(NaturalNews) Organic gardening may produce physiological changes to boost your physical and mental health, a number of studies suggest.

One such change may take place as a result of the simple act of putting your hands into the soil. A study conducted by researchers from the University of Bristol in London found that contact with a naturally occurring species of soil bacteria, Mycobacterium vaccae, causes the body to release vital immune chemicals called cytokines. These, in turn, spur the brain to produce the neurotransmitter serotonin.

“We know that some of these cytokines can activate the nerves that relay signals from the body to the brain,” researcher Chris Lowry said.

This effect may explain, in part, why people who are not exposed to dirt in childhood have higher rates of allergies, asthma and even mental health issues as adults.

In spite of what the drug companies would have you believe, there is no real evidence that serotonin affects mood directly. However, it is certainly an essential neurotransmitter that appears related to immune function, and the study’s results are highly suggestive.