Here's What You Need to Know About Food Intolerances

First things first: They're way different from food allergies.
Published December 5, 2015

“Whenever I eat that, I feel sick.” Would you say this sounds like you lately? Whether you’ve noticed nausea or tummy troubles after certain meals, a food allergy or intolerance may be to blame. But even once you’ve pinpointed which food or beverage is giving you trouble, it can be tough to distinguish between an allergy or an intolerance.

“Allergic reactions from food are spurred on by the immune system,” explains Sakina Bajowala, M.D., a board-certified allergist and immunologist in North Aurora, Illinois and fellow of The American Academy of Allergy, Asthma and Immunology (AAAAI). “In a classic case of food allergy, the IgE antibodies of your immune system trigger cells to release chemicals that cause symptoms, usually within 30 minutes after eating an offending food. Less frequently, the cells of the immune system, as opposed to antibodies that are molecules, may cause the reaction; this variety happens more in children and symptoms in this case are slower to show up.”

Many common triggers are probably lurking in your pantry and fridge right now: cow’s milk, eggs, peanuts, wheat, soy, fish, shellfish (lobster, shrimp, and crab are biggies) and tree nuts. Eat one of these and if you’re allergic, you’ll typically notice a skin reaction such as hives or itchiness, or gastrointestinal issues like diarrhea and vomiting; either type of symptom may be paired with nasal congestion and sneezing, according to the AAAAI. In the most severe case, you can have a life-threatening reaction called anaphylaxis. Even teeny amounts of the food — eating, touching or inhaling particles in the air — can lead to wheezing, throat tightness and trouble breathing. And here’s what’s really scary: “There’s no predictability with allergies,” says Dr. Bajowala. “If you’ve only had minor symptoms from eating a certain food in the past, it doesn’t mean you won’t have a severe reaction the next time.”

Though they can certainly be a nuisance, food intolerances, unlike allergies, are not fatal. These adverse reactions are not triggered by the immune system. “Oftentimes, a food intolerance involves the digestive system and results from a deficiency in a certain digestive enzyme,” says Dr. Bajowala. One of the most well-known examples is lactose intolerance, which according to the American Gastroenterological Association (AGA) affects about 50 million adults in the United States; if you’re in that group, you lack the enzyme that’s necessary to process a sugar found in cow’s milk called lactose. In this case, you’ll probably need to limit dairy products and other foods that have lactose to curtail uncomfortable symptoms such as cramps, diarrhea and gas; the amount of lactose each person can tolerate varies. Others have trouble digesting fructose, the sugar in fruits, honey and high-fructose corn sweetener found in some juices, sodas and other processed foods; sufferers will notice some gurgling going on in the tummy zone and they’ll need to figure out how much fructose their bodies can handle.

It’s crucial to figure out whether you’re dealing with a food allergy or intolerance, since the former can turn deadly. If you think you have one of these conditions, talk to your doctor for a firm diagnosis. She may suggest that you keep a food diary to help identify any patterns that lead to your symptoms. When an intolerance is suspected, you may be referred to a gastroenterologist. For potential food allergies, you’ll likely be referred to an allergist who will review your health history and perform a skin test, blood test or food challenge. If the diagnosis is positive, your doc may recommend that you carry emergency medication — an injection of epinephrine or an EpiPen — in case of accidental exposure. Whatever you do, don’t assume: “Hey, I didn’t have food allergies as a kid, so I can’t have them now.” About three percent of adults have food allergies, which accounts for allergies carried over from childhood and adult-onset allergies, which look the same as childhood allergies. Yes, an allergy might be the last thing you need, but it's good to be in the know.

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