Breastfeeding promotes healthy body composition in infants

Birth weight (BW) and breastfeeding are independently associated with the body composition of infants, regardless of sex, suggests a recent study.

“Our findings support continued breastfeeding and minimum dietary diversity (MDD) at 12 months as strategies to promote healthy body composition in early life,” the investigator said.

Specifically, every 1-kg increase in BW resulted in an increase of 0.716 kg in fat-free mass (FFM) and 0.582 kg/m² in girls at 6 months. In boys, there was an increase of 0.277 kg in FFM. [Eur J Clin Nutr 2024;78:928-935]

At 24 months, girls still breastfed at 12 months showed a reduction in fat mass by 0.225 kg, in FFM by 0.645 kg, and in FFM index by 0.459 kg/m² compared with those weaned before 12 months. In boys, the decreases in fat mass, FFM, and FFM index were 0.467 kg, 0.603 kg, and 0.628 kg/m², respectively.

“Higher BW was associated with higher FFM at 6 and 24 months, and continued breastfeeding at 12 months was associated with lower FM, FFM and FFMI at 24 months,” the investigators said. “MDD at 12 months was associated with lower FM in girls, and higher FFM and FFMI in boys.”

Consistent predictor

Irrespective of sex, the most consistent positive predictor of FFM at 6 and 24 months was BW, and these findings support those of other studies that applied different measurement techniques to assess the association between BW and FFM. [Proc Nutr Soc 2007;66:423-434; Am J Clin Nutr 2008;88:1040-1048]

“The direct association between BW and FFM is present across populations and is apparent across the lifespan; whereas the evidence is less consistent for body fat, with studies finding negative, positive or nonsignificant associations, even when the presence of intra-uterine growth restriction is considered,” the investigators said. [Acta Paediatrica 2021;110:2023-2039; PloS ONE 2019;14:e0222141]

In the present study, BW in girls also predicted higher fat mass at 24 months, but in previous studies sex difference in the association between BW and fat mass was seen only in girls aged 9 years. [Am J Clin Nutr 2006;84:739-747]

The current multicentre study obtained data from a 0-to-6–month cohort (Australia, India, and South Africa) and a 3-to-24-month cohort (Brazil, Pakistan, South Africa, and Sri Lanka).

The investigators examined body composition by air-displacement plethysmography for the 0-to-6-month cohort and by the deuterium dilution technique for the 3-to-24-month cohort. They calculated fat mass, FFM, fat mass index, and FFM index.

Independent variables made up the Gini index of the country, maternal and infant characteristics, and breastfeeding pattern at 3 months. Breastfeeding and MMD at 12 months were included for the 3-to-24-month cohort. Finally, crude and adjusted analyses, stratified by sex, were carried out.

“To our knowledge this is the first multinational study that accurately measured body composition in many countries, including low- and middle-income countries,” according to the investigators.