GI Tract Biomarkers in Infants With Different Diets

Childhood obesity is increasing with more than one-third of adolescents currently overweight
and one in five with obesity. The lifelong incidence of obesity-related morbidities is also
increasing with childhood obesity. It is not yet known how obesity develops in an individual,
specifically in early childhood. Further, it is unclear what mechanistic role a child's
earliest nutrition or changing intestinal flora has in the etiology of obesity. Very young
children are developing appetite and satiety patterns early in life. Nutrition and gut
microbial flora have impact on how these processes unfold, but specific mechanisms are not
yet well understood. The investigators hypothesize that formula-fed infants with changes in
their microbial flora are more likely to have altered carbohydrate metabolism, evidenced by
greater imbalances of fatty acid production, and are more likely to have accelerated growth
trajectory due to satiety disruption. The investigators further hypothesize that altered
carbohydrate metabolism, e.g. imbalances of short- and long-chain fatty acid levels in the
gut, stimulate cellular stress and affect specific gut hormones. This study will compare the
microbiome of the intestinal microbial flora in two groups of infants, one breast fed and the
other formula fed, using longitudinally collected fecal samples from both groups. Samples
will be subjected to shotgun metagenomic analysis and simultaneous metabolomic analysis. A
bioinformatics approach will elucidate key differences among and between sample groups, and
will further analyze bacterial gene expression levels related to carbohydrate metabolism.
This study will compare the expression of human proteins involved in cellular stress response
and gut peptide signaling by applying quantitative Reverse Transcriptase-Polymerase Chain
Reaction to human messenger RNA isolated from the longitudinally collected samples from both
groups. Finally, this study will monitor the trajectory of growth and feeding over the first
2 years of life. The project's focus on the influence of different early feeding types,
microbial flora changes, and altered carbohydrate metabolism leading to disruption of
gut-brain signaling will provide critical data for host:microbiome interactions and
translational therapeutic targets.