Food allergy

Food allergy is an adverse immune response to a food protein. They are distinct from other adverse responses to food, such as food intolerance, pharmacological reactions, and toxin-mediated reactions.
The protein in the food is the most common allergic component. These kinds of allergies occur when the body's immune system mistakenly identifies a protein as harmful. Some proteins or fragments of proteins are resistant to digestion and those that are not broken down in the digestive process are tagged by the Immunoglobulin E (IgE). These tags fool the immune system into thinking that the protein is harmful. The immune system, thinking the organism (the individual) is under attack, triggers an allergic reaction. These reactions can range from mild to severe. Allergic responses include dermatitis, gastrointestinal and respiratory distress, including such life-threatening anaphylactic responses as biphasic anaphylaxis and vasodilation; these require immediate emergency intervention. Non-food protein allergies include latex sensitivity. Individuals with protein allergies commonly avoid contact with the problematic protein. Some medications may prevent, minimize or treat protein allergy reactions.
Treatment consists of either immunotherapy (desensitisation) or avoidance, in which the allergic person avoids all forms of contact with the food to which they are allergic. Areas of research include anti-IgE antibody (omalizumab, or Xolair) and specific oral tolerance induction (SOTI), which have shown some promise for treatment of certain food allergies. People diagnosed with a food allergy may carry an injectable form of epinephrine such as an EpiPen or Twinject, wear some form of medical alert jewelry, or develop an emergency action plan, in accordance with their doctor.
The scope of problem, particularly for young people, is a significant public health issue.


Epinephrine, also known as adrenaline, is a common medication used to treat allergic reactions. Epinephrine reverses the allergic reaction by improving blood circulation. This is done by tightening blood vessels in order to increase the heart beat and circulation to bodily organs. Epinephrine is produced naturally in the body. It is produced during "flight-or-fight" response. When a person is presented with a dangerous situation, the adrenal gland is triggered to release adrenaline; this gives the person an increased heart rate and more energy to try to fight off the danger being imposed on the individual. Epinephrine is also prescribed by a physician in a form that is self-injectable. This is what is called an epi-pen.


Antihistamines are also used to treat allergic reactions. Antihistamines block the action of histamine, which causes blood vessels to dilate and become leaky to plasma proteins. Histamine also causes itchiness by acting on sensory nerve terminals. The most common antihistamine given for food allergies is diphenhydramine, also known as Benedryl. Antihistamines relieve symptoms. When it comes to dealing with anaphylaxis, however, they do not completely improve the dangerous symptoms that affect breathing.


Steroids are used to calm down the immune system cells that are attacked by the chemicals released during an allergic reaction. This form of treatment in the form of a nasal spray should not be used to treat anaphylaxis, for it only relieves symptoms in the area in which the steroid is in contact. Another reason steroids should not be used to treat anaphylaxis is due to the long amount of time it takes to reduce inflammation and start to work. Steroids can also be taken orally or through injection. By taking a steroid in these manners, every part of the body can be reached and treated, but a long time is usually needed for these to take effect.


Desensitisation may be a cure for food allergies. If the major precipitating allergen is a pollen then this is targeted by current protocols for desensitisation, not the food analogue allergen. Injections are used, as sublingual drops are not suitable for sufferers of oral allergy.
Prof. Dr. Ronald van Ree of The University of Amsterdam and The Academic Medical Center expects that vaccines can in theory be created using genetic engineering to cure allergies. If this can be done, food allergies could be eradicated in about ten years.


The most common food allergens include peanuts, milk, eggs, tree nuts, fish, shellfish, soy, and wheat — these foods account for about 90% of all allergic reactions. The most common food allergies in adults are shellfish, peanuts, tree nuts, fish, and egg. The most common food allergies in children are milk, eggs, peanuts, and tree nuts.
Six to eight percent of children under the age of three have food allergies and nearly four percent of adults have food allergies.
For reasons that are not entirely understood, the diagnosis of food allergies has apparently become more common in Western nations in recent times. In the United States, food allergy affects as many as 5% of infants less than three years of age and 3% to 4% of adults. There is a similar prevalence in Canada.
Seventy-five percent of children who have allergies to milk protein are able to tolerate baked-in milk products, i.e., muffins, cookies, cake.
About 50% of children with allergies to milk, egg, soy, and wheat will outgrow their allergy by the age of 6. Those that are still allergic by the age of 12 or so have less than an 8% chance of outgrowing the allergy.
Peanut and tree nut allergies are less likely to be outgrown, although evidence now shows that about 20% of those with peanut allergies and 9% of those with tree nut allergies will outgrow them.