Phytoestrogens: the pediatric perspective

Sex Hormones, Gonadotropins, and Sex Hormone-binding Globulin in Infants Fed Breast Milk, Cow Milk Formula, or Soy Formula

Measurement of endogenous hormones in early life is important to investigate the effects of hormonally active environmental compounds. To assess the possible hormonal effects of different feeding regimens in different sample matrices of infants, 166 infants were enrolled from two U.S hospitals between 2006 and 2009. The children were classified into exclusive soy formula, cow milk formula or breast milk regimens. Urine, saliva and blood samples were collected over the first 12 months of life. Estradiol, estrone, testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and sex hormone-binding globulin (SHBG) levels were measured in the three matrices. Lower estradiol and LH levels were found in urine and saliva samples of soy formula-fed boys compared to cow formula-fed boys. Higher LH level was found in urine samples of soy formula-fed girls compared to cow formula-fed girls. However, we found neither a neonatal testosterone rise in the boys nor a gender-specific difference in testosterone levels, which suggests that urinary testosterone levels may not accurately reflect blood levels during mini-puberty. Nevertheless, our study shows that blood, urine and saliva samples are readily collectible and suitable for multi-hormone analyses in children and allow examination of hypotheses concerning endocrine effects from dietary compounds.

BSACI guideline for the diagnosis and management of cow's milk allergy

This guideline advises on the management of patients with cow's milk allergy. Cow's milk allergy presents in the first year of life with estimated population prevalence between 2% and 3%. The clinical manifestations of cow's milk allergy are very variable in type and severity making it the most difficult food allergy to diagnose. A careful age- and disease-specific history with relevant allergy tests including detection of milk-specific IgE (by skin prick test or serum assay), diagnostic elimination diet, and oral challenge will aid in diagnosis in most cases. Treatment is advice on cow's milk avoidance and suitable substitute milks. Cow's milk allergy often resolves. Reintroduction can be achieved by the graded exposure, either at home or supervised in hospital depending on severity, using a milk ladder. Where cow's milk allergy persists, novel treatment options may include oral tolerance induction, although most authors do not currently recommend it for routine clinical practice. Cow's milk allergy must be distinguished from primary lactose intolerance. This guideline was prepared by the Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI) and is intended for clinicians in secondary and tertiary care. The recommendations are evidence based, but where evidence is lacking the panel of experts in the committee reached consensus. Grades of recommendation are shown throughout. The document encompasses epidemiology, natural history, clinical presentations, diagnosis, and treatment.

Gastrointestinal metabolism of phytoestrogens in lactating dairy cows fed silages with different botanical composition

Dietary phytoestrogens are metabolized or converted in the gastrointestinal tract of ruminants, only limited knowledge exists on the extent and location of this conversion in vivo. The objective of this study was to quantify the gastro-intestinal metabolism of phytoestrogens in lactating dairy cows fed silages with different botanical composition. Four lactating rumen cannulated Norwegian Red cattle were assigned to a 4 × 4 Latin square with 1 cow per treatment period of 3 wk. The 4 treatment silages were prepared from grasslands with different botanical compositions: organically managed short-term timothy (Phleum pratense L.) and red clover (Trifolium pratense L.) ley (2 yr old: ORG-SG); organically managed long-term grassland with a high proportion of unsown species (6 yr old; ORG-LG); conventionally managed perennial ryegrass (Lolium perenne L.) ley (CON-PR); and conventionally managed timothy ley (CON-TI). The herbages were cut, wilted, and preserved with additive in round bales, fed as a mix of the first and third cut at 90% of ad libitum intake, and contributed to 70% of the total dry matter intake. Milk, feed, omasal digesta, urine, and feces were collected at the end of each period and analyzed for the concentrations of phytoestrogens by using a liquid chromatography-tandem mass spectrometry technique. Concentration of total isoflavones was highest in ORG-SG and lowest in CON-TI silage, whereas the content of total lignans was highest in the grass silages. The isoflavones were extensively metabolized in the rumen on all diets, and the recovery of formononetin and daidzein in omasum, mainly as equol, averaged 0.11 mg/mg. The apparent intestinal metabolism was less severe as, on average, 0.29 mg/mg of the omasal flow was recovered in feces. The plant lignans were also strongly degraded in the rumen. However, the flow of lignans to omasum and excretion in feces were, on average, 7.2- and 5.2-fold higher, respectively, than the intake of the plant lignans matairesinol and secoisolariciresinol, known as precursors of mammalian lignans. Thus, excretion to milk could not be directly related to intake, implying that plant lignans other than matairesinol and secoisolariciresinol in forage are precursors for enterolactone production in the rumen and for its content in milk. Equol followed mainly the flow of large particles out of the rumen, whereas the mammalian lignans were distributed between phases proportional to dry matter flow. The main metabolism of phytoestrogens occurred in the rumen and the main route of excretion was through feces and urine, with only a small part being excreted in milk. The concentration of phytoestrogens in milk can be manipulated through intake but the intermediate transfer capacity to milk appears to be limited by saturation.

