Elimination diets are diets in which people stop eating specific foods for a period and then challenge their body by adding the food back into their diet and evaluating how the body responds. Elimination diets are used to detect food allergies and food intolerances. They are not nutritionally balanced and are intended to be used only for diagnostic purposes.
For centuries it has been known that some people develop unpleasant symptoms (adverse reactions) to certain foods that other people can eat without any problems. However, it was not until the 1900s that food allergies began to be investigated in rigorous and scientific ways and studies on food allergies started appearing in reputable medical journals. Elimination diets developed out of this scientific interest in the effects of food on the body.
Food intolerances also cause adverse reactions, but these reactions do not involve the immune system and are not life threatening. Lactose (milk sugar) intolerance is an example of a food intolerance. It is caused by the body producing too little of the enzyme lactase, which is needed to digest lactose. Although surveys show that in the United States up to 30% of families believe they have at least one member with a food allergy, the actual documented rate of food allergies is about 6% in infants and children and 3.7% in adults. On the other hand, in Hispanic, Jewish, and Southern European populations, the rate of lactose intolerance is about 70%, and it reaches 90% or more in Asian and African populations. Food intolerances are much more common, but true food allergies tend to be much more severe. In this article, “food sensitivities” is used to include both food allergies and food intolerances.
The most common symptoms of food sensitivities are nausea, diarrhea, bloating, excessive gas, hives, rashes, eczema, headaches, migraine, asthma, wheezing, and hay fever–like symptoms. These symptoms may occur immediately after eating the trigger food or may not develop for hours. Most immediate reactions are severe allergic responses that can result in anaphylactic shock, a condition in which the airways swell shut and the person cannot breathe. Foods most likely to cause immediate reactions are peanuts, tree nuts, and shellfish.
Delayed symptoms are difficult to detect and are sometimes called “masked” food sensitivities. The most common foods that cause delayed sensitivities are dairy products, egg, wheat, and soy; however, sensitivities vary widely and can be caused by many foods. The amount of a trigger food that it takes to cause a response also varies considerably from person to person.
A true elimination diet is very rigorous and needs to be implemented under the direction of a physician, often in consultation with a registered dietitian. For the elimination diet to be useful, the patient must follow the diet strictly. Cheating invalidates the results.
For 2–3 weeks, a person on the elimination diet cannot eat any of the following foods, according to the Institute of Functional Medicine (this list may be modified by the physician):
The individual must avoid all medicines containing aspirin (salicylates) and food colorings. After several weeks on these restricted foods, one new food is introduced in larger than normal amounts. This is the challenge food, and it is eaten for three days in a row. If no symptoms appear, the dieter continues to eat that food in normal amounts and adds another challenge food. If symptoms appear, the challenge food is stopped immediately and no new challenge food is introduced until symptoms disappear. During this time the dieter keeps a food journal, writing down everything that is eaten and any symptoms, either physical or emotional, that appear. It can take two to three months to work through all challenge foods.
People with symptoms that interfere with their daily lives benefit greatly from pinpointing which foods are causing the symptoms so that these foods can be eliminated from the diet. People with less severe symptoms may find the process of elimination and challenge too costly and disruptive to make it worthwhile.
Many people who suspect that certain foods are causing their symptoms try modified elimination diets found on the internet or elimination diets they devise themselves. These diets have varying degrees of success. For example, many people try eliminating all dairy products to see if their symptoms of lactose intolerance—bloating, cramping, diarrhea, and gas—improve. This do-it-yourself approach may be adequate for people with mild sensitivities to only one food or food group, but it is risky for people with severe intolerances. People with moderate to severe sensitivities need professional guidance to eliminate nonobvious sources of the potential problem food.
One risk of all elimination diets is that they are not nutritionally balanced. They increase the risk that vitamin and mineral deficiencies will develop. Anyone going on a full elimination regimen needs to consult a registered dietitian about how to use dietary supplements to ensure adequate, balanced nutrition.
A second risk is that people who self-diagnose symptoms as food intolerances using a non-medically supervised elimination diet may be ignoring symptoms of more serious and progressive diseases such as celiac disease, Crohn's disease, gastroesophageal reflux disease, irritable bowel syndrome, or other health problems that need medical treatment.
Finally, anyone suspected of having a moderate to severe food allergy should be under the care of a physician. Food challenging is best done in a healthcare setting in case severe reactions occur.
The medical community accepts elimination diets as a standard way to diagnose food sensitivities. A true elimination diet is quite restrictive, is time intensive to implement, and should be supervised by a healthcare professional. Many shortcut, “do-it-yourself” elimination-style diets are available on the internet. Although people who believe they have a food intolerance often try these diets, they are not accepted by healthcare professionals as diagnostically accurate, and they may cause short-term vitamin and mineral deficiencies.
See also ADHD diet ; Arthritis diet ; Dietary supplements ; Food allergies ; Lactose intolerance diet .
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Academy of Nutrition and Dietetics, 120 South Riverside Plz., Ste. 2000, Chicago, IL, 60606-6995, (312) 899-0040, (800) 877-1600, firstname.lastname@example.org, http://www.eatright.org .
Chronic Fatigue and Immune Dysfunction Syndrome Association of America (CFIDS), PO Box 220398, Charlotte, NC, 28222-0398, (704) 365-2343, http://www.cfids.org .
Institute for Functional Medicine, 505 S. 336th St., Ste. 500, Federal Way, WA, 98003, (253) 661-3010, (800) 228-0622, Fax: (253) 661-8310, http://www.functionalmedicine.org .
Tish Davidson, AM