The science of food allergies

More than 90% of America's food allergies are triggered by 9 foods.

Adults are developing food allergies that they didn’t have as children

Research published in 2019 found that almost half of 40,000 surveyed adults with food allergies developed a new food allergy as adults, underscoring that our immune systems may newly misclassify substances later in life.

Why some people have allergies

Why do some people have allergies while others don’t? One theory suggests allergies are a relic of our evolutionary past. Our immune system, once primed to fight parasites, now mistakes harmless substances for threats.

Allergies occur when our immune system mistakenly considers a substance a threat

Immunoglobulin E antibodies, or IgE antibodies, may bind to an allergen, effectively labeling it as a threat. That triggers a cascade of actions in the body, including the release of histamine, which causes the characteristic itching and hives of allergies. Sometimes a cooked version of an allergen—like a cooked carrot—may look different enough from its raw form to the immune system that antibodies ignore it, and no allergic response takes place.

One-third of kids with food allergies report being bullied because of it, surprising parents

Research published in 2021 surveyed how more than 100 kids with food allergies were treated by their peers. About one-third of the surveyed kids had their allergies used against them. Bullying tactics included that their allergens were sometimes intentionally put in their food or thrown at them. Parents usually had no idea this bullying was happening.

Modern conveniences may be contributing to allergy increases

A combination of genetics and how the environment changes our genes are likely contributing to the rise in allergies. But daily conveniences, such as dishwashers and packaged baby food, also change the level of bacterial exposures in early life, with potential implications for allergy development, experts from Mount Sinai Health System state in this video discussion.

CRISPR technology is removing allergens from common foods

Proteins responsible for allergies to eggs, milk, wheat, peanuts, and other foods can be genetically edited out of foods to reduce the risk of life-threatening reactions. The technique has also been used to produce caffeine-free coffee beans, spicier tomatoes, allergen-free pets, and more nutritious fish.

The word allergy is partly derived from the Greek word 'allos' for 'other'

For people with allergies, their immune systems recognize substances as a harmful "other"—cuing an inflammatory response. This podcast explores allergy details and related topics, including how scientists are interested in if the same allergic response mechanisms could underpin other health issues, including severe, painful symptoms around the time of menstrual cycles. Since estrogen acts on white blood cells called mast cells, which leads to the release of histamines—similar to what happens during allergic responses—an understudied question is whether the same process is fueling some of the uncomfortable symptoms around menstruation. An allergist guest notes this raises questions about if antihistamine medications like Pepsid might alleviate them, something that hasn't yet been explored in clinical trials.

Allergy tests identify antibodies, but not whether allergy symptoms may appear

Skin prick tests and blood tests, the two most common allergy tests, both detect the presence of allergen-specific antibodies. But just because the body has those antibodies doesn’t mean that a person is “allergic” to a substance or that they will develop symptoms of an allergy when encountering the substance. Allergists work with families to interpret the results and sometimes combine that data with approaches including exposure challenges—giving someone a tiny bit of the food or substance they may be allergic to—under medical supervision.

Unlike food allergens, encountering inhaled allergens—like pollen—rarely causes life-threatening illness.

Alpha-gal allergy is a problem for red meat lovers, and that same alpha-gal sugar is an issue for xenotransplants, too—since it's present in pigs, human bodies reject pig-to-human transplants as foreign once they detect the substance.

Kids often grow out of allergies to milk and eggs

Between 60% and 80% of kids with allergies to milk or eggs outgrow them by age 16. The immune system doesn’t always recognize and respond to baked forms of these allergens, so when kids eat muffins and other cooked food products, their immune system may become more habituated to them and overcome food sensitivities. Aging out of other allergies is less common.

Autoimmune disease prevalence and incidence are on the rise—but no one knows why

Researchers theorize that environmental factors, including shifts to less healthy diets, air pollution, infections, stress, climate change, and exposures to xenobiotics—substances like pesticides, plastics, and toxins that incite immune responses—may all be fueling epigenetic changes to our bodies that make people's immune responses go awry.

Seasonal allergies don't always show up in childhood

The human immune system may become sensitized to pollen and develop an allergic reaction to it after prolonged exposure. Other triggers for new seasonal allergies may include exposure to new environments and changing climate conditions that affect allergy season length and conditions for various pollens.

Amish kids have far fewer allergies than the general population

Only about 7% of Amish children in a northern Indiana community have tested positive for common allergens in routine skin prick tests, whereas half of the general US population tests positive for them. Asthma is also extremely uncommon among the Amish, even when compared with other farming communities. Researchers are interested in exploring if approaches like exposing kids across the general population to Amish farm dust might stave off some allergies.

Gut microbiome rewrites may help reduce allergies

Researchers are investigating different strategies to determine if one day they could give people a combination of gut microbes to set them up for fewer allergies. In animal research, scientists have already prevented severe allergic responses in allergy-prone mice—supplying them with gut microbes from healthy, non-allergic human babies.

Researchers are investigating if nanoparticle treatments could combat allergies

In rodent work, Northwestern University’s Evan Scott (now at the University of Virginia) and his colleagues have been trying to attack allergies with specially designed nanoparticles—miniscule lab-made objects that can penetrate cells. They stud the nanoparticles with a tiny bit of the allergen specific to the allergy (i.e. cashew protein for cashew allergy) and antibodies that shut down allergic response processes.

