Food allergy is actually an abnormal response triggered by the immune system to food as if it is threatening. Food intolerance looks similar to food allergies. However, the difference lies in how each one of them affects an individual. Food allergy is extremely intrinsic and to an extent, affects the internal organs.
On the other hand, food intolerance is less severe, mostly just affects the digestive system due to the inability to digest that particular food properly, leading to an upset stomach. Most of the people suffer from food intolerance only, but they confuse it with food allergy.
In order to understand how symptoms manifest, it is of utmost importance, in this case, to understand how an allergic reaction to food occurs. An allergic reaction is a bi-step process as discussed further.
Step1: On exposure to the food allergen for the first time, the body reacts abnormally and produces IgE antibodies against the perceived allergen. These circulate throughout the entire body with blood and attach themselves to basophils (found in blood) and mast cells (found in sites like the nose, lungs, throat, gastrointestinal tract, skin, etc.).
Step 2: The next time the body is exposed to a particular food allergen, it gets alert and alarms the tissue that releases histamine in large quantity. Depending on the site of release, allergy symptoms are caused, ranging from mild to severe to potentially life-threatening (for example, in anaphylaxis).
The time span for an allergic reaction manifesting into symptoms can vary between a few minutes to several hours post exposure to the food allergen. The site of mast cells for release of histamine greatly affects the location and timing of the reaction.
Who is at Higher Risk?
If a person has a family history of developing a food allergy, it creates even greater chances for him/ her to have the same or similar reactions. If both the parents have some kind of allergic reaction to food, it is very likely that the child would have that too.
Symptoms of food allergies largely depend on the sites of mast cells that release histamines. It is possible that these sites are located in nose, ears, or throat leading to itching in mouth, having a trouble in swallowing and breathing, and swelling of lips and tongue. If the location is in the gastrointestinal tract, it may lead to vomiting, diarrhoea, and abdominal pain. If it is in the skin, it might lead to hives, itching, decolourization, pigmentation, worsened eczema, etc.
If a person has an allergy to a particular food, it is advisable to abstain from similar types of food. For example, if somebody is allergic to crab, he/ she should abstain from shrimp, crayfish, lobster, etc. too as they might also trigger the reaction. This is called cross reactivity.
It is always advisable to abstain from foods which cause an allergic reaction in an individual. However, in case it has already occurred, there are two major types of medication which help in relieving the symptoms. Antihistamines are used for treating mild to chronic reaction, whereas adrenalines are used for severe reaction like in anaphylaxis.
Food allergy is usually a condition for life and cannot be permanently treated. However, symptoms can be relieved. Therefore, it is advisable to avoid the allergy, causing group of food.