Health & DiseaseSoil Biology

Gardening Bliss


A spoonful of happiness?

Need cheering up after my last article? Keep reading….

There may be more to post-gardening joyfulness than we’ve previously realised. It seems that our heavy breathing amongst the rosemary and rhubarb has us inhaling a soil bacterium with a subversive agenda – that of saving us from depression.

If you have problems with the following passage, don’t despair – read the one after and all will come clear (a budding poet, I am):

Peripheral immune activation can have profound physiological and behavioral effects including induction of fever and sickness behavior. One mechanism through which immune activation or immunomodulation may affect physiology and behavior is via actions on brainstem neuromodulatory systems, such as serotonergic systems. We have found that peripheral immune activation with antigens derived from the nonpathogenic, saprophytic bacterium, Mycobacterium vaccae, activated a specific subset of serotonergic neurons in the interfascicular part of the dorsal raphe nucleus (DRI) of mice, as measured by quantification of c-Fos expression following intratracheal (12 h) or subcutaneous (6 h) administration of heat-killed, ultrasonically disrupted M. vaccae, or heat-killed, intact M. vaccae, respectively. – PubMed Central

Layman’s translation:

Some researchers have proposed that the sharp rise in asthma and allergy cases over the past century stems, unexpectedly, from living too clean. The idea is that routine exposure to harmless microorganisms in the environment—soil bacteria, for instance—trains our immune systems to ignore benign molecules like pollen or the dandruff on a neighbor’s dog. Taking this “hygiene hypothesis” in an even more surprising direction, recent studies indicate that treatment with a specific soil bacterium, Mycobacterium vaccae, may be able to alleviate depression.

… Some studies have found that treatment with M. vaccae, the inoffensive soil bacterium, eases skin allergies, and other reports—such as the cancer study—show that it can improve mood. Christopher Lowry, a neuroscientist at the University of Bristol in England, had a hunch about how this process might work. “What we think happens is that the bacteria activate immune cells, which release chemicals called cytokines that then act on receptors on the sensory nerves to increase their activity,” he says.

… The results so far suggest that simply inhaling M. vaccae—you get a dose just by taking a walk in the wild or rooting around in the garden—could help elicit a jolly state of mind. “You can also ingest mycobacteria either through water sources or through eating plants—lettuce that you pick from the garden, or carrots,” Lowry says. – Is Dirt the New Prozac, Discover Magazine

So there you go, gardening is a great way to beat (the) depression, in both senses of the word.

Hat Tip: Rhamis

Further Reading:

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