Got the blues? There's nothing like getting down and dirty say researchers from Bristol University and University College, London.
The study led by Dr. Chris Lowry and team, claims that the ubiquitous soil-borne bacteria Mycobacterium vaccae, can actually replicate the effects of anti- depressant drugs.
The study sprung from reports of lung cancer patients who were treated with the bacteria. They reported feeling less depressed and vouched for a betterment in life quality after the treatment.
Following this, it was seen that mice exposed to the bacteria produced higher levels of serotonin and had better immunity. The scientists found that the bacteria stimulated the immune system and activated a group of neurons in the brain, which produce the mood enhancing chemical serotonin.
Says Lowry, who published the report in the journal Neuroscience: "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 spend more time playing in the dirt.
"This soil, which carries the bacteria, is pretty ubiquitous and is found almost anywhere.
"But we now need to find a way of getting it in our system, which we haven't done yet."
This work is expected to help the understanding of why an imbalance in the immune system leaves some individuals vulnerable to mood disorders like depression.
Canadian researchers have also been exploring the links between serotonin, mood and immunity.
A team at Georgetown University Medical Center recently discovered serotonin is passed between key cells in the immune system, and that the chemical can activate an immune response.
This suggests that serotonin may restore a healthy immune function in people who are depressed and prone to infections.
This research also appears to support the 'hygiene hypothesis'; a theory that too much emphasis on cleaning and hygiene could be affecting our immune systems. This also argues that a rise in conditions like asthma and allergies could be linked to lack of exposure to various microorganisms.