Gut Feelings - How Your Belly Affects Your Mood

How your belly affects your mood.

- Lisa Turner

No matter how fit you are, and no matter how beautiful, tan, perfectly coiffed, or finely muscled, it all comes down to one thing: you’re basically a skin sack filled with bacteria. Of the estimated 100 trillion cells in the body, only about 10 percent are human. The rest are bacteria—up to 5 pounds worth, and most of them in the gut. And according to emerging research, they can have a profound impact on mood, behavior, and well-being.

Researchers have long known the bacterial makeup in the gut exerts a powerful influence on health. Studies show that a dysfunction in the internal ecosystem can increase the risk of a range of chronic diseases and conditions, including obesity, diabetes, asthma, sinusitis, colorectal cancer, and immune disorders. New research is also pointing to an intimate connection between the microbial makeup of the gut—called the microbiome—and anxiety, depression, autism, and brain chemistry.

Sometimes called the “second brain” or the “gut brain,” the digestive tract is the body’s only organ to house its own nervous system. Called the enteric nervous system, this neural network consists of 500 million neurons, five times the amount in the spinal column. It operates independently from the central nervous system, and continues to function even when the vagus nerve—the main channel of communication between the gut and the brain—is severed.