Who’s captaining this ship anyway? How your microbiome governs your gut and your brain

By Alive & Well

We’ve all heard about the human genome, that series of chromosomes that makes us who we are. But what about our microbiome? What is it, and what role does it play?

The personal microbiome is the population of bacteria that lives in each of us – primarily, in our guts – and when you look at the sheer numbers of the things, it’s easy to see why they’re the subject of so much research. Each personal microbiome is believed to contain ten times more cells than the human body itself.

That’s right, we’re outnumbered – and pretty convincingly

But here’s the thing: it’s increasingly clear that the balance of ‘good’ versus ‘bad’ bacteria can have significant impacts on our health and our brains, particularly our moods and behaviour.

Last week the Proceedings of the National Academy of Sciences[1] reported the results of some research on mice that showed a gut bacteria called Lactobacillus rhamnosus (often found in yoghurt – the real stuff, not the low fat no fat sugary fruity stuff) was found to positively affect mood, persistence and resilience. Biologically, it balanced levels of the stress hormone corticosterone and improved the number of receptors for gamma-aminobutyric acid, a natural chemical messenger that helps manage nerve cell activity.

So what are the implications for human health?

The Human Microbiome Project

The Human Microbiome Project

The good news is that the National Institutes of Health in the U.S. is on the case of finding out whether a similar process happens in humans. In 2008 they launched the Human Microbiome Project to find out whether changes in microbial communities in a range of places in the body (gut, skin, nose etc) have an impact on human health. So far they’ve looked at the role of gut microbiome in ulcerative colitis, obesity and Crohn’s Disease, and how our skin’s microbiome affects psoriasis, acne, atopic dermatitis and immunodeficiency.

The results are encouraging and eagerly anticipated, for lots of reasons but most importantly because they seem to be consolidating the view that our bacteria can be allies in our health, that they help build great immunity and help fight diseases. So it begs the question: as products such as probiotics become increasingly popular, will they become part of our GPs’ toolkits? Will antibiotics be restricted to acute conditions only, since they also affect the ‘good’ bacteria? And not just for humans – for that kind of change to be effective, we would need to do the same for the animals we eat as well, i.e. use antibiotics only when they’re needed, rather than adding ‘preventative’ antibiotics into their food every day as a matter of course.

In the meantime, we’re big fans of the fermented drinks and vegetables encouraged by holistic GPs, naturopaths and the Body Ecology Diet’s Donna Gates. They ensure we get the benefits of ‘good’ bacteria naturally – and the more we hear about research into the microbiome, the more I realise just how important this food group is. You won’t find it on any food pyramids yet, but one day, who knows?!

Do you eat fermented foods? Have probiotics helped your health?


1. Bravo JA, Forsythe P, Chew M, Escaravage E, Savignac HM, Dinan TG, Bienenstock J, Cryan JF. 2011. Ingestion of Lactobacillus strain regulates emotional behaviour and central GABA receptor expression in a mouse via the vagus nerve. Proceedings of the National Academy of Sciences. Published ahead of print August 29, 2011. Full text can be found here: http://www.pnas.org/content/early/2011/08/26/1102999108.full.pdf+html?sid=8620268b-1e26-4126-a12b-b04022d1bc60