All foods, even processed foods, contain some type of protein, whether it be animal- or plant-based. When a reactive immune system encounters the wrong protein, it will cause the body to overreact in an effort to flush the protein out and remove the threat of harm from the body.
For some with food allergies, their immune system may respond negatively to only one type of food protein but will respond normally to the rest. Others can have an immune system that is reactive to multiple proteins, causing the patient to avoid many types of food to avoid their triggers.
Common Symptoms of a Food Allergy
When the immune system overreacts to a food protein, the food allergy patient can develop resulting symptoms like:
- Anaphylaxis (see Anaphylaxis section below)
- Coughing
- Choking
- Facial swelling
- Nasal congestion
- Nausea, vomiting, and diarrhea
- Rashes and hives
- Uneasiness throughout the body
- Wheezing and other breathing issues
Nine Major Food Allergies in the US
Because proteins are the triggers for allergies and there are proteins in all foods, technically any food can cause an allergic reaction when exposed to the wrong immune system. However, there are 9 foods that the US Food and Drug Administration considers major allergens that must be identified on all food labels. These include:
Cow Milk
A cow milk allergy most often occurs in infants and children and is considered one of the most common food allergies among younger patients, affecting nearly 2% of children in the US. While most children grow out of their milk allergy by the time they reach adulthood, some patients can experience lifelong allergies to cow’s milk. Adults can even develop an allergy later in life without any previous sensitivity.
Milk contains many proteins, but the two main allergens that can trigger the immune system are casein and whey.
Signs of a Milk Allergy
If you’re curious whether you or your child has a milk allergy, pay attention to any reactions after ingestion. In addition to the common allergic reactions (see above), milk allergies can also cause:
- Bloody or loose stools
- Stunted growth in children
- Unexplained weight gain
Milk Allergy Vs. Lactose Intolerance
Milk allergies are often confused with lactose intolerance, but there are significant differences between the two.
A lactose intolerance means that the digestive system does not produce enough lactase enzymes to properly break down the lactose sugar found in milk, which can interfere with how it is processed and discarded from the body. It only affects the digestive system, including the stomach and intestines.
A milk allergy, however, causes the body’s immune system to react and can lead to painful or dangerous allergy symptoms throughout the body.
Eggs
Another common trigger among infants and children are eggs, specifically egg whites. Eggs whites consist of several proteins that trigger immune systems and lead to allergic reactions.
Data shows that roughly 2% of children are affected in infancy and childhood. Similar to cow’s milk, most children outgrow their egg allergy by the time they reach the age of six. Others may stop experiencing allergic reactions by adulthood, and some may experience allergies for the rest of their lives. An adult-onset egg allergy is rare, but it has been reported throughout the years.
Can I Separate the Egg Yolk from the Egg White?
The short answer is no. Even though the triggering proteins are found in egg whites, the yolk is so heavily exposed to egg whites that there is no way to ensure the yolk is trigger-free, even after separation.
Can I Bake the Allergens Out of Egg?
Many patients have found success when consuming foods that include baked eggs*. When the egg proteins are heated for a long enough time, their structures will change (this is called denaturing) and can essentially confuse the immune system enough so that it does not react.
Some patients are able to moderately consume breads and other baked goods that include egg. If you are planning to introduce baked eggs to your child, speak with your allergist first and create a plan with them to progress safely.
*Baked eggs should not be confused with cooked eggs. Baked goods are exposed to high levels of heat for 30 minutes or more, giving the proteins enough time to denature. Cooked eggs, while also exposed to high heats, are only exposed for a few minutes, making it unlikely for all proteins to change structure in time.
Fish
Fish allergies affect nearly 1% of the US population and most commonly appear in adulthood. Fish that trigger allergic reactions in some people can include:
- Catfish
- Cod
- Salmon
- Snapper
- Trout
- Tuna
Any finned fish can cause allergies, and a person could find themselves allergic to only one type, several types, or even all types of finned fish. The allergy-inducing protein shared among all finned fish species is parvalbumin.
If you are allergic to one finned fish, most allergists recommend avoiding all fish unless test results show which types you can tolerate. Even then, it is recommended to eat fish with caution.
Also note that fish allergies and shellfish allergies are different. Being allergic to one does not mean you are automatically allergic to the other since the triggering proteins are different in each (parvalbumin in fish and tropomyosin in shellfish).
Shellfish
Shellfish cause allergic reactions in approximately 2% of the US population and can affect both children and adults. In fact, roughly 60% of shellfish allergy patients do not experience their first reaction until adulthood. In most childhood cases, children with shellfish allergies never outgrow their sensitivity to them.
Shellfish contain the protein tropomyosin, which can cause the immune system to overreact. Similar to a fish allergy, shellfish allergy patients can only be allergic to one, multiple, or all shellfish.
There are two main groups of shellfish eaten in the US: crustaceans and mollusks.
Crustaceans include:
- Crab
- Crawfish
- Lobster
- Shrimp
Mollusks include:
- Clam
- Mussel
- Octopus*
- Oyster
- Scallop
- Snail
- Squid*
*Although octopus and squid lack external shells, they consist of tropomyosin and are categorized as shellfish due to their evolutionary history.
Peanuts
Peanuts are a major allergen in children and adults. About 2% of children suffer from peanut allergies, and 80% of these children will remain allergic to them for the remainder of their lives. While rare, adults can develop a peanut allergy at some point.
Like egg whites, peanuts contain many proteins that can cause allergic reactions, the three main ones being Ara h 1, Ara h 2, and Ara h 3. These proteins are members of the cupin protein superfamily.
Is a Peanut Allergy the Same as a Tree Nut Allergy?
A peanut allergy and tree nut allergy are not the same, since peanuts and tree nuts consist of differing proteins that can cause immune systems to react. However, many patients with a peanut allergy also experience a tree nut allergy. In fact, roughly 40% of tree nut allergy patients are also allergic to peanuts.
Can I Safely Consume Peanut Oil with a Peanut Allergy?
If a dish includes refined peanut oil, chances are that it is safe to eat for those with a peanut allergy. Oils, especially refined oils, do not contain the source’s proteins as they are removed from the oil through an extensive refining process. If a product you’d like to eat includes peanut oil, make sure it is refined first.
Tree Nuts
Slightly less common than a peanut allergy, tree nut allergies affect about 1% of children and adults in the US. Most patients with a tree nut allergy experience lifelong affects; very few outgrow it. And, like many allergy triggers, tree nuts usually begin causing reactions in early childhood, although some can develop an allergy in adulthood.
Tree nuts include:
- Almonds
- Brazil nuts
- Cashews
- Hazelnuts
- Macadamia nuts
- Pecans
- Pistachios
- Walnuts
Like egg whites, tree nuts contain many proteins that can trigger immune systems and cause reactions. While some can be allergic to one or two tree nuts, many patients are allergic to all of them.
Is a Tree Nut Allergy the Same as a Peanut Allergy?
A tree nut allergy and peanut allergy are not the same, since each consist of differing proteins that can cause immune systems to react. However, many patients with a tree nut allergy also experience a peanut allergy. In fact, roughly 40% of tree nut allergy patients are also allergic to peanuts.
Sesame
While a sesame allergy is the least common allergy on this list, it is still major enough to now be identified in the allergy section on food labels. Sesame is a common ingredient in many processed foods, and over 1 million children and adults in the US are allergic to its proteins.
Like egg whites, peanuts, and tree nuts, sesame contains multiple allergenic proteins that can trigger the immune system.
Soy
A soybean allergy is another common childhood allergy that children tend to grow out of over time. In rare cases, patients will experience allergies throughout their life, and others can develop the allergy well into adulthood.
Soybeans are legumes, just like peanuts, and they contain several proteins that are considered allergens. In general, soy tends to cause mild reactions in most soy allergy patients, but severe symptoms, including anaphylaxis, can still occur.
Wheat
A wheat allergy is another common allergy in children and adults, affecting roughly 1% of the US childhood population. Patients tend to outgrow their wheat allergy by the time they reach their teens, but some can experience allergies throughout adulthood. Others can develop an allergy to wheat at some point in adulthood.
The wheat proteins that trigger the immune system are albumins, globulins, prolamins, and glutelins.
Wheat Allergy Vs. Gluten Intolerance Vs. Celiac Disease
Wheat allergies are often confused with gluten intolerance or celiac disease, but there are significant differences between the three.
A wheat allergy affects the body’s immune system, causing it to react with painful or dangerous symptoms.
A gluten intolerance does not affect the immune system at all. Instead, the digestive system struggles to break down the protein compound gluten, which is found in many wheat and grain products. When gluten is not properly digested, the digestive system struggles to process and discard it from the body. Those with a gluten intolerance often experience bloating, stomach pains, headache, joint pain, skin rash, and more. Symptoms can vary in severity and duration.
Celiac Disease is an autoimmune disease that also affects the digestive system, especially the small intestines. Wheat and other grains containing gluten trigger antibodies to attack the small intestine, and even the smallest amount of gluten will initiate an attack. Symptoms are similar but more severe to gluten intolerance and can last for days or weeks.
Food Allergies Can Lead to Anaphylaxis
Food allergy reactions can vary in type and severity. However, the most severe reaction is anaphylaxis. If you or someone you know is experiencing anaphylaxis after consuming a triggering food, you will notice worsening symptoms like:
- Facial swelling
- Chest tightening
- Hives and rashes
- Nausea, vomiting, and diarrhea
- Stomach pain
- Swelling in the mouth, tongue, or throat that can block the airway
- Wheezing or difficulty breathing
You can also experience anaphylactic shock, which include:
- Confusion
- Drop in blood pressure
- Increased heart rate
- Loss of consciousness
- Sudden weakness
To protect yourself or your loved ones with a food allergy from the dangers of anaphylaxis, always carry an epinephrine injector (such as an EpiPen), pay close attention to food labels, inform wait staff at restaurants of your allergy, ask friends about the ingredients of anything they prepared for a dinner or game night, and take other protective measures to avoid or treat an attack.
Should you or your loved one experience an attack, apply the epinephrine injector according to its directions and seek emergency medical help immediately.
If you experience symptoms of food allergies or anaphylaxis, talk to the specialists at Langford Allergy.
Dr. Langford and our team offer thorough allergy testing and can help you understand your immune system’s reaction to certain foods. Whether your food allergies are mild or reach anaphylactic levels, we will create an effective treatment and management plan to ensure you are prepared. Schedule an appointment or call our office to learn more: 478-787-4728
Related articles:
Symptoms of Anaphylaxis: What You Need to Know
4 Ways to Enjoy the Holidays with a Tree Nut Allergy (or Any Allergy)