High serum isoflavone concentrations are associated with the risk of precocious puberty in Korean girls

OBJECTIVE

The gradual decrease in the age of onset of puberty raises concerns about the contribution of phytoestrogen intake on sexual maturation. However, no data are available on the association between serum isoflavone (genistein, daidzein) concentration and central precocious puberty (CPP). The aim of the study was to test the association between serum isoflavone concentrations and the risk of CPP in Korean girls.

STUDY DESIGN

A case-control study was conducted at Inje University Hospital in Korea. One-hundred and eight girls with CPP (aged 8·6 ± 0·8 year) and 91 age-matched controls (aged 8·5 ± 0·8 year) were examined.

RESULTS

Serum concentrations of daidzein (P = 0·0202), genistein (P = 0·0021) and total isoflavones (P = 0·0009) were higher in children with CPP than in normal children. When the children were categorized into three groups according to total serum isoflavone as follows: <30, 30-70 and ≥70 nmol/l, serum concentrations of daidzein, genistein and total isoflavones significantly increased across three categories of serum isoflavone (P < 0·0001). The prevalence of CPP was significantly higher in children with serum isoflavone level of ≥30 nmol/l than those with serum level of <30 nmol/l (P = 0·0008). The adjusted OR for precocious puberty increased significantly across a range of total serum isoflavone (OR = 4·39; 95% CI: 1·83-10·51 vs OR = 5·22; 95% CI: 2·07-13·20; P = 0·001).

CONCLUSION

These results suggest that elevated serum isoflavones may be associated with the risk of CPP in Korean girls.

Effect of glycosidation of isoflavones on their bioavailability and pharmacokinetics in aged male rats

There are limited reports on the bioavailability and pharmacokinetics of isoflavones in elderly humans and aged animals. The present study was conducted to assess the effect of glycosidation of isoflavones on their bioavailability and pharmacokinetics in aged (20 month old) male Fischer-344 (F-344) rats. The F-344 rat, developed by the National Institute on Aging, is an inbred rat model that is commonly used for aging studies and resembles many features of aging humans. Three sources of isoflavones; Novasoy (a commercial supplement), a mixture of synthetic aglycons (daidzein, genistein and glycitein), and a mixture of synthetic glucosides (daidzin, genistin, and glycitin) were tested. Following administration, blood samples were collected at different times (0-48 h post-oral gavage and 0-8 h post-IV dosing). Plasma isoflavones and 7-hydroxy-3-(4'-hydroxyphenyl)-chroman (a metabolite of daidzein) were measured by LC/MS. The extent of absorption was determined by comparing the area under the curve (AUC) of the plasma-concentration time curve after intravenous (IV) administration with that following oral administration. The extent of bioavailability was then calculated as: %bioabailability = (AUC(or)/AUC(IV))x(Dose(IV)/Dose(or))x100. Bioavailabilities for genistein were significantly (p = 0.013) higher for the aglycon (35 +/- 9%) compared with the glucoside forms (11 +/- 3%). In contrast, the bioavailabilities for glycitein were significantly (p = 0.011) higher in Novasoy (27 +/- 13%) and the glucoside form (21 +/- 10%) compared with the aglycon (8 +/- 3%). No significant differences in the bioavailability of daidzein were observed in aged rats dosed with aglycon, glucoside or Novasoy. However, aged rats were able to produce equol as early as 8 h post-dosing. In summary, the source of isoflavones had significant effects on genistein and glycitein bioavailability in aged male rats.

