Our Brains Or Our Gut Bugs: Who’s Actually In Control?

Woman jumping in front of wall.

Are we masters of our own behaviours or, are tiny microbes actually in charge of how we behave?

It’s something that I find myself pondering more and more (I know, my deep thoughts go weird places, I’m sorry!)

Did you know that your gut is host to hundreds of different types of microbes and that, collectively, these microbes are referred to as your microbiota? They live in your gut, looking like a coral reef - each microbe growing into a small colony, affecting the environment around them.

The good microbes in your microbiota are called probiotics. Probiotics affect how food is digested, as well as how the gut lining absorbs food. But, that’s not all! Since your gut lining is host to receptor sites for your immune system and nervous system, probiotics can also affect how you think, feel and perform. Some gut bacteria can even produce neurotransmitters (chemical messengers). That’s right – microbes in your gut can send messages to your brain! But, as I’ve been wondering lately, how do our gut bugs actually, like in real-life ways, influence how we behave?

Sending Out an S.O.S

The number of genes in your gut microbiome significantly outnumbers the human genes in your body. Some microbe genes can produce compounds that can interact directly with your nervous system. Amazing! So, your behaviour is regulated in part by gut microbes. Two behaviour patterns researchers believe your gut microbes can affect in particular are how we interact socially and how we manage stress.

Two behaviour patterns researchers believe your gut microbes can affect in particular are how we interact socially and how we manage stress.

Stressed Out?

Traffic. Being late. Computer with error messages. Yikes! Stress comes in many forms, all of which can inflict a gut wrenching feeling. But, your gut’s relationship with stress goes way farther, as research is just starting to suggest. Science in this area is still in its infancy; however, preliminary findings suggest that having a healthy gut microflora may reduce the amount of cortisol produced and released when you are faced with those hair-pulling, not going to make it ‘on time’ moments.

FUN FACT: A probiotic strain of Lactobacillus brevis can produce GABA (a.k.a. the “chill out” neurotransmitter).


Is it possible that tiny microbes affect whether you feel depressed? There is evidence of a really different looking microbiome in those who struggle with depression, and researchers have found that there are increased circulating levels of antibodies against bad gut bugs in depressed patients (suggesting bacteria moving from gut to blood stream, scary!).

What a fascinating possibility of probiotics being like a natural anti-depressant...

In mice, the microbiome absolutely appears to affect depression. Preliminary research out of the University of Virginia School of Medicine suggests that certain probiotics may help a mouse feel less depressed (one probiotic found in yogurt was even shown to be effective – but remember, pleeeeease get a plain, unsweetened variety to ensure the gut bugs haven’t feasted and then died before you can eat them!). Does this apply to humans? We’re not sure yet in depressed patients - but we do know that probiotics can help generally mentally healthy people really elevate their mood. So what a fascinating possibility of probiotics being like a natural anti-depressant, I will be eagerly watching for that research! It will be one delicious future if we can eat our way to happiness. (Oh, just imagine if they could put these helpful microbes into chocolate, which is a great prebiotic aka. food for your probiotics). 

A Lasting Thought

The health of our microbiome declines with age. Many studies show long-term care residences have less diverse microbiota than those living in the community. With increasing prevalence of dementia around the globe, researchers are curious as to whether the gut microbiome has an impact on cognitive health with advanced age.

What to Eat?

It can be confusing. A 2014 study suggested that a vegan diet may be helpful by reducing the number of pathogenic bacteria in the gut microbiome. Recent research, this year, found a link between a vegetarian diet and depression. Please keep in mind, the golden rule in science : Correlation does NOT equal causation. This means that, if we’re looking at these results critically, this study did not show that a vegetarian diet causes depression, only that there is some sort of relationship between the two (so, maybe depressed people could be opting to try this diet more often - get how a correlation could go either way?). A high fat diet appears to have negative effects on the gut microbiome, altering it in a way that encourages inflammation. But, not all fats are bad for your brain! Omega-3 fatty acids have been shown in many studies to promote brain health, including reducing stress and fighting depression.

Nutrition can be so confusing at times. But don’t fret! As always, NeuroTrition has got your fork covered. We wrote a blog, HERE, giving you 7 deliciously evidence-backed ways to feed your gut microbiome, and a plate full of other helpful tips to achieve healthy bugs in your gut.

  1. Allen, A.P., Dinan, T.G., Clarke, G. & Cryan, J.F. (2017) A psychology of the human brain-gut-microbiome axis. Social and Personality Psychology Compass, 11(4).
  2. Dinan, T. G., Stilling, R. M., Stanton, C., & Cryan, J. F. (2015). Collective unconscious: How gut microbes shape human behavior. Journal of Psychiatric Research, 63, 1–9.
  3. Liu, X., Cao, S., & Zhang, X. (2015). Modulation of Gut Microbiota-Brain Axis by Probiotics, Prebiotics and Diet. J Agric Food Chem., 16;63(36):7885-95.
  4. Glick-Bauer, M., & Yeh, M. C. (2014). The health advantage of a vegan diet: Exploring the gut microbiota connection. Nutrients, 6(11), 4822–4838.
  5. Murphy, E. A., Velazquez, K. T., & Herbert, K. M.(2015). Influence of high-fat diet on gut microbiota: A driving force for chronic disease risk. Current Opinion in Clinical Nutrition & Metabolic Care, 18(5), 515–520.
  6. Robertson, R. C., Oriach, C. S., Murphy, K., Moloney, G. M., Cryan, J. F., Dinan, T. G. & Stanton, C. (2017). Omega-3 polyunsaturated fatty acids critically regulate behaviour and gut microbiota development in adolescence and adulthood. Brain, Behavior, and Immunity, 59, 21–37.
  7. Marin, I.A., Goertz, J.E., Ren, T., Rich, S.S., Onengut-Gumuscu, S., Farber, E., Wu, M., Overall, C.C., Kipnis, J. & Gaultier, A. (2017). Microbiota alteration is associated with the development of stress-induced despair behavior. Scientific Reports, 7: 43859

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