title: 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.
authors.affiliation: Department of Pediatrics, University of Oklahoma Health Sciences Center, Harold Hamm Diabetes Center, Oklahoma City, OK 73104, USA. dfields@ouhsc.edu
authors.forename: D A
authors.initials: DA
authors.lastname: Fields
authors.forename: E W
authors.initials: EW
authors.lastname: Demerath
mesh_terms: D015502:Absorptiometry, Photon; D050154:Adiposity; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D001942:Breast Feeding; D002657:Child Development; D003430:Cross-Sectional Studies; D005260:Female; D005947:Glucose / Q000032:analysis*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007328:Insulin / Q000032:analysis*; D015850:Interleukin-6 / Q000032:analysis*; D020738:Leptin / Q000032:analysis*; D039382:Maternal Nutritional Physiological Phenomena; D008895:Milk, Human / Q000737:chemistry*; D009825:Oklahoma; D010865:Pilot Projects; D011247:Pregnancy; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis*
chemical_list: C508600:IL6 protein, human; D007328:Insulin; D015850:Interleukin-6; D020738:Leptin; D014409:Tumor Necrosis Factor-alpha; D005947:Glucose