Effects of clover-grass silages and concentrate supplementation on the content of phytoestrogens in dairy cow milk

A 2 x 2 factorial continuous experiment was conducted with 28 Norwegian Red dairy cows in early lactation to compare milk content of phytoestrogens when feeding ad libitum white clover (WCS) or red clover (RCS) grass silages prepared from the second and third cut without and with 10 kg/d supplementation of a standard concentrate. The cows were offered either RCS or WCS for 88 d (period 1) and thereafter a mixed red clover-white clover-grass silage for 48 d (period 2). Total dry matter intake and milk yield were not affected by forage type but increased with concentrate supplementation. Intake of isoflavones was several times greater in RCS than in WCS, whereas intake of lignans was greater in WCS. Concentrate supplementation reduced the intake of most phytoestrogens. Compared with WCS, RCS diets yielded milk with a greater content of flavonoids, whereas milk from WCS diets had greater contents of the mammalian lignans enterodiol and enterolactone. The content of the isoflavan equol was particularly high in RCS diets. There was no apparent carryover effect of clover type on milk phytoestrogen content because there was no difference in content between the silage treatments 3 wk after the cows were transferred to the same silage diet (period 2). Concentrate supplementation reduced the milk contents of the flavonoids equol, biochanin A, and daidzein and increased the content of mammalian lignans. The effects of silage type and concentrate supplementation on milk contents of the individual phytoestrogens were related to the intake of the compound or its precursor, except for the effect of concentrate on mammalian lignans, for which the intake of the known precursors was also reduced. Overall, this study shows that feeding cows with silage containing red clover increases the milk content of flavonoids at both low and high concentrate supplementation levels, and decreases the content of nonflavonoids such as mammalian lignans, when compared with silage containing white clover. The increased content of phytoestrogens in milk may be important when the health benefits of milk are studied.

Breast development in the first 2 years of life: an association with soy-based infant formulas

OBJECTIVE

To evaluate the estrogenic effect of soy-based formulas in female infants. These formulas contain significant amounts of phytoestrogens, compounds with structural similarity to estradiol.

PATIENTS AND METHODS

A cross-sectional study consisting of 694 female infants ages 3 to 24 months that consecutively attended 10 general pediatric clinics, none of them having been referred for breast development. The presence of breast buds served as a marker for the endocrine effect of soy-derived phytoestrogens.

RESULTS

Of the participants, 92 had consumed soy formulas for more than 3 months. Breast tissue was more prevalent in the second year of life in infants fed soy-based formula vs those that were breast-fed and those fed dairy-based formula (22.0% vs 10.3%; P = 0.02) with an odds ratio of 2.45 (95% confidence interval 1.11-5.39). No differences in breast bud prevalence were observed during the first year of life. Unlike infants on dairy-based formulas and breast-feeding, infants fed a soy-based formula did not demonstrate a decline in the prevalence of breast during the second year of life.

CONCLUSIONS

We suggest that phytoestrogens impose a preserving effect on breast tissue that is evolved in early infancy, leading eventually to a slower waning of infantile breast tissue.

Exposição ambiental a interferentes endócrinos com atividade estrogênica e sua associação com distúrbios puberais em crianças

A substância exógena que causa efeitos adversos na saúde de um organismo ou sua descendência, como resultado de distúrbios na função hormonal, é denominada interferente endócrino. Nos últimos anos, produtos ambientais com atividades hormonais têm sido documentados como causadores de anormalidades puberais ou reprodutivas em animais. Os poucos casos comprovados em humanos foram aqueles relacionados a exposições acidentais. Apesar disso, pediatras e pais recomendam a suspensão de todos os alimentos potencialmente contaminados, em especial carne (aves, gado) e derivados da soja quando a criança apresenta alguma alteração puberal. Estas recomendações, se não embasadas cientificamente, podem ter conseqüências deletérias, não apenas pela eliminação de fontes protéicas da dieta, como também por retardar a investigação de causas tratáveis. Por outro lado, a não investigação dos efeitos adversos destes produtos é da mesma forma danosa. Esta revisão descreve os principais interferentes endócrinos responsáveis por alterações puberais em humanos e conclui que, excetuando exposições acidentais a altas quantidades destes produtos, mais estudos são necessários para responsabilizar a ação crônica e em baixas doses destas substâncias na alteração do tempo de desenvolvimento puberal em nossa espécie.

