By: Dr. Melody Khorrami, PharmD, RPh, INHC

Oh, dopamine! —the feel-good neurotransmitter, the rush that every human seeks in the form of novelty, learning new things, and reward. We are hard-wired to seek out certain behaviors that give that release of dopamine into the body. When you do something that feels pleasurable to you or gives you a novel human experience, dopamine is released into your system, and your brain craves more. Dopamine plays a crucial role in your “reward center” ⁽¹⁾ and contributes to some important aspects of your body’s functions, such as memory, mood, attention, learning, pleasure, and motivation. It also acts as a hormone in the body and is important for brain function and protecting the brain from developing certain neurological conditions. ⁽²⁾ There are a variety of ways to increase dopamine in the body, and one novel way that is being looked at by researchers very closely is the link between the gut and the brain through the microbiota-gut-brain axis.

The immune system, vagus nerve, and hypothalamus-pituitary-adrenal axis are all involved as mediators of this axis. The vagus nerve is the main component of the parasympathetic nervous system, which regulates your digestion, immune system, and heart rate. But the vagus nerve also has a large role in your mood.

In the world of biohacking routines for aging and brain health, many nootropic manufacturers—companies responsible for creating cognitive boosting formulations that support focus, energy, and memory—have begun exploring aspects of dopamine modulation by looking at the gut-brain axis. Nootropics offer possibilities for more natural approaches to addressing healthy dopamine levels and supporting a positive mindset. Understanding this space better will allow for manufacturers to create formulations that can potentially improve cognition, alertness, and focus.

As research in the space of the gut-brain axis continues, we learn that the brain and the gut are deeply connected, and important signals go back and forth between them. Intrinsic enzymatic activities of the gut microbiota are critical in the role of dopamine metabolism, the synthesis of dopamine, and the breakdown of its metabolite.⁽²⁾ 

The human gastrointestinal tract hosts trillions of microbes, which, when working together in harmony, play an important role in maintaining homeostatic mechanisms and the host’s immune function. ⁽²⁾

For the past decade, we have seen many studies that have looked at the role of the gut microbiome and its connection to the immune system, drug and nutrient metabolism, the maintenance of mucosal barriers, and protection against certain pathogens.⁽³⁾ Gut microbes are also important in improving insulin sensitivity, helping with digestion through the production of short-chain fatty acids from complex carbohydrates, and reducing inflammation in the intestines.^(4,5) 

The relationship between the gut and the brain continues to be studied. Several studies show that you can change the bacteria in the gut using probiotics or fecal microbiota transplants, and this can create changes in brain activity and certain cognitive behaviors by modulating neurotransmitters.⁽⁶⁾ While the exact mechanism is not fully known, studies have also shown an important relationship between certain microbes and the dopaminergic pathway system in the central nervous system and in the GI system that can cause certain behavioral changes.⁽²⁾ Further studies will be needed to confirm the role of certain bacteria in this pathway system, but the following microbes have been shown to modulate certain receptors connected to the dopamine reward system and may play a role in certain health conditions and disorders linked to the dopaminergic system: Prevotella, Bacteroides, Lactobacillus, Bifidobacterium, Clostridium, Ruminococcus, and Enterococcus.⁽²⁾

Patients who have certain mental health conditions have been shown to have a lower amount of Bifidobacterium and Lactobacillus when compared to their healthy controls. This could point to probiotics having a role in modulating the dopamine pathways. ⁽²⁾ 

While more research is needed to understand the exact mechanism of the gut bacteria and their relationship to dopamine pathways, the evidence does point to a significant relationship between the two. The more we can study this pathway and the roles of certain bacteria responsible for it, the more insight we can have into the roles of certain bacteria or the lack thereof for conditions related to imbalances in dopamine, such as Parkinson’s disease, attention deficit hyperactivity disorder, depression, anxiety disorders, and autism. The future holds great promise in further confirming how we can hack the dopamine system through the gut-brain axis.

References: 

1. https://my.clevelandclinic.org/health/articles/22581-dopamine
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8962300/#:~:text=Furthermore%2C%20gut%20microbiota%20contain%20intrinsic,well%20as%20its%20metabolite%20breakdown
3. https://pubmed.ncbi.nlm.nih.gov/25846071/
4. https://pubmed.ncbi.nlm.nih.gov/30971437/
5. https://pubmed.ncbi.nlm.nih.gov/26100928/
6. https://pubmed.ncbi.nlm.nih.gov/29723105/
7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10843545/#:~:text=The%20gut%20microbiota%20has%20a,dopamine%2C%20GABA%2C%20and%20glutamate.&text=Mental%20disorders%20such%20as%20schizophrenia,are%20associated%20with%20gut%20microbiota