What is Egg Allergy?
Egg allergy is a reaction of the body’s immune system against eggs. Proteins present in the egg white are more likely to cause an allergy than the proteins present in the yolk. Some people can be allergic to both.
The overreaction of the immune system results in an allergic reaction. The immune system recognizes the protein in egg white/yolk as foreign and produces histamine and other chemicals that lead to the symptoms of an allergy.
Egg allergy is very common in children. Most children usually grow out of it before adolescence. In the US, about 2 percent of the total children population are known to be allergic to eggs. Egg allergies usually occur during infancy and become severe between 6 and 15 months of age. There are cases of egg allergy reported in adults also.
Signs and symptoms are usually very mild and can be easily managed. The allergy can be life-threatening in rare cases where there is a severe allergic reaction like anaphylaxis. This impairs breathing and can send the body into shock if immediate action is not taken.
If you’re allergic to eggs, you may be at an increased risk of other food allergies like milk or peanut allergy, allergies to pet dander, pollen, or dust mites, atopic dermatitis, and asthma.
Symptoms of Egg Allergy
The symptoms vary from person to person and can usually occur immediately after consumption or after a few hours. The symptoms are common to those seen in other allergic reactions.
- Skin inflammation, swelling, hives
- Redness of face
- Nasal congestion
- Stomach pain, vomiting, diarrhea
- Signs and symptoms of asthma-like wheezing, cough, shortness of breath
- Pale or blue skin
- Sneezing
- Dizziness
- Anaphylaxis in severe cases
- Lip or eyelid swelling, itchy ear, nose, or throat (usually in adults)
The Genetics Behind Egg Allergy
Variations in certain genes have been observed in people with egg allergies. Studying these variations can help predict if a person has a higher risk of getting the allergy compared to other people.
ABCB11 Gene
The ABCB11 gene encodes a protein in the liver called bile salt export pump. Bile salts present in bile released by the liver are transported through this pump. This is an indication of healthy liver function. Variation in this gene is found to be associated with egg allergy.
rs16823014
rs16823014 is an SNP found in the ABCB11 gene. The minor allele, A allele, is found to increase one’s risk of developing egg allergy.
ERCC4 Gene
The ERCC4 gene encodes the ERCC4 protein, which is a DNA repair endonuclease. It is known to participate in DNA repair and recombination along with other proteins. Variation in this gene is found to be associated with egg allergy.
rs6498482
rs6498482 is an SNP found in the ERCC4 gene. The minor allele, the C allele, is associated with an increased risk of egg allergy in individuals.
If one or both the parents have any food allergy or other allergic diseases like asthma, hives, or eczema, the child has an increased risk of egg allergy.
Non-Genetic Factors that Influence Egg Allergy
Age: Children are more prone to having an egg allergy. Allergic reactions are less likely to occur in older people.
Atopic dermatitis: Children who have this skin problem are more likely to develop a food allergy.
Diagnosing Egg Allergy
Skin-prick test: A small amount of liquid containing egg protein is allowed to seep into the skin on the back or forearm by piercing. After 15-20 minutes, if signs of allergy like redness are observed, the person is said to be allergic to eggs. You can determine which protein of egg you’re allergic to using this test.
Blood test: Blood samples are tested for the presence of allergic antibodies against egg proteins.
Oral food challenge: Small amounts of eggs are consumed under the supervision of an allergist or trained staff to see if any reaction occurs.
Food elimination diet: If the symptoms disappear on eliminating eggs from your daily diet, you may be allergic to eggs.
Managing Egg Allergy
The best way to manage any allergy is to avoid the allergen causing it. This can prevent severe allergic reactions.
Food products: Start reading the labels on food products. Most foods that include the words emulsifier, binder, coagulant, or any other ingredients that begin with ova contain eggs and should be avoided.
Various food items like mayonnaise, baked goods, frostings, and processed meat contain eggs. Be sure to read the ingredients carefully and find out if any form of egg is present in the item to avoid an allergic reaction. Make a list of all the products that contain eggs or related proteins and avoid them.
Egg replacers: Several egg replacers are available in the market. These include applesauce, yogurt, vinegar, baking soda, mashed banana, and ground flax or chia seeds. These can be used instead of eggs while baking. There are various other protein sources that you can include in your diet instead of eggs.
Allergy bracelet or necklace: Children should wear an allergy bracelet or necklace that informs people of the allergy, especially if the child can develop a serious reaction to eggs.
Vaccines that contain egg proteins: There are a few vaccines that contain egg proteins. Examples include the flu vaccine, yellow fever vaccine, and MMR vaccine. Inform the healthcare professional about your allergy before they prescribe any vaccination or medication to you.
Severe allergic reactions: Epinephrine in an auto-injector is usually used to treat anaphylaxis, which is a severe allergic reaction. This should be carried with a person susceptible to severe allergic reactions and used when symptoms start to occur.
Summary
- Egg allergy is a reaction of the body’s immune system against the protein present in eggs. They are treated as a foreign substance and attacked by the immune system. Egg allergy is more common in children than in adults. Most children outgrow their symptoms as they grow old except in certain cases.
- The symptoms of egg allergy are common to other allergies. They include redness, inflammation, stomach pain, and shortness of breath.
- Variations in certain genes are found to increase the risk of egg allergy. The A allele of rs16823014, an SNP found in the ABCB11 gene, and the C allele of rs6498482, an SNP found in the ERCC4 gene, are known to increase your risk for egg allergy.
- There are a few tests that can be done to find out if the egg proteins are a trigger for your allergic reactions.
- The best way to prevent symptoms is to avoid the consumption of eggs. Make sure you know the ingredients present in the food you’re eating. Several egg replacers are available to use in baking.
References
https://acaai.org/allergies/types-allergies/food-allergy/types-food-allergy/egg-allergy
https://www.healthline.com/health/allergies/egg
https://www.ncbi.nlm.nih.gov/pubmed/25710614
https://www.mayoclinic.org/diseases-conditions/egg-allergy/symptoms-causes/syc-20372115
https://www.healthline.com/nutrition/egg-substitutes
https://medlineplus.gov/genetics/gene/abcb11/
https://www.genecards.org/cgi-bin/carddisp.pl?gene=ERCC4
