That enriching feeling you get when you take care of your plants isn’t just from pride in your work or the anticipation of the great buds you’re growing, something unexpected also lightens your mood around the garden. Inhalation of Mycobacterium vaccae, a bacterium that naturally occurs in soil, activates serotonin systems in the brain and shows antidepressant-like effects in mice.
Scientists from the Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology at the University of Bristol injected dead M. vaccae directly into the windpipes of unconscious mice, a way to simulate inhalation of this bacterium. After the mice woke up, they looked at their brains and found increased serotonin metabolism in areas of the brain related to mood regulation. In addition, behavioral experiments indicated that inhaling this type of bacteria had antidepressant-like effect as a consequence of its unforeseen influence on the brain.
Other research shows M. vaccae might make you smarter as well. Mice fed live M. vaccae navigated mazes faster than those that had a clean, bacteria-free diet. This same study found that these positive effects may only be temporary. The same mice that were off the bacteria-laden diet for three weeks went back to navigating mazes as slow as their counterparts that had been eating the “clean” diet the whole time.
M. vaccae naturally occurs in soil, and simply inhaling the same air might be enough to get the necessary exposure. Unfortunately, hydro growers might be missing out on these happy bugs that make your smart. Indoor soil growers should inoculate with cow dung in their compost. Cow dung is rich in M. vaccae, maybe it’s making dairy farmers happy too! Outdoor growers likely already have plenty of exposure to M. vaccae, but a few cow patties here and there won’t hurt anybody.
Besides inhaling volatilized M. vaccae, “you can also ingest mycobacteria either through water sources or through eating plants—lettuce that you pick from the garden, or carrots,” according to Christopher Lowry, first author on the paper “Identification of an immune-responsive mesolimbocortical serotonergic system: potential role in regulation of emotional behavior.”
Gardening has always been a great hobby for these feeling a little blue. Nothing else can replace the awe-inspiring experience of watching something grow, or the reward of a delicious crop you grew yourself. If you go for organic soil, weed smoke won’t be the only thing you inhale that makes you feel great!
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