This was a fascinating interview on BBC Radio 4 with the eminent Professor Graham MacGregor and Dr Jim Al-Khalili. Professor MacGregor is an expert on salt in the diet, and has alot to say about salt, the requirements in our diets and the Food Industry. You can listen on BBC radio 4 catchup here. Also some interesting comments about rehydration and water. This is a UK-based programme, and I think it is accessible outside the UK.