Our bodies are bustling with a community of around 100 trillion bacterial cells that make up our gut microbiome. It also contains at least 150 times more genes than the human genome. When scanning the internet for information on this complex organ, numerous studies show how gut health plays a role in digestion, mental health, and immune function.
Unfortunately, even with all this data, one area that still needs further investigation is how the work environment affects gut health in humans. The are several studies discussing the impact of environmental toxins and other pollutants on gut microbiota. Still, few consider how work environment stressors, such as sleep deprivation, affect gut health in individuals. Below, we highlight what the latest research reveals on this topic and discuss the importance of further investigation into this area, especially for those who work in high-risk workplace environments.
Why Gut Health is Crucial to Wellbeing
The microbiome comprises all genetic material within a microbiota (i.e., the human gut), shaping immune system development and function. It reinforces the gut barrier, aids in digestion, modulates enteric and central nervous system activity, and protects against pathogens. However, some infections can actually help gut microbes prevent certain viruses. For example, a recent study in mice reveals that bowel infections can help gut-dwelling microbes fight off pathogens. The mice were exposed to the bacterium Klebsiella pneumoniae, a human pathogen. Recipients of microbes from mice with a history of Y. pseudotuberculosis infection were better protected from Klebsiella than were recipients of microbes from mice that hadn’t been tainted with the infection. The results suggest that intestinal infections’ train’ mice to produce taurine, which favors the growth of taurine-eating, protective gut bacteria.
However, most shifts in the GI tract spur alterations in the gut microbiome, known as dysbiosis. Dysbiosis is associated with transient health issues, including GI inflammation, increased susceptibility to illness and infection, obesity, heart problems, and mental health issues. Some researchers even suspect that the gut microbiome may play a role in autism spectrum disorders (ASDs). The bottom line, when it comes to the microbiome, “It’s a vital organ in your body and you need to look after it. If you do that, it will look after you,” states Tim Spector, an epidemiologist at King’s College London.
Work Environment & Gut Health – What Research Tells Us
“The microbiome is associated with everything – pick a disease, it’s associated,” says James Kinross, a microbiome scientist at Imperial College London. The research on these associations is vast, and every week, scientists are discovering something new. According to Harvard Health, “Numerous studies have suggested that stress may be a significant factor when it comes to developing gastrointestinal disease or disorders. The relationship between environmental or psychological stress and gastrointestinal distress is complex and bidirectional: stress can trigger and worsen gastrointestinal pain and other symptoms, and vice versa.” Because of this bidirectional relationship, research in this area is crucial.
One literature review published in Frontiers in Microbiology summarizes the latest evidence concerning the impact of psychological, environmental, and physical stressors on gut microbiota function on military personnel. It also includes other studies on these impacts, but this research was mostly performed on animals. Although stressors come in many forms, the biological stress response is governed by the hypothalamic-pituitary-adrenal axis (HPA) and sympathetic nervous system (SNS). Stressor-induced activation of the HPA axis and SNS stimulates the release of glucocorticoids and other hormones, affecting the modulation of the immune system and GI function. Thus, chronic stress can exceed an organism’s adaptive capacity, causing reduced physical and cognitive performance, illness, and disease. This review focused on a study that analyzed psychological stress, sleep deprivation, work environment extremes (heat and cold), environmental pathogens, noise, physical activity, and diet. Certain stressors were selected for their direct relevance to military personnel.
One finding suggests that as little as 4 to 6 hours of heat exposure can severely affect the intestinal epithelium. Moreover, hyperthermia of the intestinal wall can damage the gut barrier and potentially cause inflammation and sepsis. Another finding revealed that sleep deprivation had been associated with several physiologic effects that could alter the GI environment and impact the gut microbiota. First, inadequate sleep (less than 7 hours a night) is thought to activate a stress response as evidenced by increased HPA-axis activity and cortisol release in both mice and humans. Second, rodent models of sleep deprivation have demonstrated increased oxidative damage and cell death in the intestine, in addition to infection of body tissues with pathogenic bacteria found in the intestine. The latter finding suggests that immunosuppression and gut barrier dysfunction may result from sleep deprivation and facilitate bacterial translocation from the gut lumen into the systemic circulation.
Circadian rhythm disruptions and gut health were also examined. Disturbance of this loop can be caused by factors that interrupt light-dark cycles, such as shift work, rotating work, and social schedules. Within the GI tract of mice, variable feeding schedules and diet composition have also been shown to disrupt circadian rhythms. The health effects of this disruption are increasingly recognized and include both short and long-term health decrements such as increased GI permeability, altered immune responses, increased susceptibility to inflammation and GI epithelium damage, and multiple chronic inflammation-associated diseases, including irritable bowel syndrome and inflammatory bowel disease.
Why More Research is Needed
Evidence from this literature review collectively indicates that certain work environment stressors change the composition, function, and metabolic activity of the gut microbiota. Unfortunately, the review also highlights that translation of these findings to humans is largely lacking. This gap makes it difficult to conclude with certainty that transient or cumulative exposures to psychological, environmental, and physical stressors have any consistent impact on the human gut microbiota.
Additionally, this review discusses a real need for translational research to demonstrate the impact of work environment stressors on the human gut microbiome, especially for those in high-risk professions like the military. The report also highlights the need to know how the gut microbiota can be manipulated (i.e., exercise, diet) for better health. Finally, the review suggests the key question for many of these studies should be to what extent any stress-induced changes in the gut microbiota persist and the functional consequences. It was also recommended that findings from these investigations would be strengthened by developing technologies for non-invasively measuring the GI environment.
