What Causes Food Allergies, Signs and Symptoms With its 10 Types.

What research says about food allergies.

For some people, a peanut, or bite of a shrimp can cause a cascade of reactions in the body’s immune system to react wildly. It can sometimes lead to deadly consequences. But what exactly is happening in the body to confuse shellfish and nuts with a true threat? It is the food allergy that is causing all this havoc.

Food allergy is an abnormal reaction to food substances. A person’s body perceives certain nutrients in food as toxic, triggering an inflammatory reaction that may damage their health. Even a small amount of food can cause associated signs and symptoms. Such allergies are quite widespread. In fact, they impact around 6% of adults and 8% of children globally.  Every three minutes, someone in the United States has a food allergy reaction. According to the CDC, 300,000 visits to the emergency room are caused by allergic reactions in children yearly.

Science of Food Allergy.

In order to understand food allergies, we need to understand how the body evaluates food in the first place. Generally, in an immune system, the body continually uses different antigens to deem them either dangerous or harmful. Allergies are induced by an unexpected immune reaction to an allergen, a usually safe allergen trigger. The immune system will then produce immunoglobulin E (IgE), which causes mast cells and other blood cells to rupture and release histamine (a substance that is released by the body as a defense mechanism) into circulation.

But it’s equally essential to distinguish food allergy from food intolerance which can cause uncomfortable symptoms but does not cause any immune response involvement in it. It means if one is lactose intolerant, then they are not allergic to milk. However, an allergy develops when the body’s immune system responds inappropriately to any compounds present in certain food such as proteins, whereas food intolerance includes digestive difficulties caused by an inability to break down specific enzymes. How do enzymes help the body with different chemical reactions? Read here.

Types of Food Allergies.

True food allergies fall into two major categories:

  • Immunoglobulin E (IgE) mediated. Immune cells in your body produce IgE antibodies in response to a specific foodstuff, causing an allergic reaction. An antibody is a type of protein in the blood that is used by the immune system to identify and combat infections. Within a few hours of ingesting the food allergen, an IgE-mediated allergic response may cause moderate to severe symptoms, including anaphylaxis.
  • Non-IgE mediated. Other components of the immune system, such as T-cells, are involved in a reaction to the perceived danger in a non-IgE food allergy. An allergic response that is not IgE mediated might include cutaneous or digestive symptoms, or a combination of those symptoms, such as vomiting and diarrhea, and can develop up to three days after consuming the food allergen.

The majority of food allergies are IgE-mediated. There are many other kinds of allergies that can affect us in daily life. Learn about them in this article here.

Symptoms of Food Allergy. Untitled design 4

Depending on the kind of food, symptoms may appear minutes, hours, or even days after exposure. Some of the major symptoms are as follows:

  • Tingling/itching in the mouth.
  • Fever.
  • Face. tongue, lips, throat, and gum swelling.
  • Trouble breathing.
  • Swallowing difficulty.
  • Abdominal cramping.
  • Diarrhea.
  • Vomiting.
  • Hives. (Sometimes, the skin may become red and itching without developing a rash).
  • Rashes and Itch.
  • Low blood pressure.
  • Dizzy and lightheadedness.

Top Food Allergens.

Although any food might probably induce an allergy, the vast majority of food allergies are caused by only 8 foods. FDA also denoted these foods as the cause of 90% of food allergy responses in the U.S.

Food that causes allergic reactions is called allergens. Below are some of the top allergens studied and well documented.

1. Milk Allergy.

Milk allergy is an abnormal immune system reaction to milk and milk-containing products.  Babies and younger children are the most likely age group to have an allergy to cow’s milk, affecting 2–3% of infants and toddlers. 90% of children outgrow the disease by age 3, thus it’s rare in adulthood. Symptoms are usually the same as in any allergic reaction. Many confuse a milk allergy with lactose intolerance since the symptoms are similar. Milk intolerance does not involve the immune system, unlike milk allergy. Both also have different treatment regimens.

