Food allergy involves adverse reaction of immunity system to determined foods (mostly proteins). Food allergies represent an important health problem affecting mainly children (6-8%). Symptoms can vary form mild (hives) to severe reactions such as anaphylaxis. The amount of food allergen that can trigger an allergic reaction is different in each patient and trace of allergens (little microgram) can be enough to induce a reaction. Hence, rigorous information about foods that contain allergens is very important to allow allergic people manage their diet.