title: Absolute Quantitation of Human Milk Oligosaccharides Reveals Phenotypic Variations during Lactation.
abstract: The quantitation of human milk oligosaccharides (HMOs) is challenging because of the structural complexity and lack of standards.
  
  
  
  The objective of our study was to rapidly measure the absolute concentrations of HMOs in milk using LC-mass spectrometry (MS) and to determine the phenotypic secretor status of the mothers.
  
  
  
  This quantitative method for measuring HMO concentration was developed by using ultraperformance LC multiple reaction monitoring MS. It was validated and applied to milk samples from Malawi (88 individuals; 88 samples from postnatal month 6) and the United States (Davis, California; 45 individuals, mean age: 32 y; 103 samples collected on postnatal days 10, 26, 71, or 120, repeated measures included). The concentrations of α(1,2)-fucosylated HMOs were used to determine the mothers' phenotypic secretor status with high sensitivity and specificity. We used Friedman's test and Wilcoxon's signed rank test to evaluate the change in HMO concentration during the course of lactation, and Student's t test was used to compare secretors and nonsecretors.
  
  
  
  A decrease (P < 0.05) in HMO concentration was observed during the course of lactation for the US mothers, corresponding to 19.3 ± 2.9 g/L for milk collected on postnatal day 10, decreasing to 8.53 ± 1.18 g/L on day 120 (repeated measures; n = 14). On postnatal day 180, the total concentration of HMOs in Malawi milk samples from secretors (6.46 ± 1.74 mg/mL) was higher (P < 0.05) than that in samples from nonsecretors (5.25 ± 2.55 mg/mL ). The same trend was observed for fucosylated species; the concentration was higher in Malawi milk samples from secretors (4.91 ± 1.22 mg/mL) than from nonsecretors (3.42 ± 2.27 mg/mL) (P < 0.05).
  
  
  
  HMOs significantly decrease during the course of lactation. Secretor milk contains higher concentrations of total and fucosylated HMOs than does nonsecretor milk. These HMO concentrations can be correlated to the health of breastfed infants in order to investigate the protective effects of milk components. The trials were registered at clinicaltrials.gov as NCT01817127 and NCT00524446.
authors: Department of Chemistry.|Foods for Health Institute, and.
authors: Gege
authors: G
authors: Xu
authors: Department of Chemistry.|Foods for Health Institute, and.
authors: Jasmine Cc
authors: JC
authors: Davis
authors: Department of Chemistry.|Foods for Health Institute, and.
authors: Elisha
authors: E
authors: Goonatilleke
authors: Foods for Health Institute, and.|Department of Food Science and Technology, University of California, Davis, CA.
authors: Jennifer T
authors: JT
authors: Smilowitz
authors: Foods for Health Institute, and.|Department of Food Science and Technology, University of California, Davis, CA.
authors: J Bruce
authors: JB
authors: German
authors: Department of Chemistry, cblebrilla@ucdavis.edu.|Foods for Health Institute, and.
authors: Carlito B
authors: CB
authors: Lebrilla
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007774:Lactation / Q000502:physiology*; D008895:Milk, Human / Q000737:chemistry*; D009844:Oligosaccharides / Q000737:chemistry* / Q000378:metabolism
chemical_list: D009844:Oligosaccharides
keywords: fucosylation; human milk oligosaccharides; lactation; mass spectrometry; secretor