ALLERGIES
REACTIONS TO FOOD
It is estimated that almost one-third of people say they, or a family member, have a food allergy. The reason for this discrepancy is that we often fail to discriminate between food allergies and food intolerances. True food allergies involve the body’s immune system, whereas a food intolerance originates in the gastrointestinal system and involves an inability to digest or absorb certain substances.
Doctors do not completely understand why so many people have allergies, though heredity is an important consideration. If both parents have allergies, their children will almost always have them well, although the symptoms and allergens may be quite different. Food allergies in infants and children, however, tend to lesson as they grow, and the problem may disappear by adulthood.
Allergies develop in stages. When the immune system first encounters as allergen - a substance that it mistakenly sees as a harmful foreign invader- it signals specialized cells to make antibodies, or immunoglobulins, against it. If the substance again enters the body, the antibodies programmed to mount an attack against it will go into action. In some instances, the response will not produce symptoms; but the stage will have been set for a future antigen-antibody reaction and an allergic response.
COMMON SYMPTOMS
There are many symptoms of food allergies, including nausea, vomiting, diarrhea, constipation, indigestion, headaches, skin rashes or hives, itching, shortness of breath , and in severe cases, wide-spread swelling of the skin and mucous membranes. Swelling in the mouth or throat is potentially fatal because it can block the airways to the lungs.
Allergens usually provoke the same symptoms each time, but many factors affect intensity, including how much of the offending food was eaten, and how it was prepared.
Pinpointing allergens
Some allergens are easily identifies because symptoms will develop immediately after eating the offending food. Many people have mild allergies to various fruits and vegetables. Cooking can often reduce the allergenic potential of foods as proteins responsible for allergies are degraded by heat.
Allergens are not always readily identified. It may be necessary to keep a carefully documented diary of the time and content of all meals and the appearance and timing of subsequent symptoms.
In more complicated cases, allergy tests may be required . one or more of the follwing may be used:
Skin test : The most common test, where food extracts are placed on the skin, which is then scratched or pricked, allowing the penetration of a small amount of the extract. Development of hive or itchy swelling usually indicates an allergic response.
RAST (RADIOALLERGOSORBENT TEST ) BLOOD STUDY
Small amounts of the patient’s blood are mixed with food extracts and then analyzed people, who may have a severe reaction to the skin test.
MEDICALLY SPERVISED ELIMINATION DIET AND CHALLEGE TESTS
The patient is put on a hypoallergenic diet of foods that are unlikely to cause allergies , at which time all allergic symptoms should completely disappear. The doctor then administers small amounts of food or food extracts to see if an allergic response occurs.
LIVING WITH FOOD ALLERGIES
Once allergens have been identified, eliminating those foods from the diet should solve the problem. But this can be more complicated than it sounds. Some of the most common food allergens are hidden ingredients in many processed foods. In some cases, the real culprit may be a contaminant or an accidental additive in food. For example, some people who are allergic to orange juice and other citrus juices may actually be able to tolerate the peeled fruits themselves, since it is limonene, the oil in citrus peels, that often produces the allergic reaction.
Avoiding hidden allergens
People with food allergies may experience allergic reactions to “safe” foods because of the following
1. Contamination of foods through improper handling
2. Misleading labels, for example, when eggs are listed as an emulsifier
3. Ingredient switching, for example, when a shortage of vegetable oil results in substitution with a tropical oil such as coconut oil.
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