Not long ago, Beijing Tongren Hospital treated over 70 employees from a local company. Many of them exhibited symptoms such as facial flushing, nausea, vomiting, and confusion. Upon investigation, doctors discovered that all the patients had eaten braised squid at the company canteen during lunch. After receiving symptomatic treatment, their conditions improved rapidly. The medical team suspected that the cause was food poisoning due to spoiled eel or stale squid.
Histamine poisoning typically occurs after consuming fish that are high in histidine, especially blue-skinned, red-fleshed species like tuna, mackerel, sardines, squid, and others. When these fish spoil, bacteria break down histidine into histamine, which can lead to poisoning when consumed in large amounts. Experts explain that as fish deteriorates, enzymes in the body increase, accelerating the breakdown of amino acids into harmful substances, including histamine. Marine migratory fish, such as certain types of mackerel, tend to have higher levels of this enzyme, making them more prone to histamine buildup if not handled properly.
The symptoms of histamine poisoning usually appear quickly—within an hour, sometimes as fast as 5 minutes, and rarely taking more than 4 hours. Common signs include facial redness, dizziness, headaches, rapid heartbeat, chest tightness, difficulty breathing, and even blurred vision or swollen lips. Some individuals may also experience nausea, abdominal pain, hives, or a drop in blood pressure.
These types of fish are often highly prized for their flavor, which makes them popular on dining tables. Unfortunately, this also leads to frequent cases of food poisoning. For example, in April 2002, a food poisoning incident in Shenyang affected 53 people, with 9 requiring serious medical care. In May 2006, over 20 villagers in Hengshui suffered from similar issues after eating contaminated fish.
To prevent histamine poisoning, it’s important to focus on both purchasing and preparation. When buying seafood, always check the eyes (they should be clear and bright), the color of the flesh, and the firmness of the body. Avoid fish with sunken eyes, discolored skin, or soft, unresponsive flesh. Also, make sure the fish is properly refrigerated or frozen. If not, it’s best to avoid it.
Once purchased, cook the fish as soon as possible. Adding vinegar during cooking can help reduce the levels of histamine. For squid, it's recommended to remove the internal organs, which contain high concentrations of histidine, then rinse and soak the meat in water for 4–6 hours. This process can reduce histamine by up to 44%. Additionally, adding cranberry or other acidic fruits during cooking can further lower histamine content by about 65%.
People with known allergies should avoid eating these types of fish altogether. Being cautious with seafood, especially those high in histamine, can significantly reduce the risk of poisoning and ensure a safer dining experience.
**Attachment: Examples of Blue-Skinned Red-Fleshed Fish**
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