We investigate the incredible link between your brain and your gut.
While it's long been known that your mental health can have a big impact on digestive conditions like Irritable Bowel Syndrome (IBS), it's only recently that we've begun to understand the incredible link between your brain and your gut.
In this guide, we'll lift the lid on this fascinating subject and explore some of the unbelievable ways in which your brain and gut interact.
The Second Brain
The connection between the mind and the digestive system is something we seem to understand instinctively. After all, the English language is full of references to it â€“ when you have a â€˜gut feeling' about something or have â€˜butterflies in your tummy', for instance.
But recent research has begun to shed light on just how accurate these sayings actually might be.
Your digestive system is home to a complex community made up of untold billions of microorganisms, collectively known as â€˜microbiota' or â€˜gut flora'. This community even enjoys the use of its own neural network, known as the enteric nervous system (ENS) and is often referred to as â€˜the second brain'.
While it can't write a sonnet or solve intricate mathematical equations, through its complex interactions with the rest of our body, the ENS can have an unbelievable impact on our mood, general health and even the way in which you think.
It communicates with the rest of the body through hundreds of millions of neurons and scientists now believe much of this communication may be two-way â€“ with your microbiota having a huge influence on your mental state.
How the Brain and Gut Interact
It's long been known that your gut bacteria have their proverbial fingers in many different physiological pies â€“ from metabolism and digestion to allergies and the immune system.
But some incredible research now suggests your gut flora may also play a crucial role in a range of psychological issues, like brain development and stress responses. They produce neurotransmitters and there's growing evidence that they can influence our moods and behaviour.
We're colonised by gut bacteria within the first few days we're alive and they're with us from cradle to grave. John Cryan, professor of anatomy and neuroscience at University College Cork, found that in mice at least â€“ the diversity of gut bacteria was profoundly reduced in those subjected to early-life stress.
â€œIf you don't have microbiota you have major changes in brain structure and function, and then also in behaviour, he told the BBC.
Similarly, Japanese researchers found that mice that were raised without any gut bacteria showed a heightened response to stress, which was subsequently reduced by introducing a type of symbiotic bacteria.
Cryan went on to replicate this effect in regular mice, feeding them a common type of bacteria and demonstrating a reduction in both stress responses and anxiety-related behaviours.
Another study attempted to alter the composition of gut flora using probiotics and examine the effects on participant's brains using magnetic resonance imaging (MRI). Twenty-five subjects were examined, with 12 eating yogurt two times a day and the rest standing as a control group.
Two weeks later, the participants were once again put under an MRI and when compared to the control group â€“ those who'd eaten yogurt reacted more calmly when shown a series of pictures of facial expressions, ranging from sadness to anger and so on.
The researchers suggested this could be due to the yogurt altering the makeup of the participant's microbiota, causing the production of compounds that altered their brain chemistry.
According to a systematic review of the available research to date from 2013, which mainly focused on animal testing, the reach of microbiota in brain function was widespread.
â€œKey findings show that stress influences the composition of the gut microbiota and that bidirectional communication between microbiota and the central nervous system influences stress reactivity. Several studies have shown that microbiota influence behaviour and that immune challenges that influence anxiety- and depressive-like behaviours are associated with alterations in microbiota, said the authors.
Gut Flora and IBS
In 2012, Collins et al. attempted to explain how the interplay between gut flora and the brain could influence a wide range of diseases, including IBS and various psychiatric disorders.
They noted that stress has been demonstrated to influence several important gut functions, including motility (the movements of the digestive system), the secretion of various compounds and the composition of tissue in the gut â€“ changing the habitat of the bacteria and altering both their makeup and activity.
It's highly common for those with IBS to also suffer from mental health issues, most commonly anxiety and depression. This can be something of a chicken and egg situation though, and it's easy to understand how the unpleasant symptoms associated with the condition could easily make someone feel very upset and anxious, especially about dealing with the condition when out and about.
Whatever the correlation, it's clear that the relationship does exist and why so many IBS sufferers have reported improvements in their condition after undertaking a course of Cognitive Behavioural Therapy, employing relaxation techniques like yoga and even being prescribed antidepressants.
If you've got any questions about the relationship between the brain and the gut, or experiences you'd like to share about mental health and IBS â€“ leave us a comment below, or get in touch via Facebook or Twitter, we always love to hear from you.
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