Understanding Food Allergies
Find out what you need to know to stay well in this age of intolerance
By Richard Laliberte Published: Dec 27, 2010
Your child's classroom has become a nut-free zone. Airlines seem to treat peanut packets as if they were weapons. Your husband's uncle can't come for the holidays unless you're serving a wheat-free meal. Everywhere we turn, new food restrictions seem to stare us in the face. Are they for real?
Kelly Rudnicki of Chicago wondered, too—"until I personally had to live with food allergies," she says. Her 8-year-old son, John, got hives and vomited right after eating a puffed veggie-cheese snack at 7 months old. Tests showed he was allergic to peanuts, tree nuts, eggs, legumes and milk products like cheese, which triggered his reaction. "The worst part of having a child with a food allergy is this constant underlying fear that he could die from something that people see as completely innocent," says Rudnicki, author of The Food Allergy Mama's Baking Book. "Food allergy is a disease, not a dietary choice or a lifestyle."
Indeed, the dangers are important for everyone to understand—not just people who have food-sensitive family members. One in 20 children today is likely to have a food allergy, which pretty much means that you can expect one allergic child (or two or three) in almost every classroom. Food allergies in children under 18 increased 18 percent from 1997 to 2002, while kids' peanut allergies doubled, according to the American Academy of Allergy, Asthma & Immunology (AAAAI).
You can also develop a food allergy as an adult, and although figures are harder to come by, "most doctors believe they're rising in adults, too," says Kathleen Sheerin, MD, cochair of AAAAI's anaphylaxis education committee. One clue: A Mayo Clinic study that included adults found that cases of anaphylaxis—a severe allergic reaction in which your blood pressure plummets and airways close up—doubled from 1999 to 2008. "Adults often don't see doctors for their allergies; they just avoid the food," Dr. Sheerin says. "For every adult case that's reported, two or three—or more—probably aren't."
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As food allergies skyrocket, researchers are working hard to understand them better—and recent studies have experts rethinking long-held beliefs about how and why we react to foods. Though many people outgrow food allergies, tenacious reactions(especially to shellfish, peanuts and tree nuts) usually hang on for life.
One theory about the spike in numbers is that the wide availability of once-uncommon foods exposes us to new allergens. "We never used to see many allergies to chickpeas here in the U.S., but now more people eat hummus and we see them all the time," Dr. Sheerin says. More mysterious are adult-onset allergies to common foods. Jessica Reino of Bridgewater, Massachusetts, was 21 when she had a reaction to a watermelon drink at a party. "I took two sips and my heart started beating very fast, I got itchy and started getting tunnel vision and then broke out in hives," she says. Given her allergy-free history, doctors figured it was a passing sickness, but tests found she reacted to nuts, soy, shellfish and a wide variety of fruits. "My friends and family had a hard time understanding that I suddenly couldn't touch foods I had eaten all my life," says Jessica, now 28. Dr. Sheerin developed a shrimp allergy at age 25; her son became allergic to pine nuts at 8. "Something in our genes predisposes us to allergy, but we don't know why people react to different foods and at different ages," she says.
A lineup of usual suspects trigger 90 percent of reactions: milk, eggs, peanuts, wheat, soy, fish, shellfish and tree nuts such as cashews, walnuts and pecans. (People with hay fever can also have pollen-related reactions to fruits and vegetables.) But the symptoms, from minor itching to potentially deadly anaphylaxis, are different for everyone. That can make food allergies confusing and daunting. Managing them starts with being up to speed on recent thinking, so here's the latest on keeping family, guests, friends, classmates—and yourself—safe.
We Are What We Eat
It may be no coincidence that allergies have gotten worse as our diets have, too. Eating more processed foods (and less fresh produce) may encourage the haywire immune response that causes your body to produce antibodies that spur an allergic reaction. Some experts link fewer omega-3 fatty acids in our diets to the increased production of these antibodies.
Others suggest we're not getting enough antioxidants like vitamin C and beta-carotene, which guard against inflammation and reduce the risk of allergy attacks. "We need more research to sort out the most important influences," says Scott Sicherer, MD, professor of pediatrics at the Mount Sinai School of Medicine's Jaffe Food Allergy Institute in New York.
One of the most intriguing theories: A deficiency in vitamin D—which helps regulate the immune system— may be a culprit. A recent study found that children born in fall and winter, when there's less sunlight to trigger vitamin D production in the skin, were 53 percent more likely to develop food allergies than children born in other seasons.
