Ms. Judith Dixon
Many people have a difficult time distinguishing between food allergy and food intolerance. A food allergy is an abnormal immunologic response to a particular food or food component, which is usually a protein. Allergic reactions are classified into four categories. Type I, II, III, and IV. Types I, III, IV occur with foods.
Type I
Allergic reaction type I - is an acute or immediate hypersensitivity. The immune system reacts and responds to the allergen exposed through food. It’s produced by immunoglobulin E (IgE). It’s a protein, which is an antibody. As the cells (plasma cells) expose themselves to the allergen it attaches itself to the surfaces of mast and basophils cells. Most cells are found in the body’s tissues. The cells then become sensitized. The allergens cross-link IgE molecules where the surface area has been sensitized (most cell, or basophiles). The cell deregulates and is now granules. They serve as mediators of the allergic reaction. The important mediator is histamine. It’s responsible for the immediate reaction humans experience during an allergic reaction. Symptoms manifest themselves quickly in a variety of ways: gastrointestinal (e.g. vomiting, diarrhea, nausea, and cramps), skin related (e.g. dermatitis, eczema), respiratory (e.g. asthma, rhinitis), and others (e.g. laryngeal edema, and aphylactic shock). An individual will experience not all symptoms.
Type III
Type III - reactions are also known as immune complex reactions. It has resulted from an inflammatory process, which can begin with antigen - antibody complexes. The reaction can occur four to six hours after ingesting the food.
Type IV
Type IV - is a delayed-hypersensitivity reaction or cellular hypersensitivity. The symptoms to this reaction surface usually six to twenty-four hours after food has been ingested. It develops a slow reaction. The peak occurs after 48 hours of onset. It settles down approximately 72 to 96 hours of the initial reaction. This reaction produces a localized inflammatory response to the food ingested. True food allergies affect 1-2% of adults and 2-8% in children and infants. Type I reactions is less than 2% in children and less than 1% in adults.
Anaphylaxis can be associated with Type I, II, III, IV allergic reactions. Anaphylaxis is a sudden severe, and a potentially fatal allergic reaction that is systematic. It involves various parts of the human body, the skin, respiratory, gastrointestinal tract, and the cardiovascular system. Symptoms can occur with minutes up to two hours after ingestion has taken place. In rare cases it occurred four hours later. Anaphylactic reactions range from mild to life threatening. There are 30 out of 100,000 people and individuals who have asthma, eczema, or hay fever who are at a greater risk of experiencing an anaphylaxis allergic reaction, which the occurrences have increased annually. Foods, which induce the onset of anaphylaxis, have caused approximately 30,000 trips to the emergency room. There have been approximately 150-200 deaths occurring each year due to this allergic reaction. Again those individuals with asthma are at a greater risk for developing the reaction. Anaphylaxis in relation to food occurs in the following food groups: Proteins (tree nuts, walnuts, cashews, peanuts), Dairy (milk, soy, eggs), Meats (fish, shellfish).
The most common foods that cause allergic reactions in adults are crustacean (shrimp, crab, lobster, crayfish) fish, molluses, tree nuts (walnuts, hazelnuts, especially almonds), legumes, peanuts, soy, and eggs. In children the most common are milk, soy, eggs, peanuts, wheat and fish.
Infants and children are more susceptible to experience food allergies than adults. A newborn’s intestinal tract and immature immune system could be two factors causing food allergies. A study was conducted of 480 newborns 39% were said to have had food allergies. Out of the 39% only 8% actually had food allergies. Infants sometimes out grow their allergies. However, fish and peanut allergies may linger into adulthood. Foods that are consumed often by adults and children can cause reactions as well. In Japan rice allergy is quite common. In Scandinavia, codfish allergy is common.
(Kotsonis,1994)