Soy Isoflavones and Bone Health: The Relationship Is Still Unclear

Phytotherapeutic approach for conquering menopausal syndrome and osteoporosis

Women face a significant change in their reproductive health as menopause sets in. It is marred with numerous physiological changes that negatively impact their quality of life. This universal, transition phase is associated with menopausal and postmenopausal syndrome, which may spread over 2-10 years. This creates a depletion of female hormones causing physical, mental, sexual and social problems and may, later on, manifest as postmenopausal osteoporosis leading to weak bones, causing fractures and ultimately morbidity and mortality. Menopausal hormone therapy generally encompasses the correction of hormone balance through various pharmacological agents, but the associated side effects often lead to cessation of therapy with poor clinical outcomes. However, it has been noticed that phytotherapeutics is trusted by women for the amelioration of symptoms related to menopause and for improving bone health. This could primarily be due to their reduced side effects and lesser costs. This review attempts to bring forth the suitability of phytotherapeutics/herbals for the management of menopausal, postmenopausal syndrome, and menopausal osteoporosis through several published research. It tries to enlist the available botanicals with their key constituents and mechanism of action for mitigating symptoms associated with menopause as well as osteoporosis. It also includes a list of a few herbal commercial products available for these complications. The article also intends to collate the findings of various clinical trials and patents available in this field and provide a window for newer research avenues in this highly important yet ignored health segment.

Nutritional Quality of Conventional, Organic, and Hydroponic Tomatoes Commercialized in Quito, Ecuador

The consumption of natural foods is increasingly high, and in recent years, consumers have preferred foods from systems with responsible management of natural resources (organic, hydroponic). However, there are still contradictions regarding the nutritional content of products from these different types of crops. Our study aims to compare, for the first time, the content of antioxidants (ascorbic acid, lycopene, total phenolics, essential fatty acids), micronutrients (copper, iron, manganese, zinc), contaminants (cadmium and lead), and free radical scavenging activity between conventional, organic, and hydroponic tomatoes (Solanum lycopersicum) sold in markets in Quito, Ecuador. Ascorbic acid and lycopene were determined by HPLC/UV-Vis. Total phenolics (Folin-Ciocalteu method) and free-radical scavenging activity (2,2-diphenyl-1-picrylhydrazyl method) were determined via UV-Vis spectrophotometry. Lipid profiles were determined as fatty acid methyl esters through a GC-FID. Trace metals were determined using FAAS (micronutrients), and GFAAS (pollutants). No significant differences (p > 0.05) between antioxidant and micronutrient content among the three types of tomatoes were found. Regarding cadmium and lead, the contents were below the Codex Alimentarius threshold limits. Finally, free radical scavenging activity varied slightly (organic > hydroponic > conventional). Although the samples showed certain differences in antioxidant content, none of the tomato types could be considered nutritionally better because of the high variability of the results.

Effect of soy isoflavone supplementation on blood pressure: a meta-analysis of randomized controlled trials

BACKGROUND

Previous experimental studies have suggested that the consumption of soy isoflavones may have a potential impact on lowering blood pressure. Nevertheless, epidemiological studies have presented conflicting outcomes concerning the correlation between soy isoflavone consumption and blood pressure levels. Consequently, a comprehensive meta-analysis of all eligible randomized controlled trials (RCTs) was conducted to explore the influence of soy isoflavones on systolic blood pressure (SBP) and diastolic blood pressure (DBP) in adults.

METHODS

A thorough search of PubMed, Embase, and the Cochrane Library for relevant literature up to April 30, 2023 was conducted. RCTs involving adults that compared soy isoflavone supplementation with a placebo (the same matrix devoid of soy isoflavone) were included. The combined effect size was presented as the weighted mean difference (WMD) along with 95% confidence interval (CI), employing a fixed-effects model.

RESULTS

Our meta-analysis included a total of 24 studies involving 1945 participants. The results revealed a significant reduction in both SBP and DBP with soy isoflavone supplementation. Subgroup analyses suggested more pronounced reductions in SBP and DBP for interventions lasting ≥6 months, in individuals receiving mixed-type soy isoflavone, and among patients with metabolic syndrome or prehypertension. However, we did not detect significant nonlinear associations between supplementation dosage and intervention duration concerning both SBP and DBP. The overall quality of evidence was deemed moderate.

CONCLUSIONS

The current meta-analysis revealed that supplementation with soy isoflavones alone effectively reduces blood pressure. Additional high-quality studies are required to investigate the efficacy of blood pressure reduction through supplementation with an optimal quantity and proportion of soy isoflavone.

Modifiable lifestyle factors associated with fragility hip fracture: a systematic review and meta-analysis

INTRODUCTION

Among the various hip fracture predictors explored to date, modifiable risk factors warrant special consideration, since they present promising targets for preventative measures. This systematic review and meta-analysis aims to assess various modifiable risk factors.

MATERIAL AND METHODS

We searched four online databases in September 2017. We included studies that reported on modifiable lifestyle risk factors for sustaining fragility hip fractures. The quality of the included studies was assessed using the Newcastle-Ottawa Scale (NOS). The inclusion criteria consisted of (1) adult patients with osteoporotic hip fracture, (2) original study, (3) availability of full text articles in English, and (4) report of a modifiable lifestyle risk factor.

