Why chronic stress doesn’t just affect your mind, but can also make itself felt in your gut – and why your gut deserves some extra attention after particularly stressful periods.
Do you know that feeling? You’ve just come through a few particularly stressful weeks. Lots of appointments, deadlines, too little sleep, perhaps some family issues on top of everything else. Meals are squeezed in whenever you can, and exercise falls by the wayside more often than planned.
And at some point, you notice it: your digestion isn’t really cooperating anymore. Bloating, a feeling of fullness, constipation or diarrhea. Perhaps your gut suddenly seems more sensitive than usual.
This is not necessarily a coincidence. The brain and the gut are in constant communication. And when the nervous system is running at full speed for an extended period of time, the digestive system also feels the effects.
What’s even more interesting is that this communication works both ways. Stress can affect gut function and the microbiome – while signals from the gut can also influence the brain and the way we process stress. At the center of this communication is the gut microbiome.
Stress Is More Than Just a State of Mind
Stress is not necessarily a bad thing. The stress response is a sophisticated biological program that helps us deal with challenges.
When the brain perceives a situation as stressful, it activates, among other things, the sympathetic nervous system and the so-called HPA axis (HPA = Hypothalamic-Pituitary-Adrenal Axis). Adrenaline and cortisol are released from the adrenal glands into the bloodstream. Energy is mobilized, and the body prepares itself for performance and rapid reactions.
For a short period of time, this is useful. It becomes problematic when individual moments of stress turn into a constant state and sufficient periods of recovery are missing.
The stress response affects not only heart rate, blood pressure and attention. It can also alter intestinal motility, digestive processes, immune activity and communication between the gut and the brain.
The Gut and the Brain Are in Constant Communication
The so-called gut-brain axis describes the complex communication between the brain and the digestive tract. It operates through various pathways, including the autonomic nervous system, hormones, immune messengers and metabolic products produced, among other things, by our gut bacteria.
That is why many people know situations such as suddenly needing to use the bathroom before an important appointment, losing their appetite when nervous, or noticing that their digestion simply feels different after several stressful days.
This is not imagined. The nervous system influences the gut – and at the same time, the gut sends signals back to the brain.
This is exactly where the microbiome comes into play.
What Does Stress Do to the Microbiome?
Our gut is home to a highly complex community of microorganisms. Bacteria make up the largest and best-studied proportion. Together with other microorganisms such as fungi, archaea and viruses, they form the gut microbiome – a dynamic ecosystem that is closely connected to our metabolism, immune system and nervous system.
Gut bacteria metabolize components of our diet and produce, among other things, short-chain fatty acids. These microbial metabolites can influence various processes in the body, including metabolism, immune function and communication between the gut and the brain.
At the same time, the microbiome is by no means static. Diet, exercise, sleep, medication, age and hormonal changes can influence its composition and function. Psychological stress is also one of the factors that may play a role.
A systematic review that analyzed 13 human studies on the relationship between psychological stress and the gut microbiome came to an interesting conclusion: higher psychological stress was associated with changes in various bacterial groups. However, no consistent pattern could be identified for overall microbiome diversity. The authors therefore emphasize that larger and longer-term studies are needed to better understand exactly how stress and the microbiome are connected. (Ma et al., 2023)
This is an important point: stress does not automatically mean that the microbiome will change in the same way in every person. The relationship is complex and influenced by many other factors.
The Gut Barrier Also Responds to Stress
Another interesting aspect is the so-called gut barrier. It forms a highly selective interface between the contents of the intestine and the body.
It is not a single structure. The gut barrier includes, among other things, the mucus layer, intestinal epithelial cells with their tight junctions, immune cells and other structures of the intestinal wall. The microbiome also contributes to its function.
Psychological stress can affect gut function and has also been associated with changes in intestinal permeability. This makes studies investigating whether certain probiotics can influence the gut’s response to acute stress particularly interesting.
The results are certainly intriguing, but they are not yet conclusive enough to say that probiotics “repair” the gut barrier.
