New research suggests that one key to immunizing ourselves against anxiety and post-traumatic stress disorder (PTSD) could be right beneath our feet. Since the hygiene hypothesis was proposed 30 years ago, scientists have completed more and more research and refined the theory that exposure to the microorganisms in dirt could be beneficial to humans.
Now, Christopher Lowry, a researcher and professor of integrative physiology at University of Colorado-Boulder who studies the link between our exposure to soil and our mental health, hopes he is on the right path to finding what he calls a “stress vaccine.”
Lowry is exploring why a bacteria naturally found in soil, Mycobacterium vaccae, has been shown to reduce the inflammation in the body that’s associated with stress. For his latest research, which was recently published in the journal “Psychopharmacology,” his team isolated a fatty acid found in M. vaccae.
They found that the fatty acid bound with a receptor to block the pathways to creating inflammation, which some studies have shown can increase the risk of developing serious stress-related conditions such as PTSD.
“We think there is a special sauce driving the protective effects in this bacterium, and this fat is one of the main ingredients in that special sauce,” he said of his research.
This latest study helps inform a previous study of his, which discovered that when M. vaccae was injected into rodents, it had an effect on their behavior similar to that of anti-depressants. It also had long-lasting inflammatory effects on the brain.
The hygiene hypothesis started with the suggestion that exposure to germs via dirt helped kids’ immune systems grow stronger. This discovery is related to the “old friends” theory, an extension of the hygiene theory that posits that humans evolved alongside beneficial microbes in the environment that can help keep us healthy.
“The idea is that as humans have moved away from farms and an agricultural or hunter-gatherer existence into cities, we have lost contact with organisms that served to regulate our immune system and suppress inappropriate inflammation,” Lowry said in a statement about the research.
Lowry believes that a vaccine made from M. vaccae could be given to those in acutely stressful jobs, including first responders and soldiers. Although he estimates that it will be at least another 10-15 years before a vaccine is available for humans, researchers are hopeful about what these findings indicate for the future use of bacterium.
“This is just one strain of one species of one type of bacterium that is found in the soil but there are millions of other strains in the soils,” Lowry said. “We are just beginning to see the tip of the iceberg in terms of identifying the mechanisms through which they have evolved to keep us healthy. It should inspire awe in all of us.”