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Feeling Down? Your Gut May Be To Blame!

Exploring the connection between mental health and the gut

What do you do when you are feeling down?

I, personally, eat!

And I usually don’t feel like eating a fresh home-made meal full of microbiome-loving fibre, probiotics, and antioxidant-rich vegetables.

I’m talking about cake, crisps, chip butty, pizza, and pastries. (The kind of stuff the “bad” bacteria in our gut thrive off of….yikes)

Sure, these treats might offer a temporary distraction from the gloom, but what exactly are they doing to our gut microbes? That's the burning question!

Although still a relatively new field of research, the connection between mental health and gut health is undeniable.

We know this largely is due to the Gut Brain Axis (GBA). Because of this connection; the state of the gut microbiome may play a role in motivation, perceived energy levels, happiness, and higher cognitive functions (1).

a pink large intestine model next to a pink brain model and arrows pointing to and from each other indicating a gut brain axis connection

When emotions or stress occurs in the body, neurotransmitters and hormones help the central nervous system communicate to the gut microbiota. This influences digestion, and health of the microbiome.

This communication is in fact bidirectional, meaning if the microbiome is not healthy, this will affect the central nervous system, or the brain itself, which then impacts our moods and emotions. (1)

AKA… bad gut health could CAUSE bad mental health!


What's the Evidence?

In fact, many studies have been done on the mental effects of poor gut health, often with animals.

In one study, scientists compared depressive behaviors in two different types of mice.

The first group were raised in a germ-free environment (meaning they would have developed little to no gut microbiome). The second group were conventionally raised, meaning they were exposed to various microbiome-developing germs, and were considered “normal”.

When introduced to anxiety-provoking situations, the mice without microbiomes could not cope nearly as well as the mice with healthy microbiomes.(2).

The first group of mice also showed more depressive-like behaviours.

This experiment ( and many more like it ) (3), sheds light on just how crucial a healthy gut microbiome is for mental well-being.

Another randomized, double-blind, placebo-controlled study of 44 adults with IBS and mild to moderate anxiety and/or depression took place in Canada.

The researchers wanted to determine if improving the gut microbiome by means of a probiotic Bifidobacterium longum (BL), could have an effect on participant’s depression.

Half of them took a probiotic, and the other half took a placebo. After 6 weeks, 63.6% of the patients in the BL group had a reduction in depression scores, vs 31.8% of the patients in the placebo group.


Furthermore, after a functional MRI of the brain, the BL group also showed reduced responses to negative emotional stimuli in multiple brain areas, compared with placebo. The results were the same when tested again at week 10. (4)

Many other studies have reported similar findings of improved cognitive function and depression symptoms with probiotic supplementation. However, further investigation is warranted.

If you want to know more about which strains of bacteria are linked to mood changes, check out our blog on Psychobiotics here

So, the next time you're feeling a bit blue, remember: your gut health is a key player in your mental well-being. While there's no harm in indulging in your favourite comfort foods (hey, we're only human!), why not throw some fibre-rich options into the mix? Fresh air, sunshine, gentle exercise, and quality time with loved ones are also fantastic ways to give your microbiome – and your mood – a little boost.

Gut Love to you all!

Abby Torrie

Trainee Dietitian


Content checked and supported by Cat & Rosie, Registered Dietitians and Co-Founders of Oxford Gastro Dietitians



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