Health experts are still sorting out the reasons, but the Centers for Disease Control and Prevention (CDC) says that the number of Americans with food allergies has jumped 18 percent over the past two decades. (One possible reason: better testing.)
Today, nearly 15 million Americans have some type of food allergy, including 4 percent of all adults and 5 percent of children, according to the National Institute of Allergy and Infectious Diseases. Most food allergies develop early in childhood, but some materialize later in life.
While there are dozens of triggers, you can trace about 90 percent of food allergies back to eight allergens: milk, wheat, soybeans, eggs, peanuts, tree nuts, fish, and shellfish, says Joy Dubost, Ph.D., R.D.N., former senior director of nutrition for the National Restaurant Association. These are the eight allergens you’ll never find in Kate Farms shakes.
Below is what you need to know about those top allergens, including the signs, symptoms, and foods in which you’ll mostly likely find them.
First, an important note: Reactions to food allergens vary. If you think you have an allergy, see a health care professional. Only an allergist, using a skin-prick or blood test to measure how your body’s natural antibodies respond to various foods, can determine if you have one.
Allergen #1: Milk
Don’t confuse a milk allergy with lactose intolerance, says Nathan Myers, R.D.N., C.D.N., a clinical dietitian and adjunct professor at New York University. While a lactose intolerance could lead to some allergy-like symptoms—including diarrhea or upset stomach—it’s the result of your gut’s inability to digest certain milk sugars.
A milk allergy, on the other hand, is an immune system reaction to proteins that may cause hives, headaches, an itchy throat, and asthma, according to the American College of Allergy, Asthma & Immunology (ACAAI).
If you’re allergic to milk, you’ll need to be careful about the foods you buy and consume. “Along with checking the ingredients list for milk or dairy, look for things like whey or casein protein, which come from milk,” Myers says. “Any product that talks about added protein or protein enhancement is also something you want to examine, because that protein is often milk-derived.”
Allergen #2: Wheat
Wheat allergies are common in children, but two-thirds of kids will outgrow them at a relatively young age, according to Food Allergy Research & Education (FARE). Symptoms include hives, nausea, indigestion, stomach cramps, a stuffy or runny nose, headaches, and asthma.
Wheat allergies can lead to anaphylaxis, a life-threatening allergic reaction that often occurs within moments and can only be treated with a shot from an epinephrine auto-injector like an EpiPen. If you have a wheat allergy, it’s important to carry one. According to FARE, 20 to 25 percent of the shots administered at schools are given to people who previously didn’t know they had a food allergy.
Many people with this allergy can eat other grains, but that’s not true for everyone, according to ACAAI. It’s also important to note that a wheat allergy isn’t the same as a gluten sensitivity or Celiac disease. Because the symptoms can overlap, it is essential to confirm wheat as a potential trigger by consulting an allergist.
Of course, bread and pasta products are likely to contain wheat, but you also need to watch out for meat replacement items, like vegan burgers, which may have added wheat proteins, Myers says. Ditto sauces and dressings used in Asian cuisines.
In addition, not all gluten-free foods are free of wheat, so be sure to read labels thoroughly. Here’s a great primer on how to do so.
Allergen #3: Soybeans
You’re probably not popping soybeans in your mouth as a snack, but soy is everywhere. It’s added to many foods to boost protein and enhance the item’s texture or flavor characteristics, Myers says.
For that reason, it’s one of the most common food triggers, especially in babies and children, according to FARE. Like beans, peas, and peanuts, soybeans are a legume. But people with this allergy aren’t more likely to be allergic to peanuts or other legumes.
Symptoms of a soy allergy include rashes, itchy mouth, wheezing or asthma, a stuffy nose, cramps, and nausea, according to the ACAAI. If you have a soy allergy, you’ll need to avoid soy sauce, miso, edamame, tofu, tempeh, vegetable gum, vegetable starch and oil, most Asian cuisines, and certain vegetable broths, says Dubost.
Allergen #4: Eggs
Egg allergies affect roughly 2 percent of children, says the ACAAI, but 70 percent will outgrow them by the time they learn to drive.
