The Health Consequences of Early Soy Consumption

Abstract

Infants fed soy formula are the segment of the U. S. population that consumes the most soy. Before birth and after weaning, most Americans are not exposed to appreciable levels of soyfoods other than foods that have small amounts of processed soy components. The opposite scenario occurs in Asia, because Asians are more likely to consume relatively high levels of soyfoods throughout life, except between birth and weaning, when breastfeeding or milk-based formula are common. Soy formula is made with soy protein isolate containing isoflavones (SPI+) and supports normal growth and development in term infants. Recent data suggest that there are no long-term adverse effects of early exposure to soy formula through young adulthood. It is as yet unknown whether soy formula consumption by infants will result in health problems or benefits upon aging, but multigenerational animal studies with diets made with SPI+ have not revealed any problems. Soy isoflavones can function as estrogen agonists, antagonists or selective estrogen receptor modulators, depending on the conditions, and much research has focused on health effects of purified isoflavones. Results from several studies suggest that the effects of diets made with SPI+ differ significantly from those of diets to which purified soy isoflavones are added. Furthermore, it seems that soy protein processed to contain lower levels of isoflavones also provides significant health benefits. Further research is needed to confirm the results of the few studies that have been conducted and new studies are needed to investigate the more subtle effects that could occur during development or that could surface later in life.

Soy, phytoestrogens and their impact on reproductive health

“…As might be expected, infancy is a very sensitive period for endocrine disruption, and exposure to significant levels of phytoestrogens during this critical period of development can have potentially detrimental long-term effects on reproduction fertility and behavior. The mean daily consumption of total isoflavones in babies fed on soy formula ranges from 6 to 9 mg/kg, resulting in a much higher plasma isoflavone concentration (980 lg/L) than their breast-fed or cow-based formula counterparts (9.4 and 4.7 lg/L, respectively; Badger et al, 2002;Setchell et al, 1997Setchell et al, , 1998. By comparison, the circulating concentration of phytoestrogens in infants fed with soy formula is 13,000-22,000 times higher than the endogenous estrogen levels, or 50-100 times higher than the estradiol levels, present in pregnant women (Badger et al, 2002;Setchell et al, 1998).…”

“…The mean daily consumption of total isoflavones in babies fed on soy formula ranges from 6 to 9 mg/kg, resulting in a much higher plasma isoflavone concentration (980 lg/L) than their breast-fed or cow-based formula counterparts (9.4 and 4.7 lg/L, respectively; Badger et al, 2002;Setchell et al, 1997Setchell et al, , 1998. By comparison, the circulating concentration of phytoestrogens in infants fed with soy formula is 13,000-22,000 times higher than the endogenous estrogen levels, or 50-100 times higher than the estradiol levels, present in pregnant women (Badger et al, 2002;Setchell et al, 1998). Unfortunately, very few epidemiological or clinical studies have investigated the potential long-term effects of soy-based formula and/or isoflavone exposure on reproduction, fertility and behavior.…”

Isoflavonas em produtos comerciais de soja

“…Silvana Pedroso de GÓES-FAVONI 2 , Adelaide Del Pino BELÉIA 2, *, Mercedes C. CARRÃO-PANIZZI 3 , José Marcos Gontijo MANDARINO 3 …”

“…Estudos recentes comprovam que a administração de isoflavonas purificadas produzem efeitos biológicos menos significativos quanto a redução do risco de doenças que àqueles produzidos pelo consumo de isoflavonas e proteínas da soja [3]. Atualmente, preconiza-se que a ingesta de 25g de proteínas de soja associados a cerca de 30 a 50mg de isoflavonas diariamente são capazes de reduzir o colesterol sérico [19].…”

Soybean Products Consumption in the Prevention of Cardiovascular Diseases

“…However, the potential effects of soy foods in human health remain highly controversial (Erdman, Jr. 2000;Messina et al 2004;Mezei et al 2003;Sacks et al 2006). It has been suggested that many of the health effects of soy may be related to activation of ER and ER , mediated by soy-associated phytoestrogens, especially genistein and daidzein (Badger et al 2002).…”