Revealed: The Potentially Deadly Toxin Which Could Be Lurking Inside Your Tuna Sandwich

Your tuna sandwich could be deadly/Lara 604 for Creative Comms

It is the best selling canned fish in the UK, with more than 80,000 tons sold each year.

But a little known and potentially deadly toxin could be hiding inside your tuna fish sandwich.

Scombroid poisoning can cause a rash, diarrhoea and abdominal cramps - and in severe cases, even death - tourists Noelene and Yvana Bischoff’s deaths in Bali last year were caused by the toxin.

Mackerel, sardines and anchovies also carry the threat which occurs when the fish isn’t adequately preserved after it’s caught, prompting a build up of bacteria as the flesh decays.

Dr Kumar Gnanakumaran, a consultant immunologist at the Queen’s Medical Centre in Nottingham told The Mail Online: “Scombroid poisoning is caused mainly by eating tuna - fresh, tinned or frozen - which hasn’t been refrigerated properly at some point in the food chain.

“The symptoms can be nasty, including severe headache, acute flushing of the skin, vomiting and diarrhoea.

“Although in most people such symptoms will pass after a few hours with the help of an antihistamine tablet, in extremely rare cases it has been known to be deadly.”

It is unknown how many people suffer from Scombroid poisoning each year, mainly because the majority of sufferers are unaware of its existence - its symptoms are similar to that of an allergy.

But there are slight but important differences between a true allergic reaction and Scombroid poisoning.

“The differences are subtle but a true allergic reaction will trigger tingling or swelling of the lips or tongue as soon as the food touches them, followed by throat constriction and an itchy rash,” Dr Gnanakumaran explained.

“If you have scombroid poisoning, the reaction will start a few minutes to an hour after eating, and will be an acute attack typically lasting a few hours.

“Rather than an itchy rash, the skin will be flushed and feel as though it is burning. Other symptoms can include a severe headache, a sudden drop in blood pressure that leaves you feeling faint, a racing heart, tight chest and shortness of breath, as well as sickness and diarrhoea.

“Although allergies can develop at any time in our lives, in the majority of cases when someone without a previous fish allergy suffers a reaction after eating tuna, it will most likely be as a result of scombroid poisoning.”

Amelia Warner, national nurse advisor for Allergy UK, said the scombroid toxin is resistant to smoking, cooking, canning and freezing.

“If the toxin is already there before the fish is dispatched for human consumption, it is there for good,“ she said. “Neither can its presence be detected by appearance or smell. But if you eat fish that has a strange peppery or metallic taste, don’t carry on eating it, as this could be a sign that it hasn’t been adequately preserved.

“If you feel unwell soon after eating tuna or similar fish, take an antihistamine quickly. You may need treatment for dehydration if you have had sickness and diarrhoea. If you are unsure you must seek urgent medical attention.”