Effect of pulse consumption on obesity and the metagenome

Abstract

Grain legumes, which are commonly referred to as pulses, are staple foods in many parts of the world, but are infrequently consumed in most economically developed countries where the obesity pandemic is prominent. However, even in low pulse consuming countries such as the United States, there are sub-groups of individuals who consume large amounts of pulses. Systematic reviews of population studies indicate that pulse consumers have a lower risk for developing obesity. To determine whether these population-based findings could be modeled in preclinical systems in which such findings can be deconstructed, we used rat and mouse models of dietary induced obesity and reported that lipid accumulation was inhibited. In this study, we examined the relationship between inhibition of fat accumulation and changes in the gut associated microbiome in male C57BL/6 mice fed either a high fat diet with casein as the protein source or that diet formulation in which one of four pulses (chickpea, common bean, dry pea, or lentil) was substituted to provide 70% dietary protein with the remainder provided by casein. The seeds of each pulse were soaked, cooked, and then freeze-dried and milled; the resulting powder was used for diet formulation. Mice were ad libitum fed over the 17-week duration of the feeding trial. Cecal content was obtained at necropsy and immediately snap frozen in liquid nitrogen. Extracted genomic DNA was processed for 16s rRNA sequencing on an Illumina system. Significant differences were observed between each pulse and the high fat control diet in microbial phylogenetic diversity (p < 0.001) and accumulation of lipid in adipose depots (p < 0.01). Differences among pulses were also observed in both metrics. Microbiome alpha and beta diversity metrics, differences in abundance for each detected taxon among treatment groups, and their relationships to changes in lipid accumulation in adipose storage depots are reported.