Any food can cause an allergy. However, just a handful of foods cause at least 90 percent of allergic reactions to food. The substance that causes an allergic reaction in foods or drinks is called an “allergen.” Among children, most allergic reactions to food are caused by peanuts, milk, soybean, tree nuts, eggs, and wheat. The majority of children stop being allergic to foods later on in their childhood. Allergic adults typically react to citrus fruit, nuts, fish, peanuts, shellfish, and wheat.
The most common allergenic foods include the following:
Egg – Like most food allergies, egg allergy is more common in childhood and about half of children who have it will grow out of it by the age of 3. In a few cases, an egg allergy can cause anaphylaxis, a severe and potentially life threatening allergic reaction.
Three proteins cause egg allergy: ovomucoid, ovalbumin, and conalbumin. Cooking can destroy some of these allergens, but not others. So, some people might react to cooked eggs as well as raw eggs. Occasionally, someone might react to egg because they have an allergy to chicken, quail, or turkey meat, or to bird feathers. This is called bird-egg syndrome.
Fish allergy can often cause severe reactions, including anaphylaxis. Adults are more likely to have an allergic reaction to fish and shellfish than children, which is probably because adults eat these foods more often. People who are allergic to one type of fish, such as cod, often react to other types of fish, such as hake, haddock, mackerel and whiting. This is because the allergens in these fish are quite similar. Cooking doesn’t destroy fish allergens. In fact, some people with a fish allergy can be allergic to cooked but not raw fish.
Allergy to cow’s milk is the most common food allergy in childhood. A reaction can be triggered by small amounts of milk, either passed to the baby through the mother’s breast milk from dairy products se has eaten, or from feeding cow’s milk to the baby. Children usually grow out of milk allergy by age 3 to 5, but about one-fifth of children who have an allergy to cow’s milk will still be allergic to it as adults.
The symptoms of milk allergy are often mild and can affect any part of the body. They can include rashes, diarrhea, vomiting and stomach cramps. In very few cases, milk allergy can cause anaphylaxis.
Allergy to nuts from trees is usually lifelong. The nuts that are most likely to cause allergic reactions are walnuts, hazelnuts, almonds, pecans, Brazil nuts, pine nuts, macadamia nuts and cashew nuts.
On rare occasions, all these nuts can cause anaphylaxis in people who are sensitive. Sometimes, people with an allergy to one type of nut will also react to other nuts. People with nut allergies should talk to their doctor for advice.
Allergy to peanuts (also known as groundnuts and monkey nuts) is often lifelong. Peanuts are one of the most common causes of food allergy and can cause severe reactions, including anaphylaxis. They contain allergens that are not destroyed by cooking or roasting. Peanut allergy can be so severe that very tiny amounts can cause a reaction. Because of this, coming into contact with traces of peanut can be enough to cause a reaction in people who are sensitive. Some people with peanut allergy might also react to other legumes such as soybeans, green beans, kidney beans, and green peas.
Allergy to shellfish is quite common. Many different types of shellfish can cause reactions in people who are sensitive, including shrimp, lobster, crab, crayfish, oysters, scallops, mussels and clams.
People who are allergic to one type of shellfish often find that they react to other types. Shellfish allergy can often cause severe reactions, and some people can even react to the vapors from cooking shellfish.
Food allergies may progress or get better over time. Anyone suspecting they are allergic to a food should consult their doctor for advice.