An enhancement of oral glucose tolerance and insulin sensitivity was observed in obese, diabetic animals following administration of antibiotics to modify the gut microflora, according to results published in the FASEB Journal.
The results, building on earlier reports from researchers at Washington University School of Medicine in St Louis, Missouri, suggest a potential role for food-based approaches to modify gut microflora in obese people.
"Our results strongly support the idea that modulating gut microbiota could be beneficial for improving glycemic control and insulin sensitivity," said Dr. Chieh Jason Chou from Nestlé Research. "The next questions for Nestlé Research to answer are: Is there a gut microbiota profile that lowers the risk of obesity and diabetes development? And can we modulate gut microbiota accordingly, with food-based interventions, to improve metabolic regulation and glucose control?"
A breakthrough paper published in Nature in December 2006 reported that microbial populations in the gut are different between obese and lean people, and that when the obese people lost weight their microflora reverted back to that observed in a lean person, suggesting that obesity may have a microbial component.
At a recent scientific symposium organised by the Beneo Group, Dr. Kieran Touhy from the University of Reading noted that obese animals have significantly lower bifidobacteria levels than their lean counterparts, which suggests potential for prebiotic fibres since the growth of these bacteria is selectively promoted by inulin and fructooligosaccharides. Dr. Nathalie Delzenne from the Catholic University of Louvain in Belgium and Dr. Robert Welch from the University of Ulster presented results from animal and human studies, respectively, which indicated the potential of prebiotic supplementation to regulated food intake.
The new study, involving scientists from Nestle, the Catholic University of Louvain, and the Institute of Molecular Medicine Rangueil in Toulouse, adds and expands this knowledge base, showing that direct modulation of the gut microflora could directly affect metabolism, as well as influencing the maintenance of whole body glucose equilibrium, independent of food intake or obesity.
The researchers tested the influence of gut microflora modification in genetically (ob/ob) and diet-induced (DIO) obese mice. The animals were given broad ranging antibiotics (norfloxacin and ampicillin, at a dose of 1g/L) for two weeks.
At the end of the study, a significant improvement in fasting glucose levels and oral glucose tolerance in both ob/ob and DIO mice was observed. Moreover, this was correlated with a reduction in the levels of triglycerides in the liver and an increase in levels of glycogen in the liver.
"Our results support the idea that modulating gut microbiota could be beneficial for improving glycemic control," wrote the authors. "However, more work has to be done in order to prove that gut microbiota modulation is a safe and effective therapeutic strategy in treating or managing type 2 diabetes in humans," they concluded.
Source: FASEB Journal
Published online ahead of print, 7 March 2008, doi:10.1096/fj.07-102723
"Gut microbiota modulation with norfloxacin and ampicillin enhances glucose tolerance in mice"
Authors: M. Membrez, F. Blancher, M. Jaquet, R. Bibiloni, P.D. Cani, R.G. Burcelin, I. Corthesy, K. Mace, C.J. Chou