If you have ever travelled across time zones you will be familiar with the adverse effects on your physical function an loss of clarity and productivity – well it seems that the organisms present in your gut, share the same trip and to some extent the same consequences. Published in Cell researchers explored the consequences of this effect on adiposity and metabolic functionality. Whilst they are naturally cautious about translation from a mouse model to a human one, they noted some interesting observations, that may explain some peoples adverse physical consequences derived in part as a result of cross time zone travel.
Organisms ranging from bacteria to humans have circadian clocks to help them synchronise their biological activities to the time of day. This paper now reveals that gut microbes in mice and humans have circadian rhythms that are controlled by the biological clock of the host in which they reside. Disruption of the circadian clock in the host alters the rhythms and composition of the microbial community, potentially leading to obesity and metabolic problems.
The senior researcher proposes some human related events.
“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”
Disruption of the circadian clock in humans is a hallmark of relatively recent lifestyle changes involving chronic shift work or frequent flights across time zones. These widespread behavioural patterns have been linked to a wide range of diseases, including obesity, diabetes, cancer, and cardiovascular disease. But, until now, it has not been clear how changes in circadian rhythms actually increase the risk for these diseases. There are numerous proposals and this is a current take on the role of the microbiota, an area of intense interest these days in the links between travel and disease progression or development.
In the new study, Elinav and his team set out to determine whether gut microbes could be the missing link. When they analyzed microbes found in faecal samples collected from mice and humans at different times of day, they discovered rhythmic fluctuations in the abundance of microbes and their biological activities. The host’s circadian clock and normal feeding habits were required for the generation of these rhythmic fluctuations in the gut microbes.
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 as we already know, caused these jet-lagged mice to gain weight and develop metabolic problems associated with diabetes. Similarly, jet lag in two humans who had travelled from the United States to Israel changed the composition of gut microbes, favouring the growth of bacteria that have been linked to obesity and metabolic disease.
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.
- Intestinal microbiota exhibit diurnal oscillations in composition and function
- Feeding rhythms direct microbiota oscillations
- Chronic jet lag is associated with loss of microbiota rhythms and dysbiosis
- Jet-lag-associated dysbiosis in mice and humans promotes metabolic imbalances