Selenium supplements have hit the headlines with reports that men taking them can increase their risk of developing aggressive prostate cancer. Dr Mark Porter talks to leading expert on selenium, Margaret Rayman, Professor of Nutritional Medicine at the University of Surrey, to find the truth behind the story.

Idiopathic pulmonary fibrosis is a disease that kills more people in the UK than breast cancer. It's caused by the thickening and scarring of the part of the lung that forms the barrier between blood and air and can make your chest sound like it's full of Velcro. Mark talks to Luca Richeldi, Professor of Respiratory Medicine at the University of Southampton, about why it can be mistaken for asthma or Chronic Obstructive Pulmonary Disease - what used to be called emphysema and bronchitis. Also in the programme, as many as 1 in 20 children will experience long term constipation with no underlying cause and which doesn't get better with dietary changes. Mark visits a specialist clinic at Addenbrooke's hospital in Cambridge to meet families managing the problem.