How shift work and other types of unconventional work affects the gut microbiome

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In a recent study published in Nutrients, researchers review different studies analyzing the impact of unconventional work on worker’s health and gut microbiota (GM), as well as the potential use of probiotics in modulating the GM, addressing dysbiosis, and enhancing the quality of life for these workers.

Herein, many studies reported that the effects of unconventional work schedules on human health can be significant and detrimental. These schedules disrupt social lives, sleep patterns, and eating habits, thereby leading to increased morbidity and weight gain.

Study: Effects of Unconventional Work and Shift Work on the Human Gut Microbiota and the Potential of Probiotics to Restore Dysbiosis. Image Credit: - Yuri A /

Shift work

Shift work, including night shifts, poses risks to workers’ health and well-being. Some studies have claimed that obesity, type 2 diabetes, metabolic syndrome, cardiovascular disease, cancer, sleep disorders, irritable bowel syndrome, anxiety, and increased mortality rates are often due to unconventional working hours. Inadequate nutrition, irregular meal timing, and physiological factors also contribute to these issues.

Dietary changes

Shift workers often face changes in their dietary patterns, with workplaces becoming less physically demanding and the availability of high-energy snacks. This contributes to the consumption of food products that are high in fats, oils, and refined flour.

A lack of physical activity due to time constraints and fatigue further exacerbates this issue. These conditions lead to cardiovascular diseases due to higher body mass index (BMI), cholesterol, and triglyceride levels.

Hormonal changes

Shift work can cause hormonal changes in workers, thereby contributing to cardiometabolic problems. Hormones such as leptin and ghrelin, which regulate eating behavior and appetite, are affected by disruption of the circadian rhythm, which is otherwise known as the body’s biological clock.

Elevated levels of ghrelin and low levels of leptin throughout the night lead to increased appetite and weight gain. Shift work also increases levels of resistin and cortisol, both of which have been linked to insulin resistance and stress.

Decreased melatonin production and elevated cortisol levels further contribute to insulin resistance and inflammation.

Sleep deprivation

Insufficient sleep and circadian disruption alter cortisol levels and activate the hypothalamic-pituitary-adrenal (HPA) axis. Elevated cortisol affects glucose metabolism, subsequently leading to imbalances in glucose levels.

Sleep deprivation and circadian disruption also result in increased cortisol levels, particularly in the afternoon and evening, which may contribute to metabolic dysfunction and inflammation. Sleep restriction may trigger proinflammatory changes in the gut microbiome, thus altering bacterial abundance and potentially impacting metabolic health.

Unconventional work and gut microbiota

The work environment, including factors like shift work and specific workplace conditions, can influence the composition and health of the GM. Different work environments like hospitals have distinct microbial communities that can affect the health of workers, as they may be at a higher risk of infectious diseases due to their workplace microbiology.

Healthcare workers

Previous studies have reported that healthcare workers exhibit higher microbial diversity, with an abundance of Firmicutes and lower levels of Bacteroidetes as compared to non-medical workers. Likewise, intensive care unit (ICU) workers exhibited an increased abundance of certain bacteria associated with nosocomial infections, thus suggesting an influence of the hospital environment on GM.

Farm workers

Farm workers who frequently handle animals exhibit higher microbial richness and diversity as compared to urban residents, which may contribute to increased allergic and inflammatory diseases. These workers also exhibit a closer resemblance to the gut microbiota of pigs, with increased Bacteroides and Clostridiaceae bacteria and reduced Firmicutes levels.

Previous studies have also reported an association between insecticide exposure and reduced levels of Streptococcus bacteria.

Military personnel

Microbiota studies conducted on military personnel revealed that Ruminococcaceae was more abundant in traveler’s diarrhea (TD) positive soldiers, while Ruminiclostridium spp. was more prevalent in TD-negative soldiers. Haemophilus spp. and Turicibacter spp. were associated with alleviating gastrointestinal distress.

Long-traveler seamen

Reduced microbial diversity and functional genes related to carbohydrate metabolism were observed in long-traveling seamen, which can impact gut health and increase the risk of chronic diseases. The limited availability of fresh food contributes to the decline in gut microbial diversity.

Metal and tunnel-workers

Occupational exposure to silica, ceramic dust, and metalworking fluids (MWFs) affects GM and the health of workers. Silicosis patients exhibit lower Firmicutes/actinobacteria, while dust-exposed workers have increased proteobacteria.

MWF-exposed workers exhibit unique lung conditions and MWF-associated bacteria. Tunnel workers’ GM has been shown to reflect mental disorders, which emphasizes the role of GM in mental and cardiovascular health.

Restoring gut microbiota dysbiosis in workers through probiotics

Probiotics have the potential to alleviate the negative effects of unconventional work on GM. Several studies have explored the effects of probiotic supplementation on workers from various fields. Probiotics, such as those consisting of Lactobacillus and Bifidobacterium strains, have been shown to increase beneficial microorganisms and decrease pathogens in GM.

Clinical studies have investigated the efficacy of probiotics in various diseases. In workers, probiotics appear to moderate immune system changes and alleviate stress associated with night shifts. In seafarers, probiotic supplementation improves physical fitness, reduces anxiety, and maintains GM homeostasis.

Supplementation with short-chain fatty acids or dietary fiber intake may also reduce anxiety and depression. However, more research is needed to validate these findings and understand the underlying mechanisms.


Shift work, night work, and unconventional work have diverse effects on human health, including gastrointestinal, psychological, and cardiovascular health. These types of work disrupt sleep/wake cycles, circadian rhythms, and social life.

Preliminary findings indicate that probiotic supplementation can protect and maintain GM diversity and stability in varied working conditions. However, more research is needed to understand the effects of probiotics at an individual and personalized level.

Journal reference:
  • Lopez-Santamarina, A., del Carmen Mondragon, A., Cardelle-Cobas, A., et al. (2023). Effects of Unconventional Work and Shift Work on the Human Gut Microbiota and the Potential of Probiotics to Restore Dysbiosis. Nutrients 15(13). doi:10.3390/nu15133070
Vijay Kumar Malesu

Written by

Vijay Kumar Malesu

Vijay holds a Ph.D. in Biotechnology and possesses a deep passion for microbiology. His academic journey has allowed him to delve deeper into understanding the intricate world of microorganisms. Through his research and studies, he has gained expertise in various aspects of microbiology, which includes microbial genetics, microbial physiology, and microbial ecology. Vijay has six years of scientific research experience at renowned research institutes such as the Indian Council for Agricultural Research and KIIT University. He has worked on diverse projects in microbiology, biopolymers, and drug delivery. His contributions to these areas have provided him with a comprehensive understanding of the subject matter and the ability to tackle complex research challenges.    


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