Understanding the Gut-Brain Axis

In my newest book Gut Feelings, I talk a lot about the gut-brain axis. This special bond between these two systems starts when you are just a baby in your mother’s womb as your brain and gut are actually formed from the same fetal tissue.

This relationship between your gut and your brain facilitates communication between all areas of your body including your gut microbiome, immune system, endocrine system, and your nervous system. Since this connection impacts so many areas of your health, when either end of your gut-brain axis is out of balance it can lead to a whole slew of problems.

When it comes to chronic pain and mental health, this bidirectional relationship works to impact these conditions from both a physiological and psychological angle. On one end, problems with your gut can often present themselves in the form of anxiety and depression and on the other end, stress, fatigue, and shame from constantly being in pain can further perpetuate inflammation and sabotage your health. 

It’s a vicious cycle. But once we understand the mechanisms of how the gut-brain axis works in these conditions we can begin to address your health head on.

Physiological mechanisms of chronic pain + mental health

So how exactly does the health of your gut lead to chronic pain, and more importantly, how can it possibly impact how you feel emotionally? It all comes down to a few factors.

1. Bacterial dysbiosis

Imbalances in your microbiome - also known as bacterial dysbiosis - often seen in conditions such as irritable bowel syndrome (IBS), can contribute to both chronic pain and mental health disorders. While functional medicine has understood this relationship for a while, researchers are just starting to confirm just how real this connection truly is.

According to a recent 2019 study, (3) researchers were able to find direct evidence for the first time of bacterial dysbiosis in people dealing with fibromyalgia. They also found that the severity of a person’s chronic pain was directly influenced by the severity of their bacterial dysbiosis, proving the importance of maintaining a healthy gut.

2. Inflammation

Intestinal permeability - aka leaky gut syndrome - is another thing that can happen due to bacterial dysbiosis. When this happens, undigested food particles and bacterial endotoxins can leak into your bloodstream where they don’t belong, triggering systemic inflammation. And while inflammation has long been considered the driving force behind chronic pain, recent studies are finding that elevated inflammation in your brain is also behind everything from brain fog (4) to depression. (5) Additionally, research has shown that inflammatory cytokines that are released during chronic pain can also affect neurotransmitter function and contribute to mood changes. 

4. Neurotransmitter function

Many of your important neurotransmitters like serotonin, norepinephrine, and dopamine involved in pain modulation and mood regulation are actually made and stored inside of your gut. When you are dealing with underlying gut dysfunctions like dysbiosis, inflammation, and leaky gut syndrome it can impact your production of these neurotransmitters and ultimately, contribute to anxiety and depression.