What Is Allergy and How Many Types of Allergic Disease

Allergies are inappropriate or exaggerated reactions of the immune system to substances that, in the majority of people, cause no symptoms. Symptoms of allergic diseases may be caused by exposure of the skin to a chemical, of the respiratory system to particles of dust or pollen (or other substances), or of the stomach and intestines to a particular food.

The allergic symptoms and their severity vary depending on the type of allergen, the part of the body that is affected, and the level of sensitivity and reaction of the individual to the allergen, for example, Asthma, Bronchitis, Cyanosis, Fever, Hay fever, Hives, nausea, Vomiting, and Wheezing. Nasal allergies manifest like the common cold or sinusitis, food allergies produce nausea, vomiting and skin irritation manifests as hives.

LOW IMMUNITY: Normally, the immune system protects an individual against invading agents such as bacteria and viruses. If an individual has allergies, otherwise harmless allergens can cause his body to react as if they were dangerous invaders. In effect, the immune system is responding to a false alarm.

The immune system thinks it is protecting the individual by generating large amounts of a type of antibody specific to the particular allergen to which he is allergic. This antibody attaches itself to certain cells in his body. The next time he comes into contact with the allergen, the allergen attaches to the antibody like a key fitting into a lock. This lock-up causes the release of inflammatory substances into the system. These substances, including histamine, move into various parts of the body, such as the respiratory system, to cause allergy symptoms like runny nose, itchy eyes, and sneezing, among others.

Exposure to allergens when the body's defenses are weakened (such as after a viral infection, during puberty, or during pregnancy) may contribute to the development of allergies. People with year-round allergies are more likely to have developed them as adults. Women are more likely to have year-round allergies. Allergy symptoms can lessen as you get older, but they rarely completely disappear.

Food allergy or food intolerance affects nearly everyone at some point. When people have an unpleasant reaction to something they ate, they often think that they have an allergy to the food. One out of three people say that some member of their family has an allergy to food that has necessitated a change in their diet. Actually, however, only about 1% of adults and 3% of children have clinically proven allergic reactions to food.

Food intolerance is also an abnormal response to food, and its symptoms can resemble those of food allergy. Food intolerance, however, is far more prevalent, manifests itself in a variety of diseases, and is triggered by several different mechanisms that are distinct from the immunological reaction responsible for food allergy.

A. Some facts on food allergies:

• All symptoms of a food allergy occur within a few minutes to an hour of eating.
• A food allergy can initially be experienced as an itching in the mouth and difficulty swallowing and breathing.
• During digestion of the food in the stomach and intestines, symptoms such as nausea, vomiting, diarrhea, and abdominal pain can start. (Incidentally, gastrointestinal symptoms are those that are most often confused with the symptoms of different types of food intolerance.)
• When the allergens reach the skin, they can induce hives or eczema, and when they reach the lungs, they can cause asthma.
• As the allergens travel through the blood vessels, they can cause light headedness, weakness, and anaphylaxis, which is a sudden drop in blood pressure. Anaphylactic reactions are severe even when they start off with mild symptoms, such as a tingling in the mouth and throat or discomfort in the abdomen. They can be fatal if not treated quickly.

B. Foods that cause allergies:
There are eight types of foods that are accountable for 90% of all food-allergic reactions. The foods that most commonly cause anaphylaxis (called allergenic foods) are:

• Peanuts
• Tree nuts (walnuts, pecans, etc.)
• Shellfish
• Fish
• Milk
• Soy
• Wheat
• Eggs

C. Food Allergy Symptoms:
Symptoms of food allergies can range from mildly irritating to life threatening. The most common symptoms of food allergies are:

• Hives
• Vomiting
• Diarrhea
• Abdominal cramping
• Swelling of the throat, lips, or tongue
• Difficulty in breathing or swallowing
• Metallic taste or itching in the mouth
• Generalized flushing, itching, or redness of the skin (hives)
• Nausea
• Increased heart rate
• Plunging blood pressure (and accompanying paleness)
• Sudden feeling of weakness
• Anxiety or an overwhelming sense of doom
• Collapse
• Loss of consciousness

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