Estimated Asian adult soy protein and isoflavone intakes

Impact of Soy Foods on the Development of Breast Cancer and the Prognosis of Breast Cancer Patients

The relationship between soy food intake and breast cancer has been rigorously investigated for more than 25 years. The identification of isoflavones as possible chemopreventive agents helped fuel this line of investigation. These diphenolic compounds, which are found in uniquely-rich amounts in soy beans, possess both estrogen-dependent and -independent properties that potentially inhibit the development of breast cancer. Observational studies show that among Asian women higher soy consumption is associated with an approximate 30% reduction in risk of developing breast cancer. However, evidence suggests that for soy to reduce breast cancer risk consumption must occur early in life, that is during childhood and/or adolescence. Despite the interest in the role of soy in reducing breast cancer risk concerns have arisen that soy foods, because they contain isoflavones, may increase the likelihood of high-risk women developing breast cancer and worsen the prognosis of breast cancer patients. However, extensive clinical and epidemiologic data show these concerns to be unfounded. Clinical trials consistently show that isoflavone intake does not adversely affect markers of breast cancer risk, including mammographic density and cell proliferation. Furthermore, prospective epidemiologic studies involving over 11,000 women from the USA and China show that postdiagnosis soy intake statistically significantly reduces recurrence and improves survival.

Isoflavones in food supplements: chemical profile, label accordance and permeability study in Caco-2 cells

Consumers nowadays are playing an active role in their health-care. A special case is the increasing number of women, who are reluctant to use exogenous hormone therapy for the treatment of menopausal symptoms and are looking for complementary therapies. However, food supplements are not clearly regulated in Europe. The EFSA has only recently begun to address the issues of botanical safety and purity regulation, leading to a variability of content, standardization, dosage, and purity of available products. In this study, isoflavones (puerarin, daidzin, genistin, daidzein, glycitein, genistein, formononetin, prunetin, and biochanin A) from food supplements (n = 15) for menopausal symptoms relief are evaluated and compared with the labelled information. Only four supplements complied with the recommendations made by the EC on the tolerable thresholds. The intestinal bioavailability of these compounds was investigated using Caco-2 cells. The apparent permeability coefficients of the selected isoflavonoids across the Caco-2 cells were affected by the isoflavone concentration and product matrix.

Estimated Dietary Polyphenol Intake and Major Food and Beverage Sources among Elderly Japanese

Estimating polyphenol intake contributes to the understanding of polyphenols' health benefits. However, information about human polyphenol intake is scarce, especially in the elderly. This study aimed to estimate the dietary intake and major sources of polyphenols and to determine whether there is any relationship between polyphenol intake and micronutrient intake in healthy elderly Japanese. First, 610 subjects (569 men, 41 women; aged 67.3 ± 6.1 years) completed food frequency questionnaires. We then calculated their total polyphenol intake using our polyphenol content database. Their average total polyphenol intake was 1492 ± 665 mg/day, the greatest part of which was provided by beverages (79.1%). The daily polyphenol intake differed largely among individuals (183-4854 mg/day), also attributable mostly to beverage consumption. Coffee (43.2%) and green tea (26.6%) were the major sources of total polyphenol; the top 20 food items accounted for >90%. The polyphenol intake did not strongly correlate with the intake of any micronutrient, suggesting that polyphenols may exert health benefits independently of nutritional intake. The polyphenol intake in this elderly population was slightly higher than previous data in Japanese adults, and beverages such as coffee and green tea contributed highly to the intake.

Consumption of soy isoflavone enriched bread in men with prostate cancer is associated with reduced proinflammatory cytokines and immunosuppressive cells

We hypothesized that soy phytochemicals may have immunomodulatory properties that may affect prostate carcinogenesis and progression. A randomized, phase II trial was conducted in 32 patients with prostate cancer with asymptomatic biochemical recurrence but no measurable disease on standard staging studies. Patients were randomized to two slices of soy bread (34 mg isoflavones/slice) or soy bread containing almond powder daily as a source of β-glucosidase. Flow cytometry and bioplex assays were used to measure cytokines or immune cell phenotype in blood at baseline (day 0) and following intervention (day 56). Adequate blood samples were available at enrollment and day 56 and evaluated. Multiple plasma cytokines and chemokines were significantly decreased on day 56 versus baseline. Subgroup analysis indicated reduced TH1 (P = 0.028) and myeloid-derived suppressor cell (MDSC)-associated cytokines (P = 0.035). TH2 and TH17 cytokines were not significantly altered. Phenotypic analysis revealed no change in CD8(+) or CD4(+) T cells but showed increased CD56(+) natural killer (NK) cells (P = 0.038). The percentage of cells with a T regulatory cell phenotype (CD4(+)CD25(+)FoxP3(+)) was significantly decreased after 56 days of soy bread (P = 0.0136). Significantly decreased monocytic (CD33(+)HLADR(neg)CD14(+)) MDSC were observed in patients consuming soy bread (P = 0.0056). These data suggest that soy bread modulates systemic soluble and cellular biomarkers consistent with limiting inflammation and suppression of MDSCs. Additional studies to elucidate impact on the carcinogenic process or as a complement to immune-based therapy are required.

Isoflavone pharmacokinetics and metabolism after consumption of a standardized soy and soy-almond bread in men with asymptomatic prostate cancer

Epidemiologic associations suggest that populations consuming substantial amounts of dietary soy exhibit a lower risk of prostate cancer. A 20-week randomized, phase II, crossover trial was conducted in 32 men with asymptomatic prostate cancer. The crossover involved 8 weeks each of soy bread (SB) and soy-almond bread (SAB). The primary objective was to investigate isoflavone bioavailability and metabolite profile. Secondary objectives include safety, compliance, and assessment of biomarkers linked to prostate carcinogenesis. Two distinct SBs were formulated to deliver approximately 60 mg aglycone equivalents of isoflavones per day. The isoflavones were present as aglycones (∼78% as aglycones) in the SAB whereas in the standard SB predominantly as glucosides (18% total isoflavones as aglycones). Compliance to SB (97% ± 4%) and SAB (92% ± 18%) was excellent; toxicity was rare and limited to grade 1 gastrointestinal complaints. Pharmacokinetic studies between SB and SAB showed modest differences. Peak serum concentration time (Tmax) was significantly faster with SAB meal compared with SB in some isoflavonoids, and AUC0 to 24 h of dihydrodaidzein and O-desmethylangolensin was significantly greater after an SB meal. An exploratory cluster analysis was used to identify four isoflavone-metabolizing phenotypes. Insulin-like growth factor-binding protein increased significantly by 41% (P = 0.024) with soy intervention. Findings from this study provide the necessary framework to study isoflavone-metabolizing phenotypes as a strategy for identification of individuals that might benefit or show resistance to cancer preventive strategies using dietary soy. A standardized SB used for future large-scale randomized clinical trials to affect human prostate carcinogenesis is feasible.

Cancer therapy using natural ligands that target estrogen receptor beta

Estrogen receptor beta (ERβ) is one of the two key receptors (ERα, ERβ) that facilitate biological actions of 17β-estradiol (E2). ERβ is widely expressed in many tissues, and its expression is reduced or lost during progression of many tumors. ERβ facilitates estrogen signaling by both genomic (classical and non-classical) and extra-nuclear signaling. Emerging evidence suggests that ERβ functions as a tissue-specific tumor suppressor with anti-proliferative actions. Recent studies have identified a number of naturally available selective ERβ agonists. Targeting ERβ using its naturally available ligands is an attractive approach for treating and preventing cancers. This review presents the beneficial actions of ERβ signaling and clinical utility of several natural ERβ ligands as potential cancer therapy.

