The present invention relates to the identification of a group of microorganisms, which are relatively abundant in the microbial communities associated with fruits and vegetables typically consumed raw and therefore transient or permanent members of the human microbiota. The consumption of mixtures of these microbes at relevant doses will produce a beneficial effect in the host by reducing the propensity to diabetes, obesity and metabolic syndrome mediated in part by production of short chain fatty acids to enhance colonic butyrate production. Therapeutic methods of the invention involve the use of live microorganisms or metabolites derived from said microorganisms to establish a microbial composition in the mammalian host that will improve significantly the ability to control weight, reduce the onset of diabetes, obesity and metabolic syndrome, and improve overall health.