We humans have a second brain. Come to think of it, men have three. The second one, called our enteric nervous system, consists of some 100 million neurons that are embedded in the walls of the long tube of our gut, which starts at the esophagus and end at the anus. It measures approximately nine meters long, deeper than most swimming pools.
As important as the neurons in the gut is the kind of bacteria found there. Our body is a dwelling place for about 100 trillion bacteria and other microbes, collectively known as our microbiome. They do many important things: break down our food, fight off infection, and boost our immune system. However, scientists are finding that they may do even more than that, and have an important role in our mental health. In fact, the burgeoning field of psychobiotics may prove to be a new treatment for those with chronic depression, and especially for those who suffer from gastrointestinal issues alongside depression and anxiety.
John F. Cryan, a nueropharmacologist and microbiome expert from the University College Cork in Ireland, is one of the scientists at the forefront of exploring the link between gut and brain health. He works closely with gastroenterologists, microbiologists, and psychiatrists to study the effects of gut bacteria on the brain. His studies on mice are fascinating, and show us how gut bacteria can alter the biochemistry of our brain (the one held up by our necks).