Medicine is changing. If I’ve learned anything whilst filming for my documentary, The Gut Movie, it’s that what we think we know about human biology is changing rapidly. As we continue to discover the vast populations of microbes which inhabit the human body, we’re slowly starting to appreciate their significance in our health & wellbeing.

The microbiome (all the microbes which live on and inside of you) has a large impact on the immune, metabolic and neurological systems. Let’s have a look at four studies which demonstrate the latter; how the mirobiome, specifically the gut bacteria, have a huge impact on the health of the brain.


1: Multiple Sclerosis Reversed using Faecal Microbiota Transplantation

In an interview for The Gut Movie, I spoke with Professor Thomas Borody from The Centre For Digestive Diseases in Sydney. Borody is one of the earliest pioneers into Faecal Microbiota Transplantation (poo transplants) and we spoke about the rise in interest that FMT is receiving across medical fields. FMT has become a ‘go to’ treatment for the often deadly c.difficile infection, and is becoming much more accepted as a treatment method for conditions such as Crohn’s, IBD and IBS, and constipation.

During our time at The CDD we were privileged enough to be able to film an FMT taking place and speak intimately with Professor Borody following the procedure.

I was completely surprised when Professor Borody told me of three cases where MS patients had come in for treatment of their constipation. The FMT procedure was conducted and the constipation successfully reversed, however symptoms of Multiple Sclerosis also normalised. A neurological condition was reversed following a drastic shift in microbiota (bacteria/microbes) within the GI tract. Importantly, these positive effects have persisted up to 15 years later without relapse! 

Borody writes “Our finding that FMT can reverse MS-like symptoms suggests a GI infection underpinning these disorders. It is hoped that such serendipitous findings may encourage a new direction in neurological research.”


2: Mediterranean Diet Potential Cure For Depression

In a study conducted by Deakin University in Australia, adults with major depressive disorder were split into groups and either assigned social support, or support from a clinical dietitian who prescribed food intakes reflective of the Mediterranean Diet; lots of vegetables, fruits, wholegrains, legumes, fish, lean red meats, olive oil and nuts. These treatments extended over a 3 month period before reevaluations took place.

The results of the study, published in the international journal BMC Medicine, showed that participants in the dietary intervention group had a much greater reduction in their depressive symptoms over the three-month period, compared to those in the social support group.

At the end of the trial, a third of those in the dietary support group met criteria for remission of major depression, compared to 8 percent of those in the social support group.

“These results were not explained by changes in physical activity or body weight, but were closely related to the extent of dietary change,” Professor Jacka said. “Those who adhered more closely to the dietary program experienced the greatest benefit to their depression symptoms.”


3: Probiotics Change Neurochemistry in Mice

In a study conducted in 2011, a research team administered a specific probiotic called Lactobacillus rhamnosus to groups of rats & observed drastic changes in their neurochemistry. 

The researchers had two groups of mice, a control group & an experimental group, both of which were subjected to testing. What the researchers found is that by administering the probiotic to the experimental group of mice, levels of the neurotransmitter GABA (Gamma Amino Butyric Acid) were significantly increased. Importantly, GABA is involved in a very important interplay within the brain in actually dampening nerve impulses. Why is that important? GABA actually acts as a preventative measure from our brains becoming ‘too active’ if you will; essentially it calms the brain down. GABA has been shown to be in low levels of patients with anxiety & depression.

The researchers also found that levels of stress-induced corticosterone (stress hormones) were reduced in the mice administered the probiotic! So being exposed to the same stressors did not affect the mice receiving probiotics as much as it did the group who did not receive the probiotic. This could also be said as the mice who received the probiotic remained more biologically calm than their counterparts who didn’t receive any Lactobacillus. Another interesting note is that the researchers found that the mice receiving the Lactobacillus rhamnosus exhibited less depression-related behaviour.

This study’s biggest asset, though, was in how the researchers then retested this theory on two new sets of mice. Importantly, the Vagus nerve (the active communication link between the gut and the brain) had been removed in the new groups. The researchers found that the neurochemical & neurobehavioral effects were non existent in this ‘vagotomised’ group of mice! This gives huge strength to the standing that the microbes within our guts constantly communicate with our brains via the central nervous system; the vagus nerve.


4: Reversing Alzheimer’s With Probiotic Therapy

A study published in Frontiers in Aging Neuroscience reported incredible results using probiotic treatment on Alzheimer’s patients. In fact, the study showed actual reversals of blood indicators associated with Alzheimer’s and improvements in mental function for patients using probiotic treatment, while the control group (not taking any probiotics) continued to worsen in those same markers!

This is significant because, normally, most research into Alzheimer’s looks at the possibility of only reducing the rate of cognitive decline, not actually reversing it

Participants of the study underwent a widely used, standardised MMSE (Mini Mental Status Exam) and had their blood tested for an inflammatory marker called highly sensitive c-reactive protein (hs-CRP). Importantly, hs-CRP is a highly inflammatory marker & is often seen in higher levels in neurological conditions such as Alzheimer’s.

Of the 60 patients, 30 were given a placebo & 30 the probiotic formula. Probiotics used were Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum, and Lactobacillus fermentum.

The placebo group (no probiotic) saw increases in their inflammatory hs-CRP score by an average of 45% whilst the experimental group receiving the probiotic actually declined (thus improving their inflammation levels) by 18%!

On the MMSE tests measuring cognitive function, the placebo group dropped from a mean score of 8.47 to 8.00, whilst the experimental group drastically improved their MMSE scores from an average of 8.67 up to 10.57 (a big shift). Importantly this indicated a process of not just delaying or reducing the declining cognitive function of the participants, but actually regaining cognitive function!


I look forward to the day when conventional medicine embraces these ideas in a fully integrated approach to establishing and maintaining health & wellbeing.

Oh, one more thing, have you seen the trailer for my latest film?

Tickets and further details can be found here.

This post is brought to you by The Gut Movie Official Australian Tour. Coming to 11 cinema screens around Australia, this beautiful documentary investigates the role of the gut and microbiome in human health.

The Gut Movie Kale Brock

Sources for this article include:

Borody, T. (2017). Could Multiple Sclerosis Be Caused By Bacteria?. [online] Available at: (2017). World-first trial shows improving diet can treat major depression. [online] Available at:

Bravo, J., Forsythe, P., Chew, M., Escaravage, E., Savignac, H., Dinan, T., Bienenstock, J. and Cryan, J. (2011). Ingestion of Lactobacillus strain regulates emotional behavior and central GABA receptor expression in a mouse via the vagus nerve.

David Perlmutter M.D. (2016). The Empowering Neurologist – David Perlmutter, MD and Molly Fox, PhD. [online] Available at:

Akbari, E., Asemi, Z., Daneshvar Kakhaki, R., Bahmani, F., Kouchaki, E., Tamtaji, O., Hamidi, G. and Salami, M. (2016). Effect of Probiotic Supplementation on Cognitive Function and Metabolic Status in Alzheimer’s Disease: A Randomized, Double-Blind and Controlled Trial. Frontiers in Aging Neuroscience, 8.


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