Vitamin D , the sunshine vitamin, has been in the news again with claims that supplements could help ward off coughs , colds and flu. Dr Margaret McCartney takes a look at the study that generated the headlines.

Whether or not a severely injured person will receive blood products at the scene of an accident depends on which air ambulance service they are attended by: some air ambulances replace lost blood with red blood cells, but others replace only with saline solution. Evidence from military casualties in Afghanistan suggests giving blood before patients reach hospital leads to better survival rates, but evidence from civilian populations in the UK is less clear. A new randomised controlled trial, being conducted by six air ambulance services, will investigate which course of action has the best outcomes for patients. Mark visits the Midlands Air Ambulance to hear more from lead investigator and trauma anaesthetist Dr Nick Crombie and critical care paramedic Jim Hancox.

Phantom limb pain - pain in an amputated limb - is a common complaint among amputees. Pain medication rarely solves the problem and there is is no known cure. But now a trial in Sweden is using augmented reality to help patients relearn how to move their missing limb, and showing that chronic pain can be reduced. Mark talks to lead researcher Dr Max Ortiz.

And Margaret McCartney takes a look at the evidence for that dinner party favourite - the sitting-rising test - which proponents have claimed can predict how long you might live.