Phytoestrogens and soy based infant formula

Essex, Charles

doi:10.1136/bmj.313.7056.507

Cited by 32 publications

(28 citation statements)

References 10 publications

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“…Thus, thymic effects of genistein seen after ICI 182,780 treatment occur through non-ER-mediated mechanisms. These could involve effects on protein tyrosine kinases and͞or topoisomerase II, both of which have been shown to be inhibited in thymocytes and other cell types by high genistein concentrations in vitro (16,17).…”

Section: Genistein Decreases Thymic Size In Female and Male Mice Thromentioning

confidence: 99%

The phytoestrogen genistein induces thymic and immune changes: A human health concern?

Yellayi

Naaz

Szewczykowski

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

225

165

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Use of soy-based infant formulas and soy͞isoflavone supplements has aroused concern because of potential estrogenic effects of the soy isoflavones genistein and daidzein. Here we show that s.c. genistein injections in ovariectomized adult mice produced doseresponsive decreases in thymic weight of up to 80%. Genistein's thymic effects occurred through both estrogen receptor (ER) and non-ER-mediated mechanisms, as the genistein effects on thymus were only partially blocked by the ER antagonist ICI 182,780. Genistein decreased thymocyte numbers up to 86% and doubled apoptosis, indicating that the mechanism of the genistein effect on loss of thymocytes is caused in part by increased apoptosis. Genistein injection caused decreases in relative percentages of thymic CD4 ؉ CD8 ؊ and double-positive CD4 ؉ CD8 ؉ thymocytes, providing evidence that genistein may affect early thymocyte maturation and the maturation of the CD4 ؉ CD8 ؊ helper T cell lineage. Decreases in the relative percentages of CD4 ؉ CD8 ؊ thymocytes were accompanied by decreases in relative percentages of splenic CD4 ؉ CD8 ؊ cells and a systemic lymphocytopenia. In addition, genistein produced suppression of humoral immunity. Genistein injected at 8 mg͞kg per day produced serum genistein levels comparable to those reported in soy-fed human infants, and this dose caused significant thymic and immune changes in mice. Critically, dietary genistein at concentrations that produced serum genistein levels substantially less than those in soy-fed infants produced marked thymic atrophy. These results raise the possibility that serum genistein concentrations found in soy-fed infants may be capable of producing thymic and immune abnormalities, as suggested by previous reports of immune impairments in soy-fed human infants. S oy-based formula for human infant nutrition is widely used, with approximately 25% of formula-fed infants in the U.S. consuming soy-based formula (1). This number represents 15% of all infants in the U.S., or about 750,000 infants͞year (1, 2). Infants consuming soy formula are exposed to high levels of genistein and daidzein, estrogenic isoflavones present in soybeans and soy products. On average, infants fed soy-based formula consume 6.0-11.9 mg of isoflavones͞kg per day (3, 4), an order of magnitude greater than adults eating high-soy diets. Total plasma levels of isoflavones and genistein in soy-fed infants range from 2.0 to 6.6 and 1.5 to 4.4 mol͞liter, respectively (3), 10-fold greater than levels in Japanese adults whose diets have historically included soy, and 200-fold greater than plasma levels in infants fed cow's milk formula or human breast milk (3, 5). Levels of the free genistein aglycone as a percent of total genistein are higher in rat pups than in adults (6), but have not been measured in human infants. If a similar phenomenon occurs in humans, relative levels of the biologically active free aglycones may be even greater than the 10-fold difference documented in total (free ϩ conjugated) serum isoflavone and genistein levels in...

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Section: Genistein Decreases Thymic Size In Female and Male Mice Thromentioning

confidence: 99%

The phytoestrogen genistein induces thymic and immune changes: A human health concern?

Yellayi

Naaz

Szewczykowski

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

225

165

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“…30,31 Setchell and Cassidy 32 estimated that the amount of isoflavones ingested by infants fed soy-based formulas on a body weight basis exceeded those reported to increase the length of the menstrual cycle in adult women. However, an increased incidence of feminization in male infants 33 or an increased incidence of hypospadias in high soyconsuming populations 34 have not been observed. Even in infants fed soy-based formulas exclusively, the sulfate and glucuronide conjugates of phytoestrogens are identified in plasma, although both of these are rapidly excreted.…”

