Firstly, it is important to understand that any food or substance can cause an allergic reaction in a person, there are many different reasons why people are affected and there are many varying levels of severity of reaction.
Allergies are probably more common than you think, and it is on the rise, they are thought to affect more than one in four people, in the UK, at some point in their lives.
They are particularly common in children, while some allergies go away as a child gets older, many are lifelong, and it is possible for adults to develop allergies to things they were not previously allergic to.
An allergy is a reaction your body has to the generally harmless proteins in a particular food or substance. This reaction causes the body to release an ANTIBODY called IMMUNOGLOBULIN (IgE), IgE can cause a range of chemicals to be released the most important being Histamine.
It can, in some cases, be the smallest amount of a substance that causes the reaction down to 20 parts per million for example. Histamine causes most of the typical symptoms that occur during an allergic reaction.
Allergy symptoms include:
In some cases, a person can suffer a severe allergic reaction (anaphylaxis) or go into anaphylactic shock, which can be life threatening. This affects the whole body and usually develops within minutes of exposure to something they are allergic to.
In anaphylaxis, the immune system goes into overdrive and releases large amounts of histamine and many other chemicals into your blood. This causes the wide range of symptoms associated with anaphylaxis.
Signs of anaphylaxis include any of the symptoms above, as well as:
(Anaphylaxis is a medical emergency that requires immediate treatment.)
There is another type of food allergy known as a non-IgE-mediated food allergy, caused by different cells in the immune system. This is much harder to diagnose as there is no test to accurately confirm non-IgE-mediated food allergy.
This type of reaction is largely confined to the skin and digestive system, causing symptoms such as heartburn, indigestion, and eczema.
In babies, a non-IgE-mediated food allergy can also cause diarrhoea and reflux, where stomach acid leaks up into the throat.
In the UK and Europe there are 14 recognised allergens which are established as the most common, that is not to say that this list is definitive, as previously mentioned ANY food or substance can cause an allergic reaction, these allergens are:
This is not to be confused with a Food Intolerance, which is where a substance causes unpleasant symptoms, such as tummy pain, bloating, wind and / or diarrhoea and even skin rashes and itching but does not involve the immune system. Symptoms can be really distressing for those exposed to foods they are intolerant to and seeking help from your GP is advisable as symptoms could mean something else.
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