Some children have a right to be angry. It's not hard to see why a child who has suffered abuse, trauma or bereavement might be angry with the world and everyone in it.

But what's the answer when a child in a loving home is angry about 'nothing' and, at the same time, 'everything'? Are they simply being rude and disagreeable - or is there some hidden trauma that you, the parent, remain unaware of? The obvious options would include therapy or medication.

Nobody ever suggests food allergy testing to a parent tearing their hair out while trying to pacify an angry child and restore peace in their home. But anger, it seems, may be as red and raw a reaction to some foods as the welts that appear around the lips of other allergy sufferers.