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Pontifications on Poison

Being some ramblings on events associated with poisonous plants.

Friday 22nd March 2013

I wonder when something becomes known rather than news. I say this because of the publication of a review1 of the diagnostic approach to and management of aristolochic acid nephropathy (AAN) looking at what has been learned about dealing with the condition in the twenty years since it became known.

Of course, it isn’t and if you go to the plant page for Aristolochia clematitis, birthwort, you’ll see that I’ve written extensively about the condition and blogged about it a number of times.

Nonetheless, this review article, whose abstract begins ‘It has been 20 years…’  is being reported, at least in the headlines, as if it were a new discovery.

Aristolochia clematitis, birthwort

Aristolochia clematitis, birthwort’s headline ‘Herbal Medicine May Cause Kidney Failure’2 manages to both suggest this is a new discovery and that there may still be doubt about the effect of aristolochic acid (AA) though the piece itself makes it clear that there is two decades worth of work to draw on showing that AA does cause kidney failure.

Voice of America’s ‘Herbal Medicines Linked to Kidney Disease’3 might lead the reader to assume this is a new finding and the piece itself doesn’t help. Though the first paragraph refers to ‘previous studies’ the second describes the review as ‘research’ and calls it ‘a wake-up call’ as though nothing had been done about the risks, to date. There is no mention of the FDA’s warning against use of any remedy containing AA that was issued in 2001. asks ‘Could herbal medicines cause kidney failure?’4 as if there is doubt in the matter and its first paragraph refers to ‘the news that these ‘natural remedies’ may be causing more harm than good is quite alarming’. The FDA warning is mentioned but without giving a date so that it seems to be something that has just happened. After that poor start, the piece does go on to interview a pharmacologist who details the situation well.

The Times of India avoids introducing doubt by headlining its report ‘Herbal medicines causing kidney failure, bladder cancer in India’5 but then goes a little too far the other way by stating ‘Herbal medicines are causing millions in India to develop kidney failure and bladder cancer’. The National Kidney Foundation, India says kidney diseases ‘rank 3rd amongst life-threatening diseases’ and have a prevalence of 100/million of the population. That suggests around 1.2 million sufferers but the NKF also says 22.5% of those require dialysis pointing out the difference between kidney disease and kidney failure. There are 200,000 deaths each year and around 90,000 transplants.

The danger of over-stating a serious problem is that it tends to cause disbelief. Some years ago, a UK charity claimed that child abuse affected almost half of all children. When pressed, however, it turned out that its definition of ‘abuse’ was cast so wide as to include a sharp telling off from a parent. The result of that overstatement was that many people assumed child abuse was not a problem after all. The same could happen if people think the figures for AAN are unreliable. There is a big difference in perception between 'millions' and 'just over a million'.

Aristolochia clematitis, birthwort

Aristolochia clematitis, birthwort

Medscape News is the only report I’ve seen that gets to the core of the problem. Its headline, ‘Chinese Herb Remains Health Threat Despite Widespread Bans’6 makes it clear that AAN is not a new discovery and that action has been taken to try and control the availability of AA.

The largest problem now is getting the message through to those in Taiwan and China who think that the campaign against products containing AA is just another example of western medicine not understanding. In that situation, speaking of ‘could’ or ‘may’ provides a get out.

I know good science is always doubtful and hesitates to make over dogmatic pronouncements because something else may be discovered tomorrow. But, though this justifies saying that taking products containing AA ‘may’ result in kidney disease, that is not the same thing as saying that AA may cause kidney disease. The science is strong enough to say that AA does cause kidney disease and bladder cancer in the same way that you can say smoking does cause lung diseases.


1.    The Epidemiology, Diagnosis, and Management of Aristolochic Acid Nephropathy: A Narrative Review Annals of Internal Medicine 19 March 2013, Vol 158, No. 6
2.    Herbal Medicine May Cause Kidney Failure 20th March 2013
3.    Herbal Medicines Linked to Kidney Disease Voice of America 19th March 2013
4.    Could herbal medicines cause kidney failure? 20th March 2013
5.    Herbal medicines causing kidney failure, bladder cancer in India Times of India 19th March 2013
6.    Chinese Herb Remains Health Threat Despite Widespread Bans Medscape News 18th March 2013



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