Estimation of dietary flavonoid intake and major food sources of Korean adults

Epidemiological studies have suggested that flavonoids exhibit preventive effects on degenerative diseases. However, lack of sufficient data on flavonoid intake has limited evaluating the proposed effects in populations. Therefore, we aimed to estimate the total and individual flavonoid intakes among Korean adults and determine the major dietary sources of these flavonoids. We constructed a flavonoid database of common Korean foods, based on the food list reported in the 24-h recall of the Korea National Health and Nutrition Examination Survey (KNHANES) 2007–2012, using data from the Korea Functional Food Composition Table, US Department of Agriculture flavonoid database, Phenol-Explorer database and other analytical studies. This database, which covers 49 % of food items and 76 % of food intake, was linked with the 24-h recall data of 33 581 subjects aged ≥19 years in the KNHANES 2007–2012. The mean daily intake of total flavonoids in Korean adults was 318·0 mg/d, from proanthocyanidins (22·3 %), flavonols (20·3 %), isoflavones (18·1 %), flavan-3-ols (16·2 %), anthocyanidins (11·6 %), flavanones (11·3 %) and flavones (0·3 %). The major contributing food groups to the flavonoid intake were fruits (54·4 %), vegetables (20·5 %), legumes and legume products (16·2 %) and beverages and alcohols (3·1 %), and the major contributing food items were apples (21·9 %), mandarins (12·5 %), tofu (11·5 %), onions (9·6 %) and grapes (9·0 %). In the regression analysis, the consumption of legumes and legume products, vegetables and fruits predicted total flavonoid intake the most. The findings of this study could facilitate further investigation on the health benefits of flavonoids and provide the basic information for establishing recommended flavonoid intakes for Koreans.

Genistein suppressed epithelial-mesenchymal transition and migration efficacies of BG-1 ovarian cancer cells activated by estrogenic chemicals via estrogen receptor pathway and downregulation of TGF-β signaling pathway

BACKGROUND

Epithelial-mesenchymal transition (EMT), which is activated by 17β-estradiol (E2) in estrogen-responsive cancers, is an important process in tumor migration or progression. As typical endocrine disrupting chemicals (EDCs), bisphenol A (BPA) and nonylphenol (NP) have a potential to promote EMT and migration of estrogen-responsive cancers. On the contrary, genistein (GEN) as a phytoestrogen is known to have chemopreventive effects in diverse cancers.

METHODS

In the present study, the effects of BPA and GEN on EMT and the migration of BG-1 ovarian cancer cells and the underlying mechanism were investigated. ICI 182,780, an estrogen receptor (ER) antagonist, was co-treated with E2 or BPA or NP to BG-1 cells to identify the relevance of ER signaling in EMT and migration.

RESULTS

As results, E2 and BPA upregulated the protein expression of vimentin, cathepsin D, and MMP-2, but downregulated the protein expression of E-cadherin via ER signaling pathway, suggesting that E2 and BPA promote EMT and cell migration related gene expressions. However, the increased protein expressions of vimentin, cathepsin D, and MMP-2 by E2, BPA, or NP were reduced by the co-treatment of GEN. In a scratch assay, the migration capability of BG-1 cells was enhanced by E2, BPA, and NP via ER signaling but reversed by the co-treatment of GEN. In the protein expression of SnoN and Smad3, E2, BPA, and NP upregulated SnoN, a negative regulator of TGF-β signaling, and downregulated pSmad3, a transcription factor in the downstream pathway of TGF-β signaling pathway, suggesting that E2, BPA, and NP simultaneously lead to the downregualtion of TGF-β signaling in the process of induction of EMT and migration of BG-1 cells via ER signaling. On the other hand, the co-treatment of GEN reversed the downregulation of TGF-β signaling by estrogenic chemicals.

CONCLUSION

Taken together, GEN suppressed EMT and migration capacities of BG-1 ovarian cancer cells enhanced by E2, BPA, and NP via ER signaling and the downregulation of TGF-β signal.

Individually modifiable risk factors to ameliorate cognitive aging: a systematic review and meta-analysis

A number of health and lifestyle factors are thought to contribute to cognitive decline associated with age but cannot be easily modified by the individual patient. We identified 12 individually modifiable interventions that can be implemented during midlife or later with the potential to ameliorate cognitive aging. For ten of these, we used PubMed databases for a systematic review of long-duration (at least 6 months), randomized, controlled trials in midlife and older adults without dementia or mild cognitive impairment with objective measures of neuropsychological performance. Using network meta-analysis, we performed a quantitative synthesis for global cognition (primary outcome) and episodic memory (secondary outcome). Of 1038 publications identified by our search strategy, 24 eligible trials were included in the network meta-analysis. Results suggested that the Mediterranean diet supplemented by olive oil and tai chi exercise may improve global cognition, and the Mediterranean diet plus olive oil and soy isoflavone supplements may improve memory. Effect sizes were no more than small (standardized mean differences 0.11-0.22). Cognitive training may have cognitive benefit as well. Most individually modifiable risk factors have not yet been adequately studied. We conclude that some interventions that can be self-initiated by healthy midlife and older adults may ameliorate cognitive aging.

Food Sources of Protein and Risk of Incident Gout in the Singapore Chinese Health Study

OBJECTIVE

Prospective studies evaluating diet in relation to the risk of gout in Asian populations are lacking. The purpose of this study was to examine the relationship between the consumption of dietary protein from each of its major sources and the risk of gout in a Chinese population.

METHODS

We used data from the Singapore Chinese Health Study, a prospective cohort of 63,257 Chinese adults who were 45-74 years old at recruitment during the years 1993-1998. Habitual diet information was collected via a validated semiquantitative food frequency questionnaire, and physician-diagnosed gout was self-reported during 2 followup interviews up to the year 2010. Cox proportional hazards models were used to calculate the hazard ratios (HRs) and 95% confidence intervals (95% CIs), with adjustment for potential confounders, among 51,114 eligible study participants who were free of gout at baseline and responded to our followup interviews.

RESULTS

A total of 2,167 participants reported physician-diagnosed gout during the followup period. The multivariate-adjusted HRs (with 95% CIs) of gout, comparing the first quartile with the fourth quartile, were as follows: 1.27 (1.12-1.44; P for trend < 0.001) for total protein, 1.27 (1.11-1.45; P for trend < 0.001) for poultry, 1.16 (1.02-1.32; P for trend = 0.006) for fish and shellfish, 0.86 (0.75-0.98; P for trend = 0.018) for soy food, and 0.83 (0.73-0.95; P for trend = 0.012) for nonsoy legumes. No statistically significant associations were found with protein intake from other sources (red meat, eggs, dairy products, grains, or nuts and seeds).

CONCLUSION

In this Chinese population living in Singapore, higher total dietary protein intake from mainly poultry and fish/shellfish was associated with an increased risk of gout, while dietary intake of soy and nonsoy legumes was associated with a reduced risk of gout.

Correlation of Serum Thyroid Hormones Autoantibodies with Self-Reported Exposure to Thyroid Disruptors in a Group of Nonsegmental Vitiligo Patients

Vitiligo is a pigmentary disorder strongly associated with autoimmune thyroid disorders (ATD). Thyroid hormones antibodies (THAb) directed toward thyroxine (T3) and triiodothyronine (T4) (T3- and T4-Ab) are rare in the general population but are increased in individuals wit ATD and extrathyroid autoimmune disorders. Because it is known that alcohol, smoke, iodine, and some thyroid disruptors can elicit the appearance of ATD, the aim of our study was to evaluate possible correlation between T3- and T4-Ab expression and past toxic exposures in vitiligo patients. Seventy vitiligo patients were examined and self-reported exposure to thyroid disruptors (4,4'-isopropylidenediphenol, perchlorates, polychlorinated biphenyls (PCBs), hexachlorobenzene, resorcinol, dichlorodiphenyltrichloroethane, alachlor/amitriole, nitrate, thiocyanate, soy isoflavones), iodine intake, smoke, and alcohol consumption were investigated through standardized questionnaires. Immunoglobulin (Ig)M-T3-Ab, IgG-T3-Ab, IgM-T4-Ab,and IgG-T4-Ab were dosed by a radioimmunoprecipitation technique. Seventy-seven (95.7 %) patients had at least one type of THAb. Most of them had contemporarily both T3- and T4-Ab (50/70). We found a significant association between PCBs and T4-IgG-Ab (P = 0.039) and between food intake containing nitrate, thiocyanate, and soy isoflavones with (IgM + IgG)-T3-Ab (P = 0.041). Our study underlines a possible influence of diet and environment in vitiligo patients in eliciting THAb. Therefore, in the event of a positive exposure to thyroid disruptors, an evaluation of thyroid function might be useful to early detect possible associated thyroid autoantibodies such as THAb.

