Overview of Food Allergies
Food allergy is an exaggerated response by the immune system to a food that the body mistakenly identifies as being harmful. Once the immune system decides that a particular food is harmful, it produces specific antibodies to that particular food. The next time the individual eats that food, the immune system releases moderate to massive amounts of chemicals, including histamine, to protect the body. These chemicals trigger a cascade of allergic symptoms that can affect the respiratory system, gastrointestinal tract, skin and cardiovascular system.
In some people, symptoms appear in only one body system, while in others symptoms appear in several systems. These symptoms can range from mild to severe and may be life-threatening depending on the individual and type of exposure. Scientists estimate that approximately 11 million Americans suffer from potentially life-threatening food allergies. Of these 11 million, 2 million are school-aged children. There is no cure for food allergy and avoidance is the only way to prevent an allergic reaction.
Although eight foods are responsible for the most reactions, it is important to remember that ANY food can cause a serious allergic reaction.
Although an individual can have a life-threatening allergic to any food, including fruits, vegetables and meats, over 90 percent of allergic reactions are caused by the following eight foods:
- Tree nut (walnut, cashew, pecan, hazelnut, almond, etc.)
Most, but not all, childhood allergies to milk, egg, soy and wheat, are outgrown by age 5. Peanut and tree nuts typically cause the most severe allergic reactions and approximately 90 percent of fatal and near-fatal reactions are due to these foods. Allergies to peanut, tree nuts, fish and shellfish are often considered lifelong.
Ingestion of the food allergen is the principal route of exposure that leads to allergic reactions. For sensitized individuals, ingestion of even very minute amounts of foods can, in certain instances, result in fatal reactions without rapid intervention. While it is also possible for a child to have an allergic reaction to tactile (touch) exposure or inhalation exposure, research has shown that they are extremely unlikely to result in severe or life-threatening reactions. Nevertheless, if children with life-threatening food allergies touch the allergens and then put their fingers to their eyes, nose or mouth, the exposure becomes an ingestion and may cause anaphylaxis. The quantity of food necessary to trigger an allergic reaction may depend upon multiple variables. Each individual’s level of sensitivity may fluctuate over time. The type and severity of symptoms can vary for a specific food in an individual and for different foods in someone with multiple food allergies. A food allergy fact sheet is available at http://www.foodallergy.org/.
What Is Anaphylaxis?
Anaphylaxis is a potentially life-threatening medical condition occurring in allergic individuals after exposure to an allergen. People with allergies have over-reactive immune systems that target otherwise harmless elements in our diet and environment. During an allergic reaction to food, the immune system identifies a specific food protein as a target. This initiates a sequence of events in the cells of the immune system resulting in the release of chemical mediators such as histamine. These chemical mediators trigger inflammatory reactions in the tissues of the skin, the respiratory system, the gastrointestinal tract, and the cardiovascular system. When the inflammatory symptoms are widespread and systemic, the reaction is termed “anaphylaxis,” a potentially life-threatening event. Anaphylaxis refers to a collection of symptoms affecting multiple systems in the body. These symptoms may include:
Swelling of any body part
Itchy tongue, mouth and/or throat
Sense of impending doom
Anaphylaxis may occur in the absence of any skin symptoms such as itching and hives. Fatal anaphylaxis is more common in children who present with respiratory symptoms or GI symptoms such as abdominal pain, nausea or vomiting. In many fatal reactions, the initial symptoms of anaphylaxis were mistaken for asthma or mild GI illness, which resulted in delayed treatment with epinephrine auto-injector.
Fatal anaphylaxis is more common in children with food allergies who are asthmatic, even if the asthma is mild and well controlled. Children with a history of anaphylaxis or those whose prior food reactions have included respiratory symptoms such as difficulty breathing, throat swelling or tightness are also at an increased risk for severe or fatal anaphylaxis.
Anaphylaxis characteristically is an immediate reaction, occurring within minutes of exposure, although onset may occur one to two hours after ingestion. In up to 30 percent of anaphylactic reactions, the initial symptoms may be followed by a second wave of symptoms two to four hours later and possibly longer. This combination of an early phase of symptoms followed by a late phase of symptoms is defined as biphasic reaction. While the initial symptoms usually respond to epinephrine auto-injector, the delayed response may not respond as well to epinephrine auto-injector or other forms of therapy used in anaphylaxis.
Children experiencing anaphylaxis should be observed in a hospital emergency department for a minimum of four to six hours or longer after initial symptoms subside, to monitor for signs or symptoms of a biphasic reaction. In the event a biphasic reaction occurs, intensive medical care can immediately be provided.
For those children at risk for food-induced anaphylaxis, the most important management strategy in the school is prevention. In the event of an anaphylactic reaction, epinephrine auto-injector is the treatment of choice and should be given immediately. Sometimes, if symptoms do not subside, a second epinephrine auto-injector is necessary. Reports indicate that as many as one-third of individuals experiencing anaphylaxis may require a second (epinephrine) injection to control their reaction until they can get to a hospital (http://www.epipen.com/user.aspx, 2005).
Studies (Sampson, 1992 and Bock, 2001) show that fatal and near-fatal anaphylactic reactions are sometimes associated with not using epinephrine auto-injector or delaying the use of epinephrine treatment. When in doubt, it is better to give the epinephrine auto-injector and call the Emergency Medical System for an ambulance. Fatalities are more likely to occur when epinephrine administration is withheld.
Summary of Anaphylaxis
Food allergies are more prevalent in younger children. Every food allergy reaction has the potential of developing into a life-threatening event. Several factors may increase the risk of a severe or fatal anaphylactic reaction: asthma or a history of asthma; a previous history of anaphylaxis; peanut, tree nut, and/or shellfish allergies; presentation with gastrointestinal or respiratory symptoms, and delay in the administration of or failure to administer epinephrine auto-injector.
