Do you love food? Whether you're a foodie or someone who just likes eating, there is so much to choose from. We know that too much of the wrong kind of food can be bad for our health, but for some people having a food allergy means eating certain things can actually be harmful - and now, it seems, this is affecting more and more of us.

An allergy is caused by the immune system fighting substances in the environment, known as allergens, that it should see as harmless. Food allergies can cause life-threatening reactions, which means people have to spend their lives following strict dietary restrictions and worrying about the ingredients of everything they consume. Allergy specialist Dr Adam Fox says "if you look back over, say, 30 or 40 years… there are much more allergic problems around now than there were."

We often hear about people having allergies to dairy products and to peanuts. Last year a 15-year-old girl died after suffering a fatal allergic reaction from eating a baguette containing sesame seeds. This led to a call for better food-labelling laws.

Research has found that this problem is particularly affecting children. More and more of them are having allergic reactions to certain foodstuffs. Writing for the BBC website, Dr Alexandra Santos from King's College London says "food allergy now affects about 7% of children in the UK and 9% of those in Australia, for example. Across Europe, 2% of adults have food allergies."

So what might be the cause? Dr Santos says the increase in allergies is not simply the effect of society becoming more aware of them and better at diagnosing them; it seems to be more environmental. She says possible factors are "pollution, dietary changes and less exposure to microbes, which change how our immune systems respond."  She points out that it's very common for migrants who move to another country to develop asthma and food allergies in their new location.

A lot of work is being done to try and find a cure, but that's not easy. So for now allergy sufferers must watch what they eat and they must rely on clear and accurate labelling.