A food allergy is an inappropriate immune response to the proteins found in the offending food. To understand what happens, you first have to have a very, very basic understanding of a protein.
In very simple terms, a protein is a bunch of amino acids linked together. When we eat proteins, our bodies have to break those links so that they can absorb the singular amino acids. Our bodies add those amino acids to the pool of amino acids that it draws from to build the proteins that we require every second of the day.
Imagine this chain is a protein (the rectangles are the amino acids and the links are the bonds that connect the amino acids). To properly digest, absorb, and utilize proteins that we eat, our bodies have to break these bonds.
When someone has a food allergy, this protein digestion process does not work properly. His or her body cannot break all the links between the amino acids, so it ends up absorbing some larger, leftover chains of amino acids. While the body recognizes lone amino acids as nutrients and knows to add those to that ongoing pool of amino acids, it has no idea what these larger chains are. Because it doesn't recognize them, it labels them as dangerous, foreign invaders and then mounts an inflammatory immune response to destroy them.
This immune response is what causes the physical symptoms of a food allergy. Allergies often will manifest as a mild physical reaction like a skin rash or gastrointestinal distress, but they range in severity and can be life-threatening.
The most common signs and symptoms of food allergy are:
- tingling in the mouth
- hives, itching, or eczema
- swelling of the lips, face, tongue, or throat
- wheezing, nasal congestion, or trouble breathing
- abdominal pain, diarrhea, nausea, or vomiting
- feeling dizzy, lightheaded, or faint
Note that there is a difference between a food allergy and a food intolerance. Not all adverse reactions to foods are true food allergies. Nonimmunological reactions (i.e. when your body does not mount the aforementioned immune response) to a substance in a food are called food intolerances or food sensitivities.
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