 People don't realize how hard it really is to have so many allergies. Food allergies can have a serious and sometimes disruptive impact on a person's everyday life. Fortunately, the incidence of food allergies is rather low. Only 1% of the adult population and 3-4% of children have true food allergies. One of the real issues in food allergy is how severe a problem is it. And for the vast majority of people who think they have food allergies, a workup will actually find no evidence for that. Dr. Dean Metcalf of the National Institute of Allergy and Infectious Diseases is one of the nation's leading experts on food allergies. He and his colleagues are searching for a better understanding of the mechanisms and treatments for food allergies. What some people may think of as food allergies may actually be some other problem entirely. Doctors need a great deal of information before making a true diagnosis. A physician starts by taking a history from the patient and looks for certain historical features that he knows are seen with a true food allergy. Certain things like hiving, for example, or a problem that comes on within a few minutes after eating a food. And sometimes on the basis of history alone, he can feel comfortable that indeed the patient does have a food allergy and then give advice on the basis of that. If he's not sure, he may try to do skin testing. Doctors sometimes use what's known as a food challenge to determine allergies. Usually this involves giving patients suspect foods in capsule form to await a reaction. The patient does not know the contents of the capsule so that psychological expectations do not play a role in the outcome. A food allergy is due to an abnormal immune response to the proteins within a food. Now, ordinarily the body uses these responses to defend itself against infection, bacteria or viral infections. But in some patients they abnormally react to the food. So when they take in the food, the body has some sort of reaction against the food as if the food were a foreign invader. And those reactions take several forms. The most common allergic response is an immediate hypersensitivity reaction. This occurs suddenly and may bring about rashes, hives, respiratory trouble, stomach cramping, vomiting or shock-like symptoms in severe cases. Another less common response is called a delayed hypersensitivity reaction. Its onset is slow and may cause problems with absorbing food resulting in diarrhea and weight loss. Mast cells are specific cells found throughout the body but most commonly in the lungs, skin and digestive tract. When some individuals breathe in or eat certain foods, the body forms a specific kind of protein against the foods called immunoglobulin E. This protein, also known as IgE, then fixes on the surface of the mast cell. When that food protein comes in contact with IgE on the surface of the mast cell, the cell pushes out chemicals into the tissues that cause the patient to become symptomatic. The medicines used to treat food allergies are directed toward blocking the effects of these chemicals released by mast cells or by trying to shut off mast cells themselves or by effects on these tissues that are affected by the chemicals. For example, antihistamines block the effect of histamine which is released by mast cells. Epinephrine or adrenaline in part shuts down the mast cell from spitting out the chemicals and in addition constricts blood vessels to raise the blood pressure of people in which the blood pressure is falling due to a severe food allergy. Most common food allergies in adults tend to be peanuts, tree nuts like walnuts, fish and crustacea such as shrimp, lobster, crayfish and crab. Children, however, are more likely to have reactions to milk and soy products. Between 3 and 5% of all children, if put on formulas, will develop a reaction to the formula. In families where there is a history of feeding problems, breastfeeding is strongly recommended. Children rarely become allergic to the mother's milk. Some food additives have been associated with allergies. The most common is sulfites which have a particularly strong effect on asthmatics but other food additives can be problematic as well. Doctors recommend that people who are sensitive should pay close attention to food labeling. You can develop food allergies almost any time in life. Of course it's common to develop food allergies in infancy and childhood and in fact children may develop allergies throughout their teenage years but even adults can develop food allergies for the first time and sometimes it takes them by great surprise. They can be in their 20s or 30s and suddenly one day each shrimp and have hives and suddenly they're allergic to that food and they realize that. The treatment for food allergies is first and foremost avoidance. If someone accidentally ingests a food to which they are allergic and the reaction is severe treatment must be administered immediately. Patients who have experienced shock-like reactions or severe systemic reactions should always carry with them epinephrine also known as adrenaline. Children with severe food allergies can lead a fairly normal life if precautions are taken. For example, the school nurse or school official should be told how to treat the child and medicine should be readily available. A procedure should be in place so that the child can be taken care of at school if inadvertent exposure occurs. Education is key. Parents and the child need to know how to prepare foods that are appropriate for the child's diet. Current research in food allergy is taking a number of directions. One is to improve diagnosis by isolating the proteins from foods and using them for skin testing. Other studies are trying to determine how allergy shots and other medications can possibly block or prevent food allergies. Researchers are also improving existing medications used to treat patients after accidental ingestion. Maybe someday we'll have a cure but right now I don't see anything on the horizon so I think in terms of food allergies we are limited to what we're doing right now and will be for some time which is avoidance of foods and question and treating inadvertent exposure. I can do anything basically anybody else can. I just can't go certain places or eat certain things. It's just basically staying away from what you cannot eat and you're basically going to stay fine and it's just a normal life. It's like a portion of it taken out.