An exclusion diet is also known as an elimination or challenge diet. The most common reason for an exclusion diet is to diagnose an allergy or intolerance. An exclusion diet is a two step process that first requires elimination of all suspected allergens followed by reintroduction of foods one at a time. Exclusion diets should be supervised by a physician due to the risk of nutrient deficiencies.
Allergies
Allergies are an abnormal immune system reaction to foods that are normally harmless. According to the Cleveland Clinic, allergy symptoms include asthma, hives, runny nose, vomiting, diarrhea and swelling in the throat or mouth. A severe allergic reaction is anaphylaxis, a life-threatening condition that can cause loss of consciousness, difficulty breathing and heart palpitations. The foods that account for 90 percent of all food allergies are wheat, eggs, peanuts, tree nuts, fish, shellfish, milk and soy.
Elimination
The first step in an exclusion diet is to avoid all suspected food allergens. According to the University of Wisconsin Integrative Medicine, or UWIM, elimination should last for at least two weeks without exceptions. The Jefferson Myrna Brind Center of Integrative Medicine, or JMBCIM, says usual foods that are eliminated during the first phase include the most common food allergens as well as sugar, alcohol, caffeine, corn, citrus, yeast, fermented foods and gluten.
During the elimination phase, individuals should note any changes in symptoms. The UWIM notes that some people find that their symptoms worsen before they start to improve. Individuals should consult a physician if symptoms worsen or increase for longer than two days. Reading ingredient lists is very important during the elimination phase. You may also want to avoid eating packaged or processed foods and dining at restaurants because there is less control over what is in a dish or meal.
Challenge
The challenge phase of an exclusion diet reintroduces eliminated foods into the diet to test for adverse reactions. According to the UWIM, foods should be reintroduced one at a time every three days. On the first day of reintroduction, a small amount of food should be consumed in the morning. If no symptoms arise, larger portions should be eaten in the afternoon and evening. The JBMCIM says a food that does not cause an adverse reaction is probably not an allergen and can be safely eaten once all eliminated foods have been tested. Foods that cause a return of symptoms should be immediately re-eliminated and avoided indefinitely or retested at a later time.
Modified Elimination Diet
A modified elimination diet is a type of exclusion diet that tests for common intolerances like lactose and gluten. Intolerances differ from allergies because they are not immune reactions. According to the UWIM, a modified elimination diet follows the same process as a regular exclusion diet but focuses on restricting dairy products and gluten. Dairy products contain lactose and include milk, cream, cheese, yogurt, butter and ice cream. Gluten is a protein found in wheat, spelt, kamut, oats, rye, barley and malt. Other foods that may be eliminated on a modified elimination diet include fatty meats, alcohol, caffeine, yeast and refined sugars.
Considerations
The UWIM says several rounds of exclusion diets may be necessary to identify food allergens. Children often outgrow food allergies, which may be grounds for periodic use of an exclusion diet to retest for allergies. Exclusion diets should be supervised by a physician because elimination of multiple foods can lead to nutrient deficiencies, especially when conducted over a long period of time.
References
- Cleveland Clinic: Food Allergies
- Cleveland Clinic: Special Diets for Food Allergies
- Jefferson Myrna Brind Center of Integrative Medicine: Elimination/Challenge Diet
- University of Wisconsin Hospitals and Clinics: Modified Elimination Diet
- University of Wisconsin Integrative Medicine: Elimination http://www.fammed.wisc.edu/files/webfm-uploads/documents/outreach/im/handout_elimination_diet_patient.pdf
