Gut key to child weight

Imbalances in bacteria can predict obesity from age 5

Imbalances in a toddler’s gut bacteria may play an important role in the development of obesity, international researchers say.

The new study has found the make-up of a toddler’s gut bacteria can predict whether they will be overweight at five years old.

The findings, presented at this year’s European Congress on Obesity in Ireland, also suggest changes to the gut microbiota that predispose adults to obesity may begin in early childhood.

“The reason these gut bacteria affect weight is because they regulate how much fat we absorb,” said lead researcher Gael Toubon, from Paris Cite University.

The make-up of the gut microbiota changes in the first few months and years of life and disruption to its development is associated with conditions, including inflammatory bowel disease, type 1 diabetes and childhood obesity.

Mr Toubon and colleagues examined how the gut microbiota of children at 3.5 years from two French nationwide birth cohorts was associated with their BMI at five years old and changes in their BMI between two and five years old.

They included 143 preterm infants and 369 full-term infants born in metropolitan France in 2011 in the study.

Stool samples were collected at 3.5 years. Genetic microbiota profiling revealed a positive association between BMI z-score (a measure of body weight based on height for each age group by sex) at five years and the ratio of the gut bacteria Firmicutes to Bacteroidetes that are directly involved with obesity. The more Bacteroidetes compared with Firmicutes in the gut, the leaner individuals tend to be.

“Children with a higher ratio of Firmicutes to Bacteroidetes will absorb more calories and be more likely to gain weight,” Mr Toubon said.

The analysis also found that six specific types of gut bacteria were highly predictive of BMI z-score at five years old.

Greater abundances of three categories of bacteria – Eubacterium hallii group, Fusicatenibacter, and Eubacterium ventriosum group – were identified as a risk factor for a higher BMI z-score. Greater numbers of three types of bacteria – Eggerthella, Colidextribacter, and Ruminococcaceae CAG-352 – were associated with a lower BMI z-score.

“Our findings reveal how an imbalance in distinct bacterial groups may play an important role in the development of obesity,” Mr Toubon said.