The human gut consists of more than 1 000 species and over 7 000 subspecies of microbes, mostly bacteria producing compounds that have direct affects in the brain. For example, they can increase the love hormone, and reduce the stress hormone.

Bacteria in the intestines produce neurotransmitters such as the anti-anxiety neurotransmitter, GABA (gamma-aminobutyric acid), the happiness neurotransmitter, and the feel-good neurotransmitter, which may directly impact brain function and mental health.

The gastrointestinal tract is sensitive to emotions, and symptoms in the gut can be triggered by emotions, for example depression, anxiety, sadness and elation.

Research has shown that an unhealthy mix of gut bacteria can contribute to depression, anxiety, stress and other mental health and mood issues.

Infections, stress, eating too many processed foods and taking too much medication can all trigger inflammation that can radically change the microbiome in the gut.
These changes in the gut microbiome can result in intestinal permeability, (leaky gut), inflammation, or lack of bacterial diversity all of which have been associated with depression and mood issues.

If the microbiome is disrupted, then so is the connection between the gut and the brain.

By increasing the diversity and abundance of bacteria in your gut, you can improve your mood and brain function and even treat your anxiety or depression.

A healthy and balanced gut microbiome is critical for a healthy brain.