This is because the fibre found in whole fruits is intact, and the sugar is contained within the fruit's cells. It takes our digestive system a while to break these cells down and for fructose to enter the bloodstream. But this is not the case with fruit juice. “Fruit juice has most of the fibre removed,” says Emma Elvin, senior clinical advisor at the charity Diabetes UK. This is why, unlike whole fruit, the fructose in fruit juices counts as ‘free sugars’ – which also include honey and the sugars added to foods. It’s recommended by the World Health Organisationthat adults have no more than 30g of added sugar, the equivalent of 150ml of fruit juice, per day.