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Study: Pandemic Lifestyle Changes Altered the Gut Microbiome

Cedars-Sinai Investigators Find the Microbial Composition of the Small Intestine Underwent Significant Changes That Could Impact Health

Lifestyle changes made during the COVID-19 pandemic—such as increased hand washing and use of disinfectants—may have led to changes in the gut microbiome, according to investigators at Cedars-Sinai.

Scientists compared the small intestine luminal fluid and blood of 56 adults who underwent upper endoscopies before the pandemic to those from 38 patients who had the diagnostic examination of the small bowel (small intestine) during the outbreak. All participants tested negative for the virus that causes COVID-19.

“We found significant differences in duodenal microbial populations in the intrapandemic group when compared to the pre-pandemic group. For example, there were lower levels of potential bacterial disruptors of the small bowel microbiome in the intrapandemic group, such as the genera Escherichia-Shigella, which can be associated with serious illnesses,” said Ruchi Mathur, MD, a professor of Medicine at Cedars-Sinai and the corresponding author of the study.

Investigators also observed a relative abundance of Deinococcus-Thermus, bacteria that thrive in more extreme conditions.

Results of the study are published in the journal Digestive Diseases and Sciences.

“This finding suggests some of the lifestyle changes brought about by the COVID-19 pandemic, such as the increased use of sanitizers and surface disinfectants, may have inadvertently influenced the microbial composition of the small bowel, which is known to be highly influenced by lifestyle practices,” said Mathur, whose study was done within the Medically Associated Science and Technology (MAST) program at Cedars-Sinai.

Investigators suggest the findings could have implications for overall health.

“The changes in duodenal microbial composition may have potential implications for human health. The small bowel is an important site for nutrient absorption, metabolism and immune function. As a result, any changes in the balance of microbes could possibly impact the health of the individual,” said Ava Hosseini, MPH, a research associate with MAST and lead author of the study.

In addition to shifts in the microbial composition of the small bowel, investigators noted a reduction in the levels of certain kinds of inflammatory markers.

“Circulating levels of the proinflammatory cytokine interleukin-18 were also significantly lower in the intrapandemic group compared to the pre-pandemic group. Previous studies have associated elevated production of this cytokine with the pathogenesis of various diseases, such as rheumatoid arthritis, Type1 diabetes and Crohn’s disease,” said project scientist Gabriela Leite, PhD, a co-author of the study.

Understanding how the composition of microbial communities in the small bowel can be influenced by external factors, such as lifestyle changes, is a vital area of research in human health, according to the investigators.

“Though small, this study reveals how sudden, seismic shifts in human behavior—like those we experienced during the pandemic—can impact our physiology. We’ve identified some of the ripple effects a significant global event had on a critical microbial ecosystem within the human body—the impact of the ‘macro’ on the ‘micro’,” said Mathur.

DOI: https://doi.org/10.1007/s10620-023-08061-6

Funding: This study was supported in part by the Monica Lester Charitable Trust.

Read more on the Cedars-Sinai Blog: What IBD Patients Should Know About COVID-19