Health Benefits of Dirt

Western culture tends to associate all germs with a devastating disease, when in fact, the vast majority of microbes are beneficial, if not essential, to our and our pet’s well-being. In 2007, the National Institutes of Health initiated a $173 million dollar, a five-year project called the Human Microbiome Project,” that extensively characterized microbial communities on the human body to create baseline data for future health and disease research connected to the microbiome. The European Commission followed with a $28 million dollar project called “MetaHIT: Metagenomics of the Human Intestinal Tract” which set out to establish associations between human intestinal microbiota genes and health and disease (1). More than 80% of bacteria on this planet is benign or beneficial to us. Of the 20% or so, that is pathogenic, some bacteria may be so only in certain conditions of dysbiosis, such as h. pylori (2). The bacteria on and in our body outnumber human genes estimated 10 to 1. This foreign matter is called the “microbiome” which is a collection of bacteria, archaea, viruses, protozoa, helminths, and fungi that symbiotically live in and among us. The bacteria in the gut microbiome have over 6,500 functions, including the ability to synthesize hormones, digest food, crowd out pathogens, metabolize drugs, synthesize B-complex vitamins and fat-soluble vitamins as well as help the body absorb nutrients such as calcium and iron (3, 4). There have been thousands of studies done on the human microbiome. While research into the canine microbiome is less robust, the canine microbiome has been shown to function in much the same way as the humans (5).

One bacteria found naturally in soil, that has garnered a lot of interest and funding over the last decade, is Mycobacterium vaccae (M. vaccae). M. vaccae was first cultured in cow dung in Austria, hence it was given the name “vaccae” meaning cow in Latin. In the past decade, M. vaccae has been tested as immunotherapy for depression, asthma, dermatitis, asthma, cancer, psoriasis, eczema, leprosy, and tuberculosis.

Improved Mood

Exposure to dirt can improve mood. We have known for decades that a simple stroll in green space can release feel-good hormones and have beneficial psychological and physiological effects on the participants. The term, “forest bathing” became popular in Japan in the 1990s and there is robust research behind the health benefits of exposure to forests (6). More recently, researchers have isolated a bacterium in soil that contributes to these positive feeling while reducing anxiety. For example, a research group at Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, University of Bristol, Bristol, England, UK, has shown that M. vaccae stimulated a newly discovered group of neurons which increased levels of serotonin and decreased levels of anxiety in mice. They injected M. Vaccae into mice and exposed them to a variety of stress tests. The mice given M. vaccae exhibited far less stress behavior than the untreated mice. In fact, the M. vaccae treated mice acted as if they were on antidepressants (7).

Specifically, it is thought that M. vaccae may affect the brain indirectly by causing immune cells to release cytokines that influence neurotransmitters like serotonin.

A 2016 study by Reber, et al, supports that M. vaccae provides health benefits by increasing “resilience to stress-related pathologies in part through the induction of Treg and an anti-inflammatory bias (8).”

Improve allergy symptoms

There is mounting evidence that autoimmune disorders, including allergies which is the number one reason dog guardians visit their vet for the past 10 years, are due to increased isolation from the commensal bacteria in the environment (8, 9). This concept is called the “Hygiene Hypothesis” and is a theory that excessive deterrence of early childhood exposure to dirt and pathogens can inhibit the full development of the immune system. Again, research with M. vaccae shows promise towards the reduction of allergy symptoms in humans and canines (10).

A 2007 study showed that “a single injection of a heat-killed suspension of M. Vaccae was found to be well tolerated and effective in treating mild to moderate cases of Canine Atopic Dermatitis (CAD) demonstrable for 3 months (11).” Similar studies showed improvements in human trials (12) including the ability to boost immune response (13) as well as a reduction of asthma symptoms in mice (14).

Improve cognitive function

There is a growing field of study that supports the bidirectional relationship between the gut and the brain via the vagus nerve, frequently referred to as the gut-brain axis (GBA). Basically, research supports that the bacteria in our gut can control some of our actions (15). Dorothy Matthews and Susan Jenkins at the Sage Colleges fed live M. vaccae to mice, then measured their ability to navigate a maze compared to control mice not fed the bacteria. Results showed that "Mice that were fed live M. vaccae navigated the maze twice as fast and with less demonstrated anxiety behaviors as control mice (16).”

