I think the 5-a-day idea was intended to guide people away a bit from the endless highly calorific pizza, KFC, Burgers etc, which are all a pastry/beige colour, and get them to go for filling but not fattening colourful stuff, fruit, vegetables, five times a day. It's not so much about vitamins and healthy foods, as reducing the vast intake of stodgy stuff which is the cause of much of the obesity. If they stuff an apple in their mouth, they aren't munching on a doughnut!