Genistein and cancer: current status, challenges, and future directions

Primary prevention through lifestyle interventions is a cost-effective alternative for preventing a large burden of chronic and degenerative diseases, including cancer, which is one of the leading causes of morbidity and mortality worldwide. In the past decade, epidemiologic and preclinical evidence suggested that polyphenolic phytochemicals present in many plant foods possess chemopreventive properties against several cancer forms. Thus, there has been increasing interest in the potential cancer chemopreventive agents obtained from natural sources, such as polyphenols, that may represent a new, affordable approach to curb the increasing burden of cancer throughout the world. Several epidemiologic studies showed a relation between a soy-rich diet and cancer prevention, which was attributed to the presence of a phenolic compound, genistein, present in soy-based foods. Genistein acts as a chemotherapeutic agent against different types of cancer, mainly by altering apoptosis, the cell cycle, and angiogenesis and inhibiting metastasis. Targeting caspases, B cell lymphoma 2 (Bcl-2)-associated X protein (Bax), Bcl-2, kinesin-like protein 20A (KIF20A), extracellular signal-regulated kinase 1/2 (ERK1/2), nuclear transcription factor κB (NF-κB), mitogen-activated protein kinase (MAPK), inhibitor of NF-κB (IκB), Wingless and integration 1 β-catenin (Wnt/β-catenin), and phosphoinositide 3 kinase/Akt (PI3K/Akt) signaling pathways may act as the molecular mechanisms of the anticancer, therapeutic effects of genistein. Genistein also shows synergistic behavior with well-known anticancer drugs, such as adriamycin, docetaxel, and tamoxifen, suggesting a potential role in combination therapy. This review critically analyzes the available literature on the therapeutic role of genistein on different types of cancer, focusing on its chemical features, plant food sources, bioavailability, and safety.

Improving the estimation of flavonoid intake for study of health outcomes

Imprecision in estimating intakes of non-nutrient bioactive compounds such as flavonoids is a challenge in epidemiologic studies of health outcomes. The sources of this imprecision, using flavonoids as an example, include the variability of bioactive compounds in foods due to differences in growing conditions and processing, the challenges in laboratory quantification of flavonoids in foods, the incompleteness of flavonoid food composition tables, and the lack of adequate dietary assessment instruments. Steps to improve databases of bioactive compounds and to increase the accuracy and precision of the estimation of bioactive compound intakes in studies of health benefits and outcomes are suggested.

An effective and simple procedure to isolate abundant quantities of biologically active chemopreventive Lunasin Protease Inhibitor Concentrate (LPIC) from soybean

Lunasin is a 5-kDa soybean bioactive peptide with demonstrated anti-cancer and anti-inflammatory properties. Recently, purification methods have been developed to obtain gram quantities of lunasin. However, these methods are cumbersome, time consuming and cost-prohibitive. To overcome these constrains we have developed a novel method which involves extraction of soybean flour with 30% ethanol followed by preferential precipitation of lunasin and protease inhibitors by calcium. The calcium precipitated protein fraction, which we termed as Lunasin Protease Inhibitor Concentrate (LPIC), contains three abundant proteins with molecular weights of 21, 14 and 5 kDa. This simple procedure yields 3.2g of LPIC from 100g of soybean flour and the entire isolation procedure can be completed in less than 2h. Treatment of THP-1 human monocyte cell lines with LPIC resulted in suppression of lipopolysaccharide-stimulated cytokine expression, demonstrating that the LPIC isolated by our simple procedure is biologically active.

Soy and breast cancer: focus on angiogenesis

Epidemiological studies have revealed that high consumption of soy products is associated with low incidences of hormone-dependent cancers, including breast and prostate cancer. Soybeans contain large amounts of isoflavones, such as the genistein and daidzain. Previously, it has been demonstrated that genistein, one of the predominant soy isoflavones, can inhibit several steps involved in carcinogenesis. It is suggested that genistein possesses pleiotropic molecular mechanisms of action including inhibition of tyrosine kinases, DNA topoisomerase II, 5α-reductase, galectin-induced G2/M arrest, protein histidine kinase, and cyclin-dependent kinases, modulation of different signaling pathways associated with the growth of cancer cells (e.g., NF-κB, Akt, MAPK), etc. Moreover, genistein is also a potent inhibitor of angiogenesis. Uncontrolled angiogenesis is considered as a key step in cancer growth, invasion, and metastasis. Genistein was found to inhibit angiogenesis through regulation of multiple pathways, such as regulation of VEGF, MMPs, EGFR expressions and NF-κB, PI3-K/Akt, ERK1/2 signaling pathways, thereby causing strong antiangiogenic effects. This review focuses on the antiangiogenic properties of soy isoflavonoids and examines their possible underlying mechanisms.

Efficacy of phytoestrogens for menopausal symptoms: a meta-analysis and systematic review

OBJECTIVE

To perform a meta-analysis examining the efficacy of phytoestrogens for the relief of menopausal symptoms.

METHODS

Medline, Cochrane, EMBASE, and Google Scholar databases were searched until September 30, 2013 using the following key words: vasomotor symptoms, menopausal symptoms, phytoestrogens, isoflavones, coumestrol, soy, red clover. Inclusion criteria were (1) randomized controlled trial (RCT), (2) perimenopausal or postmenopausal women experiencing menopausal symptoms, (3) intervention with an oral phytoestrogen. Outcome measures included Kupperman index (KI) changes, daily hot flush frequency, and the likelihood of side-effects.

RESULTS

Of 543 potentially relevant studies identified, 15 RCTs meeting the inclusion criteria were included. The mean age of the subjects ranged from 49 to 58.3 and 48 to 60.1 years, respectively, in the placebo and phytoestrogen groups. The number of participants ranged from 30 to 252, and the intervention periods ranged from 3 to 12 months. Meta-analysis of the seven studies that reported KI data indicated no significant treatment effect of phytoestrogen as compared to placebo (pooled mean difference = 6.44, p = 0.110). Meta-analysis of the ten studies that reported hot flush data indicated that phytoestrogens result in a significantly greater reduction in hot flush frequency compared to placebo (pooled mean difference = 0.89, p < 0.005). Meta-analysis of the five studies that reported side-effect data showed no significant difference between the two groups (p = 0.175).

CONCLUSION

Phytoestrogens appear to reduce the frequency of hot flushes in menopausal women, without serious side-effects.

Role of phytoestrogens in prevention and management of type 2 diabetes

Type 2 diabetes (T2D) has become a major public health threat across the globe. It has been widely acknowledged that diet plays an important role in the development and management of T2D. Phytoestrogens are polyphenols that are structurally similar to endogenous estrogen and have weak estrogenic properties. Emerging evidence from pre-clinical models has suggested that phytoestrogens may have anti-diabetic function via both estrogen-dependent and estrogen-independent pathways. In the current review, we have summarized the evidence linking two major types of phytoestrogens, isoflavones and lignans, and T2D from epidemiological studies and clinical trials. The cross-sectional and prospective cohort studies have reported inconsistent results, which may due to the large variations in different populations and measurement errors in dietary intakes. Long-term intervention studies

using isoflavone supplements have reported potential beneficial effects on glycemic parameters in postmenopausal women, while results from short-term small-size clinical trials are conflicting. Taken together, the current evidence from different study designs is complex and inconsistent. Although the widespread use of phytoestrogens could not be recommended yet, habitual consumption of phytoestrogens, particularly their intact food sources like soy and whole flaxseed, could be considered as a component of overall healthy dietary pattern for prevention and management of T2D.

