Most of us know (and feel) how the brain can affect our gastrointestinal tract. From getting ‘butterflies’ when facing a nerve-wracking task, getting the runs when we’re anxious, or feeling stomach pains when stressed – there’s no question that our emotions and state of mind can trigger different reactions in our gut.
However, what’s often misunderstood (or not considered at all) is the way communication between the gut and brain, actually works both ways. Gastrointestinal problems can be a symptom of mental distress, but at the same time, gastrointestinal problems can influence the brain – in some cases contributing to stress, depression or anxiety1.
New meaning to ‘gut feeling’
The biochemical and physical communication network that exists between the entire gastrointestinal tract and the brain, is known as the gut-brain axis. While there are about 100 billion neurons in the brain, we also have over 100 million in the walls of our gut2. This communication network is known as the enteric nervous system (ENS) – and it runs all the way from the esophagus to the rectum. While its primary function is to control the entire physical digestive process, it also communicates with the brain via the central nervous system.
The vagus nerve, one of the biggest nerves in this gut-brain axis, is able to transmit signals both ways. Some studies have shown that stress can inhibit the function of the vagus nerve – which in turn, inhibits the function of the gut, resulting in problems like indigestion and discomfort3.
Gut health and brain health
Signals can also be sent between the gut and brain through chemical neurotransmitters. While different feelings and emotions emanating from the brain produce neurotransmitters, the cells and microbes in the gut can also produce neurotransmitters such as gamma-aminobutyric acid (GABA) which helps to control fear and anxiety4.
This means the microbial bacteria in the gut can negatively or positively affect brain health – so by extension, eating foods that contain, or encourage the growth of, good gut bacteria can have an impact on our brain function and hormones in our bodies5. For example, high-fibre foods that are good for the gut, have been shown to reduce stress hormone in the body, while some fermented foods actually cause changes in brain activity.
What the gut-brain axis means for IBS patients
While it was long thought that anxiety and depression exacerbated symptoms of irritable bowel syndrome (such as bloating, constipation and diarrhea) new research has shown that functional problems in the gut can send signals to the brain that trigger anxiety and depression6.
This is why better understanding of the gut-brain-axis is key for the treatment of IBS. Simply treating the physiological symptoms in isolation is often not as effective as an integrated approach that includes relaxation therapies, and/or depression and anxiety treatments7.
The functional medicine approach
The intrinsically connected nature of the gut and brain means that treatments that benefit one, can also benefit the other. This is fundamental to the approach we take in functional medicine. We seek to understand the physiological, lifestyle and environmental factors that contribute to your overall health – understanding that each patient is unique and each combination of symptoms requires a tailored treatment approach.
1, 6 The Brain-Gut Connection. John Hopkins Medicine.
2, 3, 4, 5 The Gut-Brain Connection: How it Works and the Role of Nutrition. Healthline. 2018.
7 The gut-brain connection. Harvard Health Publishing.