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Did you know your gut produces many of the brain chemicals that influence your mood and behavior? Two of the most important—dopamine and serotonin—aren’t just made in the brain. In fact, much of their production happens in your digestive system, and your gut microbes play a surprising role in how much of these “feel-good” chemicals your body has access to.
In this article, we’ll explore how serotonin and dopamine are made, the surprising role your gut microbiome plays in regulating them, and what this could mean for your mental health.
Serotonin: the gut’s star neurotransmitter
Serotonin is often called the "feel-good" chemical because it influences mood, sleep, and anxiety [1]. But its role goes far beyond mental health. In fact, about 90% of your body’s serotonin is made in the gut, not the brain. This production happens in specialized gut cells known as enterochromaffin cells, and it plays a key role in regulating digestion and gut motility.
While gut microbes don’t make serotonin directly, they have a powerful influence on its production and availability. Some bacteria can stimulate enterochromaffin cells to make more serotonin, or affect how it's absorbed and recycled in the body [2]-[4].
One way microbes boost serotonin is by producing short-chain fatty acids (SCFAs)—beneficial compounds that signal enterochromaffin cells to increase serotonin output [2], [4]. Lab studies also suggest that bacteria like Akkermansia muciniphila may enhance serotonin production and slow down its reuptake in the gut lining, potentially increasing its local effects [3].
Another important piece of the puzzle is tryptophan, an amino acid you get from food that serves as the raw material for serotonin. Gut microbes can influence how tryptophan is broken down, directing it toward serotonin production or down other pathways [5]. Foods high in tryptophan include whole milk, tuna, turkey, chicken, oats, cheese, and peanuts [6].
Dopamine: Made by gut cells and microbes
Dopamine is a key neurotransmitter best known for its role in motivation and reward. But what many people don’t realize is that nearly half of the body’s dopamine is produced in the gut, where human cells use the amino acids tyrosine or phenylalanine—found in foods like soybeans, beef, fish, seaweed, tofu, and eggs—as the starting material [7]-[9]. In the gut, dopamine plays a role in digestion, movement, and stomach acid release [10], [11].
Gut microbes can influence dopamine levels in several ways: by helping to produce it, breaking it down, or diverting its precursors toward other compounds. For example, some Clostridium species may support dopamine production by producing the SCFA butyrate, which stimulates dopamine-producing cells. Others, however, may break down dopamine directly [12].
Enterococcus bacteria stand out for their ability to produce dopamine on their own [13]-[15]. Yet, they can also use tyrosine to make other compounds, potentially reducing the amount available for dopamine synthesis [16], [17]. In addition, these bacteria are not desirable in high numbers, as they can cause infections and are often resistant to antibiotics [18].
Gut microbes, mood, and mental health
Your gut microbiome plays a key role in shaping the production of brain-related chemicals like dopamine and serotonin. When we think about these chemicals affecting mental health, we usually picture them acting directly in the brain. But here's the catch: neither gut-made dopamine nor serotonin can cross the blood-brain barrier. So can these gut-derived neurotransmitters influence your mood or mental health?
Yes, they can.
Take gut-made serotonin, for example. It doesn’t just support digestion, it also sends messages to your brain by stimulating the vagus nerve, the key communication highway between your gut and brain [19]. These signals can influence how you feel, how you manage stress, and even how your body responds to inflammation.
The role of gut-derived dopamine in mental health is less well understood, but emerging research in mice suggests that the vagus nerve may be able to detect dopamine made in the gut [20]. That means it’s possible that your gut dopamine also contributes to mood and emotional balance—another reason to care for your gut microbes.
Does your gut microbiome support serotonin and dopamine production?
In Tiny Health’s adult and child gut health test reports, you’ll find several metrics related to serotonin production, such as the presence of certain bacteria and genes involved in serotonin-related pathways.
A metric for dopamine isn't currently included—and for good reason. As it turns out, the same bacteria can influence dopamine levels in different ways depending on factors like diet, gut environment, and host response. This makes it difficult to create a reliable, science-backed metric at this time.
It’s also important to remember that neurotransmitter production depends on more than just microbes. Other key factors include:
- The availability of nutrients like tyrosine and tryptophan from your diet
- Your body’s gene expression, immune activity, and gut function
- The complex interactions between your microbes and your body
While the science isn’t at a point where we can predict mood or neurotransmitter levels from the microbiome alone, your report gives you a research-based view of how your gut may be laying the foundation for healthy serotonin signaling.
How to support and boost serotonin in your gut
Now that we understand how your gut microbiome influences the production of neurotransmitters, here are practical ways to naturally encourage healthy serotonin production and improve your gut-brain connection.
- Vagal nerve stimulation: Practice deep breathing [21]. Mechanical stimulation of enterochromaffin cells—through actions like gut contractions or gentle pressure in the intestinal wall—can trigger serotonin release, which in turn activates serotonin receptors on the vagus nerve [19].
- Diet: Eat tryptophan-rich foods (turkey, eggs, nuts) and prebiotic fibers (onions, garlic, bananas) to feed enterochromaffin cells and serotonin-supporting microbes.
- Fermented foods: Include yogurt, kefir, and sauerkraut to promote a balanced gut microbiome.
- Lifestyle: Exercise regularly, meditate, get quality sleep, and avoid excessive antibiotics or alcohol to maintain a healthy gut environment.
Caring for your gut-mind connection
Your gut is more than just a digestive organ—it’s a chemical factory with deep ties to your brain. By producing and modulating chemicals like serotonin and dopamine, your gut and its microbes may influence how you feel, think, and respond to stress. Supporting your gut through a balanced diet, stress management, and probiotics (if needed) could be one way to care for both your mental and physical health.
If you’re curious about how your gut may influence serotonin production, an Adult Gut Health Test can offer a glimpse. Already tested yourself or your child? Look for the “Serotonin production in your gut” under the “metrics related to conditions” section.