Improve Quality of Life for Cancer Patients

Multiple studies have shown improved quality of life for cancer patients when injected with M. vaccae. The benefits to cancer patients were first discovered over a decade ago by Dr. Mary O’Brien, who gave lung-cancer patients a serum of M. vaccae, in hopes that it would boost their immune system. Results showed that the patients that were given the M. vaccae serum reported feeling happier and suffered less pain than those who did not receive the bacteria (17). Other research showed life extension of cancer patients up to 4 months (18).

Technology in studying microbes

M. vaccae is just one bacteria in an ever-growing area of research into the benefits of a diverse microbiome to overall health and wellness across many species. Thanks to advancements in new genetic sequencing technology, 16 S ribosomal RNA (16SrRNA), researchers have the ability to identify, classify and quantify microbes in a variety of ecosystems from water biomes to gut microbiome. This technology has allowed researchers to identify the roles of bacteria in both healthy individuals and patients with various disorders. The microbiome is the fastest growing area of research in the pharmaceutical industry, and we are just beginning to rediscover how our ‘old friends’ have a profound impact on our health.

Exposure to M. Vaccae

You don’t need a laboratory to expose your dog to beneficial microbes. Environmental exposure to beneficial environments has been an integral part of DC Shiba Inu Rescue’s drug-free allergy program for 5 years. Some approaches include:

1. Ask your local organic farmer if you can take a hike around their farm with your dog.

2. Find dog-friendly nature preserves that have not been chemically sprayed and allow your dog to get dirty.

3. Find natural springs and rivers that your dog can swim and roll in.

If you have a yard:

4. Stop using chemical fertilizers, fungicides, herbicides, or pesticides.

5. Apply organic matter (compost) and complementary planting techniques.

6. Spend time in the garden with your dog.

7. Feed meals in the yard.

8. Play ball and other games in the yard.

9. Provide edible herbs.

Obtaining a diverse microbiome means eating diverse foods from species-appropriate diet of the particular subject and exposing the individual to natural commensal bacteria in their environment while reducing external and topical toxins that reduce the microbiome. High-stress events are shown to vastly deplete the diversity of the gut microbiome (19), which can have implications on our training methods for the long-term health of our dogs. Letting go of our cultural obsession with anti-germ warfare and sagaciously reintroducing diversity can be beneficial to our pets and us.

Is dirt the magic bullet that can ‘cure’ your dog’s ailments? Unlikely, but is a piece of the puzzle in an ever-growing field of research that supports the importance of the millions of bacteria living in the gut. Breathing in, playing in, and eating in the dirt is showing to be beneficial to our pet’s overall health. In its simplistic form, we know that a diverse microbiome is one of the best predictors of health across species as with any ecosystem, but as research continues, the value of stability, function, and structure will undoubtedly be considered (20).

(1) https://www.nature.com/articles/500016a

(2) Missing Microbes: How the Overuse of Antibiotics Is Fueling Our Modern Plagues by Martin J. Blaser (2014) Holt New York, USA

(3) The GI Microbiome in Domestic Animals – Contribution to Health and Disease, Jan S. Suchodolski, MedVet, ACVM (Immunology).

(4) https://www.sciencedirect.com/science/article/pii/S1931312812003587?fbclid=IwAR0EXB-S8AbgphEo8ODDywUY00AM_eYC5U6hVldksCdgBj7HC3dAGEVQI4E

(5) https://pubmed.ncbi.nlm.nih.gov/25414978/

(6) https://www.npr.org/sections/health-shots/2017/07/17/536676954/forest-bathing-a-retreat-to-nature-can-boost-immunity-and-mood?fbclid=IwAR22iUrp6iBEtVj5lb-d_JXyDZoUmX9_AVb8zSrDTwwOyErCq0XyDjIj7Qo

(7) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1868963/

(8) https://www.ncbi.nlm.nih.gov/pubmed/27185913

(9) https://www.veterinarypracticenews.com/top-10-vet-visit-reasons-for-dogs-and-cats/?fbclid=IwAR0_V_nEVmJw9RIdkZCwIOydPnra90oJiKjrVkBT3FZhNh3IaF_TTtnMAlo

(10) https://onlinelibrary.wiley.com/doi/full/10.1002/vms3.24?fbclid=IwAR0TVkll-wA6O-V40y-Zzh3XzQg-gQLXM7Kl-qp5xhtxEj80rErvP3kIGNE

(11) https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-3164.2007.00579.x?fbclid=IwAR0Ia4aPGCyahf6Yr6Cmd8bHoW6tOJtibYB5z-YX5PCvdUZRQiBvZ2kLbqk

(12) https://www.ncbi.nlm.nih.gov/pubmed/11240956