anxiety and gut health

How anxiety and gut health are connected

Scientists have discovered a powerful link between anxiety and gut health. Gut health and anxiety connect via the trillions of microbes in our gut – called the gut microbiome – because they produce important molecules that influence our brain.

These discoveries have turned traditional assumptions about mental well-being upside down, quite literally!

And with this shift in focus comes the exciting possibility of better ways to help manage our mental health. So, just how closely are gut health and mental health connected?

1. What is the link between anxiety and gut health?

In order to understand the link between gut health and anxiety, we need to understand a little bit about the gut microbiome.

In short, the microbiome is the collection of all microbes – mainly bacteria but also fungi and viruses – that naturally live in and on our bodies. The gut and skin microbiomes are by far the largest ones.

In fact, there are more bacterial cells in the human body than human cells; more than 40 trillion bacterial cells vs. about 30 trillion human cells. What’s more, these microbes weigh roughly as much as our brain!

Indeed, far from being harmful, we live in harmony with these microbes when we’re healthy. Many play a powerful role in our physical and mental health.

2. How does gut health affect anxiety?

How is it even possible for microbes to affect our brain? Let’s take a closer look!

The gut microbiome can affect mental health and anxiety in several ways, including:

Production of messenger molecules

Microbes produce and communicate via molecules that act as messengers, travelling through the blood to the brain, where they trigger certain responses.

Over 90% of the ‘happy molecule’ serotonin is produced in our gut:

  • An unhealthy gut can lower the production of serotonin, leading to anxiety and depression

Other neurotransmitters that influence our brain are:

  • GABA
  • Dopamine
  • Melatonin

Bacteria in our gut help produce and respond to these neurochemicals, which allows the brain to regulate mood and function.

Signalling via the Vagus Nerve ‘super highway’

  • Other bacteria may use chemical signals to stimulate the vagus nerve, which runs between the base of the brain to our gut and physically connects them

Indirectly, via inflammation

  • Inflammation of the gut has been linked to mental health, including anxiety and depression
  • Increased levels of inflammatory molecules called cytokines directly correlate with symptoms of depression and anxiety

Notably, digestive conditions such as irritable bowel syndrome and inflammatory bowel disease have been associated with increased rates of anxiety and depression.

3. Can we ease anxiety by changing our gut microbiome?

Enhancing beneficial bacteria in the gut, for example, through the use of probiotics, prebiotics, or dietary change, has the potential to improve mood and reduce anxiety in both healthy people and patient groups.


4. How can we improve or restore the gut microbiome?

When there are changes in the types or amount of these microbes, our microbiome becomes imbalanced, a state called dysbiosis. Dysbiosis can be harmful and restoring balance and optimizing our microbiome is important in order to restore health.

Probiotics, mood, and anxiety: Practical advice 

Current trends suggest that the global probiotics market size could reach over USD 66 billion by 2024. Choosing a probiotic from the ever-expanding selection of commercially available products can be daunting for anyone.

Many bacteria that have been shown to have an effect on our mood and mental well-being, are part of two groups of bacteria (genera) called Lactobacillus and Bifidobacterium.

According to Dr Michael Ruscio:

“Within the Lactobacillus / Bifidobacterium category, the most commonly researched species for mental health have been:

  • Bifidobacterium longum (B. longum)
  • Bifidobacterium infantis
  • Lactobacillus acidophilus
  • Lactobacillus helveticus
  • Lactobacillus plantarum
  • Lactobacillus rhamnosus

Based on current research, a good probiotic for anxiety includes a high-quality, multi-species Lactobacillus / Bifidobacterium blend.

Butler and her team (2019) note that different strains have different psychological effects. Simply put, ‘strain’ refers to the third part of the probiotic name and it’s worth noting, it’s not always listed despite its importance.

For example, Lactobacillus rhamnosus (strain JB-1) failed to impact mood or anxiety levels in healthy males, while Lactobacillus casei (strain Shirota) demonstrated an ability to improve mood in healthy volunteers with low baseline mood score

Butler, 2019

Here are some of the probiotic strains proven to have a positive effect on mood, based on human studies (Butler, 2019):

  • Lactobacillus helveticus R0052
  • Lactobacillus acidophilus W37
  • Lactobacillus brevis W63
  • Lactobacillus casei W56
  • Lactobacillus salivarius W24
  • Lactococcus lactis W19 and W58
  • Bifidobacterium longum R0175
  • Bifidobacterium bifidum W23
  • Bifidobacterium lactis W52

5. What negatively affects the gut microbiome?

At first do no harm, is the oath all medical doctors have to take.

The same applies to our gut microbiome. By far the largest volume of evidence is for a gut healthy diet and lifestyle. As a result, nutritional psychiatry has become an important topic, looking at how you can calm your mind with food.

Remember, you ARE what you eat:

Summary & actions

We now know for sure that our gut has a powerful effect on our brain, and vice versa, via the gut-brain axis.

Gut health and mental health connect through various routes, e.g. by influencing the production of messenger molecules, dysbiosis and inflammation.

Enhancing beneficial bacteria in our gut with probiotics, prebiotics or diet has the potential to improve mood and reduce anxiety.

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