What are food allergies?
A “food allergy” is an abnormal immune response to contact with food, typically when eaten but sometimes can occur with skin contact as well. Our immune system is a complex network of cells and proteins. Its purpose is to protect us from infections from bacterias, viruses or parasites. For whatever reason, people can develop an abnormal reaction which stimulates the immune system to react to something that is otherwise seemingly harmless to the body, like food. Most importantly, and especially with children, these allergic reactions can progress quickly to a severe condition called “anaphylaxis” which can cause death within minutes.
A person can have an allergic reaction to food or non-food substances, such as pollen and latex. Food allergies are often confused with food intolerances, which can also be severe or distressing, but not associated with an immune reaction. Common food “intolerances” include gastroesophageal reflux (GERD), in which acid from the stomach backs up into the lower esophagus often after eating certain foods, or lactose intolerance, which is an enzyme deficiency that results in an inability to digest lactose found in milk. Celiac disease is another digestive disorder caused by the ingestion of gluten found in wheat and other grains, but is actually not a true food allergy. The difference between celiac disease and wheat allergies is discussed here.
The most common and severe allergic reactions are triggered by a normal immune protein circulating in our bloodstream called the IgE antibody. The immune system consists of both cells (T cells, B cells, dendritic cells, etc.) as well as proteins called antibodies. The purpose of antibodies is to recognize substances found in infections caused by bacteria, viruses and parasites, which are not suppose to be present in our body, and tag them for the rest of the immune system to attack and remove. There are 5 types of immunoglobulins which each play a specific role in an immune response: IgG, IgA, IgM, IgD and IgE. For reasons that are not fully understood, the immune system sometimes tags things it shouldn’t, and therefore causes an allergic reaction. Allergic reactions caused by IgE are labelled as “IgE-mediated” allergies. To learn more about IgE and the immune system, click here.
IgE-mediated allergic reactions are significant because of the severity of the reaction, as opposed to non-IgE mediated reactions which are often less severe. A mild allergic reaction may result in itchy skin or hives. Unfortunately, severe IgE-mediated allergies can progress quickly to “anaphylaxis” which is potentially fatal. Without prompt treatment, anaphylaxis can result in death within minutes. Anaphylaxis can cause a rapid constriction of a person’s airway, resulting in an inability to breath, which is especially dangerous in people with asthma. It can also result in a rapid drop in blood pressure causing cardiac arrest. Sometimes antihistamines such as Benadryl can be helpful for mild allergic reactions. However, for true anaphylactic reactions, epinephrine and prompt medical attention are the primary treatments for anaphylaxis. There is no way out of this…get an epinephrine injector and click here to learn more about how to use it.
The number of people affected by food allergies appear to be increasing each year. Some of this increase maybe related to increased awareness which results an increased rate of diagnosis, but most surveys and studies have shown a clear increase in the number of people affected in recent years, especially among children. It is estimated that about 5 percent of adults are affect by food allergies and anywhere from 5-10 percent of children are affected, possibly more. Exact numbers can be hard to pinpoint due to the fact that mild allergies or allergies to only one food, can be under diagnosed and under reported to healthcare professionals. Also, food intolerances or preferences are sometimes inappropriately reported as allergies. The onset of food allergies can occur throughout a person’s life, well into adulthood. My husband discovered that he had a wheat allergy, which is probably non-IgE mediated, when he was over 40 years old.
The nine most common food allergies are milk, egg, fish, crustacean shellfish, tree nuts, peanuts, wheat, soybeans and sesame. These nine allergens are required by the FDA to be clearly listed separately on food labels (https://www.fda.gov/food/food-labeling-nutrition/food-allergies). There are other foods which can cause allergies such as corn and mustard, which are not required to be listed separately, but should be listed in the ingredients if they are present. If you are allergic to these other ingredients, you just have to look harder and more carefully at the ingredients list. Often, people who are allergic to tree nuts, might not be allergic to coconuts, but coconuts are considered a type of tree nut.
For people with severe food allergies, the best treatment is avoidance. Outgrowing food allergies is a possibility, but the greater number of food allergies that a child is born with, the less likely he or she will outgrow all of them. Much research has gone into various treatments such as desensitization or drug treatments such as Xolair. This is an evolving topic with some controversy which we might discuss in a future post.
I hope you found this introduction to food allergies helpful and encourage you to do your own research to learn more. Education is important in dealing with food allergies for both you and your family.