Puffer fish: a ‘delicatessen’ more poisonous than cyanide


For some it is a delicacy and others do not find it so exquisite. What there is no doubt is its dangerousness . The fugu or puffer fish ( Lagocephalus sceleratus ) can cause what is considered the most serious food poisoning produced by fish . In Europe the commercialization of this type of fish is prohibited, but in Japan it has been consumed since time immemorial and it is also prepared in other countries of Southeast Asia. And it has always caused poisonings and deaths , especially when it is cooked by inexperienced hands.

What makes it so appreciated from a gastronomic point of view? The family doctor and clinical microbiologist Manuel Linares, from the IO Foundation , points out that there are “those who say that it has a distinctive flavor , a priori quite harsh, powerful. Although most of the time she makes up with the sauce that accompanies it ”. It clarifies that what truly contributes to its continued consumption is culture and tradition.

A toxin 1,000 times more powerful than cyanide
Whether it is really a delicatessen or not, the puffer fish draws attention for its habit of bloating its stomach with water when it feels threatened and, above all, for the toxin it has along with the rest of the species of its family, the tetraodontids. The so-called tetrodotoxin , according to Emilio Salgado, from the Clinical Toxicology Unit of the Emergency Service of the Hospital Clínic de Barcelona , “is 1,000 times more potent than cyanide .” This means that it can kill an individual weighing only 10 micrograms per kilogram, compared to the 100 milligrams of cyanide per kilo required to cause the same effect. “A small amount can be lethal,” he stresses.

Apparently, it is precisely its poison that makes it so popular in the kitchen. “The meat of this fish, consumed in the form of sashimi, produces a very curious sensation on the palate , which has to do with tetrodotoxin”, reveals Salgado. Therefore, those who consume it “are poisoning themselves with extremely low amounts to get that tingling or tingling effect in the mouth .”

But is that risk worth taking? The toxicologist is clear that not. Linares clarifies that in Japan there is “a cooking school specialized in knowing how to clean fish so that no toxin remains in the food, ” although he acknowledges that very few Japanese chefs have the authorization of their Government to manipulate fugu and, as a general rule, it is worth remembering that “zero risk does not exist”.

This is how poison works
Tetrodotoxin is a neurotoxin and, as such, it is capable of interrupting nerve transmission, producing progressive muscle paralysis . Salgado recounts the sequence of intoxication due to the consumption of this fish : “Let’s imagine that a person goes to a Japanese restaurant, asks for puffer fish, has the bad luck that a novice chef prepares it and becomes intoxicated. The first thing you will notice, 10-15 minutes after ingestion, is that the tongue and the inside of the mouth go to sleep . This is a consequence of the inactivation of the sensitive nerve fibers of the oral cavity ”.

Immediately afterwards you will begin to have gastrointestinal symptoms, mainly nausea and vomiting . As the toxin makes its effect, both on the motor fibers and on the sensory fibers, the affected person feels tingling or loss of sensitivity in both the fingers and toes. After a short time, you will not be able to move your legs or arms .

“As the poisoning progresses, problems appear with the most important muscles, which are used for swallowing and motor coordination , among other functions,” continues the toxicologist. “Finally, it will be difficult for him to breathe and that is going to be what is going to cause his death.” In fact, he adds, “there are studies that show that, of all the musculature of the human body, the most sensitive to tetrodotoxin are the fibers of the diaphragm (a muscle located between the pectoral and abdominal cavities that is essential for respiration), whose paralysis leads to death by suffocation ”.

In the final stages of intoxication, a loss of consciousness occurs , “partly due to the effect of the toxin on the neurons of the central nervous system, but also due to the lack of oxygen derived from diaphragmatic paralysis.”

No antidote, but supportive treatment
The above sequence can be stopped and reversed with prompt and proper treatment. There is no antidote for puffer fish toxin, but advanced life support measures can save the lives of those affected and, in fact, mortality has dropped considerably since they exist. The key is, as the Clinic doctor explains, to stop diaphragmatic paralysis, for which the patient is intubated to connect him to a respirator until the effect of the toxin wears off. “Serum intake is also important to maintain high blood pressure because tetrodotoxin affects the small fibers of the smooth muscle of the vascular muscles, which produces a very marked hypotension .”

Possible medical uses of fugu toxin
Some preliminary studies have shown that, at low doses, “tetrodotoxin could be a great analgesic , emerging as a substitute for opiates to relieve severe pain,” says Linares.

However, at present there is no approved medical use and the Clinic toxicologist doubts that anything good can ever be extracted from such a poisonous fish: “There is no doubt that it is a very good anesthetic , but the necessary amount to produce anesthesia leads you to death. It has no medical application due to the great danger of consuming minute quantities ”.

It is a fish native to the Indo-Western Pacific Ocean, but it seems that it is spreading to other areas “Since it was first detected in 2003 in the Turkish waters of the Mediterranean, alarms have sounded about the explosion of its population in Israel , Turkey, Crete, Egypt and possibly Libya and Tunisia, some specimen reaching the waters of Spain (Denia in 2012, Pitiusas Islands in 2014, Torrevieja in 2016 Torrevieja…) ”, warns Linares.

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