Zane Hoffman, of Port Chalmers Primary School, asks :-

How does food colouring make kids hyperactive?

Steve Duffull, a phamacologist at Christchurch Hospital, responded.

This is a very good question, but unfortunately it is also hard to answer.

Hyperactivity describes children who are always on-the-go. These children find it hard to stay still, and run around all the time and climb furniture. It is hard for parents and doctors to tell the difference between hyperactivity and other problems. Because of this it is hard to find out what may be causing a child to be hyperactive.

Some food that children eat may change the way they behave. Some of these children seem to get better when they change what they eat. Very few children who are hyperactive to foods are also hyperactive to food colouring. This means that only a very small number of children might be hyperactive to food colouring. When children are hyperactive after eating food colourng the effect is usually small and is not always noticed by the parents. There may be other causes.

It is not known how food colouring causes this problem. It may be that the chemicals in some food colourings may cause changes in how the brain works thus causing hyperactivity. Hyperactivity caused by food colourings usually wears off even if the child does not stop eating food containing the colouring.