Fungi in babies’ guts influence later risk of obesity

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A new study using CHILD data has found that the fungi living in an infant’s intestinal tract are linked to that child’s later risk of becoming overweight or obese.

The study, published in Cell Reports Medicine, looks at data on intestinal fungi (known as the gut mycobiome), BMI (Body Mass Index, a measure of body fat based on height and weight) and a host of related factors from 100 CHILD Cohort Study participants over the first five years of life.

“While past research has found strong associations between the bacteria living in an infant’s gut (the bacterial gut microbiome) and later obesity risk, little was known before now about the role of early-life gut fungi in obesity outcomes,” comments co-author Dr. Marie Claire Arrieta, Associate Professor in the departments of Physiology, Pharmacology and Pediatrics of the University of Calgary.

“This study is a good first step, as it shows us that there is a link—mycobiome maturation does have an impact on infant growth trajectories. However, larger studies of this kind are needed to sort more clearly through all the mediating factors involved.”

The researchers found that the richness of fungal populations in kids’ guts decreased for most kids between three and 12 months of age, but for 25% of kids the opposite was true: their mycobiome increased in richness, also referred to as biodiversity. The reasons for these different patterns appear related to various factors, most especially the child’s and the parents’ BMI, as well as the bacterial microbiome.

In turn, the relationship between these different degrees of fungal maturity and later risk of obesity was also not straightforward. Whether fungal richness was associated with a higher or lower BMI score by five years of age appeared to depend on an individual’s early-life exposures or lifestyle; in particular, mom’s eating habits, her BMI, antibiotic exposure of the child, and gut bacteria.

The study also found that the presence different kinds of common gut fungi—including Malassezia, Saccharomyces, and Rhodotorula—during a child’s first year of life had different impacts on that child’s later risk of obesity.

“All in all, this study has made clear that gut fungi may play a role in children’s growth patterns and later risk of becoming overweight,” concludes Dr. Arrieta.

“We plan now to collaborate with others on larger studies to deepen our understanding of this relationship. And as always, we are grateful to the families in CHILD and other birth cohorts whose contributions make this research possible.”

RELATED FINDING: Baby’s gut fungi may influence allergies.