This Gut Bacteria May Alter Stress Response

Summary: One of the new studies shows that specific microbial populations, particularly L. reuteri, play a vital role in regulating circadian rhythm and stress responses during specific times of the day. Moreover, it found that the population of these microbes also changes during the day.

 There are trillions of microorganisms living in the human gut. In fact, the number of gut microorganisms is more than the total number of human body cells. Hence, some researchers suggest they may contribute significantly to health and even body weight. It is pretty simple to guess that if so many microorganisms live in the body,  they must have some critical role in health. Now, one of the groundbreaking studies shows that changes in a specific gut microbiota population may alter stress response.

Science is increasingly realizing the value of the gut-brain axis. It is also learning more about how gut microbiota may influence the HPA-axis (hypothalamus-pituitary axis) and thus influence hormonal health, consequently affecting every body function.

Further, awareness is also increasing regarding the adverse impact of chronic stress on health. These altered stress responses are both due to external and internal factors. If external triggers are easier to identify, internal factors altering stress responses are more challenging to understand. Moreover, nobody thought tiny microorganisms living in the gut could have a significant say in brain health and stress responses.

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Of course, it is insufficient to say that some gut microbiota changes alter stress responses. It is vital to understand the exact nature of these changes and their underlying mechanism so that these unwanted gut microbiota changes can be reversed.

One of the new studies shows that changes in the specific gut microbiota population disturb circadian rhythm, thus adversely impacting mental health.

This new study found that changes in the gut population of Limosilactobacillus reuteri altered HPA axis responses and, thus, the stress response system. It made the body prone to stress during specific times of the day when individuals were more likely to experience anxiety.

University College Cork and APC Microbiome Ireland did this breakthrough research. They found compelling evidence that L. reuteri has a significant role in HPA axis regulation.

Finding or identifying a specific microbial population influencing specific body functions is not easy, especially considering that there are trillions of them. Moreover, their impact on health is mild but considerable in the long run.

Researchers found that if the population of this particular gut microbiota was reduced, it resulted in hyperactivation of the HPA-axis at a specific time of the day, resulting in altered brain stress responses. This also altered the circadian rhythm or the body’s biological clock, which had grave health consequences.

The human body faces stress at specific times of the day. For example, one is unlikely to face stress when sleeping. Thus, the body’s ability to manage stress changes depending on the time of the day and it is mainly regulated by circadian rhythm. It appears that L. reuteri plays an important role in helping the body maintain this rhythm, thus the ability to counter stress.

Researchers say that these findings are opening the way to whole new kinds of treatments they call psychobiotic interventions. Which essentially means using probiotics to manage mental health conditions. It means identifying specific microbial strains that play a greater role in brain health and monitoring their population. If that population is altered, it must be restored for optimal mental health.

This research is groundbreaking since it is not about the role of microbiota in digestion or metabolism. It shows that specific microbial strains can alter diurnal stress responses. It shows that gut microbiota plays an important role in deciding how we handle stress throughout the day. Further, this study also found that the population of gut microbiota also changes during the day, which also influences its role in mental health. It means that even the gut microbiota population follows a circadian rhythm.

All this means that boosting mental health using microbiome-based interventions is quite challenging. However, this research brings science a step closer to the goal.

Source:

Tofani, G. S. S., Leigh, S.-J., Gheorghe, C. E., Bastiaanssen, T. F. S., Wilmes, L., Sen, P., Clarke, G., & Cryan, J. F. (2024). Gut microbiota regulates stress responsivity via the circadian system. Cell Metabolism. https://doi.org/10.1016/j.cmet.2024.10.003