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Eating Dirt to Find Happiness

February 12, 2011

Jacob Schor, ND, FABNO


The bacteria Mycobacterium vaccae are distant relations to Mycobacterium tuberculosis, the agents responsible for causing tuberculosis yet supposedly they are harmless. were was first isolated from cow manure and so were named ‘vaccae’, after the Latin word for cow.


Various strains of mycobacterium have been experimented with and used because of their action on the immune system.  Most people are familiar with the use of Bacillus Calmette-Guerin (BCG), which is an inactivated form of the bacterium Mycobacterium tuberculosis, for the treatment of bladder cancer.  M. vaccae in have been shown to be beneficial in the treatment of asthma but failed to out perform the placebo in the treatment of atopic dermatitis or psoriasis.  


Researchers who were testing the potential of M. vaccae in treating lung cancer reported some fascinating findings in 2004.  A total of 419 patients had been treated for lung cancer, 209 receiving chemo alone and 210 receiving chemo plus once a month injections of dead M. vaccae bacteria. The bacteria injections did not make a difference in the lung cancer; survival duration was pretty much equal with the placebo group but the researchers noticed something unusual.


"It was supposed to be a double-blind study, but the investigators could nearly always tell who was on the genuine treatment because their whole attitude, their demeanour, changed," says Charles Akle, chair of the company that manufactured the M. Vaccae product used in the study. "They just looked better."


These impressions were born out by the data.


Patients who received only chemotherapy had greater deterioration in their Global Health Status score (-14.3) than patients who received the M. vaccae injections along with chemotherapy, so much so that the authors concluded that the mycobacterium, “… significantly improved patient quality of life without affecting overall survival times.”


Lowry et al offered up evidence of a plausible explanation for this phenomenon in 2007.  Writing in the May issue of Neuroscience they claimed that administration of M. vaccae triggered an immune reaction that activated a specific subset of serotonin generating neurons in mice. This is similar to what Prosac does. Lowry also studied how exposure to the bacteria changed stress responses.  They used a standard test of stress response, known as ‘swim time’, the longer a mice dropped in a beaker of water continued to swim the better their tolerance to stress.  Control mice swam for an average of two and a half minutes, while the M. vaccae–injected animals paddled for four.


Last May at the 110th General Meeting of the American Society for Microbiology, two researchers reported that exposure to M. vaccae enhanced learning ability.


Dorothy Matthews and Susan Jenks reported that mice who had snacked on peanut butter laced with live M. vaccae bacteria were able to find their way through a maze twice as fast as those in the control group.  The mice also exhibited a reduction in anxiety behaviors as well.  Even a couple of weeks after exposure the mice retained their skills. It wasn’t until three weeks after exposure that the effects tapered off. 


Matthews and Jenks used this data to support their idea that our modern urbanized lifestyles have reduced exposure to these microorganisms and as a result we are more depressed and less capable of learning.


I’ve written about the benefits of exposure to green space in prior newsletters.  It’s hard to imagine that one kind of bacteria alone can account for all the benefits gained by being outside.  Yet it certainly may be part of the answer.  While I contemplate this idea, I might as well take the dog out for a walk, perhaps I’ll nibble on a bit of dirt while I’m at it as well.


Links to related articles:


Walking the Dog, Green Spaces and the Determinants of Health

July 21, 2009

Ruminations while walking the dog.....



Ants, Fungus and Sugar

October 5, 2009

A rare fungus that infects a rare ant that lives far away gives us insight to help explain a peculiar symptom.




April 2007

Infection with toxoplamosis parasites makes rats love cats [link]








Yazi D, Akkoc T, Yesil O, Ozdemir C, Aydońüan M, Koksalan K, et al. Treatment with Mycobacterium vaccae ameliorates airway histopathology in a murine model of asthma.  Allergy Asthma Proc. 2008 Jan-Feb;29(1):67-73.


Berth-Jones J, Arkwright PD, Marasovic D, Savani N, Aldridge CR, Leech SN, et al.

Killed Mycobacterium vaccae suspension in children with moderate-to-severe atopic dermatitis: a randomized, double-blind, placebo-controlled trial. Clin Exp Allergy. 2006 Sep;36(9):1115-21.


Netto EM, Takahashi D, de Fátima Paim de Oliveira M, Barbosa P, Ferraz N, Paixão A, Oyafuso LK, et al.  Phase II randomized, placebo-controlled trial of M. vaccae-derived protein (PVAC) for the treatment of psoriasis.  Vaccine. 2006 Jun 5;24(23):5056-63.


O'Brien ME, Anderson H, Kaukel E, O'Byrne K, Pawlicki M, Von Pawel J, Reck M; SR-ON-12 Study Group. SRL172 (killed Mycobacterium vaccae) in addition to standard chemotherapy improves quality of life without affecting survival, in patients with advanced non-small-cell lung cancer: phase III results.  Ann Oncol. 2004 Jun;15(6):906-14.



Linda Geddes. “Infectious moods: The happiness injection” New Scientist:

19 January 2011 issue 2795


Lowry CA, Hollis JH, de Vries A, Pan B, Brunet LR, Hunt JR, et al. Identification of an immune-responsive mesolimbocortical serotonergic system: potential role in regulation of emotional behavior.  Neuroscience. 2007 May 11;146(2):756-72.

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