Free sugar and sugar alcohol concentrations in human breast milk.

OBJECTIVES: The goal was to determine the free sugars and polyols in human breast milk, both term and preterm, for comparison with formula milks.
METHODS: Methodology was developed for the measurement of the free sugars and polyols in breast milk. There were 16 samples collected from women who delivered at term and 17 samples from women delivering preterm. For purposes of comparison, samples were also collected from four commercial formulas for term infants and eight from commercial formulas for preterm infants as well as one sample of cows' milk. All samples were frozen immediately and analyzed by high-performance liquid chromatography techniques.
RESULTS: Except for lactose concentrations, no significant differences were detected for all other sugars and polyols between term and preterm breast milk samples. Within breast milk samples, two patterns emerged, with one group containing additional elution peaks for compounds not yet identified. A second group did not contain these compounds. There were a number of significant differences between breast milk and formulas, particularly for inositol, glycerol, glucose, and galactose. All milks contained significant concentrations of mannose.
CONCLUSIONS: There are no significant differences among breast milk samples for free sugar and polyol concentrations except lactose. However, some milk contains additional peaks that could be of dietary or genetic origin. Formula milk has relatively high concentrations of glucose and galactose compared with breast milk, suggesting some lactose hydrolysis.