Soy provides modest benefits on endothelial function without affecting inflammatory biomarkers in adults at cardiometabolic risk

SCOPE

Systemic inflammation, endothelial dysfunction, and oxidative stress are involved in the pathogenesis of the metabolic syndrome (MetS). Epidemiological evidence supports an association between whole soy food consumption and reduced risk of cardiovascular disease (CVD). The objective of this randomized, controlled, cross-over study was to evaluate the effects of soy nut consumption on inflammatory biomarkers and endothelial function and to assess whether isoflavone metabolism to secondary products, equol, and/or O-desmethylangolensin (ODMA), modifies these responses.

METHODS AND RESULTS

n = 17 adults at cardiometabolic risk were randomly assigned to the order of two snack interventions, soy nuts, and macronutrient-matched control snack, for four weeks each, separated by a two week washout period. Outcome measures included biomarkers of inflammation, oxidative stress, and glycemic control (ELISA and clinical analyzers), endothelial function, and arterial stiffness (peripheral arterial tonometry (PAT)), and isoflavone metabolites (LC-MS/MS). Results revealed that consuming soy nuts improved arterial stiffness as assessed by the augmentation index using PAT (p = 0.03), despite lack of improvement in inflammatory biomarkers. Addition of equol and/or ODMA production status as covariates did not significantly change these results.

CONCLUSION

Soy nuts when added to a usual diet for one month provide some benefit on arterial stiffness in adults at cardiometabolic risk.

Dose-dependent effects of isoflavone exposure during early lifetime on the rat mammary gland: Studies on estrogen sensitivity, isoflavone metabolism, and DNA methylation

SCOPE

Isoflavone (ISO) exposure during adolescence modulates 17β-estradiol (E2) sensitivity of the adult mammary gland. The present study investigated the dose dependency of these effects focusing on proliferation, estrogen receptor dependent and independent gene expression, as well as DNA methylation and ISO metabolism.

METHODS AND RESULTS

Female Wistar rats were lifelong exposed to an ISO-depleted diet or to diets enriched with a soy ISO extract (ISO-rich diet (IRD)) causing plasma concentrations as observed minimally (IRDlow) and maximally (IRDhigh) in Asian women. The extract was characterized by both phytochemical analysis and E-Screen. Rats were ovariectomized at postnatal day (PND) 80 and treated with E2 from PND94 to 97. In contrast to uterine response, body weight and visceral fat mass were affected by ISO. In the mammary gland, both E2-induced proliferation (proliferating cell nuclear antigen staining) and estrogen receptor activation (progesterone receptor staining) were significantly reduced by IRDhigh but not by IRDlow, which however attenuated Gdf15 mRNA expression. DNA methylation analysis revealed significant differences in the promoter regions of Aldhl1, Extl1, and WAP between IRDhigh and ISO-depleted diet.

CONCLUSION

Lifelong exposure to ISO results in dose-dependent differential effects on proliferation, gene expression, and DNA methylation in rat mammary glands. Yet, a decrease in estrogen responsiveness was only achieved by IRDhigh.

A novel soybean (Glycine max) gene encoding a family 3 β-glucosidase has high isoflavone 7-O-glucoside-hydrolyzing activity in transgenic rice

A previous study demonstrated that purified Glycine max β-glucosidase (GmBGL) could hydrolyze glucosyl isoflavone to the aglyconic form. This study reports the cloning and functional characterization of a soybean cDNA encoding the β-glucosidase. GmBGL was isolated by use of a purified soybean N-terminal amino acid sequence and conserved sequences of β-glucosidase genes from other plants. Sequence analysis of GmBGL revealed an open reading frame of 1884 bp encoding a polypeptide of 627 amino acids with a calculated molecular mass of 69 kDa. Phylogenetic analysis classified the GmBGL into the glycosyl hydrolase 3 family. In soybean, the GmBGL transcript was predominantly accumulated in roots and leaves. To examine the enzymatic activity and substrate specificity, GmBGL was ectopically expressed in transgenic rice. Purified GmBGL protein from transgenic rice could catalyze the hydrolysis of genistin and daidzin to produce genistein and daidzein, respectively, which confirmed GmBGL as a functional β-glucosidase with isoflavone glucoside-hydrolyzing activity. This paper reveals that GmBGL is a key enzyme in transforming glucosyl isoflavones to aglycones in soybean, which may help in genetic manipulation of aglycone-rich soybean seeds.

Soy food intake and treatment outcomes of women undergoing assisted reproductive technology

OBJECTIVE

To study the relation of dietary phytoestrogens intake and clinical outcomes of women undergoing infertility treatment with the use of assisted reproductive technology (ART).

DESIGN

Prospective cohort study.

SETTING

Fertility center.

PATIENT(S)

A total of 315 women who collectively underwent 520 ART cycles from 2007 to 2013.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Implantation, clinical pregnancy, and live birth rates per initiated cycle.

RESULT(S)

Soy isoflavones intake was positively related to live birth rates in ART. Compared with women who did not consume soy isoflavones, the multivariable-adjusted odds ratios of live birth (95% confidence interval) for women in increasing categories of soy isoflavones intake were 1.32 (0.76-2.27) for women consuming 0.54-2.63 mg/d, 1.87 (1.12-3.14) for women consuming 2.64-7.55 mg/d, and 1.77 (1.03-3.03) for women consuming 7.56-27.89 mg/d.

CONCLUSION(S)

Dietary soy intake was positively related to the probability of having a live birth during infertility treatment with ART.

Intake patterns and dietary associations of soya protein consumption in adults and children in the Canadian Community Health Survey, Cycle 2.2

Soya foods are one of the recommended alternatives to meat in many dietary guidelines. While this is expected to increase the intake of some nutrients, potential concerns regarding others have been raised. The purpose of the present study was to examine the prevalence and the association of soya food consumption with nutrient intakes and dietary patterns of Canadians (age ≥ 2 years). Cross-sectional data from the 2004 Canadian Community Health Survey (Cycle 2.2; n 33 218) were used to classify soya consumers and non-consumers. Soya consumers were further divided into two groups based on their soya protein intake. Sample weights were applied and logistic regression analysis was used to explore the association between nutrient intakes and soya consumption, with cultural background, sex, age and economic status being included as covariates. On any given day, 3·3 % (n 1085) of Canadians consume soya foods, with females, Asian Canadians and adults with post-secondary education being more likely to be soya consumers. As a whole, adolescent and adult respondents who had consumed at least one soya food during their 24 h dietary recall had higher energy intakes, as well as increased intakes of nutrients such as protein, fibre, vitamin C, vitamin B6, naturally occurring folate, thiamin, Ca, P, Mg, PUFA, Fe and K and lowered intakes of saturated fat. These data indicate that soya food consumption is associated with improved diet quality of Canadians. However, future research is necessary to investigate the association between increased energy intake and soya consumption.

