Allergy probably dates back to when we had lots of parasitic infections, things like worms and bugs that used to live in us, and still do in some parts of the world. By and large we've got rid of this but we've still got the capacity in the body to respond and what happens is this capacity is switched to dealing with things that aren't really bad.

Other factors are: we're living in a much cleaner environment so our bodies are not getting tolerant of stuff, and that's one of the reasons why we've probably got an increased sensitivity to allergy.

Think of the body like a shop. If you walk in through the front door of this shop you get treated like a customer. That's like, if stuff goes in through your mouth, and the body says, "OK, yeah, this is a foreign protein but it's coming in through the mouth, it's food.

Say you climb over the wall at the back of the shop, what are they going to think? "He's not up to any good or she's going to knick from us, because what we think happens with allergy is the protein instead of coming in through the front door may actually come in through the back door - 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.

Particularly if you've got eczema so you get particles of food protein which actually enter the body through the skin, just like climbing over that back wall at the shop and the body reacts the same way as the shop would and it calls in the security.