Possible Adverse Effects of Soy Isoflavone Mixture on Pregnant and Lactating Rats and their Suckling Pups

Abstract

There is general agreement that soy isoflavones can be beneficial to health in adults. However, isoflavones are well known as endocrine-disrupting chemicals. The possibility that soy foods might adversely affect the reproductive system of mothers and infants should be considered. The aim of this study was to evaluate the adverse effects of a soy isoflavone mixture on rat dams and their offspring. The rat dams were fed diets containing the isoflavone mixture (commercial name: Soyact, aglycone type) at 0, 0.25, 0.5 and 1.0 g/kg as total isoflavones from pregnancy day 5 to postnatal day 13. We found that the dietary soy isoflavone mixture decreased the dam body weights in a dose-dependent manner and that the number of pups also tended to decrease. Genistein and daidzein were detected in the blood of the dams and the stomach contents of the suckling pups. The concentrations of daidzein were higher than those of genistein. We also found the transfer of isoflavones to the fetus. The reproductive output and fetus numbers were not significantly different in the isoflavone groups compared with the control group. The number of absorbed fetuses tended to increase though not significant. Our experiments suggested that soy isoflavones have the possibility of inducing adverse effects on endocrinic functions and others in animal studies at very high doses.

Histopathological Effects of Aloe barbadensis and Soybean Oil on Rat Liver

“…In another study it was emphasized that consumption of soy provided benefits to control lipid levels (Lin et al, 2005). However, it was indicated that raw unprocessed soybean oil contains a toxic factor and it downgrades the growth of rats pups (Ikegami et al, 2006).…”

Effect of Daidzein 120 Mg Supplementation to Menopausal Symptoms and Quality of Life in Non Equol Producer Women

“…Until recent, no studies had shown any side effect by taking daidzein supplementation. High doses administration of phytochemical shown no effective effect or may not safeand Ikegami's study showed high-dose isoflavone (1 g per kg body weight) in pregnant mouse related to low birth weight to the fetus [30,31]. Usage of plant-based derived preparations, such as soy isoflavone needs further investigations to reveal its real pharmacological and physiological effect for number of dosage in certain period of administration [32].…”

The onset of puberty in female mice as reflected in urinary steroids and uterine/ovarian mass: interactions of exposure to males, phyto-oestrogen content of diet, and ano-genital distance

“…Given the rich distribution of oestrogen receptors in female reproductive tissue (Cooke et al 1997, Couse et al 1997, Fitzpatrick et al 1999, Jefferson et al 2002, exposure to phyto-oestrogens can influence oestrogen-related action at the pre-pubertal uterus (Wang et al 2005, Takashima-Sasaki et al 2006 and ovaries (Jefferson et al 2002, Takashima-Sasaki et al 2006). These compounds are also able to cross the placental barrier (Brown & Setchell 2001, Ikegami et al 2006, potentially having a significant effect on prenatal hormonal exposure.…”