Food Allergens Some people are allergic to peanuts and tree nuts.   In adults, the most common foods to cause allergic reactions include:   Shellfish such as shrimp, crayfish, lobster and crab   Peanuts - it is one of the major foods to cause severe anaphylactic reactions   Tree nuts such as walnuts   Fish   Egg   In children, the most common food allergens are:   Egg   Milk   Peanuts   People with food allergy should try to avoid eating the related food, and read all packaging labels of the ingredients before consumption.   Food Allergy Symptoms There is a wide range of food allergy symptoms. Frequently the first part of the body to react to food allergy is the gastrointestinal tract, resulting in vomiting, abdominal pain, and diarrhea. As the immune response to food affects other areas of the body, a person may develop hives (urticaria), swelling, sneezing and a runny nose, asthma or difficulty in breathing. The most severe food allergy reaction is anaphylaxis. It is a systemic, life-threatening shock that may occur minutes after a person eats an allergenic food. Anaphylactic reactions are characterized by breathing difficulty caused by edema (swelling) of the throat or bronchi. It may also cause severe asthma, hives, a drop in blood pressure and loss of consciousness, and death if not treated immediately. Another type of allergic reaction from food is eczema in which the skin becomes crusty, red, scaly and itchy. In children, eczema is frequently due to foods, but it can also be a pre-existing condition made worse by certain foods. For adults, probably fewer than one in 20 has an associated food allergy.   Peanut Allergy Peanut allergy is the most common cause of food-related allergy and anaphylaxis. Allergic reactions to peanuts are often acute and severe. The average protein content of a single peanut is 161mg. It only requires about 50mg of peanut protein to cause an allergic reaction in peanut-sensitive people, although some people may be much more sensitive and react even to the smell of peanut. Peanut products are in a large range of processed food, such as peanut butter, snacks, sweets, baked foods, table nuts, breakfast cereals, dried fruit and nut mixes, chilli and spaghetti sauces, gravies, cooking oil, pastries, ice-creams, deserts and garnishes. Therefore allergic reaction can occur on the first exposure to an actual nut. Peanut allergens can be secreted in breast milk; hence sensitization may even occur in infants as a result of the mother eating food with peanut during pregnancy. Since peanut allergy is for life, sensitive people have to avoid eating food with peanut as ingredients altogether.