Question: Why do i have to eat certain foods when i have an allergy

Kevin O'Dell answered on 26 Jun 2014:

Good question. It’s usually to do with your immune system which is normally really good at recognising things like bacteria that can cause infection.

For reasons that are not entirely understood some people have a perfectly good immune system that for some reason also thinks (for example) that pollen is trying to kill you. So when pollen goes up your nose it treats it as if pollen is very dangerous and reacts in a similar way to having a cold. This is hay fever.

Food allergies are similar to this. The bodies of people with food allergies misinterpret certain chemicals in certain foods in a strange way. Quite often they’ll be a genetic reason for this, but in most cases it won’t be as simple as having one defective (mutant) gene.