And among adults, the incidence of clinically proven food allergies drops to about 4 percent of the population.

A food allergy, or hypersensitivity, is an abnormal response to a food that is triggered by the immune system. The immune system is not responsible for the symptoms of food intolerance, even though these symptoms can resemble those of a food allergy. It is extremely important for people who have true food allergies to identify them and prevent allergic reactions to food because these reactions can cause devastating illness and, in some cases, be fatal.

Also, someone with two allergic parents is more likely to develop food allergies than someone with one allergic parent.

Food allergens (the food fragments responsible for an allergic reaction) are proteins within the food that usually are not broken down by the heat of cooking or by stomach acids or enzymes that digest food. As a result, they survive to cross the gastrointestinal lining, enter the bloodstream, and go to target organs, causing allergic reactions throughout the body. While in some instances cooked foods may be tolerated while raw foods are not, you should consult with an allergist before ingesting any food to which you have a past history of allergy.

An allergic reaction can last from a few minutes to several hours, and the symptoms change as the food passes through the body. A person may first experience itching in the mouth as he or she starts to eat the food. After the food is digested in the stomach, abdominal symptoms such as vomiting, diarrhea, or pain may start. When the food allergens enter and travel through the bloodstream, they can cause a drop in blood pressure. As the allergens reach the skin, they can induce hives or eczema, or when they reach the lungs, they may cause asthma-like symptoms.

Children are more likely to outgrow allergies to milk or soy than allergies to peanuts, fish, or shrimp.

This is called cross-reactivity. People with ragweed allergies often find that eating cantaloupe will produce an intense itching in the mouth. Another example of cross-reactivity: A person allergic to shrimp may also be allergic to lobster, crab, and crayfish.

Bacterial contamination in meat can cause what appears to be an allergic reaction, but it's really a form of food poisoning. Also, certain types of poorly refrigerated or spoiled fish contain high levels of a chemical called histamine, which may cause what appears to be an allergic reaction in some people. This reaction is called histamine toxicity.

Once you and your health care provider have identified the food to which you are sensitive, you'll need to remove the food from your diet. To do this, you should read the detailed ingredient list for each food before you eat it. Many allergy-producing foods such as peanuts, eggs, and milk appear in foods one normally would not associate them with. Peanuts, for example, are often used as a protein source, and eggs are used in some salad dressings.