The gut and the brain are intricately connected through the gut-brain axis, a communication system that involves the nervous system, hormones, and the immune system. The brain and gut are connected by the vagus nerve, which sends signals between the gut and the brain, influencing mood, stress response, and digestion. Studies have found that the gut microbiota could influence the brain and mental health in several ways, such as microbial regulation of neuro-immune signaling, microbiota-mediated tryptophan metabolism, microbial control of neuroendocrine function, and microbial production of neuroactive compounds.The gut also produces neurotransmitters like serotonin, responsible for regulating emotions, making gut health crucial to mental well-being.
Mental health is a topic we hear brought up a lot, especially as we transition into the colder, darker months of the year and we are forced to adapt. Many factors can influence our mental health, such as work-life balance, home environment and diet but also, surprisingly, our gut. Over 40 million adults, roughly 19.1% of adults in the US struggle with an anxiety disorder and most even develop symptoms before the age of 21. Surprisingly, people with digestive disorders have a higher risk of depression and anxiety and these mental conditions could actually be independent predictors of the severity of certain digestive symptoms, such as diarrhea and other gastrointestinal disturbances. The intestinal tract is the largest micro ecosystem in the human body. There are trillions of bacteria living in the human intestinal tract, which collectively contain more than 100 times the genomic DNA of humans, and its role in influencing our mental well-being cannot be overstated.
Anxiety can manifest in various ways, affecting both the mind and body. Common symptoms of anxiety include constant worry or fear, irritability or restlessness, fatigue or muscle tension, upset stomach, nausea or digestive issues and more. Research shows that the prevalence of psychiatric disorders, including anxiety and depression are significantly higher in an Irritable Bowel Syndrome population compared to the relative general adult population, with increased intestinal permeability being a possible culprit. Within our GI tract, the enteric nervous system (ENS) has millions of nerve cells and is believed to affect motivation and cognition as well as trigger big emotional shifts in individuals experiencing Irritable Bowel Syndrome. Signals sent from nerves embedded in the GI tract may send irritation signals to the central nervous system that can induce mood changes. The GI tract can also place stress on the microbiota by releasing certain cytokines, such as TNF-alpha, MCP (monocyte chemoattractant protein) and neurotransmitters, which in turn correlate with symptoms of anxiety. This release is what causes the intestinal permeability of the blood-brain barrier, enhancing the detrimental effects of the molecules, followed by exaggerated systemic response to external stimuli such as stressors.
It’s surprising to learn about the connection between diet and mental health, as highlighted by expert insights. Here, we feature Dr. Uma Naidoo, the MoodFoodMD, a Harvard trained nutritional psychiatrist, professional chef and nutritional biologist, instructor @ MasterClass and author of “Calm your Mind with Food”,and the national & international bestseller: “This is Your Brain on Food.”, who shares valuable information on how nutrition impacts mental well-being. Nutritional psychiatry refers to the use of healthy whole foods and nutrients to improve your mental well being, not excluding the use of supplements, prescription medications or very important forms of psychotherapy. Here, Dr. Uma Naidoo discusses the crucial yet widely overlooked “mood food connection.”
One mechanism that explains this mood food connection is the gut brain connection. A healthy gut is a happy and calm mind. When the gut microbiome is disrupted by conditions such as inflammation - this impacts our mental well being. One important factor that can cause inflammation is the food that we eat.
Using food as a tool to improve mental-wellbeing is significant as well as accessible. Dr. Naidoo claims “--it is important to also intentionally avoid more inflammatory foods that can trigger aspects of poor mental fitness such as anxiety, brain fog and fatigue.”. However, what are these inflammatory culprits? “--such foods include processed seed oils like corn and soybean found in many fried or processed foods, added or refined sugars found in soda and baked goods, processed wheat producers like white bread and pasta, and excess alcohol.”
Dr. Uma Naidoo highlights that by recognizing the "mood food connection," we can use nutrition strategically to enhance mental well-being, while being cautious of foods that may contribute to inflammation and affect our mental health.
Depressive disorders are characterized by neuroplastic, organizational changes, and neurochemical dysfunction. What does this mean? Essentially, those cytokines that are released stimulate the hypothalamic-pituitary-adrenal (HPA) axis. The cascade that ensues includes the release of corticotropin releasing factor, which then stimulates the release of adreno-corticotropic hormone (ACTH), further prompting the release of cortisol – our stress hormone that acts as a negative feedback signal resulting in inflammation. Studies show that individuals with depression have higher levels of bacteria Oscillibacter and Alistipes, gram-negative bacteria in people with depression that may explain the contribution of microbiota in development and/or maintenance of depression. Gram-negative bacteria contain lipopolysaccharides (LPS) in their outer cell membrane. LPS interacts with macrophages and stimulates the immune response through the release of pro-inflammatory cytokines, which as we know can cascade into adverse mental health effects.
Further evidence shows that Major Depressive Disorder patients had higher levels of Prevotella, Klebsiella, Streptococcus and Clostridium XI, but lower levels of Bacteroidetes. These organisms are relevant because other studies show that altered gut microbiota could affect the expression of proteins in several tissues related to the gut-brain axis, thereby contributing to the development of depression.
Now that we understand the vital connection that is the gut-brain axis from our recent Jona Journal Blog on Brain Health, and can view it through the lens of mental health, let's see how Jona analysis fits in. When thinking about World Mental Health Day, it’s important to focus on the individual. Measures to promote positive mental well-being are not one size fits all, which is why an analysis is key when dealing with mental health issues. As previously mentioned certain bacteria are hallmarks of differing conditions, such as lower abundances of Bacteroidetes and higher abundances of Actinobacteria being observed in people with depression.Understanding what microorganism resides in your gut can be crucial in identifying, preventing and even improving mental illness. With this understanding, one can make dietary and lifestyle changes that could change the composition of your microbiome. Research states that people with digestive disorders are at higher risk for mental health conditions, so being able to address both digestive and mental health concurrently is crucial. Having continued access to a toolkit of actions to better your gut and in turn your mental health is invaluable.
