For some people, a simple peanut or a bite of shrimp can cause the body's immune system to wildly overreact, in some cases the result can be deadly. But what exactly is happening in the body for it to confuse nuts or shellfish with a threat?
By definition, a reaction to a food is only considered an actual allergy, if the immune system is involved - and if the response is caused by immune cells called IGNs.
It's important to distinguish an allergy from a sensitivity or intolerance, which involves uncomfortable symptoms, such as a reaction but one that doesn't cause an immune response. So if you're lactose intolerant, you're not allergic to milk.
Scientists are still not sure what causes allergies, and why this affects the balance of the immune system. One theory is that being too clean, or hygienic, can play a role in helping the body to develop allergy reactions later in life.
For more theories and what happens to the body during an allergic attack watch the report above.