Lately, you have probably heard about the gut microbiota. This concept, which a few years ago was practically unknown to the vast majority of the population, is very much on the rise because more and more people suffer from problems related to an imbalance in their microbiota.
In this article we will focus on the connection popularly known as the gut-brain axis. The scientific community has suggested that the gut microbiota could play a vital role in finding treatments for neurodegenerative, metabolic and psychiatric diseases, including stress-related mood disorders such as depression and anxiety.
The gut is considered the most important immune organ in the adult, as it contains most of the body’s immunocompetent cells, and has also been found to be the second most important organ in terms of the number of neurons. This discovery gave rise to the name gut-brain axis.
The two-way communication between the gut and the brain is based on the connection of endocrine, immune and neural networks that serve as a duct for transporting information about the state of function of various organs and the state of health.
In other words, the brain and the gut are interconnected. Recent studies show that there is a link between our gut microbiota and the brain, which is why we can improve mental and brain health, among other interventions, by modulating the microbiota. Not only a poor diet can damage the microbiota, but also the abuse of drugs or an infection can alter the composition of our microbiota and affect this gut-brain axis.
The human gut microbiota consists of bacteria, viruses, fungi, and other microorganisms that reside mainly in the intestines. While some of these microbes are harmful, the vast majority are beneficial and essential for various bodily functions, including digestion, immune response, and the production of vital nutrients.
However, the microbiota’s influence extends beyond just physical health. Through complex interactions with the nervous, endocrine, and immune systems, the microbiota is now believed to have a significant impact on brain function and mental health.
Several studies have shown that imbalances in gut microbiota—often referred to as dysbiosis—are linked to anxiety, depression, and other mood disorders. Researchers found that individuals with depression tend to have a less diverse microbiome, with reduced levels of beneficial bacteria such as Lactobacillus and Bifidobacterium. These bacteria are responsible for producing short-chain fatty acids and neurotransmitters that support a healthy mood.
In animal studies, transplanting gut bacteria from anxious or depressed individuals into healthy mice often results in anxiety-like or depressive behaviors in the mice. This further underscores the idea that our gut bacteria influence how we feel and respond to stress.
The gut microbiota is deeply involved in regulating the body’s stress response. When we experience chronic stress, the gut barrier becomes more permeable—a condition often referred to as “leaky gut”—which allows harmful bacteria and toxins to enter the bloodstream. This can trigger systemic inflammation, which has been linked to mood disorders and cognitive decline.
Conversely, a healthy microbiome can help mitigate the effects of stress by producing anti-inflammatory molecules and regulating the release of stress hormones such as cortisol.
The gut microbiota also plays a role in cognitive processes, including memory and learning. Emerging research suggests that a diverse and balanced microbiota supports cognitive health by producing essential neurochemicals and promoting synaptic plasticity—the brain’s ability to adapt and learn.
In animal models, certain strains of bacteria have been shown to improve memory and cognitive performance. For instance, Lactobacillus rhamnosus has demonstrated the ability to enhance memory in mice, offering potential therapeutic avenues for neurodegenerative diseases like Alzheimer’s.
The microbiota’s influence extends to neurodevelopmental disorders such as autism spectrum disorder (ASD). Researchers have observed differences in the gut microbiomes of children with ASD compared to neurotypical children. While the exact mechanisms are still being studied, it is hypothesized that the gut microbiota may influence brain development and function during critical early stages of life.
Clinical trials have shown that improving gut health through diet, probiotics, or prebiotics can alleviate some behavioral and gastrointestinal symptoms in children with ASD, pointing to a promising area for future therapeutic interventions.
Maintaining a healthy gut microbiota may be key to improving mental well-being. Here are some science-backed strategies to foster a balanced microbiome: