Millions of people in the UK have a food allergy.
It is when the body's immune system reacts unusually to certain foods.
But where do they come from? And should people be worried about having one?
Newsround has spoken to Amena Warner from the charity Allergy UK to get answers to the big questions about food allergies.
"Food allergy is an unusual immune response to a food or to some foods in a food group that have similar proteins, such as peanuts," says Amena.
"Your body's immune system is there to defend itself against infection such as bacteria, parasites, viruses.
"So when it reacts to something it shouldn't do, such as a food, it is called an 'abnormal immune response', and the food causing it will be referred to as the 'allergen'."
Amena says "Yes, it is perfectly possible and many people do. We all need to eat good nutritional food to be healthy and there are many alternative types of food."
"People living with food allergy have to be very cautious. What is very important is not to eat the food that causes the allergy. Avoidance is key.
"Always ask if there is the food allergen in anything you want to eat (if you are eating out, at a friend's house or party or even picking up a quick snack and check labels of products that are wrapped), know what the signs and symptoms of an allergic reaction are and what to do.
"If you carry an adrenaline auto injector - a rescue medication to give in an emergency - know how to use it, call for adult help and let them know you need an ambulance."
"You are not born with a food allergy, you can develop them either in childhood or as an adult," adds Amena.
"What you are born with is a tendency to develop allergy especially if your parents have an allergy such as asthma, eczema or hay fever. T
"There are things that can be done to reduce this probability."
"Only avoid a food if you know you are allergic to it or if you have been told to avoid it by a doctor or your parents/carers," Amena stresses.
"If you have any concerns talk to a parent, teacher or carer, as it may need to be discussed with your family doctor. Otherwise there is no reason for not trying new foods.
"Patient organisations like Allergy UK have lots of information on its website about food allergy - www.allergyuk.org"