The Latest Thinking on Food Allergies

Several years ago, Jane De Abreu began experiencing minor allergic reaction symptoms whenever she ate clams. Her throat would get scratchy, her heart rate would speed up, and she’d start to feel a little anxious. An over-the-counter antihistamine would get the problem under control, but she decided to meet with her doctor, just to be safe.

Abreu’s allergist conducted a special test, which involves exposing the skin to very small samples of potential allergens to detect an immune response, to confirm her allergy to clams. When it came back positive, the doctor advised her to steer clear of the offending food. The doctor also prescribed an epinephrine auto-injector in case she accidentally ingested the allergen. Two years later, she had to reach for the Epi-Pen at home when she experienced symptoms of anaphylaxis, a life-threatening reaction that can cause a person to stop breathing and go into shock, after eating take-out fish, which had never triggered symptoms in the past. “It was expired, but it saved my life,” says De Abreu, who lives in Honolulu, HI.

De Abreu isn't alone. Research shows that a whopping 10% Americans have food allergies, which breaks out to one in 10 adults and one in 12 children, recent population-based surveys show. That's in comparison to less than 4% of the population just 25 years ago. And it’s a disease that must be managed carefully, bite by bite and day by day. For these folks, consuming even seemingly benign foods—milk, eggs, nuts—can induce a dangerous, and sometimes even lethal, immune reaction.

So what’s responsible for the increase, and what are experts doing to stem the tide? Here’s a closer look at the changing landscape of food allergies in America, plus the promising therapies that could one day help many food allergy sufferers eat without fear.

Food Allergies Are Surging. Why?

Food allergies aren’t new. But they’ve gone from fairly rare occurrence to commonplace condition in a matter of decades. According to the Centers for Disease Control and Prevention (CDC), the prevalence of food allergies in children jumped from 3.4% in 1997 to 5.1% in 2011. The number of people diagnosed with peanut and tree nut allergies, in particular, have more than tripled since that time. What’s causing the surge?

There are several theories. Many experts believe the problem is related to the hygiene hypothesis—the idea that our Western, hyperclean, and modern environments expose us to far fewer microbes and germs compared to our ancestors, who routinely came in contact with dirt, dust, and farm animals from a very young age.

“We’ve become such a sanitized society, we’ve wiped out the natural pathogens that the immune system is supposed to respond to early in life, so it’s left waiting to respond to something else, and it turns on things that it shouldn’t, like foods,” says Stephanie Leeds, M.D., FAAAI, a pediatric allergy and immunology physician and assistant professor of clinical pediatrics at Yale School of Medicine in New Haven, CT.

That’s just for starters, though. Past recommendations to hold off on introducing common allergens (like peanut butter, for example) to babies before age 1 may have played a role, adds Jay Leiberman, M.D., chair of the College of Allergy, Asthma, and Immunology Food Allergy Committee in Memphis TN. (Remember when your mother-in-law made a face after you told her you couldn’t swirl in any Peter Pan or Jif into your 4-month-old’s first cereal, even in tiny amounts? Turns out her insisting that a little peanut butter was fine might have been right—and maybe even the smartest approach—all along. It’s painful to consider, we know.)

In addition, more frequent use of antibiotics and rising rates of cesarean sections may also result in changes to the gut microbiome, where the bulk of your immune system resides, which in turn increases the risk of developing a food allergy. And exposure to chemicals in plastics and/or traffic-related air pollutants may partially be to blame, as well.

Another theory? It’s possible that seemingly minor changes to food manufacturing practices may be involved. “The way they process peanuts for peanut butter has changed over the years. It could be that boiling versus roasting the peanuts, maybe that’s had an influence,” Dr. Leeds says.

Your Body on Food Allergies

Having a food allergy doesn’t simply mean getting an itch or a stomachache after eating an offending food. When a person has a food allergy, their immune system mistakenly identifies certain proteins in a food as harmful—like it would a foreign invader, such as a virus or dangerous bacteria. This triggers immune cells to release a protective antibody called immunoglobulin E (or IgE). The job of IgE is to neutralize the allergen so it's no longer a threat, per the Mayo Clinic.

