The Psychobiotic Revolution. Your Gut, Your Bugs and Your Brain
There is a part of us that is crucial to how we behave. It weighs about 3lb, and it influences everything we do. It's not our brain, but the bacteria within our gut. Those pesky little critters that might actually be the master puppeteers of our brain and our body. Shaping our moods and even influencing how we feel. Perhaps the secret to our own happiness may not lie in the self-help section of the local bookstore but maybe within, in our microbiome. Rather than a state of mind, it's more a state of gut.
John Cryan, a neuropharmacologist and microbiome expert explores the inner workings of the microbiome in his book, 'The Psychobiotic Revolution: Mood, Food and the New Science of the Gut/Brain Connection'
What’s in Our Gut Can Affect Our Emotions?
It might not be so out there as you might at first think. We use the word 'gut' in our everyday language with phrases like: gut wrenching, gutted, gut feelings, gut instinct, or butterflies in our tummy, to portray a raft of human emotions.
And this concept of a bi-directional gut/brain interaction is not new at all. Two hundred years ago and US army sergeant and surgeon William Beaumont was already investigating the inner workings of Canadian fur trader, Alexis St. Martin. St. Martin had developed a hole, or a fistula, in his abdomen following a gunshot wound. Beamont, being an inquisitive doctor, decided that in addition to treating him, it could give him an insight into what was going on in the digestive tract and the mechanics of how food could be digested. For many years he kept St. Martin as his human guinea pig, testing all sorts of concepts that laid the foundations of modern gastroenterology. Beamont also took note of St Martin’s moods and how they affected the rate of digestion. And this laid the tenet for what we know about gut/brain interaction.
The Role Our Gut Bugs Have to Play
With the advent of human brain imaging scientists could better visualize how this too was affected. That stimulation of the gut could activate key neuronal circuits that are underlining our gut feelings in the brain. And then in the last few years, we have a new player. Gut microbes; what we call the microbiota. These are potentially the master drivers along this neural communication highway. We have far more bacteria in our gut than we do cells in our body. And what we’re beginning to appreciate is that these bugs could be the culprits in how you feel when someone is bugging us.
For the most part we get these bacteria as we are born, as we’re being delivered through the birth canal of our mothers. If we were born by c-section, our bacteria are different. It comes from the hospital or the skin, and there are many other factors that influence the composition of the bacteria in early life. Factors such as infection, mode of food provision (bottle fed or breast fed), stress and antibiotic use. All of these could impact on how the gut bacteria could then influence the brain. And what we’re realizing is that there is a lifelong symbiotic relationship occurring between the bacteria and host. These bacteria have a vast array of genes that can encode for hundreds, if not thousands, of chemicals, and many of these chemicals can impact brain function.
The Gut Brain Connection
The bacteria in our gut are like little factories producing key neural transmitters, like GABA, Norepinephrine and Dopamine. Our brain is predominately made up of fats, and the fatty acid composition of our brain is altered by the metabolic activity of these bacteria. We are beginning to appreciate, that bacteria could play a role in maintaining homeostasis. We have shown, for example, in animals that if you’re stressed in early life that this will be a signature in your microbiota all the way into adulthood and that this is common with changes in behavior and physiology.
The Study of Psychobiotics
It tells us that bacteria composition early in life is needed for normal brain development. And that perhaps, an imbalance might be a predisposing factor for a number of brain disorders. Also, what this gives credence to is the concept of probiotics. These are bacteria with health promoting effects. Could we have bacteria that have positive effects on mental health? This is an area we call psychobiotics. The field is still very new, and we’re still a long way from determining the exact profile of what the ideal psychobiotic is.
Does This Translate to Humans?
It’s still very early days but there are some promising signs. A 2011 study from France showed that when healthy volunteers took two different types of bacteria, they were able to reduce their baseline anxiety levels. A more recent study from UCLA last year using human brain imaging showed that bacteria could dampen down a network involved in integrating the emotional aspects of gut brain signaling.
In the 20th century we focused on killing microbes with antibiotics. Over the last number of years, we have really appreciated that microbes have so much benefit, and their power can be harnessed in both health and disease. Perhaps the secret to our own happiness may not lie in the self-help section of the local bookstore but maybe within, in your microbiome. And that your state of mind may be dependent on your state of gut.
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