Gloria Hunniford and Chris Bavin investigate which of the claims about foods said to help people live longer are true.Also, with claims that certain foods could stop dementia in its tracks, a woman whose mother had the condition explores whether changing her diet is the key to ensuring she doesn't develop it too.The effects of booze on the brain are revealed, there are surprises as the team exposes how food affects migraines, and two diets, each said to be the world's healthiest, are compared to see which is best. But will it be the Japanese or Mediterranean diet that comes out on top?