The Sensitive Gut

Understanding IBS

The heart (and the gut) know their reasons, that reason cannot tell


Last night, it was so warm and humid, I left the window open, but by morning the temperature had dropped and shards of rain rattled against the skylight. Half an hour later the rain and wind had dropped. I trotted to the river, stopping every so often when I felt the pain in my knee. Down on the riverbank, it was warm enough to relax into a half hour’s yoga, but afterwards, while swimming upstream, a fierce squall ruffled the water into wavelets and the large raindrops pockmarked the surface with bubbles. The wind tugged at the waterproofs of the walkers beside the river as they hurried to reach the car park, but I just lay on my back and drifted downstream unencumbered by such practical considerations. Then, as I clambered up the bank, the sun appeared through a gap in the clouds and felt warm on my skin while I towelled, dressed and ran back home.

The weather is a complex system. It can change moment by moment. Meteorologists may understand the bigger picture: the turbulence caused by the earths rotation and the differences in air temperature between the poles and equator, the precipitation produced by changes in temperature and pressure, climatic changes due to industrialisation, but there are also myriad of local conditions that influence what we experience as ‘weather’.

The way our body feels and reacts is a similarly complex system. It also changes moment by moment for reasons that are not always obvious. This was illustrated by a recent demonstration of heart rate variability by Dr Alun Watkins at a recent conference I attended on ‘Gut-Brain: Heart-Brain’. Dr Watkins clipped a heart rate sensor to the ear lobe of a member of the audience and connected it to a computer so that a profile of heart rate, calculated from beat to beat variability, was projected onto the screen. Thus, we could all see how responsive the heart is to moment by moment changes in attention, concentration and emotion. Whenever Dr Watkins engaged his volunteer in conversation, the rate increased. If he asked her to do a simple arithmetical problem, it shot up even higher, but when he ignored her and addressed the audience, it settled back down to a steady rate unless he mentioned something that affected her, whereupon it increased again. Such graphical depiction of moment by moment changes in emotional tone might be a useful aid to psychotherapy offering both therapists and their clients hard data that might be related to thoughts and feelings and supporting observations on skin colour, involuntary moments, bowel sounds or facial expression.

It is not only the heart that shows such fluctuations. No biological system is ever stable. The electrical activity of the brain, the motility of the gut, the rates of intestinal absorption or secretion, muscle tone, skin conductance, pulses of hormone secretion, the activity of the immune system, blood flow to individual organs, blood pressure and every other bodily parameter change all the time according to how situations, events, memories and thoughts affect components of the autonomic nervous system. This would explain why, in people with IBS, spasms of abdominal pain, an episode of bloating or an urgent need to defaecate might occur for no obvious reason. A certain context or encounter may have no conscious significance, but the body remembers and takes note, marking it with the appropriate symptom.

If such physiological changes can occur moment by moment, consider what a devastating effect a long lasting traumatic experience such as abandonment, bereavement, neglect or abuse can have on all aspects of bodily function. Trauma stimulates the emotional/bodily centres in the brain stem while shutting down the modulating effect of the prefrontal cortex. This not only stimulates the heart, causing rapid heart rate, disturbances in rhythm and even sudden death, it can wrench the gut out of kilter, dysregulate the immune and endocrine systems, cause prolonged pain and bowel upset and much, much more. And even when it is over, anything that triggers the unconscious body-memory of what happens can rekindle the same effects. ‘The heart has its reasons that reason cannot tell’. And so does the gut, the immune-system, the endocrine system, the lungs and even the vestibular organ of balance. Dr Watkins asserted that the heart is more responsive to more positive or exciting emotion while the gut is more responsive to more negative emotion. I am not sure about the evidence for that statement, though it might fit other observations: the dorsovagal ‘despair and collapse system’ has more connection to organs below the diaphragm than above it and heart metaphors are invariably positive and relate to courage and love while gut metaphors mostly negative, and connote fear and depression.

The unconscious nature of such reactions does not mean that we just have to put up with what happens without insight or control. Just as we might wind up our physiological reactions by despair or panic, we can gain insight and alleviate them by steady deep breathing with prolonged expiration, yoga, self hypnosis, tapping on acupressure points or any one of a range of ‘mindful’ activities. These can cause the heart rate to stabilise in a rhythmic pattern, synchronous with respiration, calming the emotionally reactive centres in the brain stem (The Chimp Brain), and allowing the associative and cognitive prefrontal cortex to come back on line. In this way, triggers can be recognised and control established. Dr Watkins claims that if we can regulate our own physiology, we can control our emotions, optimising the way we think, our behaviour and the way we function in the world. He and his team use coherence training to help employees in financial and other organisations to maximise their effectiveness and leadership potential.

While Buddhists and Masters of Yoga have known for thousands of years that stabilising and regulating our own physiology can optimise our emotions, thinking, behaviour and effectiveness in the world, Dr Watkins has instrumentalised this and made it relevant to a fraught, modern world. I found his presentation a little slick and low on detail and evidence, but his message seemed sound and bridged the gap between tradition and contemporary neuroscience.

While this post is about brain heart and brain gut interactions, it does not deny or ignore the effects of other systems on the function of organs and the expression of symptoms. Other posts in this blog have tackled  the effects of diet, the microbiome, the immune system, infection on the gut. The gut, like other organs, is a complex system involving the interaction many influences. Gastroenteritis, traumatic events, allergy, depletion of the microbiome can all make the gut more sensitive and reactive to the effects of certain meals as well as the moment-to-moment fluctuations in mood. Moreover, both illness in the gut and trauma in the outside world (or contextual associations with previous trauma) trigger emotional reactions and gut symptoms and cause the prefrontal cortex to go off-line.


Notwithstanding the vicissitudes of weather, I have found slipping into cold water first thing in the morning, cools and stabilises my restless brain and stimulates positive thoughts that often seem to fuel another day of writing. Whether the results makes any sense, I could not possibly comment.

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