A common refrain in any discussion of herbal medicines is “it’s been used for hundreds/thousands of years, it must be safe”. Unfortunately this is not necessarily true. If the herbal ingredients cause chronic disease, or rare but serious side effects, these adverse events can be easily missed.
After all, comfery tea was used for centuries without people realising it caused liver disease. The once popular Sassafrass tea turned out to be carcinogenic.
Two recent publications highlight the issues around safety of herbal medicines. The first, reported here at The Conversation by the authors of the study, shows that many herbal Traditional Chinese Medicines are adulterated with a range of other plant and animal material.
While I won’t be losing any sleep over endangered Saiga antelope horn being contaminated with goat and sheep horn, it’s the range of other undeclared plant materials that are the worry.
Finding that there is undeclared Ephedra in herbal Traditional Chinese Medicines is a serious issue, as Ephedra can kill, and Ephedra containing herbal medicines are banned in Australia.
Even more worrying is the finding of Aristolochic acid in things such as laryngitis medicine. Aristolochic acid is a nephrotoxin, and more insidiously, a carcinogen.
While in these cases, the content of things such as Aristolochic acid is undeclared, Aristolochic acid containing plants are part of traditional Chinese herbal medicines. The second study I mentioned looked at the link between Traditional Chinese medicines and the high rates of a rare kidney cancer in Taiwan.
In Taiwan there is a high usage of Traditional Chinese Medicine, at least one third of the population is exposed to medicines containing Aristolochic acid. At the same time the Taiwanese have the worlds highest rates of a rare kidney cancer, urothelial carcinoma of the upper urinary tract.
The study found a “smoking gun” between the known carcinogen Aristolochic acid and the cancer, by finding the chemical signature produced when Aristolochic acid mutates DNA.
Once again I’ll remind you that Aristolochic acid containing herbs are a part of standard Traditional Chinese Medicine, not a contaminant. Despite their use for hundreds, if not thousands of years, the harm due to Aristolochic acid containing herbs has only recently come to light due to systematic research through conventional medicine.
These studies are a timely reminder that “natural” is not synonymous with “safe”, and herbals can be used for hundreds of years with serious toxicity being noticed by traditional practitioners.