Food colouring is any substance added to food or drink that gives it a colour. Typically, the food is transformed to a colour that is not naturally occurring. Given that the colour of food changes how one perceives it, food colourings are used to influence how consumers judge the flavour of the item. Colouring can sometimes be for beneficial purposes such as lengthening its shelf life. Other reasons could simply be to make the food more attractive. Furthermore, food colouring is also used in many other inedible products, generally for aesthetic purposes. A popular assumption surrounding food colouring is that it has negative health effects, namely hyperactivity in children. However, as of 2017, there is no evidence to support these claims. There are a few circumstances where there is a possible correlation between colouring and perceived hyperactivity, though the link is tenuous and limited.