Misery guts

The 20 feet of convoluted tubing linking your stomach to the outside world is commonly known as the gut, and until recently its functions were believed to be simple: finish off the messy business of food digestion, extract as many nutrients as possible and expel the remainder as waste.

The gut is also known to be populated by bacteria, all of which were once thought to be harmful. But no more. Many gut bacteria are now recognized as vital for one’s health—not just locally but, perhaps surprisingly, throughout the whole body. These microscopic inhabitants of our midriffs are increasingly being linked to a whole raft of diseases—even dementia.

Leaky gut

The new buzzword is microbiome, coined to describe the colony of literally trillions of bacteria that are the semipermanent residents of our gut. Why semipermanent? Because we ourselves can at