What Are Psychobiotics?
Psychobiotics are live bacteria (probiotics) which, when ingested, confer mental health benefits. Research has increasingly shown that good mental health comes not just from our environment, lifestyle and relationships, but also from the bacteria in our gut (see this review article). As such, psychobiotics have piqued interest from researchers worldwide as they seek to uncover more about how these microorganisms might be able to shape our biology, psychology, and behavior.
How Do Psychobiotics Work?
Psychobiotics appear to benefit mental health by influencing the biochemistry of our brains. Not all probiotics are psychobiotics. To be potentially classified as a psychobiotic, a bacterial or yeast strain should be supported by clinical research that suggests a beneficial effect on mental health at a specific amount.
For example, in animal studies, ingesting the L. plantarum PS128 psychobiotic has been observed to alter the levels of serotonin and dopamine in the brain. These neurotransmitters are involved in mood regulation and reward pathways. A different psychobiotic strain appears to influence the expression of genes in the brain related to GABA signaling, which also plays a key role in stress response.
Psychobiotics appear to do this work via the gut-brain axis. The gut-brain axis is a bidirectional communication system between the gut and the brain. It connects the digestive organs with the central nervous system via the bloodstream, vagus nerve, and immune system. This complex symphony of exchanges manages our appetite, our mood, and even our capacity to cope with stress.
Bloodstream
Gut microbes are able to biosynthesize many molecules, transforming amino acids that we eat into neurotransmitters, reactivating steroid hormones that cycle through the gut, and creating a wide variety of other potential signaling molecules.
Animal studies suggest that metabolites produced by psychobiotics such as short-chain fatty acids (like butyrate), vitamins, and amino acid metabolites may be absorbed from the gut into the bloodstream and cross the blood-brain barrier.
Vagus nerve
How psychobiotic bacteria residing within the gut can influence gene expression in the brain is far from understood. However, the vagus nerve, which connects the brain and the gut, may be one possible conduit for such “at-a-distance” effects of psychobiotics.
For example, in a study of mice fed a certain psychobiotic strain altered the amount of a key receptor for GABA neurotransmitter that exerts an effect on mental health. However, this effect of the psychobiotic was not seen unless the vagus nerve was intact. This suggests that it somehow sends a signal from the gut to the brain via the vagus nerve.
While certain psychobiotics as well as enteroendocrine cells of the gut lining produce neurotransmitters within the gut, these gut-derived neurotransmitters are not believed to travel to the brain. The effects of gut serotonin on neurotransmitter levels within the brain, for example, could be mediated by vagus nerve signaling; further studies will help to clarify this question.
Immune System
Psychobiotic metabolites such as short-chain fatty acids (SCFAs) may affect immune cells that are activated by chronic stress, affecting their release of immune-stimulating cytokines. Cytokines have targets within the brain, specifically the metabolism of brain neurotransmitters. Immune dysregulation is associated with mental health conditions. The ability of a psychobiotic to support a healthy immune response could therefore account for its effects on mental health.
What Effects can Psychobiotics Have on Mental Health?
The microbiome can influence mental health in a variety of ways. In some cases poor mental health is caused or exacerbated by poor gut health. Combating the effects of pathogenic organisms in the gut by taking a gut-health probiotic or increasing the amount of prebiotic foods in your diet may therefore contribute to better mental health.
Psychobiotics are believed to influence mental health not (only) by repairing gut health, but by other mechanisms as well. They appear to do so in both the absence and presence of gut health problems. One excellent example of such a psychobiotic is Lactobacillus plantarum PS128 (PS128).
A single-arm study of highly stressed information technology (IT) specialists demonstrated benefits of PS128 for stress and sleep quality. Participants reported less perceived stress after taking PS128. In addition, their salivary cortisol was reduced, which correlated with improvements in mood and sleep.
Psychobiotics vs Nootropics – What’s the Difference?
Psychobiotics and nootropics can both be used to enhance brain function, often in different ways.
Nootropics are substances that enhance cognitive function, memory, and focus. They are sometimes referred to as "cognitive enhancers" because they are believed to have a positive impact on brain function. Nootropics can include medications, but they can also be natural substances such as ginkgo biloba, caffeine, and mushrooms such as lion’s mane and cordyceps. Nootropics are used by a wide range of individuals, including students, professionals, athletes, and older adults who are looking to improve their cognitive performance.
Psychobiotics, on the other hand, are defined as probiotics that have positive impacts on mental health. These benefits could include nootropic effects, like benefiting cognition or memory, or they could be benefits on mood. Much of the research on psychobiotics shows an impact on mood, anxious thoughts or stress by influencing the activity of neurotransmitters and other compounds.
Interestingly, there is some overlap in neurotransmitters that affect mood, stress, and memory. For example, dopamine and serotonin affect all of these. This overlap suggests that it is possible that a psychobiotic that affects dopamine and serotonin in the brain may also be nootropic. However, different parts of the brain and other neurotransmitters are also part of the complexity of different types of brain function.
While a probiotic could theoretically exhibit both psychobiotic and nootropic effects in humans, many clinical studies tend to examine only one effect or the other. For example, a nootropic-focused study of a particular probiotic strain may not include any observations of effects of that strain on mood. Therefore, few cases to date have noted both benefits from a single probiotic strain.
In the future as more strains are studied with regards to both cognitive and mental health benefits, more psychobiotics that are also nootropics may be discovered.
How to Get Started with a Psychobiotic
When starting a psychobiotic regimen, it is recommended to consider the following steps:
- Consult with a healthcare professional: Before starting any new supplement or medical food, it is advisable to consult with a health care professional, especially if you have any underlying health conditions or are taking medications. They can provide personalized guidance and help monitor your health as your body and mind adjust to the psychobiotic you choose.
- Choose an appropriate strain: Based on your specific requirements and the potential benefits you seek, select a psychobiotic strain that aligns with your goals. Consider factors such as the strains' scientifically documented effects, safety profile, and any relevant research studies.
- Select a reliable product: Look for reputable probiotic brands or manufacturers that have a track record of producing high-quality products. It is important to ensure that the product lists strain names and amounts, and has undergone proper quality control measures.
- Follow label instructions: Read and follow the recommended amount and frequency of capsules to take per day, as provided on the product label or as advised by your health care professional. Consistency is crucial, so aim to take the psychobiotic supplement daily and at the specified amount.
- Monitor and assess effects: Keep track of any changes or improvements in your mental health and overall well-being while taking the psychobiotic supplement. It may take time to notice significant effects, so it's advisable to maintain the regimen for a sufficient duration.
Remember, individual responses to psychobiotics may vary, and it is important to give the regimen time to assess its effectiveness. If you experience any adverse effects or have concerns, consult with your healthcare professional for further guidance.
Recommended reading:
Neuralli MP or Neuralli Mood - Which Should You Choose?
What Is the Gut-Brain Axis? How Your Microbiome Can Influence Wellbeing
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