With everything from gluten sensitivity to severe nut allergies to worry about, millions of people find eating a risky business. Family Circle investigates why reactions are on the rise and what you must know about them.

By Stacey Colino

When Judi Zucker's son, Tanner, turned 14, he started getting daily headaches, rashes and acne breakouts. At first she chalked it up to puberty. But then the Santa Barbara–based writer was asked to pen a cookbook for people with food allergies and it occurred to her to have Tanner tested. Sure enough, blood work revealed that he was "off-the-charts" allergic to casein (a milk protein) and gluten. And he's not alone. These days, it seems like we're in the midst of an epidemic of food allergies. According to the Centers for Disease Control and Prevention, their prevalence among kids under 18 rose 50% between 1997 and 2011. While some food allergies (which usually emerge in childhood) can be outgrown, others are lifelong and require permanent dietary shifts. "Within 24 hours of going gluten- and casein-free, Tanner had no more headaches, and gradually his skin cleared up," says Zucker, 52, who went on to co-author The Ultimate Allergy-Free Snack Cookbook.

Because he'd had a few symptoms when younger, Zucker notes, "I wish I'd had him tested earlier." Protect your loved ones by getting the facts and recognizing the signs.

The Most Common Allergy Foods

About 90% of these allergies involve just eight foods. Here's how commonly they occur worldwide.

Celiac Disease vs. Gluten Sensitivity

Celiac Disease

What it is: While you can be allergic to gluten, celiac disease is not a food allergy. "It's a hereditary autoimmune disease that damages the small intestine and interferes with the absorption of nutrients from food," notes Scott Sicherer, M.D., a professor of pediatrics and a researcher at the Jaffe Food Allergy Institute at the Icahn School of Medicine at Mount Sinai in New York City. Left untreated, it can increase the risk of lymphoma and other types of cancer.

Symptoms: Abdominal cramping and bloating; anemia; constipation; diarrhea; fatigue; joint pain; mouth ulcers; weight loss.

How it's identified: Blood tests for gluten autoantibodies, followed by an endoscopy with a biopsy to look for damage to the small intestine.

Non-Celiac Gluten Sensitivity

What it is: A condition in which you cannot tolerate gluten and have symptoms similar to those of celiac disease, but don't have the autoantibodies or damage to the small intestine that characterize the disease.

Symptoms: Bloating; diarrhea; fatigue; headache; brain fog; joint pain; numbness in the legs, arms or fingers.

How it's identified: A blood test comes up negative for celiac disease, but following a gluten-free diet leads to improved health.

Food Allergy vs. Food Intolerance

Food Allergy

What it is: The immune system produces large amounts of antibodies called immunoglobulin E (IgE) in response to a protein in a particular food, triggering allergy cells to produce chemicals (such as histamine) that cause allergic symptoms.

Symptoms: Hives, itching and/or eczema; nausea, vomiting and/or diarrhea; respiratory and cardiovascular symptoms.

Severity: It can be life-threatening even when a small amount of the offending food is eaten.

Food Intolerance

What it is: A reaction in the digestive (not the immune) system when your body is unable to properly break down certain sugars in a particular food (such as lactose in milk) due to enzyme deficiencies or sensitivity to a naturally occurring chemical in that food.

Symptoms: Bloating; gas; diarrhea; other forms of gastrointestinal discomfort.

Severity: "A food intolerance is unpleasant but not life-threatening," says Dr. Sicherer, author of Food Allergies: A Complete Guide for Eating When Your Life Depends on It. "It affects adults more than kids."

Your Food Concerns Answered

Q. Why is there a sudden rise in the number of people diagnosed with celiac disease and food allergies? A. There's a laundry list of possibilities, from the ways food is processed nowadays to having an imbalance of folate in our diets. None have been proven and all could play a role. One leading theory is the hygiene hypothesis: "We live in too clean an environment, so our immune systems are not being exposed to and stimulated by bacteria the way they once were," explains Robert Wood, M.D., chief of pediatric allergy and immunology at the Johns Hopkins Children's Center in Baltimore. "The result may be developing an allergy."

