The findings, published in mBio, analysed data from 165 children taking part in the NoMIC study at the Norwegian Institute of Public Health in Oslo – which having started in 2002 is one of the earliest birth cohorts in the world to investigate the early life gut microbiome.
"Our study provides more evidence that the gut microbiota might be playing a role in later obesity," said lead author Maggie Stanislawski, PhD, from the University of Colorado Anschutz Medical Campus at the Colorado School of Public Health.
"If our findings can be confirmed by other studies, the gut microbiota might play an important part of the obesity prediction algorithm, to identify at-risk kids early in life, before they start to gain any excess weight that might put them at risk for later obesity."
Led by researchers at the University of Colorado Anschutz Medical Campus, in collaboration with the Norwegian Institute of Public Health, the team compared the BMI at age 12 with gut microbiota samples from six time points throughout their childhood – at day 4, day 10, one month, four months, one year, and two years.
"We looked at whether there were specific taxa that were predictive of later BMI at each time point," Stanislawski said.
The team reported qualitative differences in the composition of children's gut microbiota at day ten, however at two years that were associated with BMI z-scores at age 12.
"At the early time points, there was somewhat of a relationship between the gut microbiota taxa and later BMI, but the relationship was much stronger as the kids got older," she noted. "At one year, it was stronger than the earlier time points. At two years, it was the strongest.”
“We found this very interesting because, at two years, there wasn't any obvious phenotype in terms of whether or not the kids were going to become obese. Kids who became obese later in life didn't have high BMI z-scores at age 2,” said Stanislawski.
“The findings suggest that the gut microbiota phenotype was present before any overt sign of overweight or obesity,” she noted – adding that since the gut microbiota is influenced by diet, there is also a chance that the associations may also reflect dietary choices that are precursors to obesity.
The study also reported a potential problem with the use of probiotics in very young children – noting that some gut microbes that are generally thought to be healthy in both children and adults were associated with higher childhood BMI.
According to the authors, this finding highlights the fact that researchers do not fully understand the dynamics of the gut colonisation process.
"It might not be the best idea to give babies the same types of bacteria every day, particularly in very early life when overloading the gut with one or two strains may prevent colonisation with other types of important bacteria,” commented Stanislawski.
Future research will focus on further examining the colonisation process in relation to other markers of metabolic health in children, she noted.
Published online, Open Access, doi: 10.1128/mBio.01751-18
“Gut Microbiota in the First 2 Years of Life and the Association with Body Mass Index at Age 12 in a Norwegian Birth Cohort”
Authors: Maggie A. Stanislawski,et al