Poster Sessions

Epi-1

Yang Cao

Y. Cao, A. Calafat, D. Doerge, D. Umbach, J. Bernbaum, N. Twaddle, X. Ye, W. Rogan

Isoflavones in Urine, Saliva and Blood of Infants – Data from the Soy Estrogen and Development Study

Objective: To examine children’s exposure to isoflavones from different feeding methods and to investigate the degree to which urinary concentration reflected blood or saliva concentration. Participant: One hundred sixty-six full term infants between birth and 1 year of age were recruited into soy formula, cow milk formula or breast milk regimens according to feeding histories. Main Outcome Measures: Three isoflavones (daidzein, genistein, and equol) were measured in 381 urine, 361 saliva and 88 blood samples. Results: Concentrations of daidzein and genistein were undetectable in most blood or saliva samples from children fed breast milk or cow-milk formula. The proportion of non-detectable values was somewhat lower in urine than the other matrices. Concentrations of equol were detectable in only a few urine samples. For both daidzein and genistein, urine contained the highest median concentrations, followed by blood, and then saliva. Urinary concentrations of genistein and daidzein were about 500 times higher in the soy-formula-fed infants than in the cow-milk-formula-fed infants. The correlations between matrices for either analyte were strikingly lower than the correlation between the two analytes in any single matrix. We did not find significant correlations between isoflavone concentrations and the levels of certain hormones in children fed soy formula.