Interaction of Isoflavones with the BCRP/ABCG2 Drug Transporter

This review will provide a comprehensive overview of the interactions between dietary isoflavones and the ATP-binding cassette (ABC) G2 efflux transporter, which is also named the breast cancer resistance protein (BCRP). Expressed in a variety of organs including the liver, kidneys, intestine, and placenta, BCRP mediates the disposition and excretion of numerous endogenous chemicals and xenobiotics. Isoflavones are a class of naturallyoccurring compounds that are found at high concentrations in commonly consumed foods and dietary supplements. A number of isoflavones, including genistein and daidzein and their metabolites, interact with BCRP as substrates, inhibitors, and/or modulators of gene expression. To date, a variety of model systems have been employed to study the ability of isoflavones to serve as substrates and inhibitors of BCRP; these include whole cells, inverted plasma membrane vesicles, in situ organ perfusion, as well as in vivo rodent and sheep models. Evidence suggests that BCRP plays a role in mediating the disposition of isoflavones and in particular, their conjugated forms. Furthermore, as inhibitors, these compounds may aid in reversing multidrug resistance and sensitizing cancer cells to chemotherapeutic drugs. This review will also highlight the consequences of altered BCRP expression and/or function on the pharmacokinetics and toxicity of chemicals following isoflavone exposure.

Genistein inhibits glucocorticoid amplification in adipose tissue by suppression of 11β-hydroxysteroid dehydrogenase type 1

Excess glucocorticoids promote visceral obesity, hyperlipidemia, and insulin resistance. The main regulator of intracellular glucocorticoid levels is 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), which converts inactive glucocorticoids into bioactive forms such as cortisol in humans and corticosterone in rodents. Hexose-6-phosphate dehydrogenase (H6PD), which is colocalized with 11β-HSD1 in the intralumen of the endoplasmic reticulum, supplies a crucial coenzyme, NADPH, for full reductase activity of 11β-HSD1. Therefore, it is possible that inhibition of 11β-HSD1 will become a considerable medical treatment for metabolic diseases including obesity and diabetes. Genistein, a soy isoflavone, has received attention for its therapeutic potential for obesity, diabetes, and cardiovascular disease, and has been proposed as a promising compound for the treatment of metabolic disorders. However, the mechanisms underlying the pleiotropic anti-obesity effects of genistein have not been fully clarified. Here, we demonstrate that genistein was able to inhibit 11β-HSD1 and H6PD activities within 10 or 20min, in dose- and time-dependent manners. Inhibition of 11β-HSD2 activity was not observed in rat kidney microsomes. The inhibition was not reversed by two estrogen receptor antagonists, tamoxifen and ICI182,780. A kinetic study revealed that genistein acted as a non-competitive inhibitor of 11β-HSD1, and its apparent Km value for 11-dehydrocorticosterone was 0.5μM. Genistein also acted as a non-competitive inhibitor of H6PD, and its apparent Km values for G6P and NADP were 0.9 and 3.3μM, respectively. These results suggest that genistein may exert its inhibitory effect by interacting with these enzymes.

Association between dietary factors and breast cancer risk among Chinese females: systematic review and meta-analysis

BACKGROUND

Evidence for associations between dietary factors and breast cancer risk is inconclusive among Chinese females. To evaluate this question, we conducted a systematic review of relevant case-control and cohort studies.

METHODS

Studies were systematically searched among 5 English databases (PudMed, ScienceDirect, Wiley, Clinicaltrials.gov, and Cochrane) and 3 Chinese databases (CNKI, WanFang, and VIP) until November 2012. Random effects models were used to estimate summary odds ratios (ORs) and the corresponding 95% confidence intervals (CIs).

RESULTS

Thirty one case-control studies and two cohort studies involving 9,299 cases and 11,413 controls were included. Consumption of both soy and fruit was significantly associated with decreased risk of breast cancer, with summary ORs of 0.65 (95% CIs: 0.43-0.99; I2=88.9%, P<0.001; N=13) and 0.66 (95% CIs: 0.47-0.91; I2=76.7%, P<0.001; N=7), respectively. Consumption of fat was significantly associated with increased risk of breast cancer (OR=1.36; 95% CIs: 1.13-1.63; I2=47.9%, P=0.088; N=6). There was non- significant association between consumption of vegetables and breast cancer risk (OR=0.72; 95% CIs: 0.51-1.02; I2= 74.4%, P<0.001; N=9). However, sensitivity analysis based on adjusted ORs showed decreased risk of breast cancer was also associated with consumption of vegetables (OR=0.49; 95% CIs: 0.30-0.67).

CONCLUSION

Both soy food and fruit are significantly associated with decreased risk of breast cancer among Chinese females, and vegetables also seems to be protective while dietary fatexerts a promoting influence.

Dietary isoflavone intake is not statistically significantly associated with breast cancer risk in the Multiethnic Cohort

Given the high intake levels of soya and low incidence rates of breast cancer in Asian countries, isoflavones, substances with an oestrogen-like structure occurring principally in soyabeans, are postulated to be cancer protective. In the present study, we examined the association of dietary isoflavone intake with breast cancer risk in 84,450 women (896 in situ and 3873 invasive cases) who were part of the Multiethnic Cohort (Japanese Americans, whites, Latinos, African Americans and Native Hawaiians) with a wide range of soya intake levels. The absolute levels of dietary isoflavone intake estimated from a baseline FFQ were categorised into quartiles, with the highest quartile being further subdivided to assess high dietary intake. The respective intake values for the quartiles (Q1, Q2, Q3, and lower and upper Q4) were 0-< 3·2, 3·2-< 6·7, 6·7-< 12·9, 12·9-< 20·3, and 20·3-178·7 mg/d. After a mean follow-up period of 13 years, hazard ratios (HR) and 95% CI were calculated using Cox regression models stratified by age and adjusted for known confounders. Linear trends were tested by modelling continuous variables of interest assigned the median value within the corresponding quartile. No statistically significant association was observed between dietary isoflavone intake and overall breast cancer risk (HR for upper Q4 v. Q1: 0·96 (95% CI 0·85, 1·08); P trend = 0·40). While the test for interaction was not significant (P=0·14), stratified analyses suggested possible ethnic/racial differences in risk estimates, indicating that higher isoflavone intakes may be protective in Latina, African American and Japanese American women. These results are in agreement with those of previous meta-analyses showing no protection of isoflavones at low intake levels, but suggesting inverse associations in populations consuming high amounts of soya.

High prevalence of maternal hypothyroidism despite adequate iodine status in Indian pregnant women in the first trimester

BACKGROUND

Iodine requirements are increased during pregnancy to maintain maternal and fetal euthyroidism. There have been recent improvements in iodized salt coverage in India, but whether iodized salt is sufficient to sustain iodine requirements during pregnancy remains uncertain. Our aims were to measure thyroid status in first trimester pregnant women in southern India and assess potential determinants of thyroid function, including iodine status, thyroid autoimmunity, dietary patterns, body weight, and anemia.

METHODS

This was a cross-sectional study among 334 pregnant women of ≤ 14 weeks' gestation, in Bangalore, India. We measured anthropometrics, urinary iodine concentration (UIC), maternal thyroid volume (by ultrasound), and thyroid function. We applied a thyrotropin (TSH) upper limit of 2.5 mIU/L to classify thyroid insufficiency. Using a questionnaire, we obtained sociodemographic and dietary data, obstetric history, and use of iodized salt and iodine supplements.

RESULTS

Among the women, the mean (standard deviation) gestational age was 10.3 (2.5) weeks, 67% were nulliparous, 21% were vegetarian, 19% were anemic, and 23% were overweight or obese. Iodized salt was used by 98% of women, and they were iodine sufficient: median UIC (range) was 184.2 μg/L (8.1-1152 μg/L) and all had a normal thyroid volume. However, 18% of the women had thyroid insufficiency: 3.7% had overt hypothyroidism (83% with positive TPO-Ab), 9.2% had subclinical hypothyroidism, and 5.2% had hypothyroxinemia. Women consuming vegetarian diets did not have significantly lower iodine intakes or higher risk of hypothyroidism than those consuming mixed diets, but overweight/obesity and anemia predicted thyroid insufficiency.

