Bacteria in our guts may contribute to metabolic disorders such as insulin resistance and non-alcoholic fatty liver disease.

There is a growing awareness that the myriad of different bacteria that live within us have a significant effect on our biology, such as our response to drugs. Recent research suggests that they may also affect our metabolism and, through it, our health.

As part of a Wellcome Trust-funded functional genomics programme – the Biological Atlas of Insulin Resistance, involving laboratories at Imperial College London and Oxford University – Dumas et al. have looked at the impact of gut bacteria on impaired glucose homeostasis and non-alcoholic fatty liver disease in strains of mice susceptible or resistant to these conditions. By analysing the chemical make-up of blood samples and urine, the team discovered that the predisposition was linked to impaired metabolism of choline, an essential metabolite required for transporting fat out of the liver.

However, in some strains, changes in the action of gut bacteria that metabolise dietary choline lower choline levels in the body, exacerbating disease. Thus symbiotic interactions between gut bacteria and mammalian genome can create chemical imbalances and increase the risk of non-alcoholic fatty liver disease and insulin resistance.

More generally, the results suggest that disease states may be influenced by the number and type of bacteria present in our gut, as well as inherited factors.

External links

• Dumas ME et al. Metabolic profiling reveals a contribution of gut microbiota to fatty liver phenotype in insulin-resistant mice. Proc Natl Acad Sci USA 2006;103(33):12511–6.