Food Intolerance

views updated

Food intolerance


Food intolerance occurs when an individual is unable to digest a certain food or type of foods. Food intolerance is different from food allergy in that food allergy involves an immune system response to a particular food that can be fatal, whereas a food allergy is a digestive system response to a food that is often uncomfortable but is not generally dangerous.


Food intolerance is a very common problem in the United States. People are intolerant of a variety of foods. Some people are intolerant of just one foods, while others have problems with many different foods or types of foods. Some people experience food intolerance very strongly, with symptoms that have a serious negative impact on their quality of life. Other people know that if they eat a certain food they will probably have an upset stomach, but do not find it very troubling and sometimes indulge in the problem food anyway.

Many people confuse food allergy with food intolerance. Food allergies are serious, life threatening reactions to certain foods. In most cases the reaction occurs to the proteins found in the food. People who have allergic reactions to food experience swelling of the throat, tongue, and airway, hives, rash, and other serious problems that can be fatal without immediate emergency medical intervention. Food intolerance, however, causes gastrointestinal discomfort but is not dangerous.


As many as 25% of American adults believe that they have a food allergy. However, only about 2% of adults have a true food allergy. Instead, many people have a food intolerance. Food intolerance is very common. The symptoms vary from person to person, and can also depend on the quantity of the food consumed. Lactose intolerance is the most common food intolerance in the United States, affecting about 10% of adults. Individuals of African, Asian, Native American Hispanic, and Middle Eastern descent are more likely to be lactose intolerant.

Causes and symptoms

There are a variety of causes of food intolerance. In general, the body lacks the necessary enzyme or enzymes to break down a certain food or type of food effectively. This is generally the case for people who are lactose intolerant. In other cases, it is not completely clear what causes the food intolerance to occur.

The symptoms of food intolerance generally include some or all of the following:

  • gas
  • abdominal cramping
  • a feeling of fullness or swelling in the stomach
  • nausea
  • diarrhea


  • Does this food exist under any other names I should be aware of?
  • Is this food a common ingredient in certain types of prepared foods?
  • What are some good ways for me to get the nutrition I need now that I will not be eating this food?

These symptoms usually occur shortly after the problem food has been consumed, but in some cases can occur up to a few hours later.


When an individual is believed to have a possible food intolerance the doctor first conducts a physical examination and takes a health history to try to rule out any other possible causes of the observed symptoms. The doctor may order blood, urine, or other tests to try and ensure no other, potentially more serious, disease or condition the cause of the problems.

Once it appears likely that a food intolerance is at the root of the observed symptoms, the doctor and patient must then work together to try and determine which food or foods are causing the problems. There are two ways in which this is generally done. The first is a food diary. The patient agrees to keep a meticulous diary of everything eaten, including all ingredients used to prepare the food, and all symptoms observed. Then the doctor and patient look for common foods that were eaten before the symptoms occurred. The patient may need to keep a food diary for two months or longer before the trend becomes clear. Then that food is eliminated from the diet and the patient may be asked to continue to keep a diary for additional time to determine if the symptoms recur.

The other way in which foods that are not tolerated are often identified is called the elimination diet, also sometimes called elimination and food challenge. During the elimination diet the patient is only allowed to eat a very limited variety of foods that are known not be cause intolerance. The patient keeps a very strict diet, sometimes for two weeks or more, and waits to see if the symptoms appear. If they do not it is assumed that the problem food was successfully eliminated.

After the patient has experienced no symptoms for a certain amount of time, foods are slowly introduced back into the diet, one at a time. This is the “food challenge” part of the process. The patient eats one additional type of food, sometimes in unusually large quantities, for about three days. If no symptoms appear it is determined that that food was not the cause of the problem, and it is reintroduced into the diet in normal portion sizes. This continues until the food that is not tolerated is discovered. The drawback to this method is that it can require the patient to be on a very strict diet for two or more months.


The treatment for food intolerance is avoidance of the food that is causing the problem. When the problem food is avoided all symptoms experienced should not return. In some cases complete avoidance of the food may not be necessary; instead limiting the amount of the food eaten may be enough. Determining which food is causing the problem is the most difficult part of treating food intolerance.

Nutrition/Dietetic concerns

Removing one or more foods or types of foods from the diet completely can cause significant dietary imbalance. Individuals should never remove a food completely from the diet without consulting a doctor or nutritionist. The doctor may suggest vitamins or supplements to help the individual get enough of the nutrient usually consumed in the problem food. Other foods that are not believed to cause problems may be suggested. Depending on the type of food causing the intolerance the individual may have to learn to cook new foods or prepare foods in a different way. Individuals may find that they have to prepare separate meals or some separate dishes for them and the rest of their family. Finding delicious alternatives to the problem food that can be enjoyed by everyone may help to reduce this frustration.


Nutrition therapy can help the individual practice reading labels to help ensure that the food will be avoided completely. Working closely with a certified nutritionist or other nutrition professional can also help the individual ensure that he or she will replace the vitamins and minerals that used to be consumed in the food of which he or she is intolerant. For example, an individual who discovered he or she is lactose intolerant could be aided in devising healthy, nutritious dishes that included calcium and other important nutrients from alternative, non-dairy sources such as soy.


Lactose —A particular sugar found in milk.


The prognosis for individuals with food intolerance is very good. Once the food causing the problem has been identified avoiding the food eliminates all unpleasant symptoms. Many people actually discover that they can comfortably consume small amounts of the food, such as milk in coffee, just not large amounts, such as a glass of milk or a bowel of ice cream. For individuals who are lactose intolerant taking lactase enzyme tablets with dairy products may be enough to relieve the symptoms of lactose intolerance.


There is no known way to prevent food intolerance. To prevent the symptoms of food intolerance, the individual should avoid the food that causes the discomfort.

Caregiver concerns

Food intolerance can cause many very uncomfortable symptoms. These symptoms, can also sometimes be signs of more serious problems or illnesses. It is important not to assume that the discomfort is caused by food intolerance without seeking medical advice.

If food tolerance is discovered, removing the problem food from the individual's diet can be a very positive experience. It can make mealtime and afterwards more pleasant, as the individual is likely to be in a better mood and significantly more agreeable without the discomfort caused by the food intolerance. Care givers who are caring for individuals who cannot toilet themselves may also find that there are fewer episodes of diarrhea, and fewer episodes of repeated requests for toileting without actually having a bowel movement.



Bower, Sylvia Llewelyn. Celiac Disease: A Guide to Living with Gluten Intolerance. New York: Demos Medical Pub., 2007.

Marigny Research Group, Inc. The U.S. Market for Food Allergy and Food Intolerance Products. New York: Packaged Facts, 2004.

Wangen, Stephen. Healthier Without Wheat: a New Understanding of Wheat Allergies, Celiac Disease, and Non-Celiac Gluten Intolerance. Seattle, WA: Innate Health Pub., 2008.


“OTC: Intolerance is Trendy.” Chemist and Druggist (Nov 17, 2007) S10.

“RA Linked to Food Intolerance.” GP (Sept 1, 2006) 2.

Helen Davidson