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  • Alex Cloherty

Do microbes affect my brain? Part II

Have you ever noticed how your mood drastically changes when you're hungry? That already indicates that your stomach can have some effect on your cognition. Well, it turns out that your belly and your brain might be even more interconnected than you thought.

In the past decade or so, research has been coming out that suggests that there is real cross-talk, a two-way conversation, between the "gut" (your stomach and intestines) and the brain. This conversation is often referred to in scientific articles as the "gut-brain axis". If you read this edition of Microbial Mondays, you already know that we all have rich ecosystems of bacteria and viruses living in our guts. This new research suggests that those microbes can have far-reaching effects in your nervous system by sending messages along this communication channel.

One area in which quite a lot of research has come out is on the link between gut microbes and mood disorders - for example, depression. "Microbial dysbiosis", which is simply a bad balance of microbes in the gut, has been linked to a whole array of symptoms of depression. Symptoms that sometimes go along with depression, such as anxiety, have also been linked to gut bacteria being out of balance. Even more convincing were results with probiotics, which are products designed to help your gut find a healthy microbial balance. In studies with animals, supplying probiotics helped reduce anxiety and depression!

The balance of bacteria and viruses in the gut have also been linked to many other things, from irritable bowel syndrome (IBS) to autism. But that's not all: as I mentioned before, the gut-brain axis is a two way street.

Let's take mood as an example again. When you start to feel very sad, down, or anxious, your brain sends different signals than when you're feeling happy, excited, or content. The signals from your brain are sent throughout your body in the forms of various electric impulses and chemicals. Some of these can influence the types of bacteria and viruses that flourish back down in your gut. Scientists have found that when animals feel stressed out or sad, the balance of microbes in our guts changes. This means that things like depression or anxiety could become a positive feedback loop or downward spiral of microbes influencing the brain, which in turn again influences the microbes.

I must add a caveat at this point: this research is very new, and there is very little evidence from humans yet. Most of this took place in mice - which, though surprisingly similar to humans in many ways, are not exactly the same. But, in the meantime, I don't think it can hurt to take some simple gut-balancing steps to try improving your mental balance: eating healthy and exercising don't usually hurt!

Until next time - eat some fibre!

- Alex

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