The severity and rapid onset of food-induced anaphylaxis emphasizes the need for an effective emergency plan that includes early recognition of the symptoms of anaphylaxis, immediate administration of epinephrine auto-injector and prompt transfer of the child by the emergency medical system to the closest hospital.
The section above was based in part from the following resources, Web sites and documents:
The Food Allergy & Anaphylaxis Network. Excerpts were adapted and printed with permission.
Managing Life Threatening Food Allergies in Schools, 2002. Massachusetts Department of Education. Excerpts from the Managing Life Threatening Food Allergies in Schools are included by permission of the Massachusetts Department of Education. The Massachusetts guidelines may be revised periodically.
Overview of Glycogen Storage Disease
Glycogen storage disease (GSD) is an inherited disorder in which an abnormal amount or type of glycogen is stored in the liver. This abnormal storage results from the liver's inability to adequately regulate the metabolism of glycogen and glucose. “Glycogen storage disease occurs when an enzyme (proteins produced by the body) that regulates conversion of sugar (glucose) into its storage form (glycogen) or release of glucose from glycogen is missing” (Cincinnati Children's Hospital Medical Center [CCHMC], 2012).
“Many sugars (including glucose) are present in foods and are used by the body as a source of energy. After a meal, blood glucose levels rise. The body stores the extra glucose that is not needed right away as glycogen in the liver and muscles. Later, as the blood glucose levels in the body begin to decrease, the body uses this stored energy. These sugars, stored in the form of glycogen, need to be processed by enzymes in the body before they can carry out their functions. If the enzymes needed to process them are missing, the glycogen or one of its related starches can accumulate, causing problems” (CCHMC, 2012).
“There are at least 10 different types of GSDs, which are put into groups based on the enzyme that is missing. Approximately one in about 20,000 people are affected by glycogen storage diseases. The most common forms of GSD are types I, III and IV.
- GSD I (von Gierke disease) results from a deficiency of the enzyme Glucose-6-Phosphatase (CCHMC, 2012). It is the most common type of GSD and the effects are apparent very early in childhood. GSD I accounts for approximately 25 percent of all GSD cases” (American Liver Foundation, 2011).
- In GSD III (Cori disease) an enzyme called the debrancher is deficient, causing the body to form glycogen molecules that have an abnormal structure. This abnormal structure also prevents the glycogen from being broken down into glucose.
- In GSD IV (amylopectinosis) glycogen that accumulates in the tissues has very long outer branches. This is due to a genetic deficiency of the branching enzyme. This abnormal glycogen is thought to stimulate the immune system. The result is tremendous scarring (cirrhosis) of the liver as well as other organs, such as muscle and heart (CCHMC, 2012).
Causes of Glycogen Storage Disease
Glycogen Storage Disease (GSD) occurs when there is an absence or deficiency of one of the enzymes responsible for making or breaking down glycogen in the body. This is known as an enzyme deficiency (Association for Glycogen Storage Disease, 2012).
Symptoms of Glycogen Storage Disease
“Symptoms of GSD vary based on the enzyme that is missing. They usually result from the buildup of glycogen or from an inability to produce glucose when needed. Because GSD occurs mainly in muscles and the liver, those areas show the most obvious symptoms. Symptoms of GSD may include:
- growth failure;
- muscle cramps;
- low blood sugar;
- enlarged liver;
- swollen belly; and
- abnormal blood test (CCHMC, 2012).
The age when symptoms begin and how severe they are depends on the type of GSD. Children with GSD I rarely develop cirrhosis (liver disease), but they are at an increased risk for developing liver tumors. In some ways, GSD III is a milder version of GSD I. It also is a very rare cause of liver failure, but it may cause fibrosis (early scarring of the liver, which may be caused by a healing response to injury, infection or inflammation).
GSD II is a muscle disease and does not affect the liver. Glycogen storage disease IV causes cirrhosis; it may also cause heart or muscle dysfunction. Often, infants born with GSD IV are diagnosed with enlarged livers and failure to thrive within their first year of life; they develop cirrhosis of the liver by age three to five” (CCHMC, 2012).
Treatment of Glycogen Storage Disease
Treatment of GSD depends on the type of GSD. Some GSD types cannot be treated; others can be treated by controlling the presenting symptoms. For the types of GSD that can be treated, patients must carefully follow a special diet.
- Frequent high carbohydrate meals during the day. For some children, eating several small meals rich in sugars and starches every day helps prevent blood sugar levels from dropping.
- Cornstarch. For some young children over the age of 2, giving uncooked cornstarch every four to six hours – including during overnight hours – can also relieve the problem.
- Continuous tube feeding. In order to maintain appropriate blood glucose levels, gastrointestinal tube feedings with solutions containing high concentration of glucose may need to be administered. Younger children may have to use this treatment method during the night until they get older. In the daytime the feeding tube is sometimes removed, but the patient must eat foods rich in sugars and starches about every three hours. This treatment can be successful in reversing most symptoms.
- Drug treatment. GSD tends to cause uric acid (a waste product) to accumulate, which can cause gout (painful inflammation of the joints) and kidney stones.
- Medication is often necessary (CCHMC, 2012).
Association for Glycogen Storage Disease. (2012). What is Glycogen Storage Disease? Retrieved on July 26, 2012.
Cincinnati Children's Hospital Medical Center (CCHMC). (2012). Glycogen Storage Disease (GSD). Retrieved on July 26, 2012, from http://www.cincinnatichildrens.org/health/g/gsd/
National Center for Biotechnology Information (NCBI), United States National Library of Medicine. Glycogen Storage Disease: