Newborn babies who are fed soy-based formulas experience subtle changes in certain reproductive cells and tissues that are not experienced by infants who are breastfed or fed cow’s milk formulas. According to a new study, these changes – measured during the first year of life – indicate that potential long-term effects of exposure to estrogen-like compounds in soy formulas should be evaluated further.
The researchers investigated the development of estrogen-responsive tissues and measured specific hormone levels in 283 babies fed soy formula (102 infants), cow‘s milk formula (111 infants), or breast milk (70 infants) between 2010 and 2013. They found development in baby girls fed soy-based formulas that is consistent with increased estrogen exposure.
Soy-based formulas are often used as alternative to cow‘s milk formulas in babies who may have a milk allergy, lactose intolerance, or other feeding problems. More research is needed to determine how estrogen-like compounds in soy protein affect hormonal development. This study was funded and led by the National Institute of Environmental Health Sciences, part of the National Institutes of Health (NIH).