Disorders of the Immune System: Allergy
The most common types of allergic reactions-hay fever, some kinds of asthma, and hives-are produced when the immune system responds to a false alarm. In a susceptible person, a normally harmless substance-grass pollen or house dust, for example-is perceived as a threat and is attacked.
Such allergic reactions are related to the antibody known as immunoglobulin E. Like other antibodies, each IgE antibody is specific; one reacts against oak pollen, another against ragweed. The role of IgE in the natural order is not known, although some scientists suspect that it developed as a defense against infection by parasitic worms.
The first time an allergy-prone person is exposed to an allergen, he or she makes large amounts of the corresponding IgE antibody. These IgE molecules attach to the surfaces of mast cells (in tissue) or basophils (in the circulation). Mast cells are plentiful in the lungs, skin, tongue, and linings of the nose and intestinal tract.
When an IgE antibody sitting on a mast cell or basophil encounters its specific allergen, the IgE antibody signals the mast cell or basophil to release the powerful chemicals stored within its granules. These chemicals include histamine, heparin, and substances that activate blood platelets and attract secondary cells such as eosinophils and neutrophils. The activated mast cell or basophil also synthesizes new mediators, including prostaglandins and leukotrienes, on the spot.
It is such chemical mediators that cause the symptoms of allergy, including wheezing, sneezing, runny eyes and itching. They can also produce anaphylactic shock, a life-threatening allergic reaction characterized by swelling of body tissues, including the throat, and a sudden fall in blood pressure.
Nutrients to Protect Mucous Membranes
Vitamin A (or its precursor, beta-carotene), selenium and zinc. That's because these nutrients play important roles in the health of mucous membranes, your body's internal skin.
"If you have healthy mucous membranes, your chances of having significant allergy problems will be less. The mucous membrane is a layer of cells that secrete the slimy substance we all know and should love, because it contains an array of infection-fighting biochemicals. Mucus also shields cells from direct contact with pollen and other allergens, substances that trigger allergies.
"This mucus layer protects cells from the damaging effects of air pollution. Studies show that people who are exposed to both air pollution and allergens are more likely to have severe allergic reactions than those exposed only to allergens.
The allergic reaction itself also causes the generation of unstable molecules called free radicals, which injure your body's healthy molecules by stealing electrons to balance themselves. In the process, free radicals injure mast cells and may make them even more twitchy and prone to histamine release. Vitamins C and E, beta-carotene, selenium and other antioxidants all help to neutralize free radicals by offering their own electrons and so protect healthy molecules from harm.
Some doctors recommend taking a multivitamin/mineral supplement that covers all of the bases. For some people with allergies, avoiding certain foods can be dramatically helpful for all of their symptoms.
Some of the most serious allergic reactions--including deadly shock--can involve food. People with serious allergies usually find out through tests which foods they need to avoid. Components of certain foods may also help trigger allergies. Here's what you need to know.
Pinpoint your problem foods. If you suspect food is the culprit, see a specialist who can help you determine which foods are aggravating your symptoms, experts suggest. Peanuts, nuts, eggs, milk, soy and fish and other seafood have all been implicated in allergic reactions. And gluten, a protein found in wheat, rye, barley and oats, can cause allergy-related intestinal problems in some people.
Watch out for cross-reactions. Some people with inhalant allergies develop allergies to foods that contain similar substances.
Someone who reacts to birch pollen, for instance, may get itching or swelling of the lips, tongue, throat or roof of the mouth if he eats apples. People allergic to ragweed, on the other hand, may react to melons.
The foods most likely to cause reactions confined to the mouth: uncooked fruits, nuts and vegetables.
