Study of Infant Diets on Estrogen Activity and Development

Term newborns have anatomic and sonographic evidence of in utero estrogen exposure. Over the first six months to a year of life, as the influence of maternal hormone wanes, these findings recede. Soy infant formula contains large amounts of isoflavones (diadzein and genistein) that can occupy estrogen receptors and act as estrogens in the laboratory. A food substance with estrogen activity might prolong the effect of maternal hormones, or interfere with hormonal homeostasis the child. Two cross-sectional pilot study (SEAD 2 and SEAD 3) will be undertaken in order to establish the methods for a future, multi-center study designed to assess the potential effects of soy formula on estrogen activity in infants. Another cross-sectional pilot study (SEAD 1) will be undertaken to evaluate anatomical evidence detected by ultrasound and will be conducted at The Children's Hospital in Boston. Details of the SEAD 1 study will not be presented in this protocol. In the first pilot study (SEAD 2), 84 examinations of full-term infants, ages 0-6 months and on one of three feeding regimens (soy formula, breast milk or cow's milk formula) will be conducted. This study will establish a protocol for examining and sampling methods to be used for a later trial investigating whether exposure to soy estrogen compared to breast milk and non-soy formulas prolongs anatomical evidence of estrogen exposure and response. In addition to the physical examination, vaginal cells will be collected for cytology analysis. Breast nipple secretions, if present, will also be collected and analyzed for protein and sugar levels. In the second pilot study (SEAD 3), 372 evaluations on full-term infants will be conducted in parallel with the first study. SEAD 3 will assess the hormonal and biochemical status of full-term infants age 0-12 months. This study will establish a protocol for sampling methods to be used for collecting urine, saliva, serum, and hair samples. Endogenous hormone levels such as testosterone, estradiol, and isoflavone levels (genestein and diadzein) will be measured in serum and the results will be compared against the non-serum tests (urine, saliva and hair). The purpose of these two pilot studies is twofold. The first is to develop and finalize recruitment and collections procedures in preparation for a larger, comprehensive trial of biological response in children to soy formula with and without the estrogenic isoflavones. The second is to study the natural history of estrogen activity in infants on a variety of feeding regimens.