mentioning

confidence: 99%

Use of Soy Protein-Based Formulas in Infant Feeding

Bhatia¹,

Greer²

2008

Pediatrics

321

333

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Soy protein-based formulas have been available for almost 100 years. Since the first use of soy formula as a milk substitute for an infant unable to tolerate a cow milk protein-based formula, the formulation has changed to the current soy protein isolate. Despite very limited indications for its use, soy protein-based formulas in the United States may account for nearly 25% of the formula market. This report reviews the limited indications and contraindications of soy formulas. It will also review the potential harmful effects of soy protein-based formulas and the phytoestrogens contained in these formulas.T HE AMERICAN ACADEMY of Pediatrics (AAP) is committed to the use of human milk as the ideal source of nutrition for infant feeding. However, by 2 months of age, the majority of infants in North America are receiving at least some formula. Soy-based infant formulas have been available for almost 100 years. 1 Despite limited indications, soy protein-based formula accounts for approximately 20% of the formula market in the United States. Because an infant formula provides a source of nutrition for an extended interval, its nutritional adequacy must be proven, and the indications for its use must be substantiated and well understood. This statement updates the 1998 AAP review of soy protein-based formulas and addresses the ongoing concern of phytoestrogens in soy formulas. COMPOSITIONIsolated soy protein-based formulas currently on the market are all free of cow milk protein and lactose and provide 67 kcal/dL. All are iron-fortified and meet the vitamin, mineral, and electrolyte specifications addressed in the 2004 guidelines from the AAP for feeding term infants 2 and established by the US Food and Drug Administration. 3 The protein is a soy isolate supplemented with L-methionine, L-carnitine, and taurine to provide a protein content of 2.45 to 2.8 g per 100 kcal or 1.65 to 1.9 g/dL. The fat content of soy protein-based formulas is derived primarily from vegetable oils. The quantity of specific fats varies by manufacturer and is usually similar to those in the manufacturer's corresponding cow milk-based formula. The fat content ranges from 5.02 to 5.46 g per 100 kcal or 3.4 to 3.6 g/dL. The oils used include soy, palm, sunflower, olein, safflower, and coconut. Docosahexaenoic and arachidonic acids now are added routinely.In formulas, carbohydrate sources are corn maltodextrin, corn syrup solids, and sucrose, with content ranging from 10.26 to 10.95 g per 100 kcal or 6.9 to 7.4 g/dL. Until 1980, mineral absorption from soy formulas was erratic because of poor stability of the suspensions and the presence of excessive soy phytates. 4 Because soy protein isolate formulas still contain 1.5% phytates, and up to 30% of the total phosphorus is phytate bound, they contain 20% more calcium and phosphorus than cow milk-based formulas and maintain the ratio of calcium to available phosphorus of 1.1 to 2.0:1. With the current formulations, bone mineralization, serum concentrations of calcium and phosphorus, and alka...

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“…As seen in Table 1, processed soy foods have considerably less isoflavone content than whole soybeans. Soy-based infant formula is considered the main source of phytoestrogens in the diet of young children 6 .…”

Section: Food Sources and Consumptionmentioning

confidence: 99%

Phytoestrogens: A Review of Recent Findings

Stark¹,

Madar²

2002

Journal of Pediatric Endocrinology and Metabolism

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Phytoestrogens have been investigated at the epidemiological, clinical and molecular levels to determine their potential health benefits. The two major groups of phytoestrogens, isoflavones and lignans, are abundant in soy products and flax respectively, but are also present in a variety of other foods. It is thought that these estrogen-like compounds may protect against chronic diseases, such as hormone-dependent cancers, cardiovascular disease and osteoporosis. Furthermore, phytoestrogens are used as a natural alternative to hormone replacement therapy and to reduce menopausal symptoms. Phytoestrogens have been shown to induce both estrogenic and anti-estrogenic effects but their biological relevance and potency have not been well characterized. In children, consumption of soy-based formulas and soy milk can lead to high levels of exposure to phytoestrogens with only limited data available concerning potential benefits or adverse effects. Phytoestrogens are considered good candidates for use in natural therapies and as chemopreventive agents in adults. Safe and efficacious levels have yet to be established.

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Phytoestrogens and soy based infant formula

Cited by 32 publications

References 10 publications

The phytoestrogen genistein induces thymic and immune changes: A human health concern?

The phytoestrogen genistein induces thymic and immune changes: A human health concern?

Use of Soy Protein-Based Formulas in Infant Feeding

Phytoestrogens: A Review of Recent Findings

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