Alpha gal – an exceptional allergy

It is uncommon for individuals to develop a food allergy in the adult years of life, especially if that allergy is to red meat or pork. As we know, however, the world of medicine is full of exceptions. Alpha gal sounds like a strong female leader, but it’s actually one example of an exception in the field of allergy. Folks with food allergies generally react to certain proteins in food. However, alpha gal is not a protein, but rather a carbohydrate called galactose-alpha-1,3-galactose, which is found in non-primate, mammalian meat. In other words, alpha gal can be found in four legged hoofed animals – cows, goats, pig, lamb, etc.

Even more odd is that this allergy develops after a tick bite, although the exact mechanism is not yet fully understood. Tick bites rarely lead to an alpha gal allergy, but the ones that do tend to occur in the eastern United States. After being bitten, individuals, who may have enjoyed meats containing alpha gal for years, will be at risk for delayed anaphylaxis if they consume such meat, even if it is only a small amount. Since anaphylaxis can be life threatening, people with an alpha gal allergy should avoid all red meats and pork, and carry an epinephrine auto-injector in case there is a reaction after an accidental ingestion. For some, an avoidance to dairy is also recommended. Since this reaction is delayed, it takes longer for symptoms to develop than a regular food allergy, about 3 to 4 hours. The most common symptom is a red, blotchy, itchy rash, known as hives.

Interestingly, the allergist who discovered alpha gal is Dr. Tom Platts-Mills at UVA Charlottesville med school. He also put dust mite allergy on the map many years ago by identifying them as the active allergen in house dust.

How do you know who has an allergy to alpha gal? Since alpha gal is a carbohydrate rather than a protein, the typical skin and blood tests to meat proteins are not reliable for diagnosis. A blood test that specifically looks for a reaction to the alpha gal carbohydrate should be used in conjunction with a clinical history.

How long does the allergy last? I want my steak and bacon! The immune response to alpha gal typically declines slowly over time. An allergist will look at a combination of regular blood tests and clinical history to decide when it is time to possibly reintroduce non-primate mammalian meats into your diet.

No one nose allergies like we do.™

Note: Information contained in this article should not be considered a substitute for consultation with a board-certified allergist to address individual medical needs.

David B. Engler, MD, FACAAI, FAAAAI Dr. Engler is a board-certified allergist and immunologist who hails from Houston, Texas. He was recently voted Best Allergist/Immunologist in Houston by H Texas Magazine, an honor based on peer and reader voting, as well as a Super Doctor by Texas Monthly Magazine.

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