Bacteria in the human gut not only helps in digestion of food, but also control functions of other organs like the liver, says a new study.

The findings, published in the ‘mBio’ journal, offer new understanding of the symbiotic relationship between humans and their gut microbes and how changes to the microbiota can impact overall health.

“The gut microbiota enhances the host’s metabolic capacity for processing nutrients and drugs and modulates the activities of multiple pathways in a variety of organ systems,” said Sandrine Claus of Imperial College of London, who led the study.

Dr. Claus and her colleagues exposed germ-free mice to bedding that had previously been used by conventional mice with normal microbiota and followed their metabolic profiles for 20 days to observe changes as they became colonised with gut bacteria.

Over the first five days after exposure, the mice exhibited a rapid increase in weight (four per cent).

Colonisation also triggered a number of processes in the liver in which sugars (glucose) are converted to starch (glycogen) and fat (triglycerides) for short-term and long-term energy storage.

Statistical modelling between liver metabolic functions and microbial populations determined that the levels of glucose, glycogen and triglycerides in the liver were strongly associated with a single family of bacteria called Coriobacteriaceae.

“Here we describe the first evidence of an in vivo association between a family of bacteria and hepatic lipid metabolism. The results provide new insights into fundamental mechanisms that regulate host-gut microbiota interactions and are of wide interest to microbiological, metabolic, systems biology,” said Dr. Claus.

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