Definition :
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.
Origins :
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.
Description :
Adverse reactions to food fall into two main categories, food allergies, and food intolerances. Food allergies cause a response by the immune system. When a person has a food allergy, his or her body responds to something in food by treating it like a threatening foreign material. Immune system cells produce proteins called antibodies that act to disable this material. This process often causes inflammation and results undesirable symptoms that range from mild and annoying to life threatening. The reason why some people respond to certain foods and others do not is probably genetically based.
Food intolerances, on the other hand, 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 needed to digest lactose. Interestingly, 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 are used to include both food allergies and food intolerance.
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. One study found that in about one-third of individuals in anaphylactic shock who were brought for treatment to the emergency room at the at the Mayo Clinic in Minnesota, the shock trigger had been a food. Foods most likely to cause immediate reactions are peanuts, tree nuts, and shellfish.
Delayed symptoms are difficult to detect and are sometimes called ‘‘maskedrdquo; food sensitivities. The most common causes of 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 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 dietitian or nutritionist. 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 eats only the following foods (This list may be modified by the physician):
- grains: rice and rice products, sago, tapioca, buckwheat products, millet products
- proteins: veal, lamb, chicken, turkey, rabbit, tuna,
- bream, whiting, dried peas, lentils
- fruit: peeled pears, peeled apples, pawpaw.
- vegetables: potatoes, sweet potatoes, lettuce, parsley,
- bamboo shoots, celery, cabbage
- sweeteners and seasonings: sugar, maple syrup, sunflower oil, safflower oil, salt, garlic
- beverages: water, fresh pear juice
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 2 to 3 months to work through all challenge foods.
Function :
Elimination diets are the first part of a diagnostic technique for determining what foods are causing undesirable symptoms. Their purpose is to prepare the patient for the second part of the diagnostic process, the food challenge by cleansing the body of all possible foods that could be causing the symptoms. During the challenge phase, the patient eats the suspect food and waits to see if symptoms reappear. Elimination and challenge give healthcare professionals a way to reproducibly pinpoint exactly which foods are causing an adverse reactions so that the patient can exclude these foods from their diet.
Benefits :
People with symptoms that interfere with their daily life 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.
Precautions :
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 non-obvious sources of the potential problem food.
Risks :
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 dietitian or nutritionist about how to use dietary supplements to assure 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 syndrome, and 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. Any food challenging must be done in a healthcare setting, as severe reactions can cause anaphylactic shock and death.
Research and general acceptance :
The medical community accepts elimination diets as a standard way to diagnose food sensitivities. A true elimination diet is quite restrictive, takes a long time to implement, and should be supervised by a healthcare professional. Many short cut 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.
Post a Comment