In the last decade, one major breakthrough in microbiome research has been the discovery that the gut microbiota plays a role in nutrient metabolism and energy balance (intake and expenditure) and, consequently, in obesity. Animal studies have established that the gut microbiota plays a role in obesity by contributing to nutrient digestion and absorption, and to adiposity.
The genome of the gut microbiota (microbiome) has a larger coding capacity than the human genome, and thus provides an additional metabolic capacity, boosting a host's ability to extract energy from diet. The gut microbiota also regulates diverse aspects of cellular differentiation and gene expression involved in lipid and glucose metabolism, and in neuroendocrine and immune function, thereby contributing to the host's metabolic phenotype (lean/obese). These microbiota-mediated functions are, however, highly dependent on diet and the interplay of these interactions is largely unknown, particularly in humans. To date, the specific human intestinal bacteria which contribute to or predict obesity in a specific dietary context have not been identified.
The notion that caloric intake (from diet) and overall energy balance depends on an individual’s microbiota is particularly interesting because it implies that obesity and associated chronic metabolic disorders (metabolic syndrome, diabetes, etc.) can be prevented and treated by tinkering with the microbiota. To launch this idea and make it viable, the MyNewGut initiative will investigate the role of the gut microbiome and the microbiota in macronutrient metabolism, energy balance and markers of metabolic disease risk in tightly controlled human intervention trials. Such trials will include subjects with different phenotypes.