Study: 72% of those claiming a food allergy are wrong

Sometimes it is just better to be wrong.

A recent study investigated whether more than 2,000 people who claimed to have a food allergy actually had a food allergy. The result? Only approximately 28% of those claiming a food allergy were actually allergic to food.

In an article discussing the study, the study’s authors said it’s common for people to mistakenly confuse a food allergy with a food intolerance — which has its own set of problems, although they are less severe than true food allergies.

A food intolerance doesn’t trigger the system in the same way a food allergy does. More importantly, an intolerance doesn’t cause a life-threatening situation like anaphylaxis that some severe food allergies do. But because the symptoms of food intolerance are so similar — such as nausea, digestive discomfort, bloating, migraines or hives — it can be easy to mistake it with an allergy.

True food allergic reactions

A true food allergic reaction is differentiated from other food-related disorders by the involvement of an immune response, and specifically, two components of the immune response. The first is the production of large amounts of immunoglobulin E (IgE), an antibody in blood. The other is the activation of mast cells, which are specific cells in all body tissues, but are especially common is areas of the body that are typical sites of allergic reactions, including the nose and throat, eyelids, lungs, skin and gastrointestinal tract. Mast cells mediate allergic reactions through the release of substances, such as histamine and heparin.

An individual inherits a predisposition to produce IgE antibodies against food. As an allergenic food is digested, it triggers certain cells to produce large amounts of IgE antibodies specific to that food. This IgE attaches to the surface of mast cells the first time the food is eaten. Subsequent times the person eats the food, it interacts with specific IgE on the surface of the mast cells, and triggers the cells to release chemicals, such as histamine, to mediate the allergic reaction. If the mast cells release chemicals in the ears, nose and throat, a person may feel itching in the mouth and may have trouble breathing or swallowing. Severe reactions in the nose and throat, called anaphylaxis, can be life threatening. If the affected mast cells are in the gastrointestinal tract, the person may have abdominal pain or diarrhea. Chemicals released by skin mast cells can prompt hives.

Food allergens are proteins within food that usually are not broken down by the heat of cooking or by stomach acids or enzymes that digest food. As a result, they survive to cross the gastrointestinal lining, enter the bloodstream, and go to target organs, causing allergic reactions throughout the body.

The complex process of digestion affects the timing and the location of a food allergenic reaction. People may first experience itching in the mouth as they start to eat the food. As the food is digested in the stomach, abdominal symptoms such as vomiting, diarrhea or pain may start. When the food allergens enter and travel through the bloodstream, they can cause a drop in blood pressure. As the allergens reach the skin, they can induce hives or eczema, or when they reach the lungs, they may cause asthma. All of this can take place in a matter of seconds from ingestion.

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