What is histamine and where is it found?
Histamine is a biological compound that is naturally synthesised in humans and animals. It is found in all fish, normally at low levels, although these increase at room temperature. It is formed from the breakdown of the amino acid histidine by bacteria on the skin or in the viscera of fish and in the marine environment.
What are the sources of contamination?
The risk of a high histamine concentration depends on:
- the risk of bacterial contamination when the fish is caught and then prepared,
- the risk of bacterial proliferation in fish flesh at every step of its storage, before or after sale.
What foods are concerned?
Some species of fish are richer in histidine than others, which can lead to higher histamine production. These are mainly species of tuna, mackerel, kingfish and bonito. Other species such as sardines, herring, anchovies, jacks, swordfish and dolphinfish are also concerned.
Between 2012 and 2021, 85% of histamine poisonings recorded by French poison control centres were due to tuna consumption, 7% to mackerel and 3% to sardines.
It should be noted that in some rare cases, foods other than fish can cause histamine poisoning. These include mixed dishes such as ravioli, moussaka and mixed salad, and Emmental cheese.
What are the health impacts?
Histamine poisoning resembles an allergy and can cause the following symptoms:
- urticaria (hives),
- transient skin redness,
- vomiting, etc.
In general, the first symptoms appear 30 minutes after the meal.
In rare cases, histamine poisoning may require hospitalisation, but the outcome is usually favourable.
How can consumers limit their exposure?
To avoid bacterial proliferation that could promote the formation of histamine in fish, it is essential to maintain the cold chain before consumption, by:
- refrigerating or freezing fish as soon as possible,
- not leaving fish at room temperature or in the sun,
- if frozen, thawing the fish quickly and then eating it immediately,
- never refreezing fish that has been thawed.
Histamine is not degraded by cooking, freezing or canning.
In the event of poisoning, call a poison control centre or see a doctor.
Keep any leftovers from the fish meal for analysis and screening for contamination by histamine or micro-organisms if necessary.