Should an allergic person consume even a tiny amount of the food (or in some cases, inhale or even just touch it), their IgE antibodies respond by signaling the release of histamine, a chemical that beings triggering allergy reaction symptoms within minutes. If a person is lucky, they’ll experience a mild reaction with hives, coughing, stomach cramps, or vomiting. But, according to Food Allergy Research and Education (FARE), anaphylactic reactions are often severe, causing wheezing, shortness of breath, dizziness or fainting, mouth or tongue swelling, trouble swallowing, or throat tightness.

Once a person experiences a severe allergic reaction, they’re often plagued by fears about it happening again. “Having an allergic reaction is terrifying. When your throat begins to close, it’s like someone is choking you, but you can’t get them to stop. You can feel your bodily functions slowing down with your breath,” says Camden Benoit from Asheville, NC, of his tree nut allergy.

Making the anxiety worse is the fact that a person can never know for sure what type of reaction their body will launch. Even if someone has only experienced mild reactions in the past, there’s no guarantee that they won't have severe or life-threatening reactions in the future, per FARE, like what happened to de Abreu after eating takeout she assumed was safe.

The Most Likely Offenders

Any food can trigger an allergy, but certain menu items pose more problems than others. In fact, research shows that 90% of food allergies are caused by just a handful of foods. The most common culprits include:

• Cow’s milk. The most common childhood allergen affects up to 3% of children at age 1, per a2019 review. Cow’s milk allergies are often outgrown, but the number of children who don’t outgrow their allergy is rising, according to the School Nutrition Association (SNA).

• Eggs. Up to 2% of children are allergic to eggs, according to the School Nutrition Association. Many outgrow their allergy by the time they’re teenagers.

• Peanuts. Up to 2% of children and .6% of the overall population are affected by the most lethal food allergy of them all, one to peanuts, per research. Peanut allergies are often lifelong.

• Tree nuts. Between .4% and .5% of the population are allergic to tree nuts such as walnuts or almonds, per the SNA. Like peanut allergies, tree nut allergies are rarely outgrown.

• Fish. Just .2% of children and .5% of adults are allergic to finned fish, the SNA notes. Oftentimes, the allergy develops in adulthood.

• Shellfish. Allergies to shrimp, lobster, or crab often develop in adulthood, too. Up to 2.6% of women and 1.5% of men are affected, says the SNA.

• Wheat. Roughly .5% of people are thought to be allergic to wheat, per the SNA. Remember, wheat allergy is different than celiac disease, which is an intolerance to the protein gluten found in wheat, barley, and rye. The former can trigger symptoms like hives, swelling, or anaphylaxis; the latter primarily causes gastrointestinal symptoms.

• Soy. Soy allergies are more common in childhood, affecting around .7% of the population. Many soy allergies are outgrown by age 10, according to the SNA.

• Sesame. Nearly .5% of people are allergic to sesame, according to research.

Treating Food Allergies Today

Unfortunately, there is no cure for food allergies—yet!—so the standard treatment focuses on preventing symptoms, according to the American Academy of Asthma Allergy & Immunology? That means strictly avoiding the offending allergen and carrying auto-injectable epinephrine at all times (like Epi-Pen, Auvi-Q, or Adrenaclick) to prevent anaphylaxis. In the event that the allergen is ingested accidentally, antihistamines such as Benadryl may also be used to reduce minor symptoms, like itching or congestion, per the Mayo Clinic.

Steering clear of an allergen might seem straightforward (just don’t eat peanut butter or scrambled eggs!). But allergens often lurk in foods undetected and consuming even a tiny amount—like egg wash on a loaf of bread or drop of soy sauce in a marinade—can trigger severe symptoms. As a result, people with food allergies need to check ingredients with focused care.

“I read every single label extensively! If somebody offers me food, I immediately ask, ‘Are there tree nuts in this? Did you make it? Is it store-bought?’ Until I get to the answer of yes or no, I cannot eat this,” says 24-year-old Elena Ciaccio of Denver, CO, who was diagnosed with a peanut and tree nut allergy at age 4 and has been hospitalized for anaphylaxis three times. “I would rather be annoying than dead, or stuck with a $5,000 hospital bill.”

Thankfully, there is another option on the horizon. A growing number of allergists are turning to oral immunotherapy (OIT) to help patients become less sensitized to allergens like peanuts, eggs, and milk. “It’s similar to how we do allergy shots to someone who is pollen-allergic,” Dr. Lieberman explains. “We give the allergen, starting at a low dose to trick the body’s immune system into changing its immune response to offer some protection.”

