Q. What is the best way to identify food allergies?

A. Food allergies (or sensitivities) are linked to many common diseases, including migraine headaches, eczema, and inflammatory diseases, such as rheumatoid arthritis. The most useful way to identify food allergies is to first try a simple elimination diet to see whether symptoms improve. Start by eliminating the most common allergens: milk and all dairy products, wheat, corn, citrus, peanut butter, eggs, and processed foods. If your symptoms disappear, you’re on the right track.

By slowly reintroducing the various foods into the diet (for example, trying one “new” food every one to three days) and paying attention to which ones cause symptoms to return, you can identify the real culprit(s). Will you be able to eat that food again? That depends on whether the allergy is cyclic or fixed.

Cyclic allergies develop slowly and result from repeatedly eating a certain food. After the allergenic food is avoided for a period of time (typically three to four months), it may be reintroduced. Usually the food won’t cause symptoms again unless you eat it too frequently (such as more than once every three or four days) or in high amounts. Cyclic allergies account for roughly 80 to 90% of food allergies.

Fixed allergies occur whenever a food is eaten, no matter how much time has passed. If you have a fixed allergy, you will remain allergic to the food for life.