Will eating more foods such as fatty fish (which contain both omega-3s and vitamin D) or antioxidantrich fruits and vegetables make a difference? Preliminary studies do suggest a benefit: In one, 5- and 8-year-olds who ate plenty of foods rich in beta-carotene had lower levels of allergy antibodies and developed fewer food allergies. "While the research is still inconclusive, a healthier diet certainly never hurts," says Wesley Burks, MD, chief of pediatric allergy and immunology at Duke University Medical Center in Durham, North Carolina. Photo: Shutterstock
New Rules of Exposure
The big news is that conventional wisdom on treating—and avoiding— allergies is changing. "Keeping kids away from foods most likely to trigger allergies for the first two to three years of life was standard advice 10 years ago," says Robert Wood, MD, director of allergy and immunology at The Johns Hopkins Children's Center in Baltimore. Yet allergy rates continue to rise. One study found that British children who tend to avoid peanuts are 10 times more likely to develop allergies to them than kids in Israel, who are exposed to peanut protein earlier and far more often.
"Now we're thinking that earlier exposure may help develop tolerance," Dr. Wood says. In fact, the American Academy of Pediatrics' guidelines now advise giving children culprit foods like fish, eggs, milk and peanuts when they're ready for solids at around 4 to 6 months. Until then, exclusive breastfeeding appears to be your best bet for reducing your child's risk.
Once you find you have allergies, though, avoiding the trigger food is still the only surefire way to protect against reactions, since there is no treatment. Allergy shots, which inject small amounts of an allergenic protein, can desensitize you to inhaled allergens like pollen and ragweed, but not food. However, in small studies, researchers have found that a new technique called oral immunotherapy, which gives people small amounts of what they react to, may help. As the person is exposed more and more to the allergen, she becomes tolerant of it.
Studies presented in 2010 to the AAAAI showed that the technique can work for peanut and egg allergies. "Exposure is dangerous, so this should only be done in a very controlled way in a hospital," says Dr. Wood, who conducted the egg study. Studies have also found that 50 to 75 percent of children who get oral immunotherapy can worry less about ingesting small amounts even if they're not cured. "If it takes 20 peanuts to trigger a reaction instead of a hundredth of a peanut, that's a big difference," says Dr. Burks, who conducted the peanut study. Oral immunotherapy is too dangerous and experimental to be a widespread treatment right now, Dr. Sheerin says. "But it opens the door to many possibilities, including immunizations." Photo: Shutterstock
Avoiding the Dangers
If you don't have food allergies, what do you really need to know—and do? "You do need to worry about taking a peanut butter sandwich into a classroom where a child has a peanut allergy," Dr. Wood says. But the main issue is exposure, not necessarily the mere presence of a food. "For the most part, someone with a food allergy can be in the same restaurant, cafeteria or classroom as people eating the trigger food as long as she doesn't touch or ingest it," Dr. Sheerin says. The problem is that there's no guarantee that the child eating peanut butter won't come in contact with the allergic child or a shared object.
One of the most effective ways to help is to avoid cross-contamination, Dr. Sheerin says. For example, when hosting guests with food allergies, make sure dishes with trouble foods like nuts aren't prepared on the same surfaces or with the same utensils as other dishes. If guests are serving themselves, try to make sure spoons and spatulas stay in the right foods. "I once started itching at a dinner party because the tongs from the crab cakes were on the roast beef," Dr. Sheerin says. Follow instructions from schools to accommodate the needs of classmates and remind your child to follow rules like no sharing food and no eating on the bus. "And the family with the allergy should give the school a written emergency treatment plan from a doctor in the event of a reaction," Dr. Sicherer says.
"Food allergies can be very dangerous and warrant a high level of respect," says Dr. Wood. But you don't have to live in fear. "I've always had a severe peanut allergy and can tell you it's possible to live normally and stay safe." Photo: Getty Images
Intolerance vs. Allergy
With an intolerance, often a food irritates your gastrointestinal tract and/or can't be digested because you lack a particular enzyme. An intolerance generally causes gastrointestinal symptoms such as nausea, vomiting and diarrhea. (Less often it causes rashes, wheezing and inflamed sinuses.) Gluten and lactose intolerances are two of the most common.
If you have a food allergy, your body treats the food as an invader and produces antibodies that attack it. (An intolerance doesn't ramp up these antibodies.) Telltale symptoms include light-headedness, hives, itching, swelling, wheezing, and even life-threatening anaphylaxis.
Spurred by surging allergy rates, the National Institute of Allergy and Infectious Diseases issued guidelines in 2010 to help doctors recognize and treat true food allergies. Skin-prick tests that place small amounts of allergens under the skin to see if they cause a response can help narrow down the culprits. You may also get a blood test for the IgE antibodies that your body produces when you have an allergy, though people with higher-than-normal levels don't have symptoms about a third of the time. "The value of the blood test is that negative results are 98 to 99 percent accurate," says allergist Robert Wood, MD. "If you have suspected allergy symptoms but don't produce antibodies, you can rule out an allergy."
Richard Laliberte
Richard Laliberte is an award-winning veteran health journalist and former senior writer at Men's Health who writes for some of the nation's best-known magazines, blogs for WeightWatchers.com, and has authored several books.
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