Posted by: Prospector PJ10 JUL 2013
A case study presented at the European Society of Cardiology’s annual congress last month considered the case of a father and son admitted to a hospital emergency department in Turkey suffering from vomiting and dizziness. Both had complete atrioventricular block and atrial flutter with slow ventricular responses. It was discovered that they had eaten large amounts of honey for breakfast over the previous three days. Medical staff immediately suspected “mad honey poisoning”, which occurs after consuming honey contaminated with grayanotoxin, a neurotoxin found in nectar from Rhododendron ponticum and R luteum. Grayanotoxin binds to the sodium channels in cell membranes, maintaining them in an open state and prolonging depolarisation.
Mad honey poisoning generally lasts no longer than 24 hours. But symptoms of the more serious form can include syncope, seizures, complete atrioventricular block and even fatal tachyarrhythmias. There is no specific antidote but mild cases can be treated with atropine and selective M2 muscarinic receptor antagonists.
The condition occurs most commonly around Turkey’s Black Sea region, a major beekeeping area that is also the native habitat of R ponticum and R luteum. Honey from Japan, Brazil, the US, Nepal, British Columbia and New Zealand may also be contaminated. As little as a teaspoon of natural honey may be sufficient to cause poisoning, but the toxins are removed during the industrial process. There have been no reported cases of mad honey poisoning in the UK.
The grayanotoxin has been deliberately used for nefarious purposes. According to Pliny, Black Sea locals used contaminated honey against the armies of Xenophon in 401BC. And the toxin from “hydrated rhododendron” was used in the 2009 film ‘Sherlock Holmes’ to induce an “apparently mortal paralysis” in the main antagonist.