Gut microbes have circadian rhythms linked to their host.

bacAnother study has confirmed just how little researchers know about the impact of gut bacteria on human health. A study published in the journal Cell has revealed that gut microbes have circadian rhythms are controlled by the biological clock of their host.

Disturbing the circadian clock in the host alters the rhythms and composition of the microbial community, leading to health condition including obesity and metabolic complications.

The study involved analyzing microbes found in fecal samples collected from mice and humans at different times of day. It was discovered that there are rhythmic fluctuations in the abundance of microbes and their biological activities. When mice were exposed to changing light-dark schedules and abnormal 24 hr feeding habits, the microbial community lost its rhythmic fluctuations and changed in composition. Moreover, a high-fat diet caused these jet-lagged mice to gain weight and develop metabolic problems associated with diabetes. Similarly, jet lag in two humans who had traveled from the United States to Israel changed the composition of gut microbes, favoring the growth of bacteria that have been linked to obesity and metabolic disease.

“These findings provide an explanation for a long-standing and mysterious observation, namely that people with chronically disturbed day-night cycles due to repetitive jet lag or shift work have a tendency to develop obesity and other metabolic complications,” said senior study author Eran Elinav of the Weizmann Institute of Science. “These surprising findings may enable us to devise preventive treatments for these people to lower their risk for these complications.”

“Our findings highlight a new therapeutic target that may be exploited in future studies to normalize the microbiota in those people whose lifestyle involves frequent alterations in sleep patterns, such as shift workers and very frequent fliers,” Elinav says. “Targeting the harmful changes in the microbiota in these large human populations with probiotic or antimicrobial therapies may reduce or even prevent their risk of developing obesity and its complications.”


Thaiss et al. Trans-kingdom control of microbiota diurnal oscillations promotes metabolic homeostasis. Cell, 2014 DOI: 10.1016/j.cell.2014.09.048

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