CONCLUSION

In this urban population of southern India, pregnant women have adequate iodine status in the first trimester. Despite this, many have thyroid insufficiency, and the prevalence of overt hypothyroidism is more than fivefold higher than reported in other iodine sufficient populations of pregnant women.

Antiproliferative 4-(1,2,4-oxadiazol-5-yl)piperidine-1-carboxamides, a new tubulin inhibitor chemotype

We discovered a new chemical class of antiproliferative agents, 4-(1,2,4-oxadiazol-5-yl)piperidine-1-carboxamides. SAR-guided optimization of the two distinct terminal fragments yielded a compound with 120 nM potency in an antiproliferative assay. Biological activity profile studies (COMPARE analysis) demonstrated that 4-(1,2,4-oxadiazol-5-yl)piperidine-1-carboxamides act as tubulin inhibitors, and this conclusion was confirmed via biochemical assays with pure tubulin and demonstration of increased numbers of mitotic cells following treatment of a leukemia cell line.

Urinary isoflavonoid excretion as a biomarker of dietary soy intake during two randomized soy trials

We evaluated urinary isoflavonoid excretion as a biomarker of dietary isoflavone intake during two randomized soy trials (13-24 months) among 256 premenopausal women with a total of 1,385 repeated urine samples. Participants consumed a high-soy diet (2 servings/day) and a low-soy diet (<3 servings/week), completed 7 unannounced 24-hour dietary recalls, and donated repeated urine samples, which were analyzed for isoflavonoid excretion by liquid chromatography methods. We computed Spearman correlation coefficients and applied logistic regression to estimate the area under the curve. Median overall daily dietary isoflavone intakes at baseline, during low- and high-soy diet were 2.3, 0.2, and 60.4 mg aglycone equivalents, respectively. The corresponding urinary isoflavonoid excretion values were 0.4, 1.0, and 32.4 nmol/mg creatinine. Across diets, urinary isoflavonoid excretion was significantly associated with dietary isoflavone intake (rs=0.51, AUC=0.85; p<0.0001) but not within diet periods (rs=0.05-0.06, AUC=0.565-0.573). Urinary isoflavonoid excretion is an excellent biomarker to discriminate between low- and high-soy diets across populations, but the association with dietary isoflavone intake is weak when the range of soy intake is small.

Soy foods, isoflavones, and the health of postmenopausal women

Over the past 2 decades, soy foods have been the subject of a vast amount of research, primarily because they are uniquely rich sources of isoflavones. Isoflavones are classified as both phytoestrogens and selective estrogen receptor modulators. The phytoestrogenic effects of isoflavones have led some to view soy foods and isoflavone supplements as alternatives to conventional hormone therapy. However, clinical research shows that isoflavones and estrogen exert differing effects on a variety of health outcomes. Nevertheless, there is substantial evidence that soy foods have the potential to address several conditions and diseases associated with the menopausal transition. For example, data suggest that soy foods can potentially reduce ischemic heart disease through multiple mechanisms. Soy protein directly lowers blood low-density lipoprotein-cholesterol concentrations, and the soybean is low in saturated fat and a source of both essential fatty acids, the omega-6 fatty acid linoleic acid and the omega-3 fatty acid alpha-linolenic acid. In addition, soflavones improve endothelial function and possibly slow the progression of subclinical atherosclerosis. Isoflavone supplements also consistently alleviate menopausal hot flashes provided they contain sufficient amounts of the predominant soybean isoflavone genistein. In contrast, the evidence that isoflavones reduce bone loss in postmenopausal women is unimpressive. Whether adult soy food intake reduces breast cancer risk is unclear. Considerable evidence suggests that for soy to reduce risk, consumption during childhood and/or adolescence is required. Although concerns have been raised that soy food consumption may be harmful to breast cancer patients, an analysis in 9514 breast cancer survivors who were followed for 7.4 y found that higher postdiagnosis soy intake was associated with a significant 25% reduction in tumor recurrence. In summary, the clinical and epidemiologic data indicate that adding soy foods to the diet can contribute to the health of postmenopausal women.

Genistein inhibits human prostate cancer cell detachment, invasion, and metastasis

Prostate cancer (PCa) is the most commonly diagnosed cancer in men in the United States and the second leading cause of cancer death. Death is not caused by the primary tumor but rather by the formation of distinct metastatic tumors. Therefore, prevention of metastasis is of utmost importance. The natural product genistein, found in high amounts in soy products, has been implicated in preventing PCa formation and metastasis in men who consume high amounts of soy. In vitro studies and in vivo rodent models that used human PCa cells, as well as prospective human clinical trials, provide a mechanistic explanation directly supporting genistein as an antimetastatic agent. Specifically, our group showed that genistein inhibits cell detachment, protease production, cell invasion, and human PCa metastasis at concentrations achieved in humans with dietary intake. Finally, phase I and phase II clinical trials conducted by us and others showed that concentrations of genistein associated with antimetastatic efficacy in preclinical models are achievable in humans, and treatment with genistein inhibits pathways that regulate metastatic transformation in human prostate tissue.

Soy and soy isoflavones in prostate cancer: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

To evaluate the evidence from randomized controlled trials (RCTs) on the efficacy and safety of soy/isoflavones in men with prostate cancer (PCa) or with a clinically identified risk of PCa.

PATIENTS AND METHODS

MEDLINE, EMBASE, the Allied and Complementary Medicine (AMED), the Cumulative Index to Nursing and Allied Health Literature (CINAHL) and the Cochrane Library databases were searched. We identified RCTs investigating soy/soy isoflavones as dietary supplements or dietary components for the secondary prevention or treatment of PCa in men with PCa or with a clinically identified risk of developing PCa. Studies of multi-component formulations were excluded. Six authors were contacted for further information for the meta-analyses. Methodological quality was assessed using the Cochrane Collaboration's risk-of- bias tool. The PRISMA statement for reporting systematic reviews was followed.

RESULTS

Of the eight RCTs that met the inclusion criteria, six restricted recruitment to men diagnosed with PCa, while two included men with clinically identified risk of PCa. A large degree of heterogeneity was found with respect to dosages and preparations of soy/isoflavones administered. Most studies had small sample sizes and were of short duration. The risk of bias was assessed as low in all assessed studies except for one, for which the risk of bias was unclear. Meta-analyses of the two studies including men with identified risk of PCa found a significant reduction in PCa diagnosis after administration of soy/soy isoflavones (risk ratio = 0.49, 95% CI 0.26, 0.95). Meta-analyses indicated no significant differences between groups for prostate-specific antigen (PSA) levels or sex steroid endpoints (sex hormone-binding globulin [SHBG], testosterone, free testosterone, oestradiol and dihydrotestosterone).

CONCLUSIONS

The results of a meta-analysis of two studies suggest there may be support for epidemiological findings of a potential role for soy/soy isoflavones in PCa risk reduction; however, a clear understanding of the impact of soy/isoflavones on PSA, total testosterone, free testosterone and SHBG levels in men with, or at identified risk of, PCa could not be derived from these data, given the limitations of sample size and study duration in individual trials. A good safety profile is shown by this meta-analysis for soy/soy isoflavones supplementation.

