What happens to food after we've eaten? The ins and outs of digestion are not normally considered suitable for polite conversation. But we should know more about what goes on according to a new book by 25-year-old microbiologist Giulia Enders. Gut: The Inside Story Of Our Body's Most Underrated Organ, is already a bestseller in her native Germany. And it makes eye-opening reading, as this extract reveals... From the minute we take our first bite of food, enzymes in saliva start breaking it down. Tiny openings on our cheek secrete saliva even at the thought of food. It has a...