Food allergens are substances in some foods that cause an abnormal immune response which lead to allergic reactions in some individuals. Millions of people have a food allergy in the United States alone, leading to a series of allergic symptoms upon consuming the food that contains the allergen (1).

Table of Contents

What Are Food Allergens?
Food Allergy Symptoms
9 Most Common food Allergens
Tests for Food Allergies
Conclusion

What Are Food Allergens?

Food allergens are substances found in certain types of food that lead to an allergic reaction upon consumption. The allergic reaction is usually followed by a set of symptoms that vary from mild to severe life-threatening levels (2). Any type of food might cause an allergic reaction to the person allergic to its allergen substance, however there are some foods that are more common than others in triggering an allergic response.

The most common foods that cause allergies are often found everywhere. That’s why people with a food allergy should be cautious of their presence by carefully reading labels and avoiding places where cross-contamination with these foods are at high risk.

Food Allergy Symptoms

Symptoms that follow upon having an allergic reaction may be different from person to person. Even if an initial allergic reaction is mild, reactions could escalate to become severe or life-threatening. It’s best if action is taken the moment the person with an allergic reaction shows their first mild symptoms as it might escalate and become more severe.

Symptoms of an allergic reaction usually appear in as little as two minutes upon consuming the food containing the allergen. Some people may see the first symptoms pop up after several hours after consuming a food allergen (3). Here are some of the most common food allergy symptoms (4):

Tightness in the throat or a hoarse voice
Swelling of the skin
Swelling and itching of the lips and mouth
Diarrhea and abdominal cramps
Itchy, raised bumps (hives)
Nausea and vomiting
Itchy skin

Anaphylaxis is the most life threatening symptom of an allergic reaction. This is due to it affecting multiple symptoms within the body. Some signs of anaphylaxis might be:

Difficulty breathing or wheezing
Sensation of throat constriction
Swelling of the lips or tongue
Itching of the palms or soles of the feet
Skin flushing
Rapid heartbeat
Dizziness or feeling faint
Nausea, vomiting, or abdominal pain
Decreased blood pressure
Loss of consciousness

Anaphylaxis is a severe condition. A person suffering from anaphylaxis should seek medical attention immediately. If you or a loved one is experiencing these symptoms, emergency services should be contacted on the spot, without waiting to see if the symptoms hopefully get better over time.

The treatment for anaphylaxis usually includes the injection of epinephrine through an auto-injector such as an EpiPen or AUVI-Q (5). In fact, people who suffer from severe allergic reactions are advised to keep these auto-injectors with them at all times and use them as soon as they see or feel the first signs of anaphylaxis.

9 Most Common food Allergens

Being aware of the most common foods that cause an allergic reaction is important for taking preventative measures as soon as mild symptoms occur. There are endless potential food allergens, but about 90% of all food allergies are caused by the proteins found in 9 food sources (6, 7). Being aware of these 9 common food allergens and their symptoms can provide support and guidance in life-threatening situations.

1. Cow’s Milk

Cow’s milk mostly affects infants and toddlers. Around 2-3% of children ages 0 to 3 years old suffer from this allergy. The good news is that around 85 to 90% of children with this allergy outgrow it (8). This makes cow’s milk allergy relatively less common in adults. The first symptoms of cow’s milk allergy may manifest within the first hour up to several hours or even days upon consuming the milk (8, 9).

The way to treat cow’s milk allergy is to avoid cow’s milk and its byproducts altogether. The foods to avoid include cheese, yogurt, butter and ice cream. Breastfeeding mothers should also avoid cow’s milk and other food products made with cow’s milk if they’re feeding a child with this allergy.

2. Soy

Soybean allergy is also mostly common in infants and toddlers. Roughly 0.4 to 3.1% of this demographic suffers from soybean allergy (10). Soybean allergy is less common among the adult population as around 50% of children usually outgrow this allergy by age 7 (11).

Some children that have a cow’s milk allergy can also have soybean allergy simultaneously. Symptoms of both cow’s allergy and soybean allergy can vary. Some of the mild symptoms include a runny nose and an itchy mouth. More severe symptoms of these allergies are rashes, breathing difficulties and asthma. In some rare cases soybean allergy can also lead to life threatening symptoms such as anaphylaxis.

Avoiding soy-based products and soy sauce is important to prevent an allergic reaction. It’s also important to read labels as soy is found as an ingredient in many foods.

3. Wheat

Wheat allergies are caused by an abnormal immune response to the proteins that are found in wheat products. This allergy is more common among children under the age of 10, with most of them outgrowing the allergy soon after 12. The symptoms of wheat allergy often resemble those of celiac disease and non-celiac gluten sensitivity.

This doesn’t mean that wheat allergies are related to gluten sensitivities. Wheat allergy is something completely different that has to do with being allergic to a protein found in wheat and not from gluten itself.

4. Eggs

Egg allergy is the second most common food allergy right after cow’s milk allergy (13). Although it’s mostly common in children, studies suggest that around 68% of children grow out of this allergy by the time they reach 16 (14). There are some people that are specifically allergic to egg whites or just the yolk of the egg due to the different protein composition found in each.

It’s usually recommended to avoid eggs altogether if you have this allergy. However there are many individuals that can tolerate some egg products in baked goods (15). You should always talk to your doctor before adding any egg-contaminated food to your diet as it may lead to severe allergic reaction upon ingestion.

5. Peanuts

Most of us are well aware of peanut allergies. This is because they often come with severe and life threatening allergic reactions. About 23% of people that have a peanut allergy are also allergic to other types of tree nut (16).

There are around 4.6 million people that suffer from a peanut allergy in the United States alone. This makes it the most common allergy that affects all age groups. Most individuals develop a peanut allergy before the age of 18 (17). And only 20% of people with a peanut allergy see fewer symptoms upon consuming peanuts as they grow older (18).

The reason why people experience such severe reactions from a peanut allergy remains unknown. Interestingly, some research points out that introducing peanuts at an early age might offer protective benefits (19).

The main treatment of peanut allergy is to strictly avoid peanuts or anything containing peanuts as an ingredient. There is also an FDA-approved oral immunotherapy medication called Palforzia. This medication helps manage the more serious symptoms of peanut allergies in children and teens with ages ranging from 4 to 17 (20).

6. Tree nuts

Tree nut allergies affect up to 3% of the global population (21) . Some examples of tree nuts include walnuts, almonds, and cashews. In order to prevent a tree nut allergy, affected individuals should avoid all nuts and their related products all together.

This allergy doesn’t usually go away in adult years, but some have noticed that allergy symptoms do get milder (22). For those who are severely allergic to tree nuts, keeping an auto-injector at all times is highly recommended to prevent anaphylactic.

7. Sesame

Sesame allergy was recognized and made part of the 9 most common food allergies in 2021 by the FDA. Around 17% of children with a peanut or tree nut allergy showed signs of being allergic to sesame as well (23).

In 2023, sesame labeling as an ingredient was made mandatory in food packaging (24). Sesame is commonly found in baked goods, sauces and asian dishes.

8. Fish

Fish allergies affect 0.2% to 2.29% of population across the world (25). The primary allergen in fish is reported to be the protein Parvalbumin. Being allergic to fish often comes with more severe symptoms such as diarrhea and vomiting. Anaphylaxis is less common in fish allergies but it is a possibility.

Fish allergy is sometimes mistaken as food poisoning when the person is in the first stages of learning that they have the allergy. Fish and shellfish allergies are caused by two different allergens – parvalbumins in fish and tropomyosins in shellfish, but there’s a risk of cross-reactivity between them (26).

9. Shellfish

Shellfish allergy occurs when the body reacts to the proteins present in crustaceans and mollusks. These proteins include tropomyosin, arginine kinase, and parvalbumin. Some examples of shellfish are shrimp, lobster, scallops, squid, prawns and crayfish(27). Symptoms of shellfish allergy typically arise within a few minutes of ingestion.

The allergic reactions are typically on the more severe side. People that have a shellfish allergy are advised to stay away from consuming any shellfish in their diet. Cross contamination can also happen if a person allergic to shellfish inhaled vapors from cooking shellfish.
It’s important to be informed of all these nine food allergies as they can be helpful to provide the necessary help needed in situations where allergic reactions do occur.

Tests for Food Allergies

Paying attention to the foods that you’re allergic to can help you in the further stages of getting diagnosed. A doctor will usually help in the diagnostic process and guide you to get in contact with an allergy specialist.

You will likely talk to your doctor about your medical history and they may further recommend taking a blood test or a skin test. After the tests are performed correctly, they will likely determine whether or not you are allergic to any of the nine common allergens.

Oral Food Challenge (OFC)

An oral food challenge is a feeding test where you have to consume a small amount of the food slowly. An OFC is done under the supervision of a medical professional, and it’s highly advised for individuals to not try the test at home if they suspect an allergy.

This test is usually done after taking a blood or skin test. It’s usually a step to come to final conclusions about a food allergy you might suspect.

The process of an OFC will usually take a couple of hours. If no signs of an allergic reaction are present after consuming a small portion of the food, the healthcare professional might also require to increase the intake of the same food. This extra process may take two to three additional hours depending on your allergic responses (28).

Skin Testing

Skin testing is one of the most common ways to find out if you have a skin allergy or not. This test usually takes place in a doctor’s office, where an allergist pricks your skin with different potential allergens to see how your skin reacts to them. This procedure is fairly short and may only take up to half an hour (29).

The allergen specialists will likely use a probe that contains a small amount of the potential food allergen and place it on a small labeled area on your arm or back. The test isn’t known to be painful, but some people admit to experiencing slight itching.

The end result is determined by the development of an inflamed spot that looks similar to mosquito bite. The more inflamed the area is the more it indicates that that individual is allergic to that food allergen. However, the size doesn’t determine the severity of the symptoms the person has.

Blood Testing

When taking a blood test to find out if you have an allergy or not, doctors might also refer it to an immunoassay test. This test will measure the levels of immunoglobulin E (IgE) antibodies in your blood upon coming into contact with the food allergen (30).

This test is just like a standard blood test. A doctor will usually take a blood sample from your arm by using a needle. Even though this is the quickest and less annoying procedure out of all three, the downside is that you may have to wait several days to get the test results back.

Blood tests are usually recommended if you have a sensitive skin and aren’t comfortable enough with the skin prick test. Another reason blood tests are recommended is when the person getting tested has a high risk of experiencing a severe allergic reaction. This makes it dangerous for them to undergo both the OFC and skin testings.

Both blood and skin tests can only predict if you are allergic to an allergen or not but they don’t predict the severity of symptoms you can experience from the allergen. There are also some cases where people test positive for a food allergy but experience no allergic reactions to the food upon consuming it (31).

Conclusion

Food allergies are a global health concern as they affect millions of children and adults. Being aware and knowing how to manage food allergies is important to receive the proper medical assistance and also avoid triggering food.

Scientists continue to conduct ongoing research on food allergens and their symptoms in the hopes of finding new treatment options that prevent or minimize life threatening situations.
By continuing to stay informed, we can all work together to create a supportive and safe environment for us and others that live with food allergens.

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