Most commercially available saffron buns and cakes today contain food dyes that enhance the natural yellow provided by saffron. The very high cost of saffron - the world's most expensive spice by weight[6] - makes the inclusion of sufficient saffron to produce a rich colour an uneconomical option. The addition of food colouring in Cornish saffron buns was already common by the end of the First World War when the scarcity of saffron tempted bakers to find other ways to colour their products.[citation needed]