Why should salt have a sell-by date?

What's the point of making medicines fizzy? Why should salt have a sell-by date? Is boiled water as good as distilled for my iron? Do we actually only see half a movie? Where do foreign bodies dislodged from the eye go? Is lactose intolerance becoming more common? What causes morning sickness, and is it a risk for mother and baby? Join Dr Chris for this week's round-up of top questions from Talk Radio 702, South Africa... Like this podcast? Please help us by supporting the Naked Scientists