Story at a glance
In our previous blog we discussed the scientific discovery of the second brain, not located in your noggin where you’ll find your first brain, but oddly, in your gut. The lining of the gut with its complex network of neurons and neurotransmitter exchanges incredibly mimics the same neural functioning as the brain. It’s this similarity of function that allows the brain and the second brain to communicate with each other. But it’s more than simply the communication between these brains that’s important. The health of your gut and the mental and emotional health of your brain appear to be intimately linked.
Which brings us to the absorption and nutrition level of what goes on in your gut. The gut is now seen as shifting away from simply being about digestion and is being looked at as a key player in regulating inflammation and immunity. We’ve previously looked at elements of this in our book review blog on the book Grain Brain regarding gluten and inflammation.
We’ve heard about good intestinal flora, that is good bacteria, or in science terms, gut microbiota. A normal gut has a diverse range of bacteria, which maintains wellness. A shift away from the normal gut micorbiota is called dysbiosis, and it’s dysbiosis that we think may contribute to disease. The development of this has scientists studying microbiota to help understand the nature of gastrointestinal, autoimmune and even brain disorders.
The conversation between the gut and the brain runs two ways. They use a complex system involving the endocrine, immune and neural pathways. Whilst research is still somewhat rudimentary, it is appearing more and more like the link between the brain and the gut is a single system, both working together, rather than two separate systems.
Given how closely the brain and gut interact, there seems to be a link between how psychosocial factors can trigger symptoms in the gut. That is, people who are upset, or suffering from stress, present with gastrointestinal disorders, such as inflammation, pain and other GI tract or bowel symptoms. These are commonly referred to as functional gastrointestinal disorders (FGID). FGID’s are some of the most frequent clinical conditions seen in GP clinics. Up to 60% of these patients are also suffering from psychosocial problems. These patients display an increase in symptoms when they are stressed, they have mild anxiety or depression and the predominant bowel symptom is abdominal pain and diarrhoea. Psychotherapy has shown that it is superior to conventional medical therapy in treating FGID’s (1). It’s an interesting observation that by treating the mind, there’s an ability to heal the gastrointestinal orders. This new link between the brain and the gut may explain why a person suffering from stress negatively impacts the health of the gut.
But it’s not a one-way street. Poor gut health has been implicated in neurological and neuropsychiatric disorders. Multiple sclerosis, Parkinson’s, autistic spectrum disorders may all be potentially related to pro-inflammatory states elicited by gut dysbiosis – microbial imbalances inside the body. Our understanding of this complex interdependency between the brain and the gut is only just starting to shed light on many different disorders. Research is now suggesting that depression is an inflammatory disorder mediated by poor gut health. There’s also been connections made between age-related gut changes and Alzheimer’s disease. In fact, multiple animal studies have shown that manipulating the gut microbiota can produce behaviours related to anxiety and depression (2). If we can cause anxiety by messing around with the bacteria in our gut, then the opportunity to reduce anxiety by improving the state of our gut is revolutionary.
It appears that good mental health is linked to good gut health and vice versa. Your diet, and the microbe health of your gut impacts not only your mood and neurological abilities, but our cognitive functions may be linked too. With so many neurons, hormones and chemicals running between our brain and gut, it’s yet another reason to be ever vigilant about what it is we put in our mouths to nurture our bodies and our minds. An apple a day may well do more than keep the doctor away!
(1) [Psychotherapy in somatic diseases–for example gastrointestinal disorders]. Moser G. Psychiatr Danub. 2007 Dec;19(4):327-31. German
(2) Maes, Kubera, Leunis, Berk,J. Affective Diorders, 2012 and Berk, Williams, Jacka, BMC Med, 2013