Well, now science is backing that up. The latest research out of the United Kingdom suggests that a type of good bacteria found in dirt may affect the brain in a similar way as antidepressants.
Researchers from Bristol University and University College London discovered using laboratory mice, that a "friendly" bacteria commonly found in soil activated brain cells to produce the brain chemical serotonin and altered the mice's behaviour in a similar way to antidepressants.Check out "Gardening With Soul" and find out why gardening is good for you. I promise you will feel better afterwards.
They are suggesting this could explain why immune system imbalance could make some people vulnerable to mood disorders like depression.
Lead author, Dr Chris Lowry from Bristol University said, "These studies help us understand how the body communicates with the brain and why a healthy immune system is important for maintaining mental health".
"They also leave us wondering if we shouldn't all be spending more time playing in the dirt," he added.
Dr Lowry and colleagues became interested in the project when they heard that cancer patients treated with the bacterium Mycobacterium vaccae reported increases in their quality of life. They speculated this could be because the bacteria were activating brain cells to release more serotonin.