Alpha-Gal: Why some people are allergic to meat?
Meat allergy — is there such a thing? Yes. What initially sounds like hypochondria is an actual immune reaction of the body. .
US researchers have described a new form of food allergy associated with the bite of a tick (Amblyomma americanum). Alpha Gal syndrome is a sudden allergy to red meat and offal from cattle, pork, lamb or game after a previous tick bite. At present, this tick species is only native to North America and Australia, and has not yet occurred in Europe.
Small animal — big damage
Researchers had conducted a study on 51 children and adolescents who repeatedly suffered from severe allergic symptoms. One study showed that almost all participants had antibodies against Alpha-Gal in their blood. Alpha-Gal is a carbohydrate contained in the saliva of ticks and can only have entered the human bloodstream via a sting. After the tick bite, the immune system forms antibodies against Alpha-Gal to neutralize it. Especially in patients with strong local inflammatory reactions after tick bites, large amounts of Alpha-Gal have been detected.
If the affected person subsequently ingests meat, which also contains alpha-gal, the typical allergic symptoms are triggered. In the meat of all mammals — except humans and monkeys — the building block alpha-gal is contained, particularly high concentrations were found in fatty meat and pig kidneys. Poultry and fish, on the other hand, are free of alpha-gal and are tolerated without any problems.
Allergy with delay
A special feature of the “meat allergy” is that the immune system forms antibodies against a carbohydrate and not against a protein as is usually the case with allergies. In contrast to protein-related allergies, the symptoms of meat allergy do not occur immediately after consumption but with a delay of three to six hours due to the necessary digestive process. For this reason, the inexplicable allergic reactions can often no longer be clearly attributed to the previous consumption of red meat.
No allergic pre-existing conditions
Alpha Gal syndrome usually occurs suddenly. Patients report that they have tolerated meat and other foods for years without any problems. Infections, certain medications, or alcohol can make allergic reactions worse. Meat allergy sufferers, however, do not react to every meal. The reaction of the immune system depends on the size of the portion and the form of preparation. Allergic reactions to red meat range from itchy skin rashes and shortness of breath to life-threatening shock. Alpha-Gal syndrome is diagnosed using the classic allergy test (prick test) with meat solution. A newly developed, special blood test can detect the allergy even more accurately.
Meat allergy: danger from the grill
Meat from pork, beef and lamb is popular — not only for grilling. But for some allergy sufferers, consumption can have dangerous consequences: The first symptoms of a meat allergy are usually hives and swelling of the lips and eyes. The skin starts to itch all over the body, is reddened and covered with hives. As the disease progresses, it can lead to discomfort or even unconsciousness.
A meat allergy can develop all of a sudden, even if you never had any problems with it before. In contrast to other allergies, reactions do not occur within 20 to 30 minutes, but with a delay of three to six hours. It is not uncommon for symptoms to occur in the middle of the night.
Reaction to sugar molecule in meat
A special substance in the meat of mammals is responsible for the allergic reaction: Galactose-alpha-1,3-galactose (“alpha-gal”). The body does not react to a protein molecule, as in allergies to grass or nuts, but to sugar molecules in proteins. It was previously assumed that these molecules could not trigger allergies.
If alpha-gal enters the bloodstream, nothing happens to most people. In allergy sufferers, however, the immune system regards the substance as an enemy and produces antibodies that switch off the sugar molecule. If the affected person eats red meat again, alpha-gal again enters the intestine and hours later the blood. At this point, the immune system remembers the supposed enemy Alpha-Gal and an allergic overreaction occurs: the vessels dilate, fluid enters the skin and forms the itchy hives.
These types of meat are often affected
Alpha-gal does not occur in humans, but it does occur in the meat of mammals. Some types of meat contain particularly high levels of alpha-gal, for example offal such as pork kidneys, sweetbreads or liver. They are particularly dangerous for meat allergy sufferers.
Meat allergy due to tick bite?
Scientists have discovered tick bites as a probable cause of meat allergy. According to one study, alpha-gal enters the human bloodstream with the tick’s saliva. On first contact, the immune system becomes aware of the molecule and prepares itself for future confrontations — resulting in an allergic reaction.
Detection with blood test
With the conventional prick test on the skin, a meat allergy cannot be detected. This requires a special blood test. Anyone suffering from the allergy will not be able to eat red meat in the future. Fish and poultry are also permitted because they do not contain alpha-gal — and of course vegetables.