Learn how the gut-brain axis influences mood, stress, and concentration, and how you can specifically support your microbiome and nervous system with Brainbacs.
The Gut-Brain Axis: BRAIN TO GUT, GUT TO BRAIN
Expressions like “It sits heavy on my stomach,” “I feel sick just thinking about it,” or “Deciding based on your gut feeling” don’t come from nowhere. There is a direct connection between the brain and the gastrointestinal tract, called the gut-brain axis.
But what exactly is the gut-brain axis?
The gut-brain axis is a bidirectional communication system between the brain and the gut, operating through nerve pathways, hormones, immune messengers, and metabolic products of the gut microbiota (Lu et al., 2024).
A central element is the so-called vagus nerve, a kind of nerve highway running from the brainstem to the digestive tract. It extends from the brainstem to the large intestine and sends signals back and forth between the central nervous system and the microorganisms in the gut. Remarkably, 90% of this communication originates from the gut, and only 10% of the signals come from our brain (Dicks, 2024).
The enteric nervous system (ENS), a network of over 100 million nerve cells that permeates the gut wall, is also significantly involved in microbiome communication. Due to the high number of nerve cells and the intense exchange between gut and brain, the gut is often called the “second brain” or “belly brain” (Petrut et al., 2025).
What role do neurotransmitters and messengers play here?
The gut is not only a digestive organ but also a storage site for neurotransmitters. About 95% of the body's serotonin is produced there (Terry & Margolis, 2016). Serotonin influences mood, emotions, and the sleep-wake cycle. Other substances such as gamma-aminobutyric acid (GABA), dopamine, tryptophan metabolites, and short-chain fatty acids also play important roles in communication along the axis (Fried et al., 2021).
Research shows that inflammatory processes in the gut can lead to changes in communication between the gut and brain, partly through immunological messengers. Such changes have been linked in the literature to fluctuations in well-being and concentration (Agirman et al., 2021).
What does this mean for mood, stress, and cognition?
The microbiome acts like a pacemaker: it modulates stress responses, influences inflammation, and affects emotional resilience (Fried et al., 2021). Conversely, stress signals from the brain can influence digestive problems.
So what can we do to keep the gut-brain axis balanced or restore it?
The good news first: we can do quite a bit ourselves to keep the communication between head and gut in balance. Nutrition, stress management, and probiotic support play a decisive role in this.
How is your diet the foundation here?
A balanced, fiber-rich diet promotes the diversity of the gut flora. Fiber serves as food for the “good” gut bacteria and helps produce short-chain fatty acids, which are important signaling molecules for your brain. Regularly including vegetables, whole grains, legumes, and fermented foods lays a fundamental foundation to support the gut-brain axis.
How can you reduce and balance stress?
Stress can weaken the gut barrier, promote inflammation, and affect the balance of the microbiome. Conversely, mindfulness, meditation, exercise, and sufficient sleep can stabilize communication. Even small routines can have a positive effect here.
Probiotic support
Specific bacterial strains can be a targeted approach to additionally support the axis during stressful or demanding life phases. Studies show that certain bacterial strains can directly influence gut-brain communication. They can have anti-inflammatory effects, promote the production of neurotransmitter precursors, and improve mood and cognition (Marotta et al., 2019; Kobayashi et al., 2019).
