Free
E-newsletter
Subscribe to Housecall
Our weekly general interest
e-newsletter keeps you up to date
on a wide variety of health topics.
Mayo Clinic Housecall
Stay up to date on the latest health information.
What you get
- Free weekly e-newsletter
- Mayo Clinic expertise
- Recipes, tools and other helpful information
- We do not share your e-mail address
Causes
By Mayo Clinic staffWhen you have a food allergy, your immune system mistakenly identifies a specific food or a substance in food as something harmful. Your immune system triggers cells to release antibodies known as immunoglobulin E (IgE) antibodies to neutralize the culprit food or food substance (the allergen). The next time you eat even the smallest amount of that food, the IgE antibodies sense it and signal your immune system to release a chemical called histamine, as well as other chemicals, into your bloodstream.
These chemicals cause a range of allergy signs and symptoms. They are responsible for causing allergic responses that include dripping nose, itchy eyes, dry throat, rashes and hives, nausea, diarrhea, labored breathing, and even anaphylactic shock.
The majority of food allergies are triggered by certain proteins in:
- Shellfish, such as shrimp, lobster and crab
- Peanuts
- Tree nuts, such as walnuts and pecans
- Fish
- Eggs
In children, food allergies are commonly triggered by proteins in:
- Eggs
- Milk
- Peanuts
- Tree nuts
- Wheat
Chocolate, long thought by some parents to cause food allergies in children, rarely triggers a food allergy.
Food intolerance and other reactions
There are a number of reactions to food that cause similar symptoms to a food allergy. Depending on the type of food intolerance you have, you may be able to eat small amounts of problem foods without a reaction. By contrast, if you have a true food allergy, even a tiny amount of food may trigger an allergic reaction. Because a food intolerance may involve some of the same signs and symptoms as a food allergy does — such as nausea, vomiting, cramping and diarrhea — people may confuse the two.
One of the tricky aspects of diagnosing food intolerance is that some people are sensitive not to the food itself but to a substance or ingredient used in the preparation of the food.
Common conditions that can cause symptoms mistaken for a food allergy include:
- Absence of an enzyme needed to fully digest a food. You may not have adequate amounts of some enzymes needed to digest certain foods. Insufficient quantities of the enzyme lactase, for example, reduces your ability to digest lactose, the main sugar in milk products. Lactose intolerance can cause bloating, cramping, diarrhea and excess gas.
- Food poisoning. Sometimes food poisoning can mimic an allergic reaction. Bacteria in spoiled tuna and other fish also can make a toxin that triggers harmful reactions.
- Sensitivity to food additives. Some people have digestive reactions and other symptoms after eating certain food additives. For example, sulfites used to preserve dried fruit, canned goods and wine can trigger asthma attacks in sensitive people. Other food additives that could trigger severe reactions include monosodium glutamate (MSG), artificial sweeteners and food colorings.
- Recurring stress or psychological factors. Sometimes the mere thought of a food may make you sick. The reason is not fully understood.
- Celiac disease. While celiac disease is sometimes referred to as a gluten allergy, it isn't a true food allergy. Like a food allergy, it does involve an immune system response, but it's a unique immune system reaction that's more complex than a simple food allergy. This chronic digestive condition is triggered by eating gluten, a protein found in bread, pasta, cookies, and many other foods containing wheat, barley or rye. If you have celiac disease and eat foods containing gluten, an immune reaction occurs that causes damage to the surface of your small intestine, leading to an inability to absorb certain nutrients.
- Burks W. Clinical manifestations of food allergy: An overview. http://www.uptodate.com/home/index.html. Accessed Nov. 11, 2010.
- Food allergy: An overview. National Institute of Allergy and Infectious Diseases. http://www.niaid.nih.gov/topics/foodAllergy/Documents/foodallergy.pdf. Accessed Nov. 11, 2010.
- Lack G. Food allergy. New England Journal of Medicine. 2008;359:1252.
- Atkins D. Food allergy: Diagnosis and management. Primary Care: Clinics in Office Practice. 2008;35:119.
- Hoffman A, et al. Pollen food allergy syndrome: Update on the allergens. Current Allergy and Asthma Reports. 2008;8:413.
- Chapman JA, et al. Food allergy: A practice parameter. Annals of Allergy, Asthma and Immunology. 2006;96:S1.
- Fleischer DM, et al. Oral food challenges in children with a diagnosis of food allergy. The Journal of Pediatrics. In press. Accessed Nov. 11, 2010.
- Fried AJ, et al. Anti-IgE in the treatment of allergic disorders in pediatrics. Current Opinion in Pediatrics. 2010;22:758.
- Scurlock AM, et al. An update on immunotherapy for food allergy. Current Opinion in Allergy and Clinical Immunology. 2010;10:587.
- Xiu-Min L. Complementary and alternative medicine in pediatric allergic disorders. Current Opinion in Allergy and Clinical Immunology 2009;9:161.
- Li X. Traditional Chinese herbal remedies for asthma and food allergy. Journal of Allergy and Clinical Immunology. 2007;120:25.
- Teuber SS, et al. Unproved diagnostic and therapeutic approaches to food allergy and intolerance. Current Opinion in Allergy and Clinical Immunology. 2003;3:217.
- Guidelines for the diagnosis and management of food allergy in the United States: Summary of the NIAID sponsored expert panel report. Bethesda, Md.: National Institute of Allergy and Infectious Diseases. http://www.niaid.nih.gov/topics/foodallergy/clinical/Pages/default.aspx. Accessed Dec. 13, 2010.
Find Mayo Clinic on