Soy protein for infant feeding: what do we know?

PURPOSE OF REVIEW

This review discusses the safety, nutritional adequacy and recommendations for use of soy protein formulae, based mainly on the most relevant reports published during 2005 and 2006.

RECENT FINDINGS

Concerns have recently been raised regarding potential risks with soy protein formulae, in particular regarding their high phytoestrogenic isoflavone content. Recent data are insufficient to draw definitive conclusions on safety, but authorities and paediatric societies from several countries recently advised health professionals to use soy protein formulae only in certain cases. Indications for use of soy protein formulae, mainly for prevention and management of food allergy, have also been better defined.

SUMMARY

Soy protein formulae ensure normal growth and development in healthy term infants but they have no nutritional advantages over cow's milk protein formulae. Main indications include severe lactose intolerance, galactosaemia and need to avoid foods of animal origin. Soy protein formulae have no role in preventing allergy or in management of nonspecific gastrointestinal symptoms (e.g. infantile colic and regurgitation). They should not be used in preterm infants or infants with food allergy before age 6 months. After 6 months, soy protein formulae may be considered if tolerance to soy protein is established.

[High intake of phytoestrogens and precocious thelarche: case report with a possible correlation]

Precocious thelarche is the breast development before 8 years of age with two peaks of incidence during the first two years of life and after 6 years of age. A 4.75-year-old girl presented with thelarche associated to an excessive intake of phytoestrogens (phye). Tanner development B2P1-2, hormonal levels and pelvic US were compatible with peripheral precocious puberty. During follow-up, a daily intake of soy-based foods was observed (> 40 mg phye/day). Soy is rich in phytoestrogens, mainly genistein and daidzein. Although phye are less strong than estradiol, its concentration could be from 13,000 to 22,000 times stronger in children fed only by soy-based formulas. Parents were advised and soy intake was reduced to once a week. Progression of pubertal development ceased at B2-3P1. The patient, now 8.66 years old, keeps growing with similar bone and chronological ages. Some questions related to industrial food security, mainly the soy-based food, remain without precise answer. Although it is well known the entity of non-progressive precocious puberty and premature thelarche, pubertal development in this case was strongly related to excessive daily intake of soy and other phye-rich food that could trigger puberty as endocrine disruptor.

Soy protein infant formulae and follow-on formulae: a commentary by the ESPGHAN Committee on Nutrition

This comment by the European Society for Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) Committee on Nutrition summarizes available information on the composition and use of soy protein formulae as substitutes for breastfeeding and cows' milk protein formulae as well as on their suitability and safety for supporting adequate growth and development in infants. Soy is a source of protein that is inferior to cows' milk, with a lower digestibility and bioavailability as well as a lower methionine content. For soy protein infant formulae, only protein isolates can be used, and minimum protein content required in the current European Union legislation is higher than that of cows' milk protein infant formulae (2.25 g/100 kcal vs. 1.8 g/100kcal). Soy protein formulae can be used for feeding term infants, but they have no nutritional advantage over cows' milk protein formulae and contain high concentrations of phytate, aluminum, and phytoestrogens (isoflavones), which might have untoward effects. There are no data to support the use of soy protein formulae in preterm infants. Indications for soy protein formulae include severe persistent lactose intolerance, galactosemia, and ethical considerations (e.g., vegan concepts). Soy protein formulae have no role in the prevention of allergic diseases and should not be used in infants with food allergy during the first 6 months of life. If soy protein formulae are considered for therapeutic use in food allergy after the age of 6 months because of their lower cost and better acceptance, tolerance to soy protein should first be established byclinical challenge. There is no evidence supporting the use of soy protein formulae for the prevention or management of infantile colic, regurgitation, or prolonged crying.

