Injections of soil bacteria make mice happy
Researchers of a study published in the March 28 May 11, 2007 issue of Neuroscience discovered that injections of a soil bacterium, Mycobacterium vaccae, increased the activity of serotonin-producing neurons in mice. (The paper is titled “Identification of an Immune-Responsive Mesolimbocortical Serotonergic System: Potential Role in Regulation of Emotional Behavior.")
Lowry and his colleagues studied another set of mice, who were subjected to a stress-response test. They dropped each mouse into water for five minutes and timed how long it would take the animal to switch from active swimming to passive floating. Control mice swam for an average of two and a half minutes, while the M. vaccae–injected animals paddled for four. Researchers already know that antidepressants increase active swimming and decrease immobility. The bacteria “had the exact same effect as antidepressant drugs,” Lowry explains.Maybe this explains some people's craving for eating dirt? From a CDC article titled "Eating Dirt":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.
Among children, too, it seems eating dirt might have immunologic consequences. Maternal immunoglobulins are secreted in breast milk shortly before birth and for 1 year or more afterwards. Children often begin eating dirt a year or two after birth. As maternal immunity wanes, eating dirt might “vaccinate” children who are losing their maternal IgA, which could stimulate production of nascent immunoglobulins, especially IgA. Eating dirt might also help populate intestinal flora.
Discover magazine asks: "Is Dirt the New Prozac?" (Via Seth's Blog)
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Gardener's are just drug users. Suddenly the happiness they get from grubbing the dirt all makes sense.
Also explains rugby players.
I always figured that eating dirt indicated a lack of supervision, not a lack of nutrients.
You can also get infected, by mycobacteria.
Tuberculosis and leprosy, for example.
Not only do mice get happy from soil, they live longer as well.
This does not surprise me at all.
So earthworms are basically hippies?
Anon@3
silly scaremongering.
While you may like your cat or dog (mammals), be aware they are closely related to other mammals that will eat or trample you (wolves, tigers and water buffalo).
Yes on potentially picking up parasites from eating dirt, not really likely to get TB or Hansen's from a chunk of your back yard.
Yes, dirt is the new Prozac. Actually, Pristiq is the new Prozac, but that's not the point. The point is digging in the dirt will make you happy because you are tapping into that well of anciet human experience. It was on this planet that we evolved, after all, figures we'd be *perfectly* adapted to working with it.
The first article reference is broken; a working link is: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1868963
The article was published in the 11 May 2007 issue of Neuroscience, not 28 March 2009 (as implied).
[Full disclosure: it was published by friends of my wife.]
I have often wondered if you could get the benefits of eating dirt without the risks of infections/parasites if you microwaved it first? If it is about provoking an immunological response then the microbes don't need to be alive for that to happen, do they?
@10 Anon: I love you for having often wondered about the effects of microwaved dirt.
p.s. it works
:)
:)
:)
So perhaps us parents should think about extending the 3 second rule out to something longer to help our children "populate intestinal flora"?
The conclusion drawn from this test is flawed.
So, what this proves, in fact, is that mice keep up active swimming longer when injected with M. vaccae.
While they might be exibiting the same behavior when under the influence of antidepressants, this does not prove by any means that the mice are 'happy'.
O, and btw, stop f#cking around with animals.
#10, Anonymous:
The study used 'heat-killed' bacteria, so it is likely that it would work. Microwaving isn't a particularly good way of sterilizing soil, though- autoclaving (or using a domestic pressure cooker) is much better.
I have often wondered if you could get the benefits of eating dirt without the risks of infections/parasites if you microwaved it first?
risk of infection from dirt? parasites?
assuming you don't mistake scat for dirt, your immune system will pretty much handle anything dirt has in it.
News at 11: Dirt-injected mice enjoy drowning much longer.
Seriously, is this ethical?
I know my life got better once I started gardening.
#13 "this does not prove by any means that the mice are 'happy'"
you are right, but it's rather common for animals to eat/lick dirt or stones which provide vital minerals or, for example in tropical forests, antidotes for poisonous plants and the like. i find it convincing to claim that if something's necessary for your system evolution might have resulted in you experiencing a positive emotional response to it (and crave it).
but that might also just be the easy assumption.
"digging in the dirt will make you happy because you are tapping into that well of anciet human experience. It was on this planet that we evolved, after all, figures we'd be *perfectly* adapted to working with it."
Same could be said of hunting and warfare. Like many other constructs, this depends on degree. If you're living in a Western/northern degree of relative comfort and safety, gardening could be great, primal fun. In other contexts, "doing agriculture" could be back-breaking drudgery.
Hey man, those peasant farmers got nothing on me. Drudgery? I meet with the neighborhood "landscape committee" today. No amount of dirt (or heavy duty psychotropic medication) seems to mitigate the the urge to gouge out my own eyeballs with a pitchfork when we get together to discuss putting a few plants in the ground. Those butterflies better be goddamned grateful.
anyone who thinks they need to eat dirt, microwaved or not, just needs to follow the chain of custody of the food on their supermarket shelf or restaurant table.
Apparently it has had no positive effect on the hateful woman who has repeatedly accosted my girlfriend and her daughter for 'trespassing' when they have been walking through the neighborhood community garden....
Wolfiesma, I think I've been on that garden committee. Did anyone suggest introducing beavers into the neighborhood because hundreds of years ago the area was wetlands?
More support for the hygiene hypothesis is all: http://www.hygienehypothesis.com
Wasn't there an article here recently about the beneficial effects of parasites?
So, @7 SNIG, "Yes on potentially picking up parasites from eating dirt, not really likely to get TB or Hansen's from a chunk of your back yard." you may be entirely wrong, parasites may be the main benefit of exposure to the soil. And if the research on depression showing it is related to inflammation explains why exposure to dirt makes you "happy".
Parasites reduce inflammation, you see.