Most Likely Suspects
Food allergy patterns in adults differ somewhat from those in children. The most common foods to cause allergies in adults are shrimp, lobster, crab, and other shellfish; peanuts (one of the chief foods responsible for severe anaphylaxis); walnuts and other tree nuts; fish; and eggs.In children, eggs, milk, peanuts, soy and wheat are the main culprits. Children typically outgrow their allergies to milk, egg, soy and wheat, while allergies to peanuts, tree nuts, fish and shrimp usually are not outgrown.
Adults usually do not lose their allergies.
A Growing Problem
"The prevalence of food allergy is growing and probably will continue to grow along with all allergic diseases," says Robert A. Wood, M.D., director of the pediatric allergy clinic at Johns Hopkins Medical Institutions in Baltimore.Wood says that research over the last three decades indicates that the number of people with allergies is skyrocketing in developed and developing countries, but not in underdeveloped areas.
"The fewer germs in terms of infection and the environment, the more time the immune system has to worry about things like allergens," says Wood. "Recent studies indicate that growing up in a large family or daycare center actually decreases the likelihood of developing an allergy."
Wood, who has had a severe peanut allergy since he was a toddler, says allergic reactions to foods can vary dramatically. "They can range from just a mild rash to very severe swelling in the throat and the airways in the lungs so that there is a complete inability to breathe," he says.
Wood's parents learned of their son's allergy when they introduced him to peanut butter. "The first time I had peanut butter I developed a rash and severe swelling in my face," he says. "I'm extremely allergic. Just being around when a peanut shell is broken and dust is being released is enough to cause a reaction.
"I've had a number of very dangerous reactions," Wood says. "People with a food allergy typically walk around with a little bit of fear all the time. Once it starts, it's a fear-generating experience."
Multiple Allergies
When Sarah Buster of Columbia, Md., was 4 months old, her parents discovered that an allergy to milk was causing her eczema, a chronic skin inflammation. Her skin improved with a switch to a soy-based formula. Sarah's doctor believed there was little cause for concern since many infants have eczema and most outgrow it by age 2. Sarah didn't. Tests later indicated that she was allergic to eggs, peanuts, tree nuts, penicillin, tree pollen, ragweed, dust mites, and dogs and cats.It was then that Sarah's parents, Mike and Brenda Buster, began reading food labels as carefully as they would a legal contract. They joined a food allergy advocacy group, replaced the carpet in Sarah's bedroom and throughout the house with hardwood floors, placed dust mite covers over her bedding, gave away the family's dogs, and kept Sarah indoors as much as possible.
A small wooden chair with a wicker seat has taken the place of upholstered furniture for 9-year-old Sarah, and devices that filter dust, pollen and other particles hum both upstairs and downstairs.
For a time, soaking baths and ointment head-to-toe helped keep her skin moist, and a prescription antihistamine eased the itching enough so she could sleep. However, Sarah's eczema soon worsened again.
"Sarah's itching would be so severe that we could stand right by her and call her name and she would not respond because she was so focused on scratching," says Brenda Buster. "She would scratch until she bled because the pain felt better than the itch."
Finally, allergists at Johns Hopkins eliminated all conventional food and put her on a special formula made of amino acids. Sarah also started a four-month regime of prednisone, a drug that mimics the effects of the body's natural corticosteroid hormones and suppresses the activity of the immune system.
Eventually, her diet was expanded to six foods that doctors believed she was not allergic to: turkey, pork, rice, apples, grapes and tomatoes, supplemented by the special formula.
Sarah's skin cleared and after several months she began a series of dietary "challenges"--tests to determine whether specific foods cause an allergic reaction. Several years later, Sarah eats a more varied diet, and the Busters maintain a list of safe foods and those that cause an allergic reaction.
"The most difficult thing I have faced with my allergies is that when I see my friends eating something that I know I can't have, it just makes me feel left out," says Sarah.