Q. Does celiac disease affect only your gut? A. No. It's associated with easy bruising, mouth ulcers and anxiety. In adults, it can lead to weight loss, infertility, osteoporosis, rashes, neurological problems and an increased risk for other autoimmune disorders. In children, celiac disease may compromise growth when gluten negatively impacts hormone levels, and even lead to epilepsy, notes Joseph Murray, M.D., a gastroenterologist who specializes in treating celiac disease and a professor of medicine at the Mayo Clinic in Rochester, Minnesota.

Q. Is the food manufacturing industry jumping on the celiac disease bandwagon by adding gluten-free labels to items that don't normally contain gluten?A. The market for gluten-free foods and beverages—which are three to four times more expensive than those not marked so—reached $4.2 billion in 2012 in the U.S. and is growing. But experts say the labeling isn't a manipulation tactic. "If you have celiac disease, you have to be on top of everything—and you wouldn't believe the kinds of stuff they put gluten in these days," says Kelly Dorfman, M.S., a nutritionist in North Potomac, Maryland, and author of Cure Your Child with Food. That list includes not just surprising foods (like salad dressing) but even makeup. "I advise people with celiac disease to check that their lip products don't contain gluten," Dorfman says, "otherwise you may ingest it."

15 million adults and children in the U.S. have a food allergy—and an increasing number of kids have more than one.

Q. When you have a reaction to a food, does that mean you're allergic to it?A. Not necessarily; it could be an intolerance. Also, there are many different types of food allergies. With a common one called oral allergy syndrome, a protein shared by pollen and certain raw fruits and vegetables may negatively affect your body year-round. If you're allergic to ragweed, you may develop itching in your lips or throat after eating bananas, melons, cucumbers or zucchini. An allergy to pollen from birch trees means you may have a similar physical response when eating apples, peaches, pears, kiwis, plums, cherries and carrots. Should you have an exercise-induced food allergy, which is less common, you can develop hives or feel light-headed when you work out soon after eating a trigger food such as crustacean shellfish, alcohol, tomatoes, cheese or celery.

Q. What's the best way to check for food allergies?A. A thorough medical history, blood test and skin-prick test are all important. But the most definitive way is the oral food challenge: Small, gradually increasing amounts of the suspected food are consumed under a doctor's supervision. If an allergic reaction occurs, an antihistamine or epinephrine injection is likely administered, says Wesley Burks, M.D., professor and chair of pediatrics at the University of North Carolina in Chapel Hill. "The oral challenge can also reveal if you've outgrown your food allergy."

Q. Are there other options for treating food allergies besides avoidance and epinephrine? A. Fortunately, new and better therapies are being developed and will hopefully become available in the next 10 years. Some researchers are studying oral immunotherapy (also called desensitization), which involves eating minute portions of the food you're allergic to with incremental increases over time as a way to build up tolerance. ("Do not try this at home!" Dr. Sicherer warns. It's risky and should be done only in carefully supervised clinical trials.)

Julia Grumbine, now 14, had a life-threatening allergy to milk. After participating in a desensitization study at Johns Hopkins—in which she was carefully monitored as she ingested tiny amounts of milk with incremental increases over time—she was slowly cured of her allergy. "This has been tremendous for her," explains her mother, Lisa Grumbine, 46, a lawyer in Wilmington, Delaware. "She began to have a better social life, since every kids' party involves pizza and ice cream."

In addition, researchers are working on a peanut allergy vaccine and a skin patch to prevent reactions. "We're hopeful easier approaches will emerge to teach the body to tolerate these foods," says Dr. Wood. Until scientists are able to pave a pathway to fearless eating, vigilance remains our best defense.

Originally published in the August 2013 issue of Family Circle magazine.