What causes food allergy

A food allergy is basically the reaction of body’s immune system to an allergen present in food, most commonly protein, because it fails to recognize it as food and treats it as a foreign body. The immune system produces a substance called eosinophil which participates in a histamine reaction which is responsible for the various symptoms of the allergy. The immune system also registers the various proteins it comes across and produces a similar reaction every time it comes in contact with those proteins.

Besides this, there are several theories regarding the causes of food allergy. One of them centers on the protein present in the blood along with vaccines. There are several vaccines which are egg based and are known to cause food allergy due to the protein content. For example, yellow fever vaccine and influenza vaccine are egg based. Another theory, called the hygiene theory attributes the cause of allergies to the lack of exposure to germs and dirt in early stages of life in developed countries as it is a fact that people in underdeveloped countries have less allergies. One more theory relates the occurrence of food allergies due a change in food habit.