Increased serum and testicular androgen levels in F1 rats with lifetime exposure to soy isoflavones

The consequences of dietary soy isoflavones on serum and testicular androgen levels were examined in F1 male rats from a multigeneration study investigating the effects of diets varying in isoflavone content. Rats were fed either a soy-free casein based diet (AIN93G) or a diet in which alcohol-washed soy protein replaced casein as the protein source and to which increasing amounts of Novasoy, a commercially available isoflavone supplement were added. Analysis of these diets showed that the isoflavone content in each diet was 0 (diet 1; casein based control), 31.7 (diet 2; alcohol-washed soy-based diet control), 36.1 (diet 3), 74.5 (diet 4), 235.6 (diet 5) and 1046.6 (diet 6) mg total isoflavones/kg pelleted diet. The levels of isoflavones in diet 1 would represent a daily intake level of 0 mg isoflavones, diets 2 and 3 estimate a low soy-containing human diet (e.g. North American), diet 4 would correspond to Asian diets (e.g. Japanese) or adult humans taking isoflavone supplements, diet 5 approximates the isoflavone intake by babies fed soy based infant formula and diet 6 approximates fivefold the intake levels by babies or 10-fold the intake levels of adults consuming high isoflavone containing diets. Serum testosterone (T) from F1 male rats sacrificed on postnatal days (PND) 28, 70, 120, 240 and 360 were low at PND 28 (0.4 ng/ml), increased approximately five to sixfold at PND 70 (2.5-3.0 ng/ml) and thereafter declined to a steady state level of approximately 1 ng/ml by PND 120. However, rats on diets 5 and 6 demonstrated altered serum testosterone profiles such that at days 120, testosterone levels remained significantly elevated at approximately 3 ng/ml (P < 0.05). Serum dihydrotestosterone levels exhibited similar profiles and the levels in PND 120 rats on diet 5 or 6 were also significantly elevated (two to threefold, P < 0.05). The intra-testicular testosterone concentration in rats on diet 5 was also elevated at PND 120 compared with diet 1 (P < 0.05). These findings show that F1 male rats continuously exposed to a mixture of dietary soy isoflavones from conception onwards exhibit altered serum and testicular androgen profiles.

Altered testicular microsomal steroidogenic enzyme activities in rats with lifetime exposure to soy isoflavones

Androgen production in the testis is carried out by the Leydig cells, which convert cholesterol into androgens. Previously, isoflavones have been shown to affect serum androgen levels and steroidogenic enzyme activities. In this study, the effects of lifelong exposure to dietary soy isoflavones on testicular microsomal steroidogenic enzyme activities were examined in the rat. F1 male rats were obtained from a multi-generational study where the parental generation was fed diets containing alcohol-washed soy protein supplemented with increasing amounts of Novasoy, a commercially available isoflavone supplement. A control group was maintained on a soy-free casein protein-based diet (AIN93G). The diets were designed to approximate human consumption levels and ranged from 0 to 1046.6 mg isoflavones/kg pelleted feed, encompassing exposures representative of North American and Asian diets as well as infant fed soy-based formula. Activities of testicular 3beta-hydroxysteroid dehydrogenase (3beta-HSD), P450c17 (CYP17), 17beta-hydroxysteroid dehydrogenase (17beta-HSD) were assayed on post natal day (PND) 28, 70, 120, 240 and 360 while 5alpha-reducatase was assayed on PND 28. At PND 28, 3beta-HSD activity was elevated by approximately 50% in rats receiving 1046.6 mg total isoflavones/kg feed compared to those on the casein only diet. A similar increase in activity was observed for CYP17 in rats receiving 235.6 mg total isoflavones/kg feed, a level representative of infant exposure through formula, compared to those receiving 0mg isoflavones from the casein diet. These results demonstrate that rats fed a mixture of dietary soy isoflavones showed significantly altered enzyme activity profiles during development at PND 28 as a result of early exposure to isoflavones at levels obtainable by humans.

Phytoestrogens: a review of the present state of research

Phytoestrogens are a diverse group of plant-derived compounds that structurally or functionally mimic mammalian estrogens and show potential benefits for human health. The number of articles published on phytoestrogens has risen dramatically in the past couple decades. Further research continues to demonstrate the biological complexity of phytoestrogens, which belong to several different chemical classes and act through diverse mechanisms. This paper discusses the classification of phytoestrogens, methods of identification, their proposed mechanisms of action and botanical sources for phytoestrogens. The effects of phytoestrogens on breast and prostate cancers, cardiovascular disease, menopausal symptoms and osteoporosis will also be examined including research on benefits and risks.

Phytoestrogens: a review of recent findings

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.