Gut microbiota, neurotransmitters, and brain health

Understanding the link between the gut microbiota, neurotransmitters, and brain function unlocks exciting possibilities for mental well-being. This article uncovers the fascinating ways our gut microbiota influences key neurotransmitters and what that means for our mental well-being. Dive into the molecular dialogue between the gut and brain that’s shaping the future of mental health.

Microbiota gut-brain axis

The gut-brain axis is a communication network linking the gut and brain. A key player in this system is the vagus nerve that runs from the brainstem down through the neck, chest, and abdomen. This nerve transmits signals between the brain and the gut, with the gut’s own neural network playing a vital role.

This so- called enteric nervous system is influenced by microbes and for that reason we are now referring to this communication network as the microbiota-gut-brain axis. Microbes produce neurotransmitters and gut hormones, as well as compounds like short-chain fatty acids (SCFAs) and bile acids. These molecules are all signalling molecules that travel to the brain through the bloodstream, nervous system, and immune system. In turn, they can stimulate processes that affect gut cells and immune function, but also brain function. These interactions help maintain gut health, strengthen the gut barrier, and reduce inflammation, ultimately supporting both digestive and mental well-being.

Neurotransmitters, the brain’s chemical messengers

Neurotransmitters are the brain’s chemical messengers that enable communication between nerve cells (neurons) and regulate mood, cognition, behaviour, and stress responses. Each neurotransmitter plays a distinct role in brain function, influencing mental well-being and overall health. Disruptions in their production, release, or reuptake can lead to psychological and neurological disorders.

Balancing the brain: excitatory versus inhibitory neurotransmitters

There are two main types of neurotransmitters: excitatory (e.g., glutamate and dopamine) and inhibitory (e.g., gamma-aminobutyric acid (GABA) and serotonin). Excitatory neurotransmitters increase the activity of neurons, stimulating signals that promote alertness, motivation, and learning. In contrast, inhibitory neurotransmitters decrease neural activity, helping to calm the brain and regulate mood, sleep, and stress responses.

Gut microbiota and neurotransmitters

The exact ways in which gut microbes affect neurotransmission in the brain are still being studied. However, they influence neurotransmitter levels by producing or breaking them down, altering their availability, or affecting their transport. Let’s explore how these microbes impact key neurotransmitters and, in turn, brain function.

Serotonin

Serotonin is a key neurotransmitter affecting mood, digestion, and well-being. About 90% of the body’s serotonin comes from enterochromaffin cells, which are specialized neuroendocrine cells found in the lining of the gut.

Gut microbes can influence serotonin signalling in several ways. Some species stimulate serotonin release from enterochromaffin cells. Others affect the availability of serotonin and its precursor tryptophan, by steering it through different metabolic pathways. When the microbial balance is disrupted, this process can be altered, impacting both digestion and mood.

Dopamine

Dopamine serves multiple functions in the body. In the brain, it helps regulate mood, boosts motivation, and controls movement. In the gut, it supports digestion, blood flow, and immune responses. Although some gut bacteria can produce dopamine, the dopamine released via this route cannot cross the blood-brain barrier. The brain primarily produces its own dopamine, using precursors such as the amino acids tyrosine and phenylalanine. Similar to serotonin, gut microbes can influence dopamine-related brain functions by modulating the availability and metabolism of these precursors. They can also alter neurotransmitter-related enzymes and affect gut-brain signalling through the vagus nerve and immune pathways. This indirect regulation may impact mood, cognition, and even neurological disorders like Parkinson’s disease.

Glutamate

Glutamate is a key neurotransmitter that stimulates neurons and supports learning and memory. Its levels must be carefully controlled, as excess glutamate can lead to overstimulation and neuronal cell death, contributing to conditions like Alzheimer’s and other physiological and psychological symptoms. It exists in two forms: L-glutamate (L-Glu), the active form in the brain, and D-glutamate (D-Glu), which is less common and not typically involved in brain signalling. Certain gut microbes can convert L-Glu into D-Glu, which can then be transformed into GABA, the brain’s main calming neurotransmitter. By influencing the balance between glutamate and GABA, gut microbes may play an important role in regulating brain function and overall mental health.

GABA

GABA is a neurotransmitter that plays a crucial role in promoting relaxation and maintaining emotional balance. Certain gut microbes, like Lactobacillus and Bacteroides strains, produce GABA and may influence brain function through the gut-brain axis, supporting relaxation and emotional resilience. Since GABA is synthesized from glutamate, GABA-producing bacteria also absorb glutamate, helping to reduce excitatory signals in the brain. Additionally, bacteria like Akkermansia muciniphila help keep the gut lining strong and reduce inflammation. This creates a healthy environment that supports the balance of brain chemicals like GABA and glutamate, which are important for mood and mental clarity.

Pro-and prebiotic interventions

Probiotic and prebiotic interventions support the microbiota- gut-brain link, with growing evidence that certain strains of probiotics can modulate neurotransmitter activity. These effects are reflected in studies showing improved emotional processing (Bagga, 2018a, 2018b), reduced depression vulnerability, and enhanced cognitive performance (Chahwan, Steenbergen, Dantas). While outcomes may differ depending on factors such as probiotic strain, dosage, and duration of treatment, the growing body of evidence highlights the potential of probiotics to modulate neurotransmitter systems. This opens up exciting possibilities for developing microbiota-based therapies to support mental health and emotional well-being.

Conclusion and future perspectives

Understanding the gut’s role in neurotransmitter regulation reveals its profound influence on mental well-being. Beyond life experiences and genetics, the microbiota actively shapes mood, cognition, and stress responses. When disrupted, it may silently contribute to anxiety, low mood, or even clinical depression, reshaping our perspective on mental health.

Recognizing this gut-brain connection could transform mental health care, shifting the focus toward prevention and comprehensive treatment. That’s why at Winclove, we are passionate about exploring the science of microbiota- gut-brain communication and transforming research into evidence-based solutions. By collaborating with partners in areas like mood, depression, cognition, and autism, we strive to advance knowledge and innovation that enhance mental well-being and improve quality of life worldwide.