Unlocking mental health: Nourishing the gut‑brain connection

- Gut health is crucial for our well-being because the gut microbiota affects the functioning of the nervous system and influences mood, memory, concentration, and stress-coping abilities. One mechanism of this interaction is the communication between the gut and the brain via the vagus nerve, which acts like an "information superhighway."

Additionally, a healthy microbiota supports the production of substances beneficial to the brain and helps reduce inflammation, which results in better well-being, more energy, and more restful sleep. Conversely, imbalances in the gut, such as dysbiosis, can lead to fatigue, irritability, or low mood, says Joanna Marciszewska, a clinical dietitian.

The gut thus plays a key role in the body's functioning regarding digestion and mental health. The production of neurotransmitters such as serotonin largely takes place in the digestive system – as much as 95% of this "happiness hormone" is produced in the gut.

The gut-brain axis, in turn, is a mechanism that enables two-way communication between these two organs. This means that gut disorders can affect mental health, and conversely, stress or fatigue impacts the condition of the gastrointestinal tract.

The gut microbiota, a complex ecosystem of microorganisms residing in our intestines, is crucial for emotional balance. It regulates the production of serotonin and dopamine, which are essential for our well-being. An improper composition of the microbiota can lead to various problems, from anxiety to depression.

Microbiome imbalances can result in both a deficiency and an excess of serotonin in the gut. A deficiency is associated with a low mood, while an excess can cause anxiety, restlessness, and even hallucinations. A similar phenomenon applies to dopamine – its deficiency in the brain can lead to symptoms resembling Parkinson's disease, while an excess triggers anxiety and depression.

Thanks to the gut-brain axis, the intestines significantly impact the brain. If microbiota disturbances occur, for example, due to stress, poor diet, or antibiotics, they can affect the functioning of the nervous system in various ways—from inducing inflammation to disrupting neurotransmitter production and weakening the gut barrier.

Moreover, a lack of balance in the microbiota can affect the production of important mood-supporting substances like short-chain fatty acids or the absorption of the serotonin precursor, tryptophan. Furthermore, there is a growing body of research on psychobiotics, probiotics that support mental health, including helping to reduce depressive states, explains Joanna Marciszewska.

Studies indicate that inflammation in the intestines may be one of the key factors triggering depression. Chronic inflammation, caused partly by increased permeability of the gut barrier, leads to immune system activation. A leaky gut barrier allows undigested food components to enter the bloodstream, triggering an inflammatory response. People with depression often show higher levels of pro-inflammatory cytokines and increased activity of T lymphocytes and other immune cells. These phenomena can lead to brain changes characteristic of depression.

- We are learning more about the relationship between the gut and the development of depression, anxiety states, and, broadly speaking, the deterioration of mental health. Several mechanisms play significant roles. For example, disturbances in gut microbiota, or dysbiosis, can reduce serotonin production, contributing to depression or anxiety. Our gut microbes also affect other neurotransmitters, such as dopamine and gamma-aminobutyric acid (GABA), which play a crucial role in regulating emotions.

Disrupting these also affects the deterioration of mental condition. Intestinal permeability, associated with poor quality of the gut microbiota, can allow toxins and undigested food molecules to enter the bloodstream, causing chronic inflammation. Inflammation in the body is associated with elevated levels of pro-inflammatory cytokines like IL-6 (interleukin-6), which can negatively affect brain function, lowering mood and increasing the risk of depression, says Magdalena Klimczak, a clinical dietitian.

Mood disorders can both precede and accompany gastrointestinal diseases. Depression can be not only a result but also a cause of gut problems. An example is SIBO (small intestinal bacterial overgrowth), where mood disorders are common. Researchers observe similar connections in the case of inflammatory bowel diseases, such as Crohn's disease or ulcerative colitis.

Canadian research from the University of Calgary conducted on a sample of nearly six million people found that individuals with episodes of depression were more likely to develop these diseases. Although the mechanisms underlying this relationship are not yet fully understood, there are indications that gastrointestinal disorders may be a triggering factor for depression.

Proper dietary habits can significantly alleviate symptoms of depression. The Mediterranean diet, which supports gut microbiota balance, is at the forefront, positively affecting mental health. Experts agree – such an eating pattern can reduce the risk of depression, highlighting the importance of diet in maintaining well-being.

- To take care of your microbiota, it is worth incorporating fatty fish, such as salmon or mackerel, as well as flaxseeds, walnuts, and chia seeds, which provide omega-3 acids that support microbiota and reduce inflammation. Berries, pomegranates, dark grapes, and vegetables like broccoli and spinach, which provide fibre and polyphenols, are also beneficial. Fermented foods, natural yoghurt, and kefir are very valuable natural probiotics that positively impact microbiota diversity, lists Joanna Marciszewska.

- It is also worth eating nuts and seeds supporting gut health. Natural supplements for the intestines can include psyllium, which supports the growth of beneficial bacteria and regulates bowel movements. Additionally, she adds that to improve gut health, especially under stress, it’s worth considering introducing probiotics that help restore microbiota balance and support gut-brain communication.

Consuming fibre (vegetables, fruits, whole grain products), fermented products (e.g., kefir, buttermilk, pickles, natural yoghurt), and products rich in prebiotics (e.g., garlic, onions, bananas, asparagus, chicory) is essential. When it comes to supplements, vitamin D3 and omega-3 acids are paramount. Additionally, appropriately tailored probiotic therapy, customised to our needs, is valuable, concludes Magdalena Klimczak.