Review article: health benefits of some physiologically active ingredients and their suitability as yoghurt fortifiers

The article is concerned with health benefits of two main physiologically active ingredients namely, Isoflavones and γ-Aminobutyric acid, with emphasis on their fitness for fortification of yoghurt to be consumed as a functional food. Isoflavones (ISO) are part of the diphenol compounds, called "phytoestrogens," which are structurally and functionally similar to estradiol, the human estrogen, but much less potent. Because of this similarity, ISO were suggested to have preventive effects for many kinds of hormone-dependent diseases. In nature, ISO usually occur as glycosides and, once deconjugated by the intestinal microflora, the ISO can be absorbed into the blood. At present, it seems convincing their possible protective actions against various cancers, osteoporosis and menopausal symptoms and high levels of blood cholesterol as well as the epidemiological evidence. Γ-Aminobutyric acid (GABA), it is an amino acid that has long been reported to lower blood pressure by intravenous administration in experimental animals and in human subjects. GABA is present in many vegetables and fruits but not in dairy products. GABA was reported to lower blood pressure in people with mild hypertension. It was suggested that low-dose oral GABA has a hypotensive effect in spontaneously hypertensive. Yoghurt beyond its ability to be probiotic food via its culturing with the gut strains, it could further carry more healthy benefits when it was fortified with physiological active ingredients, especially GABA versus ISO preferring, whether, bacteriologically or biochemically, a fortification level of 50 mg ISO/kg or 200 mg GABA/kg.

Associations between urine excretion of isoflavonoids and cognition in postmenopausal women in the Women's Isoflavone Soy Health clinical trial

OBJECTIVES

To determine effect of change in urine excretion of isoflavonoids on cognitive change.

DESIGN

Post hoc analysis of isoflavonoid exposure (mean 2.7 years) during the randomized, placebo-controlled, double-blind Women's Isoflavone Soy Health trial.

SETTING

General community.

PARTICIPANTS

Healthy postmenopausal women (N = 350).

INTERVENTION

Twenty-five grams of isoflavone-rich soy protein (91 mg of aglycone weight isoflavones: 52 mg genistein, 36 mg daidzein, 3 mg glycitein) or milk protein-matched placebo provided daily.

MEASUREMENTS

Overnight urine excretion, fasting plasma levels of isoflavonoids, and cognitive function measured at baseline and endpoint.

RESULTS

Three hundred women (age: mean 61, range 45-92) completed both cognitive assessments and did not use hormone replacement therapy during the trial. Mean on-trial change from baseline in urine excretion of isoflavonoids was not significantly associated with change in a composite score of global cognition (P = .39). Secondary analyses indicated that change in urine excretion of isoflavonoids was inversely associated with change in a factor score representing general intelligence (P = .02) but not with factor scores representing verbal or visual episodic memory. Mean differences in this general intelligence factor score between women in the lowest and highest quartiles of isoflavonoid change were equivalent to an approximate 4.4-year age-associated decline. Analyses based on plasma isoflavonoid levels yielded similar but attenuated results.

CONCLUSION

In healthy postmenopausal women, long-term changes in isoflavonoids are not associated with global cognition, supporting clinical trial results, although greater isoflavonoid exposure from dietary supplements is associated with decrements in general intelligence but not memory; this finding requires confirmation in future studies.

S-(-)equol producing status not associated with breast cancer risk among low isoflavone-consuming US postmenopausal women undergoing a physician-recommended breast biopsy

Soy foods are the richest sources of isoflavones, mainly daidzein and genistein. Soy isoflavones are structurally similar to the steroid hormone 17β-estradiol and may protect against breast cancer. S-(-)equol, a metabolite of the soy isoflavone daidzein, has a higher bioavailability and greater affinity for estrogen receptor β than daidzein. Approximately one-third of the Western population is able to produce S-(-)equol, and the ability is linked to certain gut microbes. We hypothesized that the prevalence of breast cancer, ductal hyperplasia, and overall breast pathology will be lower among S-(-)equol producing, as compared with nonproducing, postmenopausal women undergoing a breast biopsy. We tested our hypothesis using a cross-sectional study design. Usual diets of the participants were supplemented with 1 soy bar per day for 3 consecutive days. Liquid chromatography-multiple reaction ion monitoring mass spectrometry analysis of urine from 143 subjects revealed 25 (17.5%) as S-(-)equol producers. We found no statistically significant associations between S-(-)equol producing status and overall breast pathology (odds ratio [OR], 0.68; 95% confidence interval [CI], 0.23-1.89), ductal hyperplasia (OR, 0.84; 95% CI, 0.20-3.41), or breast cancer (OR, 0.56; 95% CI, 0.16-1.87). However, the mean dietary isoflavone intake was much lower (0.3 mg/d) than in previous reports. Given that the amount of S-(-)equol produced in the gut depends on the amount of daidzein exposure, the low soy intake coupled with lower prevalence of S-(-)equol producing status in the study population favors toward null associations. Findings from our study could be used for further investigations on S-(-)equol producing status and disease risk.

Soy intake and breast cancer risk: an evaluation based on a systematic review of epidemiologic evidence among the Japanese population

OBJECTIVE

We reviewed epidemiological studies of soy intake and breast cancer among Japanese women. This report is one among a series of articles by our research group, which is evaluating the existing evidence concerning the association between health-related lifestyles and cancer.

METHODS

Original data were obtained from MEDLINE searches using PubMed or from searches of the Ichushi database, complemented with manual searches. Evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility.

RESULTS

Five cohort studies and six case-control studies were identified. Among the cohort studies, two studies observed that total soy intake (in terms of total amounts of soy foods or soy isoflavones) was associated with a moderate (0.5 ≤ relative risk ≤ 0.67 with statistical significance) or strong (relative risk ≤ 0.5 with statistical significance) risk reduction of breast cancer in postmenopausal women. Among the case-control studies, two studies reported a weak (0.67 ≤ odds ratio ≤ 1.5 with statistical significance or 0.5 ≤ odds ratio ≤ 0.67 without statistical significance) inverse association between total soy intake and the risk of breast cancer. In the former, this association was observed in all women combined-premenopausal and postmenopausal women-but in the latter, the association was confined to postmenopausal women. The associations of intakes of individual soy foods with the risk of breast cancer were generally null. There is some evidence that supports the biological plausibility of a protective effect of isoflavones on breast cancer risk.

CONCLUSIONS

We conclude that soy intake possibly decreases the risk of breast cancer among Japanese women.

Preparation and physicochemical properties of whole-bean soymilk

Whole-bean soymilk has been prepared by using media-milling. Some characteristics of media-milled soymilk have been determined and compared with filtered soymilk (similar to commercial ones) and whole-bean soymilk prepared by blending. There existed particles in the nano/submicrometer scale in both media-milled and filtered soymilk. The particles in blended soymilk were greater than 1 μm. Media-milled soymilk was the most stable among three samples, even after autoclaving. Solid recovery (98.44 ± 0.16%), viscosity (160.59 ± 4.26 cps), dietary fiber (22.68 ± 0.97% on dry basis), total polyphenol recovery (95.15 ± 7.09%), and isoflavone content (4.42 ± 0.03 mg/g dry solid) of media-milled samples were greater than those of filtered ones. Aglycones, the most bioactive form of isoflavone, in autoclaved media-milled soymilk were more than 2-fold those in autoclaved filtered soymilk. With almost no okara generated, the media-milled soymilk retained fiber in soybeans which would be beneficial to human health.

Dietary factors influence production of the soy isoflavone metabolite s-(-)equol in healthy adults

S-(-)equol, an intestinally derived metabolite of the soy isoflavone daidzein, is proposed to enhance the efficacy of soy diets. Adults differ in their ability to produce equol when consuming soy foods for reasons that remain unclear. Therefore, we performed a comprehensive dietary analysis of 143 macro- and micronutrients in 159 healthy adults in the United States (n = 89) and Australia (n = 70) to determine whether the intake of specific nutrients favors equol production. Three-d diet records were collected and analyzed using Nutrition Data System for Research software and S-(-)equol was measured in urine by mass spectrometry. Additionally, in a subset of equol producers and nonproducers (n = 10/group), we examined the long-term stability of equol producer status by retesting 12, 18, and 24 mo later. Finally, the effect of oral administration of the antibiotic metronidazole (500 mg/d for 7 d) on equol production was examined in 5 adults monitored during a 4-mo follow-up period. Equol producers accounted for 30.3% and 28.6% of the United States and Australian participants, respectively (overall frequency, 29.6%). No significant differences were observed for total protein, carbohydrate, fat, saturated fat, or fiber intakes between equol producers and nonproducers. However, principal component analysis revealed differences in several nutrients, including higher intakes of polyunsaturated fatty acids (P = 0.039), maltose (P = 0.02), and vitamins A (P = 0.01) and E (P = 0.035) and a lower intake of total cholesterol (P = 0.010) in equol producers. During a 2-y period, equol producer status remained unchanged in all nonproducers and in 80% of equol producers, whereas metronidazole abolished equol production in only 20% of participants. In conclusion, these findings suggest that major differences in the macronutrient content of the diet appear not to influence equol production, but subtle differences in some nutrients may influence the ability to produce equol, which was a relatively stable phenomenon.

