Cortical Responses to Speech Sounds in 3- and 6-Month-Old Infants Fed Breast Milk, Milk Formula, or Soy Formula

Abstract

Controversy exists about the safety of soy formula, with the main concern relating to potential estrogenic effects of soy protein. Since estrogens influence early brain development, we compared behavioral development and cortical responses (event-related potentials; ERPs) to speech sounds in infants fed either breast milk or formula (milk- or soy-based). Across-groups ERP measures were generally similar and behavioral measures were within normal ranges, suggesting no important influences of soy formula on behavioral development and brain function during the study period. Analyses relating ERP and behavioral measures revealed diet- and gender-specific emphases that may reflect differences in developmental trajectories of brain-behavior relationships.

A Hypothesis Regarding the Molecular Mechanism Underlying Dietary Soy-Induced Effects on Seizure Propensity

“…Soy products are rich in phytoestrogens, which are natural plant chemicals that have estrogenic and anti-estrogenic properties. The effects of phytoestrogens on fetal and early childhood development have not been extensively studied (29–31). Rodent studies indicate that the placenta acts as a sink for phytoestrogens, and that while transport of phytoestrogens across the placenta is inefficient, low levels are found in the fetus and are sufficient for activation of estrogen receptor beta (ERβ) (32).…”

Breastfeeding Is a Dynamic Biological Process—Not Simply a Meal at the Breast

“…Many developmental neuroscience studies utilizing advanced outcome assessment tools provide insights into this possibility. [9][10][11][12][13][14][15][16][17][18][19][20] Consider the neonatal brain. It weighs about 350-400 g at birth, or about 30% of the weight of the adult brain.…”

Effects of Phytoestrogens on the Developing Brain, Gut Microbiota, and Risk for Neurobehavioral Disorders

“…Other studies implicate early exposure to such compounds in affecting risk that sons will develop autism and other behavioral disorders (54,55), although it is clear that boys are already at a least 3:1 greater risk for these disorders than girls (129). Additional reports indicate babies provide soy formula do not show different behavioral patterns that those provide other types of formula (56)(57)(58)(59)(60). Taken together, the current human data do not provide a clear picture as to whether phytoestrogens or soy formula or consumption of such products by expecting mothers jeopardizes offspring brain development and risk for neurobehavioral disorders.…”

“…Other studies have found no differences in cognitive function and infants fed soy or breast milk. For instance, event-related potentials to speech sounds and behavioral measures were similar in infants fed either soy based formula or breast milk (56). While another study found differences in the electroencephalographic (EEG) activity in formula-fed vs. breastfed infants, no differences were detected between those provided soy vs. milk formula (57).…”