The health implications of soy infant formula

Abstract

Soy formula (SF) has been fed to millions of infants worldwide. It has been shown to promote growth and development as well as milk-based formula (MF). Controversy has developed over the adequacy and safety of SF. Most concerns are based on in vivo and in vitro data that raise the possibility of estrogenic effects of isoflavones contained in SF. There are few studies of children who were fed SF, and thus insufficient data are available to judge if SF feeding results in clinically significant developmental effects and if there are any long-term health consequences (adverse or beneficial). However, the Arkansas Children's Nutrition Center is conducting a prospective longitudinal study comparing growth, development, and health of breastfed children with formula-fed (SF and MF) children from birth through age 6 y. After 5 y of study, children in all 3 groups (n > 300) are growing and developing within normal limits, and there are no indications of adverse effects in the soy-fed children. Neonatal pig studies comparing SF, MF, and breast milk (BM) have shown diet-specific gene expression profiles in various target tissues. Therefore, although SF differed significantly from BM, MF also differed from BM, and SF differed from MF. Nonetheless, these animals grew and developed normally, and SF piglets had several health benefits (eg, increased bone quality) and no observable adverse effects. Thus, to date, our results suggest that SF supports normal growth and may have advantages in promoting bone development.

Dietary soy isoflavone attenuated growth performance and intestinal barrier functions in weaned piglets challenged with lipopolysaccharide

“…However, the growth performance of piglets during the overall period (days 1-14) were not affected by soy isoflavone supplementation (Table 4). This was similar with previous investigations that there were no significant difference in overall growth performance of pigs [27,28], infants [29], and diabetic rats [30] fed diets containing different soy isoflavone contents. Our results may suggest that the response of piglets to soy isoflavones is possibly depending on their health status, and more pronounced when piglets are under exposure to intestinal inflammation or damages.…”

Soybean isoflavone exposure does not have feminizing effects on men: a critical examination of the clinical evidence

“…Human infants do not produce equol, and there are no reports of enlarged testes in infants fed soy formula (44). As discussed by Badger et al (44), when piglets were fed milk infant formula, soy infant formula or were fed by a sow (breast fed) from 48 h through 21 d, testicular weights did not differ among diet groups (106). The neonatal pig models human growth, development, metabolism, and endocrine systems and like human infants, piglets do not produce equol.…”

Soybean isoflavones regulate dendritic cell function and suppress allergic sensitization to peanut

“…12,71 The potency of isoflavone is about 1,000 to 10,000 times less than that of endogenous estrogens. 72 Therefore it is possible that high consumption of soy products (as in soy infant formula) might increase the serum isoflavone levels enough to induce estrogenic activity. However, it has been shown that dietary isoflavones from soy formula do not adversely affect human growth and reproductive development.…”