Except instead of having the allergen injected via needle, as with pollen, very small amounts of the food allergen’s proteins are consumed orally in pill or powdered form, or even in regular whole food form. If you're able to tolerate the amount without a reaction, the dose is gradually increased, under medical supervision, which generally means hanging around the doctor’s office for two or more hours after ingestion before being released. OIT takes several months until you reach what’s known as a “maintenance” dose, which may confer some protection against a serious reaction occurring down the line.

Staying with the maintenance does involves serious dedication. Most people undergoing OIT need to commit to it indefinitely in order to continue reaping the protective benefits, which means consuming a maintenance dose of their allergen on a daily basis.

“If you stop the therapy, for the vast majority of patients, the allergy returns,” Dr. Lieberman says. The treatment comes with significant risks, too: An OIT allergen dose can and often does trigger minor allergic reactions, and has the potential to trigger anaphylaxis, particularly if doses are missed, which can be upsetting or scary to patients. And for the time being, doctors have no reliable way of knowing which patients are most likely to sustain a reaction, Dr. Leeds notes.

Currently, the only FDA-approved oral immunotherapy is Palforzia (Arachis hypgaea), which is for children and teens aged 4 to 17 who are allergic to peanuts, and which received approval in 2020. Similar treatments for egg and walnut are currently in development. A growing number of food allergists also offer oral immunotherapy for other allergens, such as egg and milk, using commercial food products such as egg or milk powder. Unlike Palforzia, these products have not been designed specifically to treat food allergies nor have they received FDA approval. But when administered under care of an allergist, they can be effective at reducing the risk of allergic reactions.

OIT isn’t a cure for food allergies, and a person undergoing OIT treatment still needs to avoid their allergen and carry epinephrine. The goal, instead, is to simply reduce the risk of a severe or life-threatening reaction if the allergen is unintentionally ingested. “It should be viewed as protection. You’re much, much, much less likely to have anaphylaxis from an accidental exposure,” says Dr. Leeds. Even then, the treatment isn’t always effective. Approximately 60% to 80% of patients with cow’s milk, egg, or peanut allergies respond to OIT, concluded a 2020 Frontiers in Immunology review—meaning, of course, that up to 40% didn’t.

Even so, experts still agree that for many patients, OIT offers insurance against potentially deadly reactions, and along with it, significant peace of mind for patients and their families. “Some patients definitely benefit, but it should be a shared decision to discuss the commitment and risks involved,” says Dr. Leeds.

The Future of Food Allergy Treatment

Despite its current limitations, immunotherapy holds more promise for the future. Researchers are looking at ways to make OIT more effective, including combining treatments for multiple allergens, and using OIT alongside biologic therapies or probiotics. There’s also hope that oral immunotherapy will become more refined. “Having better biomarkers—tests to run on the blood or skin—to tell us who will do really well with OIT and who won’t, those would be great, and a huge help in terms of setting families up for success,” Dr. Leeds says.

The path towards desensitization will likely involve other routes, too. Phase III clinical trials for children aged 4 to 11 are currently underway for Viaskin Peanut (DBV712), an immunotherapy skin patch for peanuts, with plans for an FDA review to follow. Researchers are also studying daily sublingual (under the tongue) drops for peanut allergies, which have been shown to be effective in toddlers. There’s even a clinical trial in the works investigating INT301, an immunotherapy toothpaste for adults with peanut allergies that can be used during a person’s daily brushing routine.

Other novel avenues are being explored, as well. Early clinical trials investigating microbiome therapy have shown that fecal microbiota transplants can enable peanut-allergic patients to consume small amounts of peanut without experiencing symptoms, while nanoemulsion (or nasal spray vaccines) have demonstrated early potential to change how the immune system responds to an allergen and prevent reactions. “The treatment landscape will change in the next five to 10 years, in the sense that there will be other modes of therapy,” Dr. Lieberman adds.

Shifting behaviors could also put children at lower risk for becoming allergic in the first place. The American Academy of Pediatrics now recommends introducing highly allergenic foods soon after infants have started solids (and as early as four months for infants at high risk for food allergies) rather than waiting until age 1 or later. “There will always be those kids with sustained and prolonged allergy,” Dr. Leeds says. “But I think we can reverse the epidemic with prevention methods."