Can prebiotic supplements change how we feel?

Prebiotics may support your emotional framework, and ease anxiety

I was lucky enough to catch up with the SMILES study lead Professor Felice Jacka (also author of Brain Changer, and Director of the Food and Mood Centre) last week to chat all things gut bacteria, brain health and mood.

In particular this pre-print, which has yet to go through the peer-review process yet clearly shows that mice fed an unhealthy diet causes an imbalance of gut bacteria and a leaky gut barrier, leading to gut bacteria wrongly translocating to the brain via the vagus nerve and directly linked to increased levels of neuroinflammation a hallmark of several neurodegenerative diseases.

Enter stage left; our gut bacteria

It stands to reason that we’re interested in how our gut bacteria might be involved in our mood.

One way to explore whether the microbiome influences mood is through fecal microbiota transplants, transferring a donor’s poo to the recipient, and noticing any effects.

Transferring poo from humans with depression to rats has beeen shown to lead to emotional changes (‘transferring the blues’), with the rats exhibiting depressive-like behaviour.

Photo by Mariana Rascão on Unsplash

If our microbiome is involved, does taking prebiotic supplements help?

Prebiotics being a group of fibres found naturally in plant foods like fruit, vegetables, beans and legumes, whole grains, nuts and seeds, that encourage the growth of a type or selected group of gut bacteria that exert a beneficial health effect on us, the host.

Prebiotic supplements are when the prebiotic fibre has been isolated, and usually in a larger dose than what a simple apple or can of beans might give you, or have been engineered in a lab.

We can’t digest prebiotic fibre ourselves, we need a helping hand from our friendly digestive helpers - our gut bacteria.

An Oxford University trial fed healthy participants a type of prebiotic called galacto-oligosaccharides for three weeks, and measured their self-reported mood status, levels of the stress hormone cortisol at waking, and their emotional cognitive function.

After three weeks, they had lower stress levels, and while they didn’t find any change in self-reported mood, they did see a difference in their emotional cognitive function - the underlying infrastructure of mood.

Supplementation of this type of prebiotic has also been shown to lower self-reported levels of pre-clinical anxiety in adolescent women in a double-blinded placebo controlled trial.

However, a recent meta-analysis found that on the whole prebiotics do not significantly improve depressive symptoms, though the writers pointed to the small numbers of study participants and the need for more research.

For now, it looks as though prebiotics and our collection of gut bacteria influence the underlying emotional framework of mood - and considering that the current studies only ran for a number of weeks, perhaps it’s in the longer term that we will see significantly noticeable benefits on how we feel by taking prebiotics.

Chat soon, Emily xx