RESULTS

Thirty-five studies, containing 1,508,366 subjects in total, were included in this study. The modifiable risk factors that were significantly associated with an increased risk of hip fracture were the following: weight < 58 kg (128 lbs) (pooled OR 4.01, 95% CI 1.62-9.90), underweight body mass index (BMI) (< 18.5) (pooled OR 2.83, 95% CI 1.82-4.39), consumption of ≥ 3 cups of coffee daily (pooled OR 2.27, 95% CI 1.04-4.97), inactivity (pooled OR 2.14, 95% CI 1.21-3.77), weight loss (pooled OR 1.88, 95% CI 1.32-2.68), consumption of ≥ 27 g (approx. > 2 standard drinks) alcohol per day (pooled OR 1.54, 95% CI 1.12-2.13), and being a current smoker (pooled OR 1.50, 95% CI 1.22-1.85). Conversely, two factors were significantly associated with a decreased risk of hip fracture: obese BMI (> 30) (pooled OR 0.58, 95% CI 0.34-0.99) and habitual tea drinking (pooled OR 0.72, 95% CI 0.66-0.80).

CONCLUSION

Modifiable factors may be utilized clinically to provide more effective lifestyle interventions for at risk populations. We found that low weight and underweight BMI carried the highest risk, followed by high coffee consumption, inactivity, weight loss, and high daily alcohol consumption.

Development of a Natural Preservative from Chestnut Flowers: Ultrasound-Assisted Extraction Optimization and Functionality Assessment

This study was carried out with the aim of optimizing the ultrasound-assisted extraction (UAE) of phenolic compounds from male chestnut flowers (C. sativa Mill) to develop a bioactive extract with potential to be used as a natural antioxidant preservative ingredient in the food industry. Time (t, 1–39 min), solvent concentration (S, 0–100%), and ultrasonic power (P, 5–500 W) were used as the independent variables for a 5-level experimental circumscribed central composite design (CCCD) coupled with response surface methodology (RSM) to optimize the extraction of phenolic compounds by UAE. Regarding the variables, the three showed a significant effect on the extraction of phenolic compounds. The content of phenolic compounds (including flavonoids and tannins) and the extraction yield (extract weight gravimetrically assessed) were the response criteria for the optimization. Based on the statistically validated predictive polynomial models, it was possible to reach a maximum content of phenolic compounds at the global optimal conditions of 24 ± 3 min, 259 ± 16 W, and 51 ± 7% ethanol. Additionally, pentagalloyl-glucoside and trigalloyl-hexahydroxydiphenoyl-glucoside were the major phenolic compounds identified. The optimized extract was then analyzed for their biological properties. The bioactive potential of the chestnut flower extract obtained under these optimized conditions was evaluated using in vitro assays for antioxidant, anti-inflammatory, and antimicrobial activity, as well as cytotoxicity and hepatotoxicity tests. The results revealed that the enriched extract has antioxidant, antitumoral, and anti-inflammatory activities without toxicity issues. Overall, this study allowed to define the optimal conditions for the extraction of phenolic compounds from chestnuts male flowers by UAE, to obtain an enriched extract with biological properties that could be further used as a natural antioxidant ingredient with applications on functional foods.

Nutritional Supplements and Skeletal Health

PURPOSE OF REVIEW

Nutrition influences skeletal health throughout the lifespan, from the impact of maternal intakes during development, through the development of peak bone mass, to the rate of bone loss during aging. However, there are limited data available on the effects of nutritional supplements on bone density, let alone fracture risk. This review will assess the current literature, focusing on human studies, and emphasizing nutrients where bone density or fracture data are available.

RECENT FINDINGS

Calcium and vitamin D supplements, in combination, reduce fracture risk, particularly in populations with low intakes. Extensive recent analyses have supported the safety of these interventions at recommended intakes. There is growing evidence that specific isoflavones may improve bone density although fracture data are lacking. Multiple other nutrient supplements may benefit skeletal health, but data are limited. The effect size of nutrient interventions are relatively small, requiring large sample sizes for trials with bone outcomes, may be difficult to blind, and the impact of supplementation may depend on baseline intake. However, nutrition is the only intervention that can be implemented life long and on a population wide basis. Further investigation is needed into the potential benefits of nutritional supplements to determine in which settings supplements may add benefit in addition to dietary intakes.

Polyphenol-Rich Foods and Osteoporosis

BACKGROUND

Osteoporosis is a metabolic disease affecting the bone mineral density and thus compromise the strength of the bones. Disease prevention through diet is the objective of the study and discussion. Among the several nutrients investigated, the intake of phenols seems to influence bone mineral density by acting as free radical scavengers, preventing oxidation-induced damage to bone cells. In addition, the growing understanding of the bone remodelling process supports the theory that inflammation significantly contributes to the etiopathogenesis of osteoporosis.

METHODS

To provide an overview of current evidence on polyphenol-rich foods and osteoporosis prevention we made a comprehensive review of the literature focusing on the state of art of the topic.

RESULTS

Some polyphenol-rich foods, including olive oil, fruit and vegetable, tea and soy, seem to be beneficial for preventing osteoporosis disease and its progression. The mechanism is still partly unknown and may involve different pathways which include inflammation and other disease reactions.

CONCLUSIONS

However, further research is needed to better understand the mechanisms regulating the molecular interaction between osteoporosis incidence and progression and polyphenol-rich foods. The current evidence suggests that dietary intervention with polyphenol rich foods may be useful to prevent incidence and progression of this condition.

Icariin, but Not Genistein, Exerts Osteogenic and Anti-apoptotic Effects in Osteoblastic Cells by Selective Activation of Non-genomic ERα Signaling

Genistein and icariin are flavonoid compounds that exhibit estrogen-like properties in inducing bone formation and reducing bone loss associated with estrogen deficiency in both preclinical and clinical studies. However, the mechanisms that are involved in mediating their estrogenic actions in bone cells are far from clear. The present study aimed to study the signaling pathways that mediate the estrogenic actions of genistein and icariin in osteoblastic cells. The effects of genistein and icariin on the activation of estrogen receptor (ER) and the downstream mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway in murine osteoblastic MC3T3-E1 cells and rat osteoblastic UMR-106 cells were studied. As expