You know probiotics are good for your gut. But can these "friendly" bacteria also affect your mood or your behavior? John Cryan, a neuroscientist at University College Cork in Ireland, thinks it's entirely possible. He recently completed a study of probiotics and brain changes that suggests friendly bacteria in your gut can actually alter your brain's chemistry!

For this study, Cryan and colleagues fed mice broth containing the bacterium, Lactobacillus rhamnosus. The name probably sounds familiar to you. That's because you'll find the Lactobacillus strain of bacteria in most probiotic supplements and forms of yogurt.

After six weeks on this magic broth, the mice showed fewer signs of stress and anxiety! For example, the mice spend more time running through the narrow, elevated walkways and wide-open spaces. These spaces are generally scary to mice (who knew?!). The mice also pumped out fewer stress hormones when the researchers placed them in water. "This was really exciting because it tells us the animals are more chilled out and don't mount the same stress response," Cryan said.

And best of all, researchers found a link between  mice taking probiotics and brain  changes occurring in their genes that program GABA, a neurotransmitter. GABA typically dampens neural activity in the brain. And many drugs used to treat anxiety target GABA receptors.

None of these changes occurred in the mice that ate plain broth.

Mike Lyte, a microbial endocrinologist at the Texas Tech University Health Sciences Center in Abilene, commented on the work with the mice, probiotics and brain changes in Science Now. He said, "This is pioneering work. It's really showing that you can alter emotional states by regulating the microbiome."

So keep up your probiotic regimen. Not only will your digestion improve, you mood may improve as well!