Inside an Allergic Response

Lack of exposure: If an individual doesn’t come in contact with allergens like nuts and fish during infancy, it may lead to the development of allergies later on in life.

Vitamin D deficiency: Today, nearly 70% of adults don’t get enough vitamin D, which plays an important role in immune function. Studies in kids and adolescents have shown an association between low levels of vitamin D and increased sensitivity to allergies.

Off-kilter bacteria: Recent research suggests that changes in the gut microbiome may also be responsible. “Levels of both good and bad bacteria in the gut can be altered by antibiotics and antibacterial products and possibly even dietary habits—and that could lead to food allergies,” Dr. Sharif says. Preliminary animal research shows high fiber intake could boost good gut bacteria that help the immune system resist allergies, but the average American gets only 15 g of fiber per day, or 60% of the daily value.

Allergy or Not?

Intolerances are more common and not life threatening. “They’re a digestive issue and don’t involve the immune system,” explains Dr. Sharif. The symptoms vomiting, abdominal pain, diarrhea, and bloating may arise because the body lacks an enzyme needed to break down a food. Or someone may develop symptoms because she’s sensitive to particular food additives such as MSG.

Food allergies can cause digestive symptoms, too, but they rarely appear alone. “With allergies, these symptoms are usually accompanied by other signs, like itching or swelling,” Sheth says.

Intolerances are dosage dependent. “You may not experience symptoms if you eat a small serving,” says Sheth. “With allergies, even a tiny amount of food can trigger a reaction.”