There are two major allergenic proteins in cow’s milk: casein and whey.

  • Casein is present in the solid portion (curd) of curdling milk.
  • The liquid portion of milk that remains after curdling is known as whey.

If a cow’s milk allergy is diagnosed, the primary therapy is to avoid it. This includes all the related dairy products such as cheese, ice cream, yogurts, butter, milk powder, and margarine.

2. Eggs.

Eggs are an excellent source of protein, energy, and satisfaction. For people allergic to eggs, however, eating eggs in any dish may be rather uncomfortable. It is possible to have an egg white allergy but not an egg yolk allergy, and vice versa. This is because egg white and egg yolk proteins vary somewhat. Yet, the majority of allergen-causing proteins are found in egg whites, making egg white allergy more prevalent. This is one reason a food-allergic child should consult an allergist. While this allergy mostly affects children under the age of 5 and is often outgrown, some individuals retain it into adulthood almost at the age of 14. Symptoms include,

  • Gastrointestinal trouble, such as a stomachache
  • Skin manifestations, such as hives or a rash
  • Nasal congestion, runny nose, and sneezing (allergic rhinitis)
  • Respiratory issues
  • Anaphylaxis in rare cases.

There is no cure or therapy for egg allergy, however, you may be tested frequently to determine whether your tolerance for eggs improves. Due to the possibility that the shape of allergen-causing proteins may change when eggs are cooked, individuals may not need to avoid all egg-related products. Consequently, the body is less likely to react to them since it will not see them as dangerous as proven by research.

3. Fish.

Fish allergy affects 1% of the U.S. population. As it has already been observed, people become prone to this kind of allergy in childhood but it is not unusual for a seafood allergy to develop later in life. Fish allergy symptoms may range from minor to severe. Hives, nausea, and vomiting are the most frequent seafood allergy symptoms. It is possible to have varied symptoms depending on whatever sort of fish you eat.

Among more than 20,000 known species of fish, there are several with a particularly significant allergy risk. They include the following, according to studies published in Frontiers of Immunity

  • Carp
  • Cod
  • Flounder
  • Mackerel
  • Pilchard
  • Redfish
  • Salmon
  • Sea bass
  • Swordfish
  • Trout
  • Tuna

In research, it was found that people were most allergic to salmon, tuna, catfish, and cod.

A protein known as parvalbumin is the major allergen responsible for fish allergies. But it must be noted that fish intolerance differs from a fish allergy. In contrast to a fish allergy, fish intolerance is typically temporary, non-lethal, and only develops when eating fish. Typically, exposure to fish does not induce symptoms. Symptoms of seafood intolerance are often gradual rather than instantaneous, and they may not manifest at all unless you consume a great deal of fish.

4. Shellfish.

It is believed that one out of every 100 persons has an allergy to shellfish. Among the most prevalent food allergies is the immune system’s hypersensitivity to shellfish which are far more prevalent among adults than children. The following shellfish (including mollusks and crustaceans) might induce allergic responses, but it’s not limited to these only,

  • Calamari
  • Crayfish
  • Cuttlefish
  • Lobster
  • Mussels
  • Oysters
  • Prawns
  • Squid.

Tropomyosin is a protein that causes most seafood allergies and is present in crustaceans and mollusks. Other proteins that may help start an immune response are arginine kinase and parvalbumin.

It is not necessary that both shellfish and finfish have some link in between. Being allergic to one doesn’t usually entail avoiding both, however, cross-contact between fish and shellfish should be avoided. Consult your allergist to adopt the proper dietary restrictions.

5. Tree nuts.

Nut allergies are one of the most prevalent food allergies among both children and adults. Walnut, almond, hazelnut, pecan, cashew, and pistachio allergies are the most often reported tree nut allergies in children and adults. Over 2% of children have tree nut allergies, and many carry them into adulthood. If someone has a tree nut allergy, they may experience symptoms when they consume foods containing nuts or foods that have come into contact with nuts, such as peanut butter on bread, mayonnaise on sandwiches, or salads with walnuts.

