Relationship of insulin, glucose, leptin, IL-6 and TNF-α in human breast milk with infant growth and body composition

Abstract

Background: Numerous appetite, growth, obesity-related hormones and inflammatory factors are found in human breast-milk, but there is little evidence on their relationship with infant body composition. OBJECTVIE: The purpose of the present cross-sectional pilot study was to assess the cross-sectional associations of appetite-regulating hormones and growth factors (leptin, insulin and glucose) and inflammatory factors (interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α)) in human breast-milk with infant size, adiposity, and lean tissue at 1-month of age in healthy term infants.

Methods: Human breast-milk was collected from nineteen exclusively breast-feeding mothers using one full breast expression between 8:00 and 10:00 a.m. The milk was then mixed, aliquoted, stored at -80°C and then centrifuged to remove the milk fat, prior to analyses using commercially available immunoassay kits; milk analytes were natural log transformed prior to analysis. Infant body composition was assessed using a Lunar iDXA v11-30.062 scanner (Infant whole body analysis enCore 2007 software, GE, Fairfield, CT).

Results: Maternal pre-pregnancy BMI was positively associated with milk leptin concentration (P = 0.0027), and so maternal-BMI-adjusted Spearman correlations were examined between breast-milk analytes and infant growth and body composition variables. As previously reported, greater milk leptin was associated with lower BMIZ (BMI-for-age z-score based on WHO 2006 growth charts; r = -0.54, P = 0.03). Glucose was positively associated with relative weight (r = 0.6, P = 0.01), and both fat and lean mass (0.43-0.44, P < 0.10). Higher concentrations of milk insulin were associated with lower infant weight, relative weight, and lean mass (r = -0.49-0.58, P < 0.06). Higher milk IL-6 was associated with lower relative weight, weight gain, percent fat, and fat mass (r = -0.55-0.70, P < 0.03 for all), while higher TNF-α was associated with lower lean mass (r = -0.58, P = 0.05), but not measures of adiposity.

Conclusions: These preliminary data suggest for the first time that in the first months of life, breast-milk concentrations of insulin, glucose, IL-6 and TNF-α, in addition to leptin, may be bioactive and differentially influence the accrual of fat and lean body mass.

Conflict of interest statement

DAF and EWD have no conflicts of interest to report other than Mead Johnson Nutrition provided financial support for the project.

© 2012 The Authors. Pediatric Obesity © 2012 International Association for the Study of Obesity.

Figures

Figure 1

Unadjusted bivariate association between breast-milk leptin concentration measured at 1-month of age and maternal pre-pregnancy BMI.