Response of human gut microbiota to diet supplementation with soy or soluble corn fiber

Humans have been defined as super-organisms based on the large number of bacterial cells that inhabit the body, mainly in the gastrointestinal tract. Prebiotics are food components that reach the large intestine and promote the growth of beneficial bacteria, with subsequent health benefits. The main objective of this work was to determine the response of human gut bacterial communities to two potential prebiotics. Soy and soluble corn fiber were tested in postmenopausal women and adolescents, respectively. The 16S rRNA gene was used to determine the fecal bacterial community structure by PCR-DGGE, and 454-pyrosequencing of the same gene was used to determine bacterial community composition. Both supplementations led to significant changes to bacterial community structure and composition. Analysis of community composition revealed that Bifidobacterium proportions increased after supplementation with soy in postmenopausal women. Significant correlations were observed between the variability of the bacterial community after soy consumption and the amount of metabolites excreted. In adolescents, members of the phylum Bacteroidetes increased in proportion after supplementation with soluble corn fiber. Positive correlations between the major nutrients in diet (during the self-selected diet and the controlled diet with and without SCF) and the variability of bacterial community composition was observed. Additional factors that were determined to influence variation in the community in adolescents were gender and race. It was concluded that soy and soluble corn fiber acted as prebiotics favoring the proliferation of gut bacteria that are considered in the literature to be beneficial to health. These are the first reports that analyze the bacterial communities using 454-pyrosequencing after supplementation with soy in postmenopausal women and soluble corn fiber in adolescents. This research provides valuable information for the development of nutrition strategies using soy and soluble corn fiber as prebiotics