Is It Food Allergies or Just Hype?
Food Allergies, Intolerance, and Sensitivities
When Gwyneth Paltrow gave up dairy, I rolled my eyes. And when Zooey Deschanel waxes poetic about "g-free" cupcakes, it makes me want to bake some gluten-licious ones stat. In the past few years celebrities have made wheat, dairy, nuts -- you name it -- into public enemies, mostly, it seems, because cutting out these foods helps them fit into their red-carpet dresses.
But I found myself wondering if I'd been too quick to judge when my doctor prescribed an elimination diet after medication failed to get my chronic weekly migraines under control. He told me to give up alcohol, chocolate, and bacon -- in other words, joy -- plus nuts and any foods containing nitrates, sulfites, or MSG for an entire month. I did it and my migraines disappeared. Then I reintroduced these foods one by one. After some trial and error I figured out that red wine, nitrates (in my beloved bacon), and aspartame were my key food triggers.
The experience made me more sympathetic to friends who have suddenly started pestering waiters with questions about whether a sauce contains soy or cream, because they believe a certain food group is at the root of their breakouts, digestive issues, or other health woes. It turns out that food allergies really are on the rise, although experts aren't sure why. As many as one in 20 children and one in 25 adults are now allergic to some type of food. Peanut allergies have tripled in the last decade, and more than two million Americans have celiac disease, an autoimmune disorder in which the body can't process gluten. A growing pile of research suggests that certain foods can also play a role in chronic problems like migraines, irritable bowel syndrome, diabetes, asthma, and more.
At the same time, it's become difficult to determine what's a bona fide food allergy or health condition and what's just hype. Case in point: Sales of gluten-free foods in the United States grew to $4.2 billion in 2012, according to the market research firm Packaged Facts. Yet "probably 60 percent of the people who are on a gluten-free diet today do not need to be on it for medical reasons. They are responding to the hoopla and think going gluten-free is good for them," says Alessio Fasano, MD, the director of the Center for Celiac Research at MassGeneral Hospital for Children in Boston. "They may believe it's a cleaner way to eat or that they'll lose weight, but they're likely to be disappointed because they won't see drastic health changes or weight loss."Itching for an Answer
Adding to the confusion is the fact that although you might not be allergic to a food, you could be intolerant of or sensitive to it. The following three terms are used interchangeably, but they actually refer to several different conditions.
Food allergies, which usually begin in childhood, are triggered when your immune system overreacts to a particular protein in a food, typically within a few minutes to a few hours of consumption. Common symptoms are hives, itching in the mouth, and labored breathing; some people can go into anaphylactic shock.
Food intolerance often begins in adulthood and occurs when the digestive system can't break down certain foods, frequently because of an inherited enzyme deficiency. Lactose intolerance is one of the most common types. "As many as 60 to 80 percent of Asian, Hispanic, and black populations will have some degree of lactose intolerance by the time they're 50 years old," says Steve Taylor, PhD, the founder and codirector of the Food Allergy Research & Resource Program at the University of Nebraska-Lincoln. "This is probably because these cultures weren't historically dairy dependent." Food intolerance usually results in gas, bloating, and diarrhea.
Food sensitivities are harder to pin down. For instance, a significant number of people test negative for celiac disease but report similar symptoms -- gastrointestinal distress, chronic fatigue, joint pain -- whenever they eat gluten. "We know they're having an immune response," says Dr. Fasano, who estimates that 4 to 6 percent of the population may have gluten sensitivity. "But we don't know what causes it."
Scientists are more skeptical about sensitivities to other foods and chemicals, including red wine, nitrates, and MSG, which so many migraine patients, like me, credit with causing our pain. "How much of a role food plays in migraine activity is controversial, but about a third of patients associate their headache with a particular food," says Dawn Marcus, MD, a neurologist at the University of Pittsburgh Pain Evaluation and Treatment Institute and a coauthor of The Woman's Migraine Toolkit. "The best studies we have suggest that it may matter more that you eat meals on a consistent schedule."
So why did eliminating certain foods help prevent my migraines? A "nocebo" effect may have been behind the apparent miracle cure: Because I believed that giving up Pinot Noir and prosciutto would deliver a significant payoff, it did. Or perhaps I inadvertently reduced another migraine trigger like stress or fatigue. No one can say for sure.
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