The definition of stress is 'a feeling of emotional or physical tension.' It is a natural response which has been deeply wired within our DNA throughout human history. Consider our hunter-gatherer ancestors being chased by or hunting a wild animal in the middle of the jungle. Such life-threatening situations were 'immediate dangers' that were encountered during their waking days. The body responded by activating the natural fight or flight reaction and the ancestor was ready to run away from the situation or to fight the predator. There was neither no reason nor time to think and to stress about tomorrow's 'immediate dangers' because what really mattered was to be safe and to survive. During such threats, the sympathetic nervous system would trigger the release of stress hormones that would communicate with the autonomic nervous system to increase heart rate, blood pressure and respiratory rate. Everything that was needed to cope in the scenario. Pupils would dilate, skin would be much paler and muscles tense. Non-vital bodily functions such as digestion would slow down and instead, blood would be diverted to more important organs such as the brain and the lungs. These physiological changes were designed to prime the body for action and without such a cleverly designed mechanism our ancestors would not be able to survive challenges and dangers in their tough environment. That being so, stress response is not all bad and has come to our rescue as a species throughout history. Even in our modern times, short bursts of stress are actually beneficial and necessary. Running for a bus or dealing with a difficult encounter is often part of our everyday lives. Whenever this happens, the body is usually capable of returning to its pre-arousal state quickly, without impacting our general health. The problem lies when we are unable to return to the pre-arousal state quick enough, therefore prolonging the stress response; or when we are faced with stressful situations over and over again. Think back to our ancestors and their 'immediate dangers'. Surely, the dangers we encounter nowadays look nothing like they used to thousands of years ago (traffic jams, arguments, existential worries, politics etc.) nevertheless, our fight or flight response to them remains the same. On top of that, reacting to uncertainty about finances, relationships, health or future - something that is unfortunately considered a norm of modern life can also trigger the cycle of similar stress response. Everytime this happens and we activate the sympathetic nervous system repeatedly and over a prolonged period of time, the impact is felt literally in every single organ of the body. A large number of health complications may arise; ranging from insomnia, anxiety and depression to high blood pressure, heart disease, obesity or stroke. In simple terms, our body physiology has not been designed to be exposed to stress hormones as it currently stands and we now see the scale of impact it may have on the development of both acute and chronic conditions. I'd now like to focus on the connection between stress and the gut. Not only because it is fascinating but also because naturally, there has to be a connection between something so extremely important such as the gastrointestinal tract (GI tract) and how we navigate through challenging times in life. Remember ever feeling those ‘butterflies in your stomach' when anticipating something exciting or experiencing abdominal discomfort when finding yourself in an upsetting circumstance? This is because our gut is very sensitive to emotions it feels ( e.g. anger, frustration, excitement etc), and this can set off a variety of symptoms within the GI tract. The brain can send signals to the GI tract, but since this unique relationship works both ways, a GI tract can send signals to the brain as well. As a result, someone's troubled intestine may be the cause OR the result of emotions he/she feels. Scientists call this gut-brain connection the enteric nervous system (ENS), which is essentially a web of hundreds of millions of neurons hidden within the walls of the digestive tract. It is hypothesised that there are more neurons within the ENS than there are in the spinal cord. A normally operating ENS is crucial for a healthy GI tract and an absence from gut-associated symptoms. Since the microbiome within the gut is situated very close to the ENS, it is not surprising that it has the direct ability to impact its functioning and development. The gut microbiome composition is directly influenced by psychological stress. Numerous studies have found that chronic stress can reshape the gut microbiota via complex processes causing bacterial imbalances, intestinal inflammation and intestinal permeability. In one study, couples in a troubled marriage have been found to have a greater gut permeability compared to the couples in a happy marriage. When someone's gut intestinal barrier is compromised, this can result in its permeability which means that bacteria are capable of entering the bloodstream via damaged intestinal wall and produce detrimental inflammatory responses within the body. Weakened gut barrier may further deregulate other body systems such as immune, hormonal or endocrine, fueling more physiological impairment. Although there is powerful evidence to suggest that following a healthy diet (such as Mediterranean diet) can positively alter a microbiome's composition and thus reinforce the intestinal barrier, it is clear that exposure to chronic stress can also undoubtedly influence the microbiome population, bringing about various health complications. That leaves us with a notion that we need to pay more attention to our gut-brain connection and to really appreciate the intestinal microbiota within us. On top of that, having an awareness of how we react in unexpected stressful situations as well as finding our unique ways to cope with demands of life could also be useful.