Tick bites can fuel an allergy to a sugar molecule in red meat

Alpha-gal syndrome is on the rise globally as ticks spread due to climate shifts. Bites from some ticks can trigger a sensitivity to a sugar molecule called alpha-gal found in mammal meat, which can lead to allergic responses to hamburgers and steak, among other products. Listen to an expert’s tips for avoiding this allergy, including quickly removing any ticks to limit exposure to their saliva or vomit.

Autoimmune diseases affect between 5% and 10% of people worldwide, but their causes remain unknown

Autoantibodies—which attack the body—may be detectable in the body years before a patient develops symptoms, but some people may have detectable levels yet never go on to develop an autoimmune disease. This video discusses this and other unsolved mysteries with autoimmune disease.

Food allergies were first documented more than 4,000 years ago.

Scientists are using CRISPR to genetically modify felines so they don't trigger allergies in humans.

Peanut allergies dropped by 43% after doctors reversed avoidance guidance, but questions remain

The study’s data appear to confirm the policy shift. Still, since the study did not include an examination of infant diet, researchers can’t definitively say that the guideline shift led to dietary changes and thus directly caused the decline.

Inhalers, antihistamines, immunotherapy, and more have made allergies a multimillion-dollar market

Market research suggests that the allergies market will continue to grow in the years ahead as the number of allergy diagnoses increases, identifying new patients. Areas of growth include the increasing interest in immunotherapies designed to retrain the immune system through regular exposure to potential allergens via injections and under-the-tongue medical formulations, among other approaches.

One in six Americans contracts food poisoning each year.

An interactive dive into the immune system

Our bodies are equipped with an incredible system able to fight off invasive pathogens to protect us from illness. The complicated system includes lymph nodes, the spleen, bone marrow, and even the tonsils. But this same system can turn against itself, a condition known as autoimmune disorders. Follow along with this thorough, engaging explainer on the human body's defense system.

Home allergy tests don’t work well and experts urge caution

Doctors do not recommend at-home allergy test kits because their results may be inaccurate and confusing, and lead people to make lifestyle changes that are not warranted. Tests that require sending in a hair sample, for example, will not be helpful because hair does not have the relevant antibodies that blood testing would detect.

Neural replays in mice help explain food aversions

Princeton University scientists published research in 2025 analyzing how mice learn to associate certain foods or flavors with feeling ill—even when there’s a time gap between eating something and feeling sick. The work, performed with grape Kool-Aid and injections of a substance that made mice sick, traced the literal “gut reaction” of how gut distress signals are linked to neural replays of what the mouse ate.

A quick video on how your immune system works

Explore how your immune system's vast network of cells, tissues, and organs coordinate your body's defenses against bacteria, viruses and toxins with this 5-minute TED talk video.

Why processed foods can be so addictive

In recent years, many critics have voiced their concerns about the food industry and how ultra-processed foods affect our health. Despite our awareness of these issues, processed foods are still incredibly hard to remove from our diet. In this podcast by The Guardian, Dr. Chris van Tulleken explains how “junk food” is created to get us hooked, how it negatively affects us, and what we can do to improve our eating habits.

How do vaccines work? Watch this brief 101

Watch this under-3-minute video explaining how vaccines use the body's immune system to prepare our bodies against viral and bacterial threats to our health.

Find dozens of allergen-free recipes

This collection of allergen-free meal and snack recipes, designed by celebrity chefs and others, was curated by the nonprofit Food and Allergy Research & Education group. It includes items like taquitos, pizza, chickpea burgers, various desserts, and more.

Most of the world’s population has difficulty processing lactose—but that’s not an allergy

Lactose intolerance is a digestive condition that occurs when the small intestine has difficulty breaking down lactose, a sugar found in products like milk or cheese, leading to symptoms such as diarrhea or bloating. Almost 70% of the world’s population may have lactose processing issues, particularly in Asia and Africa. This is different from a condition called cow's milk protein allergy—an immune system disorder that can cause hives and anaphylaxis.

Most penicillin allergy diagnoses are wrong, leading to costlier, less effective treatments and contributing to the growing problem of antibiotic resistance.

The gut microbiome may play a major role in autoimmune disease and symptom flare-ups

Certain unhealthy foods can promote gut bacterial growth and inflammation in the lining of the gut, potentially disrupting its lining—leading to a leaky gut that may allow pathogens to dribble out into the bloodstream, fueling further inflammation that can both cause disease flare-ups and set the stage for future disease development.

Embracing poor hygiene in early life won't stave off allergies

The hygiene hypothesis, first proposed in 1989 by British immunologist David Strachan, suggests that early life exposure to microbes—like those from farm dust or pets—properly trains our immune systems to respond to threats. But sometimes the idea is misinterpreted: It doesn’t mean that poor hygiene—like failing to wash hands–will help ward off allergies; that type of behavior leads to infections and won’t help with allergy prevention.

Women typically have more robust immune responses than men

This difference helps women better combat infectious diseases, but this more turbo-charged response may also make women more vulnerable to autoimmune diseases by potentially priming their immune systems to overreact to their own cells and tissues and label them as invaders that must be destroyed. Roughly 80% of American women have autoimmune conditions.

An interactive explanation of blood transfusion

The antigens and Rh factors of blood cells (which determines your blood type) must be compatible with your immune system—which is why blood transfusions between patients must have matching types. In a mismatch, the immune system will attack and destroy donor blood cells, triggering a potentially fatal reaction.

Fungi make people sick when they invade and survive in otherwise healthy human tissue

We breathe in airborne spores frequently, but they often don't make us sick. This video details how certain concerning fungal changes can occur and discusses the role of mycologists—scientists who study fungi—in helping to improve human health.