January 2016

Baby Poop Study to Link Infant Microbiome and Obesity

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New parents who find themselves surprisingly attentive to their babies’ poop are in good company. Researchers at The Children’s Hospital of Philadelphia and the University of Pennsylvania are beginning the second phase of a study that is exploring whether baby poop is an important data source to learn how the risk of obesity develops early in life.

The research team is focused on the miniscule but mighty passengers in baby poop: the gut microbiome. The collection of bacteria and other microorganisms that live within the digestive tract and contribute to processing food could reveal a lot about early excess weight gain.

“We are enrolling moms during their third trimester and trying to characterize their vaginal and gut microbiota, look at the transmission to infants, and follow the changes of the microbiota of infants through the first year of life to see if it correlates with weight gain,” said Babette S. Zemel, PhD, principal investigator of the Infant Growth and Microbiome (I-Gram) study at CHOP, describing the ongoing first phase of study.

In the I-Gram 1 study, after delivering their babies, participating African-American mothers send in fecal samples from their babies at specified time points over the next year. The microbial analysis, just getting underway now, will characterize the communities of microbes in the samples. Participating mothers also bring their babies for periodic visits to CHOP for comprehensive measurements of physical growth and development. On months in between hospital visits, the study team collects detailed information about the babies’ nutritional intake via telephone consultations.

Taking a Close Look at Metabolomics in Infants

Now with new funding from the National Institute of Diabetes and Digestive and Kidney Diseases, the I-Gram 2 study led by Dr. Zemel and Penn gastroenterologist Gary Wu, MD, will follow this cohort — plus an additional group of babies — until two years of age, while adding new forms of molecular analysis of the microbiome. Specifically, I-Gram 2 will enable researchers to sequence the metabolome, or the chemical byproducts of the microbiome’s activities in the digestive tract, giving a clearer idea of not just what species are present in the gut, but how they are functioning in babies’ bodies.

“This will probably be one of the largest studies looking at metabolomics in infants,” said Dr. Zemel, who is director of CHOP’s Nutrition and Growth Laboratory and a research professor of Pediatrics at the Perelman School of Medicine at Penn. “It’s unique because we have very detailed information starting with the third trimester of pregnancy and now following the babies to two years of age.”

Informing Better Strategies to Prevent Obesity

This data is valuable because metabolic products of the microbiome could have a surprisingly large impact on how human bodies function. Gut bacteria, for instance, help to create about 95 percent of the body’s serotonin, which influences mood, depression, and behavior. Microbes in the human body also help make vitamins, aid digestion, and set immune tone.

In the I-Gram study, Dr. Zemel and her collaborators are seeking a detailed description of what happens in the gut microbiome as it becomes established and matures in infants born to healthy weight and obese mothers. Participants are primarily recruited from communities where obesity rates are highest in the city, and children are therefore at heightened risk of later obesity-related health problems. The researchers hope to identify early predictors of weight gain in infancy that might inform better prevention strategies.

The I-Gram study would not be possible without collaboration between Dr. Zemel and numerous other investigators at CHOP and Penn, including I-Gram 2’s Co-Principal Investigator Dr. Wu, a professor at the Perelman School of Medicine and co-director of the PennCHOP Microbiome Program, as well as the interdisciplinary team that includes Frederic Bushman, PhD, also co-director of the PennCHOP Microbiome Program; Michal Elovitz, MD, director of the Maternal and Child Health Research Unit in the Department of Obstetrics and Gynecology at Penn; Hongzhe Li, PhD in Biostatistics and Epidemiology; and Andrea Kelly, MD, in Pediatric Endocrinology at CHOP.

To learn more about the I-Gram study, see the previous article about I-Gram 1 on the CHOP Research Cornerstone blog.

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