Detection of Phytoestrogen Metabolites in Breastfed Infants’ Urine and the Corresponding Breast Milk by LC-MS/MS

To date, there has been limited information on phytoestrogen exposure and metabolism in breastfed infants. In the present work, 50 sample pairs of Chinese breastfed infants’ urine and the corresponding breast milk were collected. The contents of relevant phytoestrogen metabolites in the biosamples were detected via LC-MS/MS. The correlations between the phytoestrogen metabolite contents in breastfed infants’ urine and those in the corresponding breast milk were analyzed. The average concentrations of total phytoestrogen metabolites in breast milk and urine were 0.27 nmol/mL and 0.23 nmol/mL, respectively. Genistein and enterolactone levels in the infant urine were positively correlated with their concentrations in the corresponding breast milk samples, which implies that urine excretion can be utilized as a noninvasive parameter for precise genistein and enterolactone intake assessment. Additionally, the efficiency of PE urine excretion showed significant differences across infants with different age, gen...