Galactose-alpha-1,3-galactose (alpha-gal) is a carbohydrate found in the cells of many mammals that humans eat, such as cows, sheep, and pigs. Poultry that has been injected with natural flavoring containing beef or other mammal cells may also have alpha-gal. As a result of autoimmune responses, some people become allergic to alpha-gal.
People with this allergy may experience mild discomfort after eating meat, or they may have a dangerous reaction that leaves them unable to breathe. The spectrum of reactions to alpha-gal varies. Most instances of this allergy are triggered by tick bites.