According to Dr Peter Saul, a UK allergy specialist, allergies date back to a time when parasitic infections, like worms and bugs, were common. Whilst these problems are still common in some parts of the world, the majority of the UK is free from such parasitic illnesses. However the body still has the capacity to treat a foreign substance, like an allergen, as hostile.

Other reasons people suffer from allergies may include environmental changes like cleaner houses. This can trigger allergies because our bodies are not exposed to as many allergens, like dust, and cause a greater sensitivity to them later in life.

Dr Peter Saul uses the following simple example to describe why people suffer from allergies:

"Think of the body like a shop. If you walk in through the front door of this shop you get treated like a customer. Similarly, if substances go in through your mouth the body recognises it as a foreign protein but as it enters through the mouth also recognises it as food. Now say you climb over the wall at the back of the shop, the shop owner is likely to be suspicious that you are going to steal or cause trouble. This is what we think happens with allergies. The protein, instead of coming in through the front door actually comes in over the fence and you develop an allergic reaction to that particular food. So the next time it goes in through the mouth, hey presto, you have an allergy."

This is particularly true in the case of skin allergies, like eczema. Particles of food protein which enter the body through the skin cause the body to treat them as a hostile substance.

Dr Peter Saul MB ChB DRCOG DCH MRCGP

Allergy Specialist