A food allergy is when the body's immune system reacts unusually to specific foods.  Although allergic reactions are often mild, then can be very serious. 

In the most serious cases, a person has a severe allergic reaction (anaphylaxis), which can be life threatening. 

The UK has some of the highest prevalence rates of allergic conditions in the world, with over 20% of the population affected by one or more allergic reactions.  (M.L. Levy, 2004)

According to the Food Standards Agency around 1 to 2% of adults and 5 to 8% of children in the UK have a food allergy, with up to 1 in 55 children having a peanut allergy. In addition, some people need to avoid certain foods because of a food intolerance.