Breastfeeding may protect against overweight by modifying gut microbiota

Last Updated: 2018-06-07

By Megan Brooks

NEW YORK (Reuters Health) - Breastfeeding may protect infants from becoming overweight in the first year of life by altering the gut microbiome, while formula feeding may stimulate changes in gut microbiota that are associated with overweight, according to new data from the Canadian Healthy Infant Longitudinal Development (CHILD) study.

The analysis found that earlier cessation of breastfeeding and supplementation with formula was associated with a dose-dependent increase in risk of overweight by age 12 months and this association was partially explained by gut microbiota features at three to four months, the researchers report online June 4 in JAMA Pediatrics.

"This study provides new information to help clinicians and parents make informed decisions about infant feeding," Dr. Meghan Azad from Children's Hospital Research Institute of Manitoba in Winnipeg told Reuters Health.

"Breastfeeding has many important and long-term health benefits. Our study shows that breast milk has a tremendous impact on the infant gut microbiome, and that breastfed babies are significantly less likely to become overweight," Dr. Azad said by email.

Obesity starts early in life and it's unclear exactly how infant feeding practices affect the developing microbiota and influence weight gain, she and her colleagues note in their article.

To investigate, they analyzed data on feeding practices and fecal microbiota results for a subset of infants in the CHILD study. At three months, 579 of 1,077 (53.8%) were exclusively breastfed.

Infants who were exclusively formula fed at three months had about a twofold increased risk of being overweight at 12 months (33% vs. 19%; adjusted odds ratio, 2.04; 95% confidence interval, 1.25 to 3.32).

At three to four months, formula feeding correlated with higher microbiota diversity and enrichment of Lachnospiraceae, and this partially explained the increased risk of overweight among non-breastfed infants.

"Importantly," said Dr. Azad, "we observed a dose response, meaning that 'every bit helps' - any breastfeeding is better than none, and each additional week or month makes a difference to the gut microbiome and risk of overweight. I think this is an important message because some mothers may feel overwhelmed by recommendations for 6 months' exclusive breastfeeding. This does appear to be optimal, but even partial breastfeeding or a shorter duration is beneficial."

There were subtle but statistically significant differences in the microbiota of infants exposed to formula only briefly while in the hospital, although the clinical implications of these changes are unclear.

Dr. Azad told Reuters Health this is the first study to examine the question of "just one bottle" of formula in the hospital in relation to obesity and the microbiome.

"Our results suggest there is no major impact on obesity, but there were some subtle changes in the microbiome. More research is needed to understand what this means for health, but in the meantime we should be cautious about providing formula during this critical period shortly after birth, unless medically necessary," she said. "Formula could never replicate human breast milk because breast milk contains thousands of bioactive components that are 'personalized' for the infant. They differ between mothers and change over time."

The study had no commercial funding and the authors have no relevant conflicts of interest.

SOURCE: https://bit.ly/2sJUR3v

JAMA Pediatr 2018.