Q. What is the difference between a food sensitivity and a food allergy? Can either be "cured"?

A. Food allergies are less common than many people think. Only 2 percent of adults and up to 8 percent of children have a true food allergy, in which antibodies in the body's immune system respond to a particular food. Allergic reactions can trigger symptoms that include swelling in the mouth, stomach cramps, vomiting, diarrhea, hives, rashes, eczema, and wheezing and breathing problems; in the most dire cases the reaction may cause death. Cow's milk, eggs, wheat, tree nuts, peanuts, fish, shellfish, and soy top the list of food allergy culprits.

Food sensitivities are much more widespread than food allergies. With many food sensitivities (or intolerances), the problem lies not with the immune system but with digestion. For example, a person with lactose intolerance can get cramps or diarrhea after drinking milk because he or she lacks the enzyme lactase needed to digest milk sugar (lactose). Other common food intolerances include sensitivities to food additives, preservatives, and artificial colors. Celiac disease, in which there is an autoimmune response to the gluten in wheat or other grains, is another type of food sensitivity.

Most food allergies become known during childhood, but occasionally food allergies develop in adults. People with a true food allergy will need to avoid their trigger food(s) altogether. Some people, particularly young children, may outgrow an allergy to milk or eggs over time. Allergies to nuts, fish, and shellfish tend to last a lifetime, though immunotherapy may increase tolerance in some individuals. Taking the enzyme lactase when eating dairy products can significantly lessen the symptoms of lactose intolerance, but for other intolerances, the problem food needs to be eliminated (or only eaten in small amounts) in order to avoid symptoms. If you suspect a food allergy or other serious food sensitivity, consult your health care practitioner who can verify with testing.

This Q&A was written by Victoria Dolby Toews, MPH, author of the The Soy Sensation (McGraw-Hill, 2002) and The Green Tea Book (Avery, 1998).