The team investigates whether sugar deserves such a bad reputation, with the substance blamed for a variety of health issues beyond rotten teeth and expanding waistlines. Jem Stansfield sets out to make some granulated white sugar of his own, while Liz Bonnin explores the power it has to switch on people's brains. Maggie Philbin meets a surprise victim of fatty liver disease and discovers how sugar is being used to preserve life-saving vaccines.