While nuts, dairy and eggs may be common food allergies, allergy to red meat, though rare,  is a newly recognised food allergy which could account for up to half of unexplained cases of anaphylaxis, found a new study.

Itching and anaphylaxis, a severe allergic  reaction with symptoms that can include tongue swelling, vomiting and even shock, can be indicative of meat allergy. Try these tips on How To Beat Allergies. Unlike most allergies, which involve a protein, this allergy results from IgE (an immunoglobulin involved in immune sensitivity) sensitization to a sugar known as alpha-gal. Alpha-gal is a major blood group substance in non-primate mammals and is structurally related to blood group B. In this small Swedish study that included 39 people with a meat allergy and IgE sensitization to alpha-gal, all of the patients reported being bitten by tick, most of them more than 10 times. All but two of them had antibodies to the European tick and about a third of them had antibodies to the American tick. Because alpha-gal is structurally related to blood group B, the researchers examined the blood type of the study participants and found that all but two of them had B-negative blood.

To get a better idea of how common IgE antibodies against alpha-gal were in other populations, the researchers tested the blood of 143 healthy blood donors and 207 people with Lyme disease. They found that up to 10% of the general population and 22% of the Lyme disease patients had antibodies to alpha-gal. Furthermore, 86% of the blood donors and 78% of the Lyme disease patients who had reactions to alpha-gal had B-negative blood.