Soy, red clover, and isoflavones and breast cancer: a systematic review

BACKGROUND

Soy and red clover isoflavones are controversial due to purported estrogenic activity and possible effects on breast cancer. We conducted a systematic review of soy and red clover for efficacy in improving menopausal symptoms in women with breast cancer, and for potential impact on risk of breast cancer incidence or recurrence.

METHODS

We searched MEDLINE, Embase, the Cochrane Library, and AMED from inception to March 2013 for human interventional or observational data pertaining to the safety and efficacy of soy and red clover isoflavones in patients with or at risk of breast cancer.

RESULTS

Of 4179 records, we included a total of 131 articles: 40 RCTs, 11 uncontrolled trials, and 80 observational studies. Five RCTs reported on the efficacy of soy for hot flashes, showing no significant reductions in hot flashes compared to placebo. There is lack of evidence showing harm from use of soy with respect to risk of breast cancer or recurrence, based on long term observational data. Soy intake consistent with that of a traditional Japanese diet (2-3 servings daily, containing 25-50mg isoflavones) may be protective against breast cancer and recurrence. Human trials show that soy does not increase circulating estradiol or affect estrogen-responsive target tissues. Prospective data of soy use in women taking tamoxifen does not indicate increased risk of recurrence. Evidence on red clover is limited, however existing studies suggest that it may not possess breast cancer-promoting effects.

CONCLUSION

Soy consumption may be associated with reduced risk of breast cancer incidence, recurrence, and mortality. Soy does not have estrogenic effects in humans. Soy intake consistent with a traditional Japanese diet appears safe for breast cancer survivors. While there is no clear evidence of harm, better evidence confirming safety is required before use of high dose (≥ 100 mg) isoflavones can be recommended for breast cancer patients.

Cytology in nipple aspirate fluid during a randomized soy food intervention among premenopausal women

Because soy food consumption may influence breast tissue activity, we examined its effect on the presence of epithelial cells in nipple aspirate fluid (NAF). In a randomized, crossover design, 82 premenopausal women completed a high-soy and a low-soy diet for 6 mo each, separated by a 1-mo washout period. They provided NAF samples at baseline, 6 mo, and 13 mo during the midluteal phase of the menstrual cycle. Papanicolaou-stained cytology slides (for 33 women at baseline, 24 at low-soy, and 36 at high-soy) were evaluated in women with sufficient NAF. Mixed models evaluated the effect of the high-soy diet on epithelial cytology as compared to baseline and the low-soy diet. At the end of the high-soy diet, cytological subclass had decreased in 8 (24%) and increased in 3 (9%) women as compared to baseline, whereas the respective values were 3 (14%) and 6 (29%) for the low-soy diet samples (P = 0.32). Only the change in subclass indicated a trend in lower cytological class (P = 0.06). Contrary to an earlier report, the number of NAF samples with hyperplastic epithelial cells did not increase after a soy intervention in amounts consumed by Asians.

O-desmethylangolensin inhibits the proliferation of human breast cancer MCF-7 cells by inducing apoptosis and promoting cell cycle arrest

The aim of the present study was to investigate the anticancer effect of O-desmethylangolensin (O-DMA) by assessing cell proliferation, apoptosis and cell cycle distribution, as well as exploring the mechanisms underlying these effects in breast carcinoma MCF-7 cells. The cells were exposed to O-DMA (5–200 μM) for 24, 48 and 72 h. The results revealed that cell proliferation was significantly inhibited in a dose-dependent manner following treatment for 48 and 72 h, but not after 24 h, and resulted in the significant induction of apoptosis and the promotion of cell cycle arrest at the G₁/S and G₂/M phases. To elucidate these effects of O-DMA, the expression levels of cell cycle regulators were measured in the cells exposed to O-DMA at 150 μM for 72 h. Of the G₁/S phase-related proteins, O-DMA modulated the cyclin-dependent kinases (CDKs), with a decrease in CDK2 and CDK4 and an increase in CDK6, and downregulated cyclin D and E. With respect to the G₂/M-related proteins, O-DMA caused a reduction in CDK1, together with a slight increase in cyclin A and B. In addition, O-DMA downregulated p21^Cip1 and p27^Kip1, but not p16^INK4a and p15^INK4b, and interacted with the CDK6-cyclin D and CDK1-cyclin B complexes. In conclusion, these results indicate for the first time that the regulation of the CDK4/6-cyclin D and CDK1-cyclin B complexes may participate in the anticancer activity pathway of O-DMA in MCF-7 cells.

Genistein induces G2/M arrest in gastric cancer cells by increasing the tumor suppressor PTEN expression

Genistein, a major isoflavone found in soybeans, exhibits anticarcinogenic properties. The inhibitory effect of genistein on cell proliferation is associated with G2/M cell cycle arrest and inhibition of cdc2 activities. Here we assessed the role of PTEN in regulation of genistein-mediated G2/M cell cycle arrest in the gastric cancer cell lines (SGC-7901 and BGC-823). After 24 h following treatment, genistein induced a concentration-dependent accumulation of cells in the G2/M phase of the cell cycle. The sustained G2/M arrest by genistein in SGC-7901 and BGC-823 cells is associated with increased phospho-cdc2 (Tyr15) and decreased cdc2 protein. Genistein treatment increased Wee1 levels and decreased phospho-Wee1 (Ser 642). Moreover, genistein substantially decreased the Ser473 and Thr308 phosphorylation of Akt and upregulated PTEN expression. Downregulation of PTEN by siRNA in genistein-treated cells increased phospho-Wee1 (Ser642), whereas decreased phospho-Cdc2 (Tyr15), resulting in decreased the G2/M cell cycle arrest. Therefore, induction of G2/M cell cycle arrest by genistein involved upregulation of PTEN.

Soy isoflavone intake and breast cancer risk in Japan: from the Takayama study

The effects of soy or isoflavone intake on breast cancer need to be examined further in epidemiologic studies. We assessed the associations of soy and isoflavone intake with breast cancer incidence in a population-based prospective cohort study in Japan. Participants were members from the Takayama study, aged 35 years or older in 1992. The follow-up was conducted from the time of the baseline study (September 1, 1992) to the end of March 2008. Cancer incidence was mainly confirmed through regional population-based cancer registries. Breast cancer was defined as code C50 according to ICD-10. Soy and isoflavone intakes were assessed with a validated food frequency questionnaire. Using the Cox proportional hazard models, the association of soy and isoflavone intake with breast cancer was assessed after adjustments for age, body mass index, physical activity, smoking, alcohol consumption, education, age at menarche, age at first delivery, menopausal status, number of children and history of hormone replacement therapy. Among the 15,607 women analyzed, 172 had developed breast cancer. The relative risks of postmenopausal breast cancer were lower among women with higher intakes of soy (trend p = 0.023) and isoflavone (trend p = 0.046), although the relative risks of premenopausal breast cancer were not associated with intakes of soy and isoflavone. Decreased risks of breast cancer were found even among women with a moderate intake of soy and isoflavone. These results suggested that soy and isoflavone intakes have a protective effect on postmenopausal breast cancer.