Here's a nightmare scenario for any host. You've laid out a gorgeous buffet full of mini-quiches, deviled eggs, crudités and crab roll-ups. One of your guests is enjoying the spread when suddenly her lips and tongue swell.
She then starts itching like mad and you notice she's covered in hives. You pull the Benadryl out of the medicine cabinet, she takes some and the crisis passes. But she's no longer in much of a mood to celebrate, and heads home.
It may sound dramatic, but I hear this kind of story frequently in my office. The patient always starts out by insisting that there is no way she could be allergic to the crab or the eggs or anything else on the buffet because she has eaten those foods all her life.
But food allergies can develop at any age. What happens is that the immune system gradually reacts more and more strongly each time it is exposed to a particular food. The reaction may be so subtle for a time that you don't really notice it — until things get dramatic. So I have no trouble believing patients who seem to suddenly react to a long-time favorite item. The immune system 'sees' the offending food as a foreign invader and acts quickly by releasing histamine, which then can cause blood vessels to swell, smooth muscles to contract and skin to swell and itch. Patients often report swelling of the lips or tongue, difficulty breathing or swallowing, shortness of breath or coughing, nausea, vomiting, diarrhea, hives, itching and lightheadedness. Food allergies are responsible for most of these reactions that occur outside of the hospital setting.
Food allergies account for 30,000 emergency room visits and 200 deaths each year. The greatest risk factor for death from a food allergy is delaying treatment.
Most food allergy is caused by one of these foods: milk, egg, wheat, soy, peanuts, shellfish and tree nuts. While egg, milk and soy allergies tend to resolve in childhood, the other allergies often persist throughout life.
Food allergies are on the rise. Fifteen million Americans suffer with food allergies and 9 million of them are adults. There is evidence to suggest that the way foods are processed in the U.S. makes them more allergenic. For example, peanuts are usually dry roasted in the U.S., while they are boiled in Asia, where the rate of peanut allergy is much lower. Roasting changes the protein structure, making it more likely to provoke an allergic reaction, some scientists suggest.
The ''hygiene hypothesis'' may also play a role. This is the idea that children exposed to infections, parasites and allergens at an early age allow their immune systems to develop normal responses. Environments free of these exposures may lead the immune system to react to otherwise harmless substances, like foods.
Researchers will continue to identify causes for the increasing incidence of food allergies but that will not change the fact that many people are affected by this condition. It is important to immediately treat symptoms based on severity. Using over-the-counter medication such as Benadryl for itching or hives is often a good first step.
If symptoms progress quickly or involve breathing/swallowing difficulty or lightheadedness it is best to seek emergency medical treatment. People who know they are prone to such attacks may also carry prescribed, self-injectable adrenaline. Many anaphylactic reactions (of any cause) will recur about four to 12 hours after the initial reaction, which makes it important to be monitored especially after use of injectable adrenaline.
Unfortunately we have no treatment for food allergies other than avoidance. It is important to see an allergy specialist so that you can identify foods that truly may be allergens to you. Food allergy testing can be done via skin prick testing or blood testing, at the doctors' discretion. Testing for foods has improved over time, but remains less reliable than testing for allergens that are inhaled, such as pollen and dust mites. Because of this, food allergy testing should be done only for foods that cause symptoms consistent with an allergic reaction and by a physician who understand how to properly interpret the results.
Dr. Mona V. Mangat is a board-certified allergist and immunologist in St. Petersburg at Bay Area Allergy & Asthma. You can find her at www.bayallergy.com.