossible to distinguish these from safe products made to acceptable standards.
Where did the story come from?
The study was carried out by researchers from Murdoch University in Australia; the university also funded the study along with the Australian Research Council. The study was published in the peer-reviewed open-access journal PLoS Genetics.
This story is covered appropriately by The Independent and other news sources.
What kind of research was this?
This was a laboratory study analysing the content of various traditional Chinese medicines. The researchers say that these medicines have become more widely used in recent years, and that there are concerns about their effectiveness, safety and legality. For example, they say that some traditional Chinese medicines contain material from endangered plants and animals that have been placed under international trade restrictions.
The researchers conducting this study set out to develop methods for identifying which plant and animal materials were in traditional Chinese medicines, as these methods could help in monitoring their contents for safety and legal reasons. The approach they used was based on DNA analysis, which is an appropriate approach to identify the origins of the contents of these medicines.
What did the research involve?
The researchers analysed 28 samples from traditional Chinese medicine products that had been seized by Australian customs officers at airports and seaports because they contravened international wildlife trade laws. The researchers then extracted and analysed DNA from these samples, to look at what materials they contained.
The samples the researchers analysed included powders, bile flakes, capsules, tablets and herbal tea. They extracted DNA from these samples using standard techniques, and looked at the genetic code contained in DNA at specific sites – different animals and plants have different DNA sequences and by identifying unique sections of code it is often possible to pinpoint the species a sample came from. The researchers then used the DNA information they obtained from the samples to identify which animals and plants had been used to make them. They did this by comparing the DNA sequences they had obtained against databases featuring the genetic sequences from different animals and plants
What were the basic results?
The researchers could only obtain good-quality DNA from 15 out of the 28 samples they tested, and could get DNA sequence information from 13 of these samples. From attempting their extraction process they say that the methods of DNA extraction may need to be modified to get better DNA samples from different types of products.
The researchers identified DNA from a total of 68 plant families in the 13 samples they tested. Some of the most common plants found in the samples were liquorice root (found in 62% of samples), mint (in 46% of samples), and wild ginger (in 31% of samples). They say that one type of liquorice root plant is under threat in certain Chinese provinces due to heavy harvesting for use in traditional Chinese medicines.
Four samples contained DNA that was very similar to DNA from two plant species Ephedra or Asarum, which can be poisonous or toxic at high levels. Products containing Ephedra have been banned in the US by the Food and Drug Administration (FDA) since 2004. The researchers also identified DNA from the cashew family in two samples and from the soybean in four samples. These plants contain chemicals that can trigger allergic reactions.
Nine samples contained DNA from vertebrate animals, and four of these contained DNA from animals that are endangered and have restrictions on their trade. This included material from the Asian black bear (Ursus thibetanus) and the Saiga antelope (Saiga tatarica). Three of the samples contained bear DNA, including one labelled as ‘bear bile powder’ and one with an outline of a bear on its box. One sample contained Saiga antelope DNA, and this was labelled as Saiga antelope horn powder, but also contained goat and sheep DNA. The other animal DNA identified in samples was from the Asiatic toad, deer, water buffalo and cow. The researchers reported that 78% of samples contained animal DNA that was not clearly stated on the packaging.
How did the researchers interpret the results?
The researchers concluded that the DNA analysis methods they used provided an efficient and cost-effective way to assess the contents of highly processed traditional Chinese medicine products. They say that this will help assist in monitoring the legality and safety of these products.
This study aimed to test a method for identifying the plant and animal components of traditional Chinese medicines. This is important because there are concerns that the exact contents of some of these medicines may be unknown or labelled misleadingly. This raises the possibility that they may contain illegal materials from endangered species, that they could be harmful, or that vegetarians may unknowingly be ingesting animal-based products.
In this particular set of seized samples the study found that some of the traditional Chinese medicines contained plant materials that are banned in some countries, or that are potentially dangerous. Other samples contained material from endangered animal species, or animal material that was not disclosed on the labelling.
There are some important points worth noting:
- This study was mainly about developing the technique rather than testing materials available on the shelves.
- The study only tested traditional Chinese medicine products that had been seized by Australian customs on suspicion of breaking Australia’s international wildlife trade laws. Therefore they may not be representative of materials that have been imported and sold legally.
- The study was carried out in Australia and the ingredients or contamination found may not be representative of the products that occur in other countries. Equally, products that are illegal or prohibited in one country may not necessarily be under the same restrictions in other countries.
- The researchers noted that there is more information available about the DNA of different animal species than different plant species, so identifying which animal materials were in the samples is easier than identifying the plant materials.
- The researchers also note a number of limitations to their methods, including the fact that some DNA in the samples will have broken down during production or storage, and there may only be small amounts of identifiable DNA from some components of the medicine. This means that their methods may not identify all contributing species.
- This analysis only identifies DNA, and cannot determine exactly which other chemicals from the plants and animals are in the samples. For example, it cannot determine if toxic or allergy-promoting chemicals from the plants are present. This would need additional chemical testing.
Overall, this study has developed a technique that may help to monitor the contents of traditional Chinese medicines or other similar products. It 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 MHRA states 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.”
Analysis by Bazian