Michael Mosley runs an experiment to find out which foods are best for providing a crucial but neglected nutrient: iodine. Geneticist Dr Giles Yeo discovers why stress can make you put on weight. GP Dr Zoe Williams tackles the question: how safe are x-rays? Michael questions two experts on how the NHS spends our money. And psychiatrist Dr Alain Gregoire reveals how mental health first aid aims to reduce the rates of suicide and mental illness.

Michael Mosley teams up with Olympic athletes to test which types of exercise give you the strongest bones. Geneticist Dr Giles Yeo investigates how to stay healthy if your body clock is out of sync with yourwork day. GP Dr Zoe Williams looks into which health advice on the internet you can trust. And surgeon Gabriel Weston carries out an experiment to discover if cleaning our homes with antibacterial products could be responsible for the rise in allergies and asthma.