[44-48] F. prausnitzii was increased in the fecal microbiota of obese children in southern India that used real-time polymerase chain reaction to quantitate specific bacterial groups.[44] On the other hand, obese

adults from central India had enrichment of Bacteroides and Archaea in their fecal microbiota, along with an increase in fecal SCFA concentration.[47] Increases in Lactobacillus associated with reduction in Bacteroidetes were reported in obese adults in France.[45] On the other hand, obese preschool children in Sweden had increased Enterobacteriaceae, and reduced Desulfovibrio and Akkermanseae click here compared with their healthy counterparts.[46] Several attempts have been made to elucidate the causal nature of the association between gut microbiota and obesity. Twin pairs concordant for body mass index have been studied, and it was found that many microbial genes were shared among the twin pairs, suggesting the presence of a core microbiome.[49] In obesity, there were differences in the microbiota at phylum level (significantly fewer Bacteroidetes and Actinobacteria were found in obese twins without significant changes in phylum Firmicutes), reduced microbial diversity, and alterations in genes involved in metabolic pathways. Gastric bypass surgery

in obese individuals led to reductions in Firmicutes and increases in BGJ398 Gammaproteobacteria.[50] The link between nutrition and gut microbiota can be explained by several potential mechanisms (Fig. 2). Several of the microbial communities belonging to phylum Firmicutes are important carbohydrate fermenters MCE公司 and may help in the salvage of energy from unabsorbed dietary carbohydrate.[51-53] Fecal SCFA (representing

fermentation of unabsorbed carbohydrate in the colon) were increased in obese individuals.[47] Increased efficiency of energy salvage from food may contribute to weight gain. Increasing dietary caloric load from 2400 to 3400 kcal/day in lean volunteers resulted in gut microbiota changes and an increase in the fractional energy absorption from the diet.[53] These investigators calculated that a 20% increase in Firmicutes and a corresponding decrease in Bacteroidetes was associated with an increase in energy absorption equivalent to 150 kcal/day. Of interest, the abundant fecal microbial communities Bacteroides and F. prausnitzii were reduced, and Enterobacteriaceae increased in frail elderly individuals.[54] Restriction of dietary carbohydrate intake in obese adults resulted in reduced abundance in stool of several carbohydrate-fermenting Firmicutes including E. rectale. In addition to the direct provision of energy in the form of SCFA, microbial fermentation products also affect energy metabolism and salvage through several neuroendocrine mechanisms.