What is already known
Scientists have known that an infant’s growth trajectory and gut bacteria are linked to the risk of becoming overweight later in life. However, little is understood about the role of the community of fungi living in the gut, or the gut mycobiome, in host metabolism and childhood obesity.
What this research adds
Researchers analyzed the relationship between the gut mycobiome of 100 Canadian infants and their body mass index (BMI) in the first five years of life. In the first year of life, the team observed divergent maturational patterns in the gut mycobiome, with mycobiome richness being associated with both parental and infant BMI. Factors such as maternal diet and antibiotic use also modify associations between mycobiome richness pattern and early-life BMI. The researchers found that the levels of fungi such as Saccharomyces, Malassezia and Candida are greater in infants with a higher BMI.
Conclusions
The findings suggest that mycobiome maturation and infant growth trajectories are linked.
As childhood obesity rates continue to increase, scientists have linked an infant’s growth trajectory and gut bacteria to the risk of becoming overweight later in life. A new study suggests that the community of fungi living in the gut, or the gut mycobiome, is also associated with an infant’s body-mass index (BMI) — which can be indicative of obesity.
“Overall, our findings suggest that early-life and maternal factors may collectively influence growth dynamics in the first 5 years of life, in association with mycobiome maturational patterns and specific fungal taxa,” say the researchers, who reported their results in Cell Reports Medicine.
Although recent studies in adults have linked the gut mycobiome to obesity, little is understood about the role of gut fungi in childhood obesity. To address this question, researchers led by Marie-Claire Arrieta at the University of Calgary analyzed the relationship between the gut mycobiome of 100 Canadian infants and their body mass index z-scores (BMIz) — a measure of relative weight adjusted for child age and sex — during the first five years of life.
Fungal richness
The researchers confirmed that at 3 months, the infant mycobiome was dominated by Candida, Malassezia and Mycosphaerella, and then shifted toward Saccharomyces dominance at one year of age.
In the first year of life, the team observed divergent maturational patterns in the gut mycobiome, with 69% of infants displaying decreased fungal richness, 28% displaying increased richness and 3% displaying no change in mycobiome richness. Similar patterns were observed for fungal diversity.
Some of the top factors associated with increased fungal richness were infant BMIz at one year, parental BMIz and bacterial diversity in the first year of life. Maternal diet and breastfeeding duration were also linked to fungal richness, the researchers found. What’s more, increasing fungal richness was associated antibiotics use from six to 12 months.
Microbial interactions
The team found several fungi associated with BMIz between one and five years of age. In particular, greater abundances of Saccharomyces at three months and Malassezia at 12 months were associated with a higher BMIz at one and five years, respectively. Greater Candida abundances at 12 months also tended to be linked to higher BMIz at three years. Instead, lower levels of Rhodotorula at 12 months were associated with a higher BMIz.
“This suggests that specific fungal genera present in the mycobiome in the first year of life are differentially associated with BMIz outcomes in early childhood,” the researchers say.
Mathematical models indicated that the association between the gut mycobiome and childhood BMIz depends on the composition of the community of bacteria in the gut.
“Our results suggest that the mycobiome’s contribution to early-life BMIz is likely influenced by the bacterial microbiome,” the researchers say. Future work should evaluate the mechanism through which the mycobiome influences growth and metabolism in early life, they add.