When It’s Time to See a Doc

Adverse reactions to food are on the upswing in adults, but doctors don’t know why. What we do know: You can figure out whether you have one or if you’re suffering from something else and learn the smartest ways to handle it.Adverse reactions to food are on the upswing in adults, but doctors don’t know why. What we do know: You can figure out whether you have one or if you’re suffering from something else and learn the smartest ways to handle it.Five years ago, Johanna Bond went out to dinner with friends who were visiting her in Rochester, NY. As they chatted, Bond, a licensed mental health counselor, nibbled on an ordinary appetizer garlic bread dipped in marinara sauce. But suddenly, her gums tingled. Her throat tightened. She became nauseated and began to shake. In a panic, Bond called her mother, a former emergency room nurse. Her quick response: Get to a hospital now. You’re having an allergic reaction. At the hospital, doctors treated Bond with Benadryl, which she’d also taken on the way at her mother’s urging, and kept her there under observation for four hours.At a follow-up doctor’s appointment, tests showed that Bond, now 29, was allergic to chile pepper, an ingredient in the marinara sauce, as well as tree nuts. The doctor prescribed her an Epipen for emergencies plus steroids to reduce allergy-triggered inflammation. Bond says that before then, she had felt slight tingling in her mouth when she ate chile pepper, ut not enough to concern her. Today, however, she still struggles with what turned out to be a life changing diagnosis. She recalls standing in tears in the supermarket aisle shortly after her diagnosis because many of her favorite foods were of limits even a brand of crackers she loved, because it contained paprika, a derivative of chile pepper, for color.“It made me afraid to eat,” says Bond. “I never imagined I’d be dealing with this. I thought only kids got food allergies.” It’s a common misconception. While food allergies are twice as common in children, adults like Bond can and do develop food allergies, and it’s happening more often. Nearly half of grown-ups with food allergies first experienced them during adulthood, a 44% increase since 2004, says a study presented last fall at the American College of Allergy, Asthma & Immunology (ACAAI) annual scientific meeting. Related research shows adults most commonly have their first reaction in their early 30s.In the midst of this spike in adult onset allergies, doctors are also faced with a separate problem: an influx of people who incorrectly believe they have food allergies.“Although they’re becoming more common, food allergies still afect only 4% of adults,” says Naba Sharif, MD, an allergist at the Asthma, Allergy & Sinus Center in Waldorf, MD. “But nearly 30% of people think they have them many of whom have never seen a doctor to get tested. They feel bad after eating something, assume it’s an allergy, and simply plan to avoid that food.”And while some people genuinely believe they have an allergy, others use the term as an excuse to avoid certain foods at restaurants or in social settings. But no matter what the reason, experts worry that when allergies are misidentified, it may trivialize their severity for the increasing number of adults who actually have them.“Eventually, others may not take what can be a life-threatening condition seriously,” says Vandana Sheth, a registered dietitian nutritionist in Torrance, CA, who specializes in food allergies. “It can put people who really do have food allergies at risk.”Various foods may give you a stomachache or make you feel queasy, but true food allergies produce a specific reaction. “They have a common set of symptoms including hives, swelling, wheezing, or persistent vomiting that show your immune system is reacting to that food,” Dr. Sharif says.Think of food allergies as a case of mistaken identity: They occur when the immune system responding as if proteins in a particular food are harmful produces antibodies called immunoglobulin E (IgE) to defend against the “invaders.”The antibodies attach to cells in the skin, lungs, and gastrointestinal tract. Eat the offending food again, and the cells release the chemical histamine, which triggers symptoms like itchy skin, wheezing, and vomiting to try to expel the allergen.Allergic reactions are sometimes mild, but a 2017 study found that more adults with food allergies are experiencing anaphylaxis, a severe reaction that causes the airway to swell, blood pressure to drop dramatically, and the body to go into shock. Without immediate treatment, anaphylaxis can be fatal.Dr. Sharif believes that the high rate of anaphylaxis may be due in part to the types of foods grown-ups are usually allergic to: fish, shellish, peanuts, and tree nuts. “It’s not clear why, but these foods are most likely to cause severe reactions,” she says. Kids are also commonly allergic to peanuts, but otherwise they more typically have allergies to eggs and milk, which are more apt to be outgrown before adolescence.As to why adult-onset allergies are on the rise overall, the answer probably isn’t simple. “I don’t think there’s any one reason,” says Beth Corn, MD, medical director of the Division of Immunology Faculty Practice Associates at Mount Sinai Hospital. However, experts suspect these three things may play a role:The confusion surrounding allergies is apparent: In a 2015 survey conducted by the ACAAI, 49% of Americans said they were only somewhat or not at all knowledgeable about food allergies. Fad diets that incorrectly characterize certain foods as allergens are part of the problem; another issue, says Dr. Sharif, is that it can be easy to confuse food allergies with food intolerances (sometimes called food sensitivities). To clear things up, here are three key ways they’re different:Don’t have any symptoms of an intolerance or allergy? Cutting certain foods from your diet could do more harm than good. Excluding wheat when you don’t need to, for example, can make it harder to get enough fiber and B vitamins, while eliminating dairy could put you at risk of vitamin D and calcium deficiencies.If you have a concern about a specific food, talk to your doctor for advice, and resist relying on the sea of web search results or fad diets that claim to have all the answers. “A lot of people eat allergen-free foods, thinking they’re more nutritious or will help them lose weight,” says Sheth. “But that’s not necessarily the case.”Of course, if you do suspect you have a food allergy (see “Do You Have an Allergy or Intolerance?” at right), it’s crucial to visit an allergist for confirmation. Even if your symptoms are mild, don’t wait. “Reactions are very unpredictable,” Dr. Sharif says. “Just because yours have been mild so far doesn’t mean the next one won’t be severe.”If a certain food causes only digestive woes like an upset stomach and no other symptoms, the issue may be a food sensitivity, and you can try to first cut back on the food to test how much you can tolerate. It may take some trial and error, but allergy experts think that’s better than undergoing expensive testing or potentially harming your nutritional balances by banning certain foods altogether.Despite the public confusion over food allergies and intolerances, the fact that they’re in the zeitgeist translates into some good news: “Before 2004, there were no food labeling laws requiring manufacturers to alert people to the presence of the eight major allergens, and there weren’t as many allergen-free foods available,” Sheth says. These changes are finally making it easier for people who have allergies and intolerances to navigate their world safely.