Question: why do we have allergies

Amy MacQueen answered on 21 Jun 2011:

Hey guys!

That is actually a very good question and no one really knows the answer! An allergy is when your immune system (which is designed to protect you against harmful pathogens) over-reacts at things that are generally harmless and causes your body to mount an allergic response. This can be very uncomfortable!! Allergic responses involve a sort of T cell in your body called the Th2 cell and they also involve release of a chemical called histamine by cells called mast cells. This is why antihistamines help you when you have an allergy because they actually look enough like histamine that they can bind to things the histamine binds to and stop the histamine getting in to cause a rash etc!!
But why do some people have allergies? There is something called the “hygeine hypothesis” which goes along the lines of that the cleaner an environment you have as a child the more likely you are to develop allergies as you have not become “tolerant” to bugs as a baby/toddler because you haven’t seen them. Apparently if you have a pet (or an older brother!) as a baby you are less likely to develop allergies – because they both carry dirt! 🙂
People think this because allergies are more common in Western cultures where we have become obsessed with cleanliness and anti-bacterial sprays, processed foods etc – but this is unlikely to be the whole story as sometimes your genes pre-dispose you towards allergies. Some people are naturally more “atopic” which means they are more likely to develop allergy!
Sometimes your body can get confused – people who are allergic to latex gloves are often allergic to bananas as well because they contain similar proteins! This is called allergy “cross reactivity”.

Hope this was helpful guys, any more questions just give me a shout! 🙂