In a randomized human study involving healthy adults, a specific Lactobacillus rhamnosus strain produced changes in a marker of intestinal permeability during standardized stress exposure that were not observed in the control group. At the same time, anxiety and subjective stress levels were lower. However, for the primary measure of intestinal permeability, there was no significant difference between the groups. (Wauters et al., 2022)
The findings therefore primarily suggest that the gut-brain axis and the response to stress are interconnected – and that certain probiotic strains may be able to influence this communication.
Can the Microbiome Also Influence How We Experience Stress?
This question is receiving increasing attention in research.
Several randomized studies and meta-analyses suggest that certain probiotics may positively influence subjective stress levels and, in some cases, symptoms of anxiety or depression. At the same time, results are not consistent across all products and studies.
An early meta-analysis of seven randomized studies involving a total of 1,146 healthy adults found a reduction in subjective stress levels with probiotics. At that time, however, no significant effect on cortisol could be demonstrated. (Zhang et al., 2020)
More recent data generally confirm a possible signal, but also show that the effects tend to be moderate. A recent meta-analysis of twelve studies involving a total of 3,350 healthy working adults found small but statistically significant improvements in symptoms of stress, anxiety and depression. Cortisol levels were also lower in this analysis. At the same time, the evidence was heterogeneous, including differences in the bacterial strains used, dosages and duration of supplementation.
Research therefore provides interesting indications of a connection between the microbiome and stress processing or the experience of stress.
What Your Gut Needs After a Stressful Period
After several weeks of too little sleep, irregular meals and constant time pressure, your body needs one thing above all: better conditions for recovery and regulation.
A diet rich in fiber, regular meals, physical activity and genuine recovery – especially sufficient sleep – provide the foundation for helping the body regulate itself again.
These foundations are therefore surprisingly simple.
Fiber and Plant Diversity
Vegetables, fruit, legumes, whole grains, nuts and seeds provide different types of fiber and therefore substrates that can be utilized by gut bacteria. A varied diet thereby supports the diversity of microbial metabolic processes.
Regular Meals
Don’t forget to eat throughout the day and then try to make up for everything in one go in the evening. Regular, balanced meals help provide the body with energy and nutrients throughout the day.
Exercise
Regular physical activity is important not only for muscles and metabolism. The gut microbiome is also associated with physical activity. Exercise is therefore another building block for holistic gut health.
Sleep and Recovery
Sleep is also part of gut health. The body cannot function permanently in a state of alarm. Recovery is not a luxury, but an essential part of regulation.
Is Supplementation with Pro- and Prebiotics Useful?
In addition to diet, exercise and recovery, there is the option of specifically supporting the microbiome with probiotics and prebiotics.
Probiotics are live microorganisms that, when consumed in adequate amounts, may provide a health benefit. Prebiotics, in turn, are certain indigestible substrates that can be utilized by microorganisms in the gut.
The combination of the two is known as a synbiotic.
BioMe+ combines five probiotic cultures with the prebiotics inulin and fructooligosaccharides (FOS). It also contains 60 mg of magnesium per sachet and more than 30 billion CFU of live microorganisms.
It contains:
- Lactobacillus rhamnosus
- Lactobacillus helveticus
- Bifidobacterium longum
- Bifidobacterium animalis subsp. lactis
- Lactiplantibacillus plantarum
Some of these bacterial species have also been studied in the context of the gut-brain axis. For example, a small randomized study using a combination of Bifidobacterium longum, Lactobacillus helveticus and Lactiplantibacillus plantarum showed changes in the activity of brain regions involved in the processing of stress and emotions. (Edebol Carlman et al., 2022)
Probiotics, prebiotics and synbiotics may therefore offer an option for targeted support of gut health – although their effects always depend on the specific bacterial strains, combination and dosage.
BioMe+ combines five probiotic cultures with the prebiotics inulin and FOS and can therefore be a convenient addition to a gut-friendly lifestyle.
Because especially when life becomes particularly stressful on the outside, it is worth paying attention to what is happening on the inside: your gut.
About the Author:
Mag. Carmen CREPAZ, MSc.
Nutrition Scientist and Functional Health Coach
Master’s Degree in Nutrition and Sports
Co-Author:
Mag. DDr. Manfred LAMPRECHT
Private Lecturer in Physiology
Chief Science & Product Officer, Braingood Swiss AG
