Formula feeding changes gut microbiome and increases risk of baby being overweight

03 July 2018
Woman breastfeeding

A Canadian study has found that exclusive breastfeeding in the first three-months of life produces a different gut microbiome profile which may be protective against obesity.

The research, published in the journal JAMA Pediatrics, found infants who were partially or fully formula fed were much more likely to be overweight at 12-months.

The study of more than a 1,000 mothers and infants in the Canadian longitudinal study CHILD found:

  • Those who were partially formula-fed had a 63% increased risk of becoming overweight compared with those who were exclusively breastfed
  • Those who were exclusively formula-fed had a 102% increased risk of becoming overweight.

According to the researchers, this association is partially explained by the influence breastfeeding has on an infant’s gut microbiome —the community of microorganisms or bacteria that live in the human digestive tract.

“Breastfeeding is one of the most influential factors in shaping the infant gut microbiome,” says co-author Dr Meghan Azad, Canada Research Chair in Developmental Origins of Chronic Disease at the University of Manitoba.  

“Our research showed that partial breastfeeding and exclusive formula feeding were associated with a higher microbial diversity at three months of age, meaning more types of microbes were present in the baby’s gut, as well as an abundance of a group of bacteria called Lachnospiracae, which has been associated with infant’s being overweight,” explains co-author Dr Anita Kozyrskyi, Professor in the Department of Pediatrics at the University of Alberta.

Families enrolled in the CHILD Study provided information about their babies’ breastfeeding status and diet at three, six and 12 months of age.

DNA sequencing techniques performed in the laboratory provided information on the types and quantity of bacteria present in the infants’ digestive tracts.

Professor Kozyrskyi says the information gleaned is unique.

“This is one of the largest infant microbiome studies in the world, identifying over 900 types of bacteria from 2.6 million DNA sequences generated from more than 1,000 infants,” she says.

“We found that breastfed infants supplemented with formula were at increased risk for becoming overweight at one year of age, and had a different microbiota composition than exclusively breastfed infants; whereas breastfed infants supplemented with complementary foods only (no formula) were similar to exclusively breastfed infants with no increased risk.”

The study is also the first to evaluate the potential association of a brief use of infant formula (during the hospital stay only) with the infant microbiota and the risk of becoming overweight.

The findings revealed subtle yet significant microbiota differences at three to four months of age after use of formula only during the hospital stay after birth. However, these differences were not associated with overweight at one year of age, and the clinical implications of these changes need to be studied further, according to the researchers.

“Together, these results emphasize the importance of breastfeeding as a possible protective factor against infant overweight by modifying the gut microbiome.  They suggest that improved programs and policies to support exclusive breastfeeding could have a meaningful impact on infant health,” Dr Azad says.