While egg allergies are usually tied to compounds found in egg whites (not the yolk), Dubost says you need to avoid eggs altogether if you want to steer clear of symptoms, which can include skin reactions, breathing problems, and stomach pain.
Egg can hide in some of your favorite foods: ice cream, baked goods, and marshmallows, Dubost says. It’s also in salad dressings, mayonnaise, meringue, eggnog, and nougat. Some other names of egg protein include albumin and lecithin.
One more thing that may contain egg protein? The flu shot. If you suspect you have an egg allergy, get cleared by your doctor before getting poked this season. Egg-free vaccines are available for those 18 or older as well.
Allergen #5: Peanuts
A peanut allergy can be one of the scariest, as it causes more than half of all food allergy–related deaths each year in the United States, according to the American Academy of Allergy, Asthma and Immunology. Symptoms include itchy skin, tingling mouth or throat, runny nose, hives, and anaphylaxis, says the ACAAI. If you have a peanut allergy, it’s likely yours for life.
Because peanuts are so inexpensive, they’re used in all sorts of food products, Myers says, from crumb toppings on desserts to candy to energy bars—even those that aren’t peanut or peanut-butter flavored. Many types of Asian dishes also contain peanuts or peanut-infused sauces.
If you do have a confirmed peanut allergy, it is important to carry an epinephrine auto-injector such as EpiPen.
Allergen #6: Tree Nuts
Roughly 40 percent of people with a peanut allergy will also react to at least one type of tree nut, the ACAAI says.
This allergy generally develops during childhood and never goes away, says FARE. Symptoms include problems breathing or swallowing, abdominal pain or cramps, nasal congestion, diarrhea, and an itchy mouth or throat. It can also cause anaphylaxis.
If you have a confirmed tree nut allergy, your doctor may recommend you avoid all nuts because of the risk of cross-contact during manufacturing and processing.
“When you’re eating out, you need to be upfront with the wait staff, because many restaurants use tree nuts as a garnish,” says Myers. “Could be a couple slivers of almond, or they throw cashews in to add crunch.” Nut oils, butters, and other products may also be triggers, Myers adds.
As with peanut allergies, it’s important to carry an epinephrine auto-injector if you have a tree nut allergy.
Allergen #7: Fish
This food allergy is one of the few that develops in adulthood, says the ACAAI. Symptoms overlap with those mentioned above and can include anaphylaxis. Those who have a confirmed case should carry an epinephrine auto-injector.
If you discover you’re allergic to one fish, many doctors recommend avoiding all fish to stay out of trouble. But your allergist can help you determine if other varieties are safe.
Most fish allergies are a reaction to the protein in its flesh, but you can also be allergic to the gelatin in fish bones and skin. For that reason, watch out for sauces and condiments, Myers says. Worcestershire sauce and Caesar salad dressing contain anchovies, for example, so they both can trigger a reaction. Many Asian cuisines also contain fish or fish sauce, as do imitation crab and shellfish.
Allergen #8: Shellfish
Roughly 3 in 5 people who are allergic to shellfish experience their first reaction as an adult, says FARE. A shellfish allergy may cause a persistent cough, wheezing, a tight or hoarse throat, pale or blue-tinged skin, and dizziness, the ACAAI says. It can also be serious, so carrying an epinephrine auto-injector is recommended.
Crustaceans—shrimp, lobster, and crab—are the most common allergy triggers. Some people who have a reaction to these can tolerate other types of shellfish like mussels, clams, oysters, and scallops.
Myers says avoiding shellfish can be tricky because, like peanuts, they’re often added to food products to enhance texture.
“Shellfish shells and bones are used to create gelatin, which turns up in a lot of foods,” he says. “If you see gelatin listed as an ingredient and it’s not specified where the gelatin is coming from, you should call the food’s manufacturer to find out.”
Bottom Line: What You Can Do
If you think you may have a food allergy, keep a log of when you consume the food you’re suspicious of, along with any symptoms you feel in the 24 hours afterward. Here’s an example you can use as your guide.
Remember: Food allergies share symptoms with many other conditions, and vary in severity from person to person. Always consult your doctor or dietitian before removing any food from your diet.