Histamine: what it is and how it is formed
Histamine is a substance naturally present in our body. It modulates various functions including the secretion of gastric acid, various brain processes and the body's defense system (immune response).
Histamine can also be introduced into the body through some foods that contain high concentrations, particularly fish, aged cheese, canned foods, fermented foods and red wine.
Ingestion of high concentrations of histamine can cause even serious undesirable effects.
The "histamine" in the body is mainly produced by the bacteria present in the intestine starting from histidine, an amino acid important for the constitution of numerous proteins, including those of the muscles. Many gram-negative bacteria that commonly occur in or contaminate food are capable of producing histamine. It can therefore be concluded that the risk of histamine food poisoning is related to the presence of both histidine and gram-negative bacteria.
The most endangered fish species
Food poisoning from histamine occurs mainly through the consumption of fish and is one of the most common poisonings linked to this food in Italy and in Europe.
Histamine is not present when the fish is still alive: an excess of histamine is formed in fish stored in an inadequate and improperly refrigerated way. In fact, the bacteria present on the skin, in the gills and in the intestine, penetrate the muscle tissues and begin to produce histamine.
In principle, all species of "fishbone" improperly preserved could give rise to histamine intoxication. In practice, among the types of fish commonly consumed, high concentrations of histidine, and therefore a high risk of histamine formation, they are found mainly in fish belonging to the mackerel family, such as tuna, bonito, sardine, anchovy and mackerel. Given the very strong association with the consumption of these fish, histamine intoxication is also traditionally called scombroid syndrome.Storage conditions that induce the formation of histamine
Storage conditions that induce the formation of histamine
To avoid bacterial proliferation and the consequent production of histamine, fish should be treated in conditions of maximum hygiene and stored and thawed at low temperatures (no more than 6 ° C), avoiding the interruption of the cold chain. It is very important to provide refrigeration immediately after capture.
Histamine is produced before the deterioration of the fish can be identified through the sensory characteristics (appearance, smell, taste), especially in the presence of "additives" that give the fish apparent freshness but do not slow down its deterioration. Among these is the cafodos (or cafados), a product not authorized in Italy.
These substances are inherently free from toxicity; however their use can go beyond simple fraud and cause a health risk, as it leads the consumer to purchase a fish that is apparently good looking but already has high levels of histamine in it. The cafodos and similar products are composed of very simple and non-persistent ingredients, such as citric acid, therefore they are not detectable by laboratory analyzes. The only effective way to identify their use is during checks in fish processing and conservation sites .
It is essential to emphasize that if histamine is already present in fish meat, cooking is not able to inactivate it.Toxicity: disorders and health risks
Toxicity: disorders and health risks
In healthy people, histamine ingested with food is rapidly transformed (metabolized) by protein molecules (enzymes) specific to histamine (amino oxidase).
However, if its levels reach a critical threshold, it can be dangerous to health. It can cause reactions similar to an allergic form, including nausea, vomiting, diarrhea, skin rashes and hives, asthma and breathing problems, arrhythmia and tachycardia. In people whose amino oxidase levels are insufficient, due to a genetic predisposition, gastrointestinal diseases and drugs that inhibit them, even the ingestion of small amounts of histamine can cause severe allergic reactions.
The symptoms (symptoms) caused by histamine intoxication appear very quickly and can last up to a couple of days. There are no complications in healthy people, but in those who already have breathing problems (asthma) or blood pressure control problems, the clinical manifestations can be more severe.
If histamine intoxication is suspected, it is advisable to contact your family doctor, who will prescribe antihistamines and cortisone. In the most serious cases, in which there was the onset of respiratory disorders and low blood pressure (hypotension), it is necessary to go to the emergency room to receive the most appropriate therapy.Assessments by the European Food Safety Authority (EFSA) and legal limits
Assessments by the European Food Safety Authority (EFSA) and legal limits
In 2011, on the basis of scientific publications on the subject, the European Food Safety Authority (EFSA) evaluated histamine and concluded that, in the absence of preventive measures, there is a possible risk for consumers.
The implementation of hygiene measures aimed at limiting bacterial contamination and maintaining the cold chain play an essential role in reducing the production of histamine. For healthy people, despite the presence of scientific uncertainties, the ingestion of 50 milligrams per meal per individual. For people with histamine intolerance or with asthma and heart disease, it is advisable to stay below the detectable limits.
Current regulations (EC Reg. 854/04 and EC Reg. 2073/05) set a maximum histamine content of 200 milligrams per kilo (mg / kg) for fresh fish and 400 mg / kg for preserved products. The National Health Service has the task of supervising to verify compliance with these limits and compliance with adequate storage and transport temperatures.Advice to consumers on the conservation of fish to minimize the risk
Advice to consumers on the conservation of fish to minimize the risk
It is advisable to buy the fish from a trusted dealer, being sure of the origin and correct conservation of the product. It is extremely advisable to have the fish cleaned, eliminating the entrails and removing the gills and thus reducing the bacterial load.
Once at home, keep the fish at temperatures below 6 ° C and defrost it in the refrigerator, so as not to favor bacterial proliferation.
The use of products such as the cafodos it makes the fish shiny as if it were very fresh, but it cannot mask the principles of tissue deterioration; therefore, these illicit practices can deceive the sight, but not the other senses.
To check the freshness of the fish it is recommended to:
- feel it, to verify its firmness
- check your eyes, they must not be flattened and sunken
- smell it, to check the smell
- check the gills, they must not appear brown and dull
EFSA Panel on Biological Hazards (BIOHAZ). Scientific Opinion on risk based control of biogenic amine formation in fermented foods. Efsa Journal. 2011; 9: 2393
European Food Safety Authority (EFSA). Assessment of the incidents of histamine intoxication in some EU countries.EFSA supporting publication. 2017; 14: 1-37
Lazio region. ASL Frosinone - Food safety. Histamine and scombroid syndrome
The expert and the secrets of cafodos "Makes rotten food look fresh". The Republic; July 31, 2010