Plot: In this year’s Christmas Lectures, Dr Chris van Tulleken delves deep into our guts – to reveal the revolutionary latest science around what happens inside our bodies when we eat. He investigates how food has fundamentally shaped human evolution, uncovers the importance of our microbiome – as the extra ‘organ’ we didn’t know we had – and asks how we can all eat better in future, for the sake of our own health and the health of the planet