Gut bacteria communicates with body and regulates metabolism

intestinal-microflora-410A new study has demonstrated the amount of influence that gut bacteria have on the body. The findings published in the Proceedings of the National Academy of Sciences USA has detailed that gut bacteria communicates with their host to regulate weight gain and serum cholesterol level.

The lead researchers investigated the impact of a bacterial protein that modifies bile acids (a major component of bile secretions) in the gut and found that this protein is commonly made by gut bacteria and functions to change the chemical properties of bile acids in the gut. Increasing the levels of this protein reduces serum cholesterol levels and weight gain mice.

“Recent work by other groups has shown that bile acids act as signalling molecules in the host, almost like a hormonal network, with an ability to influence host metabolism. What we have done is to show that a specific mechanism exists by which bacteria in the gut can influence this process with significant consequences for the host,” said Dr Gahan.

Another study by the Sahlgrenska Academy, University of Gothenburg, Sweden, revealed that cholesterol metabolism is regulated by bacteria in the small intestine. The research findings were published in the journal Cell Metabolism and reveal that gut bacteria reduce bile acid synthesis in the liver by signaling through a specific protein, called the FXR receptor, in the small intestine.
The FXR receptor not only affects cholesterol metabolism but is also involved in the body’s sugar and fat metabolism.

‘Drugs that reduce cholesterol levels have, in recent years, greatly reduced deaths from cardiovascular disease. Our study is a step forward because we have shown how gut bacteria regulate the formation of bile acids from cholesterol’, said Sama Sayin, medical doctor and PhD student at the Sahlgrenska Academy, University of Gothenburg, and the study’s first author.

‘If future research can identify the specific bacteria that affect FXR signaling in the gut, this could lead to new ways to treat diabetes and cardiovascular disease’, said Fredrik Bäckhed, professor at the Sahlgrenska Academy, University of Gothenburg, who led the study.

The research also underscores the fact that disrupting the gut environment through environmental changes can lead to catastrophic effects on metabolism.


Fredrick Bäckhed et al. Gut Microbiota Regulates Bile Acid Metabolism by Reducing the Levels of Tauro-beta-muricholic Acid, a Naturally Occurring FXR Antagonist. Cell Metabolism, Volume 17, Issue 2, 225-235, 5 February 2013

S. A. Joyce, J. MacSharry, P. G. Casey, M. Kinsella, E. F. Murphy, F. Shanahan, C. Hill, C. G. M. Gahan. Regulation of host weight gain and lipid metabolism by bacterial bile acid modification in the gut. Proceedings of the National Academy of Sciences, 2014; DOI: 10.1073/pnas.1323599111

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