There are many urban legends in the kitchen: adding salt to water makes it take longer to boil, applying hot temperature to fish and meat “seals” the juices inside, the five-seconds rule, etc. Being in Japan I am concerned with a myth related to raw fish. The thing is that I’m no sure whether it is a myth or not, so I’m hoping one of you can offer some insight on this topic.

A few years back, there was a big media wave in Europe about anisakis. This is a parasite that lives (mainly) in fish intestines, but also sometimes in their muscle or below the skin. When an infected fish is eaten by a human, this parasite can infect the person causing abdominal pain, fever, nausea, vomits and diarrhea. Sometimes the individual can then become allergic to anisakis and a second ingestion of the parasite (even if dead, that is even if the infected fish has been cooked) could cause a violent allergic reaction. I personally know people who have had anisakiasis and at least one person who has become allergic to it.

It seems like the most effective ways of avoiding this is to kill the parasite by either cooking the fish (for at least one minute at temperatures higher than 60ºC or for at least 15 seconds if temperature is higher than 74ºC) or freezing it to -20ºC or lower for at least 24h). Other forms of preserving fish like in salt or vinegar do not kill the parasite. For this reason in Europe, and also in many other countries outside of Europe, it is now compulsory to freeze fish that is going to be served raw.

Wild fish is more likely to be infected with anisakis than farmed fish and also cleaning properly the fish before eating it and getting rid of the intestines  soon after the fish has been capture both reduce the risk of ingestion of the parasite (although it does not eliminate it completely).

The incidence of anisakiasis has increased a lot in the past few years due to several factors:

– The anisakis population is increasing in part due to the bad habit of throwing fish remains back to the sea after consumption.
– The increasing consumption of raw fish in the world.
– Improvement of diagnostic techniques. In fact, until the 90s, most anisakiasis cases went undiagnosed because of the similarities with other indigestion episodes and seafood allergies.

Now I am in Japan and here it is not compulsory to freeze fish before serving it raw. In fact, wild fresh fish is highly appreciated and more expensive than farmed fish or fish that has been frozen. So the question is, is it safe to eat raw fish in Japan? After doing some research on-line, I have found the following arguments in both directions:

– Yes, it is. Because Japanese people have been eating raw fish for centuries they know how to prepare it properly and clean it very well. Also, they usually it raw fish with wasabi which has the property of killing parasites (I found no satisfying reference for this claim, is it an urban legend?). In other countries it is less safe to eat it because they don’t clean it well and sometimes they don’t serve real wasabi with it but just a coloured version of horseradish mustard.

– No, it is not. It is estimated that 95% of the world occurrences of anisakiasis happen in Japan, with an average diagnosed rate of incidence of at least 1000 cases per year. By far, they are the most affected country by the disease, showing that they do have a problem.

I’m starting to think that fresh raw fish is too internalized in japanese culture to have a law forcing them to freeze it before consumption. After all, most cases of anisakiasis are not live-threatening.

What do you guys think? Do any of you know where to find more accurate information about this? Any contributions will be greatly appreciated, especially because I have been eating sushi and sashimi here in Japan for the past months and it is indeed delicious!

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