Background: Much is to be learnt about human breast milk (HBM). Objectives: The purpose of this study is to extend our knowledge of HBM by investigating the role of maternal body mass index (BMI), sex and stage of lactation (month 1 vs. 6) on HBM insulin, glucose, leptin, IL-6 and TNF-α and their associations with infant body composition. Methods: Thirty-seven exclusively breastfeeding infants (n = 37; 16♀, 21♂), and their mothers (19–47 kg m−2) were studied at 1 and 6 months of lactation. Infants had body composition measured (using dual-energy X-ray absorptiometry) and HBM collected. Results: A significant interaction between maternal BMI and infant sex on insulin levels (p = 0.0322) was observed such that insulin was 229% higher in obese mothers nursing female infants than in normal weight mothers nursing female infants and 179% higher than obese mothers nursing male infants. For leptin, a significant association with BMI category was observed (p < 0.0001) such that overweight and obese mothers had 96.5% and 315.1% higher leptin levels than normal weight mothers, respectively. Leptin was also found to have a significant (p = 0.0004) 33.7% decrease from months 1 to 6, controlling for BMI category and sex. A significant inverse relationship between month 1 leptin levels and infant length (p = 0.0257), percent fat (p = 0.0223), total fat mass (p = 0.0226) and trunk fat mass (p = 0.0111) at month 6 was also found. No associations or interactions were observed for glucose, TNF-α or IL-6. Conclusions: These data demonstrate that maternal BMI, infant sex and stage of lactation affect the compositional make-up of insulin and leptin.
Bibliographical noteFunding Information:
Mead Johnson Nutrition provided financial support (DAF principal investigator) as an Independent Investigator Trial but did not have editorial control of the paper with the CMRI Metabolic Research Program and the CMRI Chickasaw Nation Endowed Research Chair in Pediatric Diabetes providing additional support. DAF and EWD were supported by NIH HD080444 with EWD also supported by NIH HD53685 and DBA by NIDDK P30DK056336. The opinions expressed are those of the authors and not necessarily those of the NIH or any other organization with which the authors are affiliated. Preliminary data in 19 subjects irrespective of maternal BMI from this study were published previously in Pediatr Obes. We are indebted to the mothers for enrolling their infant into the study and for Catherine Wolf (study recruitment and testing of subjects) and April Teague (performing all breast milk analyses) for their work on the study. This trial was registered at http://clinicaltrials.gov as NCT02535637.
- body composition
- human breast milk
- infant feeding