Phytoestrogens in Soy-Based Infant Foods: Concentrations, Daily Intake, and Possible Biological Effects (original) (raw)
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Journal of Endocrinology and Metabolism, 2017
The consumption of soybeans and their constituents, isolated soy protein and isoflavones, has been associated with positive effects on body weight, lipid profile and insulin, which has stimulated the production and consumption of foods derived from soy. However, these polyphenolic compounds (isoflavones) have similar structure to 17-β estradiol and may act as agonists or antagonists in estrogen receptors. Due to its estrogenic activity, the safety of its consumption during critical periods of development, such as gestation and lactation, has been questioned. Studies that evaluate the effects of soybeans on endocrine metabolic parameters are still controversial. This review focuses on the role that soy and isoflavones play during critical periods of development and into adulthood.
Phytoestrogens in Soybean and Precocious Pubertal Development: Causality or Casuality?
International Journal of Pediatrics and Child Health
Introduction: Data on the effects of phytoestrogens soy exposure on pubertal timing have been equivocal. We reported a case of a girl who had eaten only soy and derivatives for her first 9 years of life and presented clinical manifestation of precocious pubertal development. Case presentation: A caucasian female infant, after 40 days of exclusive breastfeeding, was introduced to soy formula due to suspected milk protein allergy. Since then, the patient ate soy beverage and soy-based foods exclusively. At the age of 7 years and 9 months, the girl showed premature thelarche and pubarche. Advanced skeletal age was detected. Peak of LH after GnRH stimulation test was <5 mU/ml. At the age of 9 years, Tanner pubertal stage was 3, with a further advanced bone age; initial pubertal growth spurt and estrogenization of the external genitalia were also revealed. GnRH stimulation test produced a peak of LH 3.7 mU/ml. Other hormonal parameters resulted within normality ranges. Suspension of t...
Safety of Soy-Based Infant Formulas Containing Isoflavones: The Clinical Evidence
The Journal of Nutrition
Soy protein has been used in infant feeding in the West for nearly 100 y. Soy protein infant formulas have evolved in this interval to become safe and effective alternatives for infants whose nutritional needs are not met with human milk or formulas based on cow's milk. Modern soy formulas meet all nutritional requirements and safety standards of the Infant Formula Act of 1980. They are commonly used in infants with immunoglobulin E-mediated cow's milk allergy (at least 86% effective), lactose intolerance, galactosemia, and as a vegetarian human milk substitute. Largely as a result of research in animal models, concerns have been voiced regarding isoflavones in soy infant formulas in relation to nutritional adequacy, sexual development, neurobehavioral development, immune function, and thyroid disease. We discuss the available clinical evidence regarding each of these issues. Available evidence from adult human and infant populations indicates that dietary isoflavones in soy infant formulas do not adversely affect human growth, development, or reproduction.
Soy as an Endocrine Disruptor: Cause for Caution?
Journal of Pediatric Endocrinology and Metabolism, 2000
Endocrine disrupting compounds (EDCs) alter the function of the endocrine system and consequently cause adverse health effects. Phytoestrogens, natural plant compounds abundantly found in soy and soy products, behave as weak estrogen mimics or as antiestrogens. They are considered to be EDCs, and have some beneficial effects on health, including reducing the risk of breast cancer and improving metabolic parameters. However, the supporting evidence that consumption of phytoestrogens is beneficial is indirect and inconsistent. Lifetime exposure to estrogenic substances, especially during critical periods of development, has been associated with formation of malignancies and several anomalies of the reproductive systems. Phytoestrogen consumption in infants, through soy-based formulas, is of particular concern. Prospective epidemiological studies for the evaluation of the effect of phytoestrogens alone, and in combination with other estrogenic chemicals, are lacking, yet possible adverse effects should not be taken lightly.
Advances in reproductive sciences, 2017
Chemically, soy contains a group of phytoestrogens called isoflavones, predominantly genistein and daidzein. The aim of the present study was to determine the effects of post weaning consumption of dietary soy isoflavones on prepubertal and postpubertal serum levels of some reproductive hormones of male Wistar rats. The study involved investigating the effects of different doses of isoflavones in the diet. Male rats were weaned on either soy isoflavone free diet or on isoflavone containing diets, formulated by adding increasing amounts of Novasoy, a commercially available isoflavone supplement to the isoflavone free diet to give varying concentrations of isoflavones. Three isoflavone containing diets were used and these had 74.5, 235.6 and 1046.6 mg total isoflavones/kg pelleted diet. These diets represented the isoflavone concentration lower, equal to and more than that found in soy-based infant formulas respectively. The results obtained showed that; administration of low doses soy isoflavones (74.5 mg/kg) produced significant (p < 0.05) increase in serum Antimullerian Hormone levels both in prepubertal and post pubertal rats, when compared to the control groups. Administration of moderate doses of isoflavones (235.6 mg/kg) produced significant (p < 0.05) increase in serum levels of Antimullerian Hormone and Inhibin in both prepubertal and post pubertal rats when compared to the control groups. Administration of high doses of isoflavones (1046.6 mg/kg) produced significant (p < 0.05) increase in serum levels of Inhibin in both prepubertal and post pubertal rats when compared to the control groups. From this study, it was concluded that post-weaning consumption soy isoflavones produced significant changes
Testicular Development in Male Rats Is Sensitive to a Soy-Based Diet in the Neonatal Period
Biology of Reproduction, 2014
Approximately 30% of infants in the United States are exposed to high doses of isoflavones resulting from soy infant formula consumption. Soybeans contain the isoflavones genistin and daidzin, which are hydrolyzed in the gastrointestinal tract to their genistein and daidzein aglycones. Both aglycones possess hormonal activity and may interfere with male reproductive development. Testosterone, which supports male fertility, is mainly produced by testicular Leydig cells. Our previous studies indicated that perinatal exposure of male rats to isoflavones induced proliferative activity in Leydig cells and increased testosterone concentrations into adulthood. However, the relevance of the neonatal period as part of the perinatal window of isoflavone exposure remains to be established. The present study examined the effects of exposure to isoflavones on male offspring of dams maintained on a casein-based control or whole soybean diet in the neonatal period, that is, Days 2 to 21 postpartum. The results showed that the soybean diet stimulated proliferative activity in developing Leydig cells while suppressing their steroidogenic capacity in adulthood. In addition, isoflavone exposure decreased production of anti-Mü llerian hormone by Sertoli cells. Similar to our previous in vitro studies of genistein action in Leydig cells, daidzein induced proliferation and interfered with signaling pathways to suppress steroidogenic activity. Overall, the data showed that the neonatal period is a sensitive window of exposure to isoflavones and support the view that both genistein and daidzein are responsible for biological effects associated with soy-based diets.