How many times did you feel too stressed to eat, or felt nauseous before an exam or presentation? Ever had a “gut-wrenching” experience? That’s because the gastrointestinal system is extremely sensitive to emotions like sadness, anger, anxiety and stress, which can trigger symptoms in the gut.
Psychosocial factors influence the actual physiology of the gut as well as symptoms which means that stress or depression/sadness can affect movement and contractions of the gastrointestinal tract and make inflammation worse. The health of the gastrointestinal system is extremely important to our overall well-being as it’s responsible for the functioning of digestive and immune systems. Plus, beneficial bacteria have the capability of affecting the body’s vitamin and mineral absorption, hormone regulation, digestion, vitamin production, immune response, toxins elimination and mental health.
This connection between brain and gut goes both ways, so digestive symptoms can be the products of feeling stressed, anxious, sad but also the root of the feelings.
The gut is connected to the brain via the vagus nerve which extends from the brain stem down into the neck, thorax and abdomen, the enteric nervous system and the gut-brain axis. The Enteric Nervous System or ENS, also called the “second brain” is the millions of nerve cells that line the gastrointestinal tract. It can operate autonomously and communicate with the central nervous system through the parasympathetic nervous system (responsible for rest and digest function) and sympathetic nervous system (responsible for fight and flight responses). The main role of the ENS is to control digestion, motility of the gut, local blood flow, mucosal transport and secretions and modulate immune and endocrine functions.
The gut-brain axis is a bidirectional communication between the central and the enteric nervous system, linking emotional and cognitive centres of the brain with peripheral intestinal functions. Gut microorganisms (our intestinal flora) can activate the vagus nerve and play a critical role in mediating effects on the brain and on behaviour so the gut can send and receive signals to and from the brain. So it’s no surprise that medical conditions associated with changes in mood, such as irritable bowel syndrome (IBS) and chronic fatigue syndrome (CFS), might also be related to gut microbiota. IBS, for example, is often worsened by stress and sufferers often deal with depression and anxiety.
Usual symptoms of gut disorders or digestive issues are bloating, gas and abdominal pain but they can also present as less obvious ones such as headaches, fatigue, joint pain, and immune system weakness.
So does the health of the digestive system and gut microbiome really affect our mood and feelings?
It certainly seems so.
We all have numerous beneficial and non beneficial bacteria in our gut that usually live in harmony. But when there is an imbalance between beneficial and harmful ones it can results in gut dysbiosis which happens when too many “bad” bacteria, yeast and parasites overpower the “good” ones. This can cause digestive discomfort, fermentation, bloating and with time damage to the mucosal layer of the gastrointestinal tract that becomes more permeable allowing bigger molecules and toxins to enter the blood-stream. This activates the immune system that detects unwanted compounds causing an inflammatory response, gastrointestinal symptoms, sensitivities to certain foods but also symptoms in other systems and tissue of the body.
When the gut is irritated, inflamed, damaged, the ENS sends signals to the body’s central nervous system which can then trigger changes in mood and with time may even affect memory and concentration.
Plus, the gut microbiome is mainly responsible for the production of serotonin and dopamine, as more than 90% of serotonin is found here. Serotonin is essential to regulate gut motility and function but it’s also called the “feel-good hormone”. This neurotransmitter contributes to promote feelings of wellbeing and relaxation. So a change in our intestinal flora towards more pathogenic bacteria or having a limited variety of microbes due to diet and lifestyle, will definitely have a negative effect on how we are feeling and contribute to anxious states and feelings of sadness and low mood.
Even though more studies need to be done to demonstrate the effects of gut support and probiotics on the brain and mental wellness, the evidence so far seems to make us think that a healthy gut microbiota is linked to a healthy brain. The type of food and variety of nutrients that our body obtains, absorbs and processes can have a huge positive effect on the functions of the brain and body. Definitely pay more attention to how certain foods or ingredients affect not only your digestion but your mood and state of wellbeing after eating. Focus on having a varied diet filled with different vegetables, fruits, whole grains, legumes to feed your beneficial flora so it can thrive, function at its best and positively affect body and mind.