GOING WITH YOUR GUT

HOW DO MICROBES AFFECT OUR HEALTH? LET'S COUNT THE WAYS...

-  Kathiann M. Kowalski

What's your body made of? One answer is trillions of tiny units called cells. A trillion is 1 followed by 12 zeroes, or a million million. These cells work together so you can function as a person. But that's not all. Single-celled organisms also live in and on your body. They're microbes. That means they're too tiny to see with just our eyes. And there are lots of them.

"You have 40 trillion microbes inside you," says Jack Gilbert. He's a microbiologist at the University of California, San Diego. The microbes in our bodies include bacteria and lots of other tiny organisms. They live on skin and in mouths, stomachs, and other parts. But our microbes aren't just along for the ride. They affect our health-for both good and bad. That's especially true for microbes in your gut.

WHAT GOES ON IN THE GUT?

When you eat, saliva in the mouth starts breaking down food. Most digestion, though, takes place in the gut. Your gut includes all the body's food-processing parts from the stomach on down.

The stomach churns food around. As that happens, enzymes, acid, and other substances break many of the food's chemical bonds. Food becomes chemical bits and pieces for energy and growth.

The next stop is the small intestine. Here, usable molecules move into the blood, which carries them around the body. Leftover material goes into the large intestine. That organ pulls out extra water and other chemical bits. Unused stuff becomes feces, or poop.

Our guts get help for all this work from microbesmainly bacteria. Many of those bacteria make chemicals that break apart parts of foods like fruits and vegetables.