Your Brain on Bacteria

Bacteria in your brain would normally be a bad idea;encephalitis, meningitis, or science fiction. Just a few months ago research was presented indicating that there are non-pathogenic bacteria in the brain.


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Gut-brain microbiome

I’ve talked often in these blogs about how the gut microbiome, comprised of trillions of bacteria, affects the health and function of rest of our body. How this works scientists don’t readily know but our gut is almost like another brain it seems, at times. How we treat our digestive system affects our brain function and our behaviour.




Bacterial overgrowth or species imbalance can result in nervous system or entire-body inflammation. Too much of the wrong bacteria can produce neurotoxins. Gutmicrobes affect hormone and neurotransmitter levels and directly influence the neurons that send signals to the brain, via the vagus nerve.With all these systems affected by our gut and the foods we eat, we can see how dependent we are on a well functioning digestive system for proper sleep, stress management, pain and inflammation, wound healing, and daily mental cognition.


Why are they there?

Why bacteria are in the brain isn’t known yet. And neither is how they get there. Do these bacteria newly discovered in the brain come from gut? The researchers that discovered their presence don’t know that either but they have some theories. They propose that bacteria enter the brain either through the blood brain barrier, and/or via nerves that work in the gut. Different amounts of bacteria were found in different parts of the brain, the most being found in the

  • substantianigra – a region rich in dopamine neurons which play an

important role in reward and movement,

  • hippocampus – important for long-term memory and spatial navigation, and the
  • prefrontal cortex – controls cognitive behaviour, decision making, personality, and social behaviour.




Bacteria were also found in between cells at the blood-brain barrier and in myelinated axons (nerve cells that allow for rapid transmission of electrical impulses). Due to these locations where the bacteria are primarily found, the researchers speculate that the bacteria enter the brain via the axons at the blood-brain barrier.


Bacteria, bacteria, everywhere.  While their role in the brain isn’t elucidated yet what we can say is that maintaining their proper balance with whole foods and very few processed foods is so important! If we treat our bodies well, the bacteria we share our lives with will do their best to help us in return. I’m sure the next few years will have much research on this topic. Your heart will thank you.




Dr. James Kneller treats atrial fibrillation, arrhythmia, and other heart conditions.  He is an internationally recognized authority on cardiovascular health and personal development.



Galland, L.  The Gut Microbiome and the Brain. 2014. Journal of Medicinal Food. 17(12): 1261–1272.

Session 594 – Neuroimmunology: Regulating Systems. 594.08 / YY23 – The human brain microbiome; there are bacteria in our brains! R. C. Roberts, C. B. Farmer, C. K. Walker.!/4649/presentation/32057