Food Allergies and Sensitivit... Health Article

Definition

A food allergy or sensitivity is a person's immune system reaction to eating a particular food.

Description

The word allergy comes from two Greek words: alos, meaning "other" and argon, meaning "action." When one has an allergy, he or she has a reaction other than the one expected.

Food allergies and sensitivities are the body's reaction to a specific food. In a food allergy or sensitivity, when the child eats a particular food, (such as eggs, for example) usually by the time the eggs reach the stomach or the intestines, the body reads the presence of eggs as an allergen (something harmful). It sends out immunoglobulin E (IgE), an antibody, to destroy the eggs and protect the body, releasing histamines. The body remembers and produces histamines every time the food is eaten. These histamines trigger allergic symptoms that affect many areas of the body, particularly the skin, respiratory system, nervous system, and digestive system. Digestive disorders after eating specific foods are not always allergies. These reactions can be food sensitivities or intolerances. They can also be symptoms of other, more serious digestive diseases and malfunctions.

In the United states, 90 percent of all food allergies are caused by wheat, peanuts, nuts, milk, eggs, shellfish, soy, and fish. Many other foods can be at the root of food allergies or sensitivities, especially berries and other fruits, tomatoes, corn, and some meats like pork. Migraine headaches have been associated with sensitivities to chemicals contained in red wine, deli meats, aged cheeses, and the tannins in tea.

Usually, when a child is allergic to one food in a food family, he or she will most likely react to other foods in that food family. For example, if a child is sensitive to one type of fish, he or she also may be sensitive to other types of fish. This is called cross-reactivity.

Demographics

Nearly three million children in the United States have been diagnosed with food allergies. Nearly 600,000 of them have severe allergies to peanuts and possibly twice as many have severe shellfish allergies. Each year about 200 adults and children in the United States die from food-related anaphylaxis, an extreme reaction that causes swelling of the throat and bronchial passages, shock, and a severe drop in blood pressure. Nevertheless, food allergies tend to be under-diagnosed by doctors.

Genetics seems to play a part in food allergies. If one parent has a food allergy, the child's risk of having a food allergy is doubled. If both parents have food allergies, the risk is even higher. The child, however, may be allergic to a completely different food from the one to which the parent has demonstrated sensitivity. There also is increased risk when there are other kinds of allergy-related diseases in the family, such as hay fever or asthma.

Causes

Allergies are caused by the immune system's reaction to a particular food. Usually, a child will have had a prior exposure before IgE or specific histamines are produced.

Food intolerance is often put into the same category as food allergy, even though there may be an entirely different mechanism involved. In these cases, the digestive tract reacts to a specific part of the food; for example, the protein or the sugar in a specific food. The digestive system rebels, resulting in gas, bloating, upset stomach, diarrhea, nausea, or vomiting. Many times, these responses are due to eating food contaminated with bacteria, rather than a true food allergy. In other cases, the child's reaction is due to an underlying digestive disorder such as irritable bowel syndrome, which is a chronic condition that is often triggered by specific types of food.

Gluten intolerance is not an allergy. It is a disease called celiac disease, or gluten-sensitive enteropathy. The body cannot process gluten found in wheat and other grains. Though the immune system is involved, celiac disease does not behave as a true allergy. Its treatment is like many food allergies, namely avoidance of the offending substance, which in this case is gluten.

Some children may lack a specific enzyme needed to metabolize certain foods. About 10 percent of all adults and older children have lactose intolerance. There are two forms of lactose intolerance: inherited and acquired. The inherited form (autosomal recessive) is extremely rare and severe. The acquired type is very common, and occurs in older children (not infants) and adults. It is distressing, but not life-threatening, and occurs with increased frequency in African Americans. Sometimes infants, as well as older children and adults, have a transient lactose deficiency after an episode of diarrhea.

Children with lactose intolerance have a lactase deficiency that keeps them from processing milk and milk products. These children can often drink milk that has had this enzyme introduced into the product. Some children can drink milk that has acidophilus bacteria put into it. This bacteria breaks down the lactose, or milk sugar, in the milk so that the child can tolerate it. Some children with lactose intolerance cannot drink whole milk, but can eat cheese or drink low-fat buttermilk in small quantities. This is different from a true milk allergy where even a small amount of any dairy product will produce a reaction.

Some children may also be intolerant of food colorings, additives, and preservatives. Among these are yellow dye number 5, which can cause hives; and monosodium glutamate, which produces flushing, headaches, and chest pain. Sulfites, another additive, have been found to cause asthmatic reactions and even anaphylactoid reactions. Sulfites are preservatives used in wines, maraschino cherries, seafood, and soft drinks. They are sometimes put on fresh fruits and lettuce to maintain their fresh appearance, on red meats to prevent brown discoloration, and even in prepared deli foods like crab salad. Sulfites appear on food labels as sodium sulfite, sodium bisulfite, potassium bisulfite, sulfur dioxide, and potassium metabisulfite. The U.S. Food and Drug Administration (FDA) has banned the use of sulfites as a preservative for fruits and vegetables, but they are still in use in some foods.