SOME herbal medicines have been found to contain harmful chemicals and toxins that could lead to an increased risk of heart attack or stroke.
A review of multiple studies on the ingredients in herbal medicines, which are often thought to be a natural substitute for pharmaceutical drugs, was undertaken by researchers from the University of Adelaide in South Australia, in collaboration with researchers from Curtin University and Murdoch University.
It found that a number of herbal products and Traditional Chinese Medicines contained toxic chemicals from animals and plants as well as heavy metals and pesticides.
Although the review was conducted in Australia, researchers have said the results could be extrapolated to include the global industry.
Lead author and Professor of Pathology at the University of Adelaide Roger Byard said the toxic side effects of herbal medicines are typically under-reported and have often been overlooked due to perceptions of their safety.
“The lack of systematic observation has meant that even serious adverse reactions, such as the kidney failure and liver damage caused by some plant species, have gone unrecognised until recently,” he said.
"We feel it would be appropriate for the Therapeutic Goods Administration to require manufacturers to have samples independently tested before placing them on the market.
“Legal action should be considered in cases of non-compliance with applicable regulations and preparations containing illegal substances should be banned."
The study reviewed 24 different case studies and systematic reviews of materials.
It found that about a quarter of Traditional Chinese Medicines had some form of contamination or adulteration.
The review has important implications for consumers, as more than half of those using complementary medicines (including herbal products) do not inform their doctors of use.
Patients often use these products in conjunction with conventional medications and other herbal supplements.
According to Cancer Research UK, some studies have shown that as many as 60 per cent of people with cancer use herbal remedies alongside conventional cancer treatments.
Last year, 10 children in the United States died after using homeopathic teething tablets. According to the US Food and Drug Administration (FDA), inconsistent amounts of belladonna, a toxic substance more commonly known as “deadly nightshade” were found in some teething tablets.
Co-author of the study and University of Adelaide Senior Lecturer Ian Musgrave said side effects of some herbal medicines included heart attack and stroke.
He said one of the main issues was the trend of online purchases of herbal and homeopathic medicines, where the products came from countries with less stringent regulations than Australia.
“Sometimes the ingredients that are on the label are not what you find in the medicines or it’s not a complete list of all of things that are in there,” Dr Musgrave said.
“The idea is that if we can use DNA analysis to look for herbal material and pick up things that are both meant to be and not meant to be in there, that will give us a heads up over just looking for toxic chemicals we know about.
“We know DNA testing has limitations because some herbal remedies are not herbs per se but are herbal extracts which do not contain DNA, however there are other methods for picking up materials in these kinds of herbal medicines that could also be used.”
The research paper was published in the Medical Journal of Australia today.
South Australia’s capital Adelaide has three long-standing public universities, Flinders University, University of South Australia and the University of Adelaide, each of which are consistently rated highly in the international higher education rankings.