These are the most typical symptoms of a tree nut allergy:

  • Trouble swallowing
  • Itching or swelling of the lips, tongue, throat, or other regions of the body.
  • Nausea and vomiting
  • Abdominal discomfort and cramps
  • Diarrhea
  • Anaphylaxis

It is essential to understand the difference between peanuts and tree nut allergies, it has been stated that peanuts are legumes and belong to a different plant family than tree nuts. An allergy to peanuts does not always imply an allergy to tree nuts, but being allergic to both peanuts and certain tree nuts can happen. Recent studies indicate that 25 to 40 % of peanut-allergic individuals are also allergic to tree nuts.

6. Peanuts.

This salty, nutty snack causes numerous allergies. Peanut allergies account for over half of all severe allergic food responses in the United States. Peanuts are one of the most prevalent allergens that result in fatal reactions in those who have food allergies. About 1% to 3% of children and approximately 2% of adults are allergic to peanuts. They have the potential to bring on anaphylaxis, a severe allergic response that may be deadly if not treated immediately. In most cases, the onset of symptoms occurs within minutes after first exposure. However, they may also begin in a matter of seconds or take many hours to develop.

People with peanut allergies often develop symptoms within two hours after consuming peanuts. Symptoms of peanut allergy may vary from mild to severe and often include general food allergy symptoms such as breathing difficulty, hives & rashes, and swelling around the tongue and lips. It can also progress to anaphylaxis.

According to 2018 and 2019 surveys, 6.1 million Americans are allergic to peanuts and 3.9 million to tree nuts.

At the moment, the only treatment that works is to steer clear of peanuts and products that contain peanuts. However, treatment strategies are being researched for peanut-allergic. This entails administering precise, smaller amounts of peanuts or peanut allergen powder under medical supervision in an effort to desensitize the patient to the allergy.

In the United States, over 200 individuals each year die from allergic reactions to food. the National Health Interview Survey reported that white children had the greatest frequency of food allergies from 2001 to 2013.

7. Wheat. 

Wheat allergy is a hypersensitivity to wheat-containing products. Wheat consumption and, in certain circumstances, inhalation of wheat flour might trigger allergic responses. Like any other food allergy, it mostly affects children. Nevertheless, children with a wheat allergy often outgrow it by the age of 10.

Wheat allergies are caused by IgG antibodies responding to at least one of the proteins in wheat. Albumin, Globulin, Gliadin, Glutenin, or gluten

Some individuals are sensitive to a single wheat protein, whilst others may be allergic to two or more. In addition to bread, which is a well-known source of wheat protein, there are numerous prepared foods and cosmetics (including bath and body products) and even play dough that contains any of the wheat proteins, including gluten. Wheat proteins may be found in a variety of foods, including the following:

  • Bread with bread crumbs
  • Baked goods
  • Cereals for breakfast
  • Pasta
  • Farina
  • Semolina
  • Sauce made from soybeans

Some wheat-allergic individuals get symptoms only when they exercise within a few hours after consuming wheat which is known as (Wheat-dependent exercise-induced anaphylaxis (WDEIA). Changes in your body caused by exercise might either create an allergic reaction or exacerbate an immunological response to a wheat protein. Typically, this syndrome leads to life-threatening anaphylaxis. Some people who work with wheat flour may develop breathing issues, or “Baker’s Asthma,” as a result of inhaling wheat allergens, but no symptoms while consuming wheat.

8. Soy

Soy belongs to the family of legumes, which also includes kidney beans, peas, lentils, and peanuts. Soy allergy is more prevalent in newborns and young children than in older children; roughly 0.4% of U.S. Infants are allergic to soy. Most children overcome their soy allergy, but others never do. According to 2021 research, soybeans include at least 28 allergen-causing proteins that have been discovered. Up to 88 % of soy-allergic individuals had peanut allergies or were substantially sensitive to peanuts, according to one research. All soy allergy symptoms are unpleasant and mild but not fatal. Symptoms of a food allergy often occur within minutes or hours after consuming the allergen-containing meal.

Despite the fact that soy seems to be a clearly identifiable allergy, it may be found in meat products, baked goods, chocolate, and cereals. Products that may cause soy allergies include soy Lichtin (very small amounts), Soy milk, Soy sauce, and soy protein.  It has also been studied that most soy-allergic persons can take soy lecithin and soy oils, according to studies. These compounds are fat-based, and allergic individuals respond to protein. Avoid soy and soy products to prevent hypersensitivity. Before eating a non-homemade dish, examine labels and inquire about ingredients.

9. Sesame. 

Because sesame seeds consumption is more common in the Middle East, there is more data about the allergy’s frequency — it’s the third most common allergy in Israeli children. The Food Allergy Safety, Treatment, Education, and Research (FASTER) Act made a report in 2021, making sesame the ninth major food allergen recognized in the United States.

The most common food containing sesame seeds includes hummus, baked products, snack foods, and a range of sauces and dressings. Compared to brown or black seeds, white sesame seeds are the most allergenic. Most individuals with a sesame seed allergy will have relatively minor symptoms. Approximately 15% of instances have severe responses affecting the child’s respiration.

10. Fruits & Veggies.

Some seasonal allergy patients report itching and discomfort while consuming juicy peaches or crunchy carrots. They are present in both children and adults. There have been several reports of food allergies, but celery, notably celeriac (celery root), has proved a particularly troublesome item for many people. Frequently, allergies to fruits and vegetables are caused by an allergy to Profilins. Asparagus, avocado, bell pepper, cabbage, carrot, lettuce, potato, pumpkin, turnip, and zucchini are among the other vegetables to which allergies have been attributed.

Due to the fact that fresh fruits and vegetables contain the same proteins as some pollens, it is simple to acquire oral allergy symptoms. They are usually mild and shown in the mouth and throat, with itching and swelling of the oral mucosa and the lips, tongue, and throat. Slightly more severe symptoms have been recorded occasionally. These symptoms normally happen within minutes, but might take 1-2 hours. While they are not nearly as deadly as other food allergies, they may induce anaphylaxis in rare instances.

Severe Food Reaction (Anaphylaxis). anaphylaxis food allergies

Anaphylaxis is a life-threatening allergic response of extreme severity. It may develop within seconds or minutes after exposure to allergens like peanuts or bee stings and requires immediate medical attention. Peanuts are one of the most prevalent allergens that induce anaphylaxis, which may damage several bodily systems.

Anaphylaxis occurs when an antibody, which normally fights illness, overreacts to a safe substance such as food. It may not occur the first time the trigger is encountered, but it might build over time. In youngsters, food is the most prevalent cause. For adults, medicine is the leading reason.

Anaphylaxis symptoms may include:

  • Rapid pulse
  • Dizziness or loss of consciousness
  • Confusion and anxiety.
  • Difficulty breathing due to a swollen throat
  • A drop in blood pressure and shock.
  • Paleness and weak pulse.
  • Swollen/itchy lips and tongue.
  • Hives/rashes and redness on the skin.
  • Vomiting and diarrhea.

Treatment: Anaphylaxis necessitates an adrenaline injection and a visit to the emergency department. If you do not have epinephrine, you must immediately visit an emergency hospital. These injections, for which a prescription is required, are prefilled and packaged in ready-to-use pens. If not treated immediately, anaphylaxis may be deadly. Within minutes, epinephrine may reverse the symptoms. If this does not occur, you may need a second injection within 30 minutes.

Diagnosing Food Allergy.

There is no definitive test to confirm or exclude a food allergy. Before establishing a diagnosis, your doctor will evaluate a variety of criteria. These elements include:

General Symptoms. Consult your physician about all you can remember about your symptoms, including what meals you’ve tried and how much of each you’ve had. When symptoms appeared and how long symptoms persisted.
Allergies in the family. General questions about any familial history of asthma and allergies to any substance.
Examination. A thorough examination may frequently uncover or rule out other medical conditions.
Skin Patch Test Skin prick tests may diagnose food allergies. In this test, the probable food is applied to your forearm or back. A doctor or other healthcare practitioner pricks your skin with a needle to inject the substance. If you’re allergic to test material, you’ll get a reaction. However further testing is still important
A Blood Test. Immunoglobulin E (IgE), an allergy-related antibody, may be measured in a blood test to see how your immune system reacts to certain meals.
Oral Food Challenge.  A small amount of suspected food items is given under medical supervision. If it doesn’t trigger any reaction then the food is safe to consume.
The Elimination Diet. You may be instructed to avoid suspicious foods for a week or two before reintroducing them. This may relate symptoms to allergic foods. Elimination diets aren’t perfect for diagnosis as they don’t differentiate between sensitivity and allergy.

Prevention of Food Allergy.

Despite the development of promising preventative and therapy techniques, food allergies remain incurable. Recognizing food allergies early and understanding how to manage them, including which foods to avoid, are crucial steps to prevent major health repercussions.

  1. Review Your Foods. A health practitioner may ask a patient to maintain a food diary in order to determine the allergen’s source. This will contain notes on the sorts of foods consumed, the frequency with which they are consumed, and some information on symptoms.
  2. Avoid Allergens. Allergy reactions can only be prevented by abstaining from the food in question and all products that may include it as an ingredient.
  3. Eating Out. Restaurants are risky. Waiters (and occasionally kitchen personnel) may not know every dish’s ingredient. Use a “chef card” to identify your allergy and what you can’t eat. Tell your servers about your allergies and, if possible, the chef.
  4. Always Read Labels. To avoid further allergies to the same substance, it is recommended to read labels. Even if it’s an addition or flavoring, allergens must be listed. Eggs are not usually labeled as “eggs” on product labels. Albumin, globulin, lecithin, livetin, lysozyme, words with “ova” and “ovo” as prefixes, silici albuminate, simplesse, and vitellin are keywords to watch out for. For milk, even if it is labeled “milk-free” or “nondairy,” it may include milk proteins that cause allergic reactions; thus, you must read the label carefully. Contact the manufacturer if you are unsure if a product contains milk components.
  5. Treatment Drugs. A mild to moderate allergic reaction can be treated with the use of antihistamines.
    severe allergic responses are treated with adrenaline (anaphylaxis). Based on the intensity of your food allergy, your healthcare provider may prescribe drugs, such as epinephrine auto-injectors, for you to carry at all times in case you mistakenly consume food you’re allergic to and have a response. The first-line therapy for anaphylaxis is epinephrine. Make sure your closest friends and family know how to deliver the medicine in case of an anaphylactic emergency.
  6. Prevention in Childhood. In 2015, the American Academy of Pediatrics approved studies showing that giving solid meals to very young newborns might increase the chances of allergies. It advised avoiding starting solids before 17 weeks. It advocates solely breastfeeding “as long as feasible,”.
  7. Oral Immunotherapy. Oral immunotherapy is now being researched as a potential treatment for food allergies. This treatment involves swallowing or placing little amounts of the allergenic food under the tongue (sublingual). The allergen-causing food’s dosage is gradually increased. FDA recently approved the first oral immunotherapy medicine for peanut allergy treatment in children aged 4 to 17 years old, Peanut Allergen Powder-dnfp (Palforzia). But this drug is contraindicated for eosinophilic esophagitis or asthma.

prevention and treatment of food allergyIf you sense you have a food allergy, it is recommended to see a physician. Preventing exposure to food until you see a doctor is the best course of action if you suspect an allergy. Over-the-counter antihistamines may help reduce symptoms if you eat the food and have a mild reaction.

Show More


Being a Doctor by profession, Aimen is passionate about helping people get better health in their lives. Aimen enjoys her research on Prime With Time subjects and strives to create better awareness of the problems and changes related to women's health.
Back to top button