Introduction

Our earlier article on this topic explored how these microbes influence our diets; namely how they use a carrot and stick tactic to influence us and our dietary decisions. We encourage you to read this article first as their

Studies increasingly demonstrate that the impact these microbes have on our body is much greater than previously thought. ⁽¹⁾This influence facilitated by a complex relationship that exists between our gut and our brain, known quite aptly as the gut-brain axis (GBA). In this article, we take a look into this complex connection and explore how these two organs influence each other to help us function.

Microbes produce more than 50% of your brain’s dopamine and serotonin ^(P2)

The Gut Brain Axis

This bidirectional communication channel between the gut microbiome and the brain consists of many systems. Recent research has demonstrated the important role played by gut microbes in impacting the brain’s emotional centers and higher cognitive functions. ⁽²⁾ One such way is through the microbial production of neurochemicals that complement mammalian hormones to regulate our mood and behavior. ⁽³⁾

As illustrated in our previous article, more than 50% of the dopamine and a greater portion of serotonin in our bodies originate in the intestines. ⁽⁴⁾ Many regularly occurring microbes in the gut produce dopamine. Bacterial cultures of these microbes indicate a dopamine level 10-100 times more than the typical concentration found in human blood. ⁽⁵⁾

Microbes have been found to affect your mood ^(P3)

Moody Microbes

Studies have shown how the transference of microbiota between mice, also transfers dispositions such as anxiety. When germ free, control, mice were fed fecal pellets from mice with anxiety-like behavior, the control mice demonstrated an increased level of timidity. When the anxious mice were fed fecal pellets of the control mice, their timidity diminished and they demonstrated exploratory behavior akin to the control mice! ⁽⁶⁾

Clinical trials have also demonstrated that probiotics can improve a subject’s mood. One trial had human subjects ingesting a particular probiotic, lactobacillus casei, and found that their mood significantly improved. ⁽⁷⁾ Microbiota are also largely responsible for the production of Butyrate, a short chain fatty acid, which has been shown in mice to profoundly affect the central nervous system and create noticeable changes in their moods and behaviour. ⁽⁷⁾ 

Studies indicate that microbes play a role in influencing our decisions ^(P4)

Behavioral Manipulation

Further to influencing anxiety, several studies have demonstrated other ways in which microorganisms can manipulate our behavior. One study analyzed the behavior of mice in water when fed a particular microbe. Here the mice that were given the microbe; lactobacillus rhamnosus (JB-1) and they demonstrated a reduction of stress-inducing hormones while swimming. As a result these JB-1 fed mice swam longer than control fed mice. But this enhancement disappeared when researchers severed the subject’s vagus nerve,the main neural pathways between the gut and the brain, which suggests that this nerve plays a critical role in the microbial manipulation of its host. Conversely, severing the vagus nerve of the control mice, which had not consumed JB-1, had no effect on their swimming. ⁽⁷⁾

Another example of a microbe that affects behavior is toxoplasma gondii. Rats fed with this microbe lose their fear of cat smells. And are also shown to become sexually aroused by cat urine; making them easier prey for cats. ⁽⁸⁾

There is ample evidence to suggest that what we consume, and the microbes inside us, can have a significant impact on our moods and behavior. And the above studies document how the dynamic activity of our microbiome and its complex interconnections with our brain carry a greater significance than previously imagined. And who knows? Your next meal could possibly have the secret ingredients to make you happier and more productive!