According to the National Institute of Allergy and Infectious Diseases, only 1% of adults and 3% of children in the U.S. have true immunological food allergies. However, nearly one-third of Americans have reactions to certain foods. These reactions may range from mild to severe. Here are some common food allergies, as well as a look at food intolerance, which is often mistaken for an allergic reaction.
What Is A Food Allergy?

  Allergic reactions to food can begin within minutes or occur hours after eating the food. In a very sensitive person, simply touching or smelling the food can cause an allergic reaction. The most common symptoms of food allergy involve the gastrointestinal tract. Symptoms include: 

• Swelling or itching of the lips, mouth and/or throat.
• This is followed by nausea, vomiting, diarrhea or cramping as the food enters the stomach.
• Itching, hives, skin rashes or redness occur as your body digests the food.
• Severe cases can result in anaphylactic shock, which is characterized by extreme difficulty in breathing, irregular heart beat, a drop in blood pressure and, if untreated, even death.

  Food intolerance reactions are caused by factors in the diet other than food allergens. These reactions don't involve the immune system, as allergies do, and therefore aren't classified as food allergies. For instance, you may lack certain digestive chemicals that make it difficult for you to digest milk sugar (lactose intolerance). Or your body may react unfavorably to some food additives such as sulfites or MSG. Or you may have a reaction to some substances naturally found in food such as the caffeine in coffee or tyramine in cheese. And some instances of food poisoning are mistaken for a food allergy.

  The most common trigger of food allergies are proteins, such as cow's milk, eggs, peanuts, wheat, soy, shrimp, codfish, soybeans and crab. An allergy to one member of a food group, such as legumes or seafood, may result in a person being allergic to other members of the same food group. For example, a person who is allergic to peanuts is more likely to be allergic to soybeans, peas and other legumes. 

  Food allergies are diagnosed carefully. First, a full medical history is taken, followed by a physical examination. The physician will then ask for particular information about symptoms the patient is experiencing. A detailed food diary can be an important tool to identifying the suspect food or foods. The doctor may then recommend eliminating the food or foods for a time. If the symptoms are relieved, the suspect food may be added back to the diet to see if further reactions occur. Treatment usually consists solely of avoiding the food that causes the allergy.

  For more information about food allergies, talk to your doctor or log onto these Internet sites:

The Food Allergy Network at www.foodallergy.org

The American Dietetic Association at www.eatright.org

The American Academy of Allergy Asthma and Immunology (AAAAI) at www.aaaai.org.

  You can also write to the AAAAI for more information: AAAAI, 611 E. Wells St., Milwaukee, WI 53202.