Bacteria that quell anxiety

[ThinkGutBacteria]

Scientists in Colorado and the U.K. found exposure to a soil-dwelling bacteria, Mycobacterium vaccae, works as an antidepressant by stimulating the generation of serotonin and norepinephrine in the brain. More specifically, it induces the growth of neurons that produce those two compounds. (M. vaccae is in the same genus as Mycobacterium tuberculosis, the bacterium that causes tuberculosis, but it is not pathogenic.)

 

Scientists in NY fed M. vaccae to mice, it stimulated growth of neurons and increased levels of serotonin and decreased levels of anxiety.

 

"We found that mice fed live M. vaccae navigated the maze twice as fast and with less demonstrated anxiety behaviors as control mice", says Dorothy Matthews of The Sage Colleges in Troy, New York, who conducted the research with her colleague Susan Jenks.

 

M. vaccae isn't found in the human gut, you have to continually ingest it by eating unwashed organic veggies, etc. I'm not sure if simply digging in soil (ie, gardening) would work. Maybe.

 

I dug my girls a back-yard mud pit to play in last summer. I think I'll make it bigger this year.

[Hopeny]

For us thinking about all the other stuff in soil, fifth disease, parasites, viruses from animal urine, I'll pass. My kids have immune problems, I plan to keep them out of lakes and underexposed to animal excretement as long as possible. I tried the exposure thing/not being a germaphobe and my kids are incredibly sick now. It's not one size fits all.

[ThinkGutBacteria]

No one is suggesting you start infecting your kids with H. pylori, Toxoplasma gondii, Epstein Barr virus, or anything else, but you should know that allergies/asthma/IBD and autoimmune diseases result if they're not around during early childhood. It's all about timing. There's a small window of protection--in utero or first year or two of life. However, scientists in England have injected killed M. vaccae into adult cancer patients and have seen huge improvements in patients' sense of well being.

 

What scientists are working on is finding the little bits of these organisms that confer protection and make THEM into therapies. Early results are promising.

Edited February 26, 2013 by ThinkGutBacteria

[dut]

Hi - yeh, I think the point that the hygiene hypo is trying to make is that the reason our kids have these immune issues is cos they weren't exposed early enough.

 

I'm not sure I completely buy into the hypothesis as it stands but I do find it odd that as a society/culture we're happy to cram our kids into daycares etc from very early ages but won't let them play in the dirt. But perhaps I'm a special kind of germaphobe. Animals and soil don't worry me but coughs and sneezes do

[nicklemama]

I'm with you Dut. I believe one of the reasons we vaccinate so much these days is due to the fact that parents nowadays take newborns right out into public, expecting the rest of us to vaccinate the you know what out of our kids to keep newborns safe. In the old days, you kept your newborn home. If I could roll back time and have a redo, I'd do things very differently. If I tried to tell others, they'd think I'd gone off the deep end.

[Hopeny]

My kids have a genetic immune problem, germs make them sick. My older daughter was exposed to TONS of germs in preschool and in NYC and developed asthma. One theory does not fit all even if its published in a book.

No one is suggesting you start infecting your kids with H. pylori, Toxoplasma gondii, Epstein Barr virus, or anything else, but you should know that allergies/asthma/IBD and autoimmune diseases result if they're not around during early childhood. It's all about timing. There's a small window of protection--in utero or first year or two of life. However, scientists in England have injected killed M. vaccae into adult cancer patients and have seen huge improvements in patients' sense of well being.

 

What scientists are working on is finding the little bits of these organisms that confer protection and make THEM into therapies. Early results are promising.

[ThinkGutBacteria]

My kids have a genetic immune problem, germs make them sick. My older daughter was exposed to TONS of germs in preschool and in NYC and developed asthma. One theory does not fit all even if its published in a book.

No one is suggesting you start infecting your kids with H. pylori, Toxoplasma gondii, Epstein Barr virus, or anything else, but you should know that allergies/asthma/IBD and autoimmune diseases result if they're not around during early childhood. It's all about timing. There's a small window of protection--in utero or first year or two of life. However, scientists in England have injected killed M. vaccae into adult cancer patients and have seen huge improvements in patients' sense of well being.

 

What scientists are working on is finding the little bits of these organisms that confer protection and make THEM into therapies. Early results are promising.

 

The hygiene theory fits this beautifully. There is no place with MORE asthma, for example, than inner cities, which are also typically crawling with "germs." But the whole hypothesis hinges on the TYPE of germ. There are NO traditional farm soil microbes in inner cities, for example. In fact, as soon as you urbanize an area, you see an uptick in allergy/asthma/autoimmune disease. I'm sure you can understand that the human body reacts differently to different germs, right? They're definitely not all created immunologically equal. Germs like measles will make you child (and mine) sick. Germs like Lactobacillus casei will prevent autoimmunity. Of course there are many other factors like vitamin D and genetic predisposition. These are all factored in.

[ThinkGutBacteria]

Let look at a case of "genetic predisposition" to asthma, which many consider to be an allergic disease. Humans have a certain receptor on a particular kind of T cell (immune cell) that helps drive allergy-style inflammation. The receptor is called TIM-1. People make various versions of TIM-1, some versions predispose them to getting asthma. Some strongly protect them from getting asthma.

 

As it turns out, scientists at Stanford University found ten years ago that the variant strongly associated with protection is also a really good receptor for the hepatitis A virus (HepA). Having this variety of the TIM-1 gene only protected people from getting asthma if they had been exposed to HepA.

 

Epidemiologically, HepA infection is associated with a reduced risk of developing asthma and certain allergies, and because the incidence of HepA infection has been significantly reduced in industrialized countries over the past 30 years, the discovery of a genetic interaction between HAV and TIM-1 provides a nice example of molecular genetic evidence for the hygiene hypothesis.

 

If you don't "buy" the hypothesis, how would you explain exposure to HepA protecting against asthma in people with the version of the TIM-1 gene that vigorously binds the virus? There are many many examples of this kind of evidence.