A food allergy is an adverse effect that occurs when the human body believes that a particular type of food is harmful. It is an immune reaction to food antigens. There are three major types of food allergies. It is important to differentiate between these as they are all different types of immune reactions to food antibodies.
The three main types of allergies can be classified as follows:
• Acute symptomatic type 1
• Asymptomatic type 1
• Delayed type III
Acute Symptomatic type 1
This type of allergy can be attributed largely to the immunoglobulin E (IgE) antibodies. In such cases the symptoms of the allergy occur immediately after the concerned food is ingested. In other words, the IgE reactions tend to be immediate and thus they cause the obvious allergic reactions. The IgE antibodies attach themselves to mast cells or mastocytes and to basophils in tissues in certain areas of the body such as the skin, the lungs, the gastrointestinal tract, the nose and the throat. This results in a release of large amounts of histamine and leads to allergic reactions like sneezing, itching, inflammation, stomach cramps, etc. In extreme cases there may be a sudden fall of blood pressure. This type of food allergy ranges in intensity from mild to nearly fatal.
Asymptomatic type 1
IgG4 antibodies characterize asymptomatic food allergies type 1. Instead of building up IgE the immune systems builds up IgG4 antibodies due to various factors. This is associated with a delayed food reaction and the patient may hardly experience any symptoms common to allergies. The capacity of IgG4 to release histamines is very weak and there is no inflammatory reaction. IgG4 can be considered as the antidote of IgE. IgG4 is not recommended for the detection of adverse food reactions.
Delayed type III
In this form the predominant antibody is not IgG4, but could be either IgG, IgG1 or IgG3 which could trigger the allergic symptoms. The symptoms can appear almost three days after the consumption of the particular food with the antigens and if they are not diagnosed early the ailment can become chronic instead of acute. The symptoms are different from those of food allergy type 1.
Type III (delayed reaction) are estimated to affect up to 50% of the population. When the body is unable to tolerate certain food it produces an inflammatory response and with continued consumption of the particular food the physical symptoms may appear after a few days. The low-grade inflammation settles in different parts of the body and manifests itself with different symptoms. When the person suffers these type III allergies over a prolonged period of time it could lead to chronic diseases such as diabetes type II or irritable bowel syndrome(IBS) among other ailments. Other symptoms could be headaches and migraines, skin conditions such as eczema or psoriasis, gastrointestinal ailments, body weight, high blood pressure etc.