Traditional Chinese Medicine: What’s really in that bottle?

So this was a piece I was putting together for a student magazine I write the odd piece for, but it was only published just before the copy deadline and I didn’t finish it in time. Interesting (and scary!) stuff…

Traditional Chinese Medicine (or TCM) is a single name referring to a wide range of herbal medicines, diets, and alternative therapies such as acupuncture and massage. The concepts that make up TCM are generally viewed as ‘alternative medicine’ by those in the West, but they make up 40% of all health care provided in China. While rooted in a bank of tradition stretching back some 2000 years, and still containing many notions that are not supported by evidence-based medicine, several Chinese herbal medicines have been demonstrated to have a high level of efficacy and have led to the discovery of active ingredients, and the development of new synthetic drugs. In the 1970s Chinese scientist Tu Youyou successfully identified two new antimalarial drugs (artemisinin and dihydroartemisinin), the most rapidly acting medicines that we currently have, and in 2011 she was awarded the Lasker Award for Clinical Medicine for this work. For many people, TCM occupies a precarious position between ‘vast untapped resource’ and ‘unregulated alternative medicine’.

In the past, concerns about the use of TCM have concentrated on the efficacy of the medicines, and the use of endangered animals in their preparations. However, a new paper this month have concentrated on the question of whether these medicines might be worse than ineffectual: could they actually be dangerous? In the absence of a central regulatory system, it is often impossible to confirm the precise ingredients in herbal or animal-based products. Though determining the precise chemical structure of a medicine is incredibly complicated, identifying at least some of the species that plant and animal material originates from is – in this age of Next Generation Sequencing – comparatively simple.

Next Generation Sequencing is a high throughput method that can produce huge quantities of DNA sequence relatively cheaply. By sorting through the data and fishing out two highly conserved genes (trnL and a 16S ribosomal gene, which are very similar in all eukaryotes) the scientists could begin to identify which species were present in the Chinese preparations. For the purposes of this they looked at 15 different traditional Chinese medicines that had been taken by customs at the Australian border. A similar process has been used in the past (e.g. to identify whether orchids are legally transportable varieties, or rare ones that should be left untouched), but without Next Generation Sequencing it is a laborious and time consuming process.

The published findings begin as concerning but unsurprising: the authors found material from the Asiatic black bear, classified as vulnerable by the IUCN; and saiga, a critically endangered species of antelope. Both of these species, though in theory protected, are considered valuable in Chinese medicine. However, more concerning was the discovery that the preparations contained material from numerous other species not mentioned in the ingredients lists. The preparation listed as being 100% saiga contained considerable quantities of goat and sheep DNA.

Far more concerning were the plant-based preparations: Genes from 68 different families of plants were found. So far, so unsurprising. Included on the list are Ephedra (yes, as in ephedrine); ginseng (which it is illegal to trade on an international basis) and Aristolochia. Aristolochia makes a chemical called aristolochic acid, most commonly mentioned in the context of kidney damage; liver damage and bladder cancer. This is especially interesting because the herb is used a lot medicinally in Taiwan: an area with documented high rates of bladder cancer, and another new paper suggests this is a causal link. The scientists found four medicines that contained Aristolochia and one of these definitely contained aristolochic acid. It’s hard to be more accurate than that, because identifying chemicals in a medicine is far more complicated than identifying DNA.

Pretty concerning stuff, if you ask me. I’m all for being open minded about possible sources of new medicines and drugs. But would you take Paracetamol quite so cheerfully if you couldn’t guarantee there weren’t some known carcinogens and endangered animal parts hanging about in there?

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