 Hello, I'm Claudia Hammond. Welcome back to The Evidence from the BBC. I'm at Wellcome Collection in London with a live audience and we've been talking about salt and the part it plays in our everyday lives. It makes our food taste good and it's vital to our health. But what's the right amount of salt to eat and why can this be a contentious issue? Well, to help me find out, I'd like to welcome to our panel Sue Matthews, who's a Professor of Health Economics at Lancaster University in the UK.