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Food Allergies

What Is Food Intolerance?

Thursday, March 22, 2012 - 15:49

Contributing Author: Guy Slowik FRCS

Very often, people mistake food intolerance for food allergy. Food intolerance is much more common than food allergy, and is the less serious of the two conditions.

Food intolerance is an exaggerated or abnormal physical reaction to a food or food additive (such as an artificial coloring or preservative) that does not involve an immune reaction. A chemical deficiency in the body is usually the cause of the problem.

It has nothing to do with food allergy because the reaction does not involve the body's immune system.

Causes of food intolerance

Carbohydrate intolerance

Causes Of Food Intolerance

Several factors may cause a person to have an adverse reaction to food. Sometimes a person's body will react to chemicals found naturally in foods. For example, some people get a headache after eating certain cheeses and other foods that contain a compound called tyramine. In other cases, psychological factors play a role in food intolerance.

  1. Carbohydrate intolerance. Some people cannot digest certain carbohydrates, compounds that furnish most of the energy needed in a healthy diet. Carbohydrates exist as simple sugars (sucrose, glucose, fructose, and lactose) or as glucose polymers (complex carbohydrates), such as glycogen and cellulose.
  2. Celiac disease. This disorder is caused by an intolerance to gluten, the protein found in wheat and a few other grains. In celiac disease, the cells lining the small intestine are damaged and prevent the normal absorption of food constituents, particularly fats. Celiac disease involves an immune response. However, this response does not involve IgE, an antibody involved in the allergic response. Common symptoms are gas and bloating.
  3. Toxicologic reactions and food poisoning. Foods may contain toxins that are naturally part of the food or that were added by mistake during manufacturing, shipping, or handling. For instance, some types of fish (especially tuna and mackerel) contain histadine that is converted to histamine with improper storage, which can cause an adverse reaction if the fish is stored and/or prepared improperly. Food poisoning results from contamination with bacteria or other microorganisms. Symptoms of food poisoning and histamine toxicity may closely resemble symptoms of allergic reactions.
  4. Pharmacological effects. Some foods produce symptoms that resemble reactions to drugs. For example, caffeine found in coffee, tea, and other products may cause a rapid heartbeat, sleeplessness and other effects.
  5. Psychological reactions. Psychological factors play a role in food intolerance, causing people to react to a particular food because of smell or memories, for example.

Carbohydrate Intolerance

People with food intolerance most commonly suffer from a form of carbohydrate intolerance. In many of these cases, individuals have problems digesting a carbohydrate called lactose (milk sugar). In other cases, the problem involves the digestion of sugars often found in fruit juices.

Lactose intolerance occurs when an individual is deficient in lactase, an intestinal enzyme the body needs to digest the lactose in milk and other dairy products. As a result, the undigested lactose remains in the intestines, causing abdominal cramps, bloating, and diarrhea.

Nice To Know:

A blood test or a breath test can help diagnose lactose intolerance.

Carbohydrate malabsorption syndrome, which mainly affects young children, involves the inability to digest sugars, such as sucrose, maltose, and sorbitol. A young child who gets diarrhea from drinking too much fruit juice probably cannot tolerate complex sugars.

Nice To Know:

In some children, fruit and fruit juice can cause rashes. Doctors do not know what causes this reaction. They suspect, however, that physical contact with the fruit causes the irritation, rather than an internal reaction. These reactions usually disappear between the child's 3rd and 4th birthday.

 

Food Allergies