Lots of people these days avoid eating certain foods—even healthy foods—because they end up feeling sick afterwards. And we’re not just talking about the usual below-the-belt discomforts like cramping, bloating, diarrhea and heartburn. Experts are now starting to chalk up such symptoms as fatigue, headaches, nasal congestion and clogged ears to food allergies or intolerances. Wheat currently tops the list of out-of-favor foods, because the gluten in wheat is implicated in a variety of symptoms. Also high on the list: dairy products, eggs, soy and corn. But almost any food can be a culprit, and matching symptoms with a food leaves many people and their doctors frustrated.
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We asked experts on food allergies and intolerances for the latest thinking on the subject. Here’s what they said.
- There’s way more to food allergies than peanuts.The classic, immediate, IgE-mediated peanut allergy is just one of many that have been increasing in numbers, says Dr. Mark T. DeMeo, of Rush University Medical Center in Chicago. “When I was a kid everyone and their brother went to school with a peanut butter and jelly sandwich,” DeMeo says. “Now, I send my kids to school with peanut butter and it is like I sent them with anthrax. So clearly something has changed.” Both celiac disease (a gluten-sensitivity reaction that damages the lining of the small intestine) and eosinophilic esophagitis (an allergic inflammation of the throat) are far more common than years ago, DeMeo says. “Even ulcerative colitis and Crohn’s disease are taking off,” he says. (Both of these conditions have an immune link; whether food allergies play a role is unknown.)
- But why is anyone’s guess.Antibiotic overuse, environmental toxins, poor diet and even genetic engineering of foods have been implicated in the spread of food allergies and allergy-like reactions to foods—but not proven, says Dr. Mary Kay Tobin, also of Rush University Medical Center. “The whole food processing of the grains is different than it was in the 1940s,” she says. “I think we will find that there are many antigens–what we look for as causing inflammation–related to handling wheat and perhaps to the genetic altering of some of our grains, corn in particular.”
- It’s driving doctors—and their patients—crazy. Many allergists and gastrointestinal specialists fail to diagnose certain food allergies because they do not fit into any easy testing or diagnostic patterns, says naturopathic doctor Stephen Wangen, director of the IBS Treatment Center in Seattle. “Foods can cause the kinds of widely varying symptoms that drive doctors crazy and frustrate patients,” he says. Many undiagnosed problems are delayed food allergies, which produce symptoms up to 72 hours after a food is eaten. Some doctors use not just the standard skin prick or immunoglobin E (IgE) tests, but non-traditional tests such as immunoglobin G (IgG) and immunoglobin A (IgA). Both test for delayed food intolerances. “People who react may have a wide range of symptoms, and even when they don’t have apparent symptoms, they often have underlying inflammation that eventually becomes apparent as an illness such osteoporosis or fibromyalgia,” Wangen says. “That’s why I believe it is important to try to identify the foods that are causing problems, and eliminate them, not just treat the symptoms.” Eosinophilic esophagitis, for instance, is often treated simply with stomach-acid reducing proton pump inhibitor drugs (the same drugs used to treat heartburn) rather than finding and eliminating the allergens triggering the problem.
- People can have both respiratory and GI allergy symptoms, says Tobin. “They tend to be seasonal, and occur at the same time, so people who have irritable bowel syndrome will also report nasal congestion, and may have eczema or asthma,” she says. If their intestinal lining is examined under a microscope, it will show an increase in histamine-producing mast cells, the same sort of cells that produce hay fever. These people often see a reduction in their GI symptoms when they take antihistamines, drugs traditionally reserved for inhalant allergies. “We have a fair number of people whose GI symptoms improve when they take a combination of Zyrtec and Zantac, two types of antihistamines,” Tobin says.
Allergies can cross-react.If you’re allergic to pollen, you can also react to similar foods, DeMeo says. People who are allergic to ragweed, for instance, may also react to bananas and melons. And people allergic to birch pollen may react to apples, carrots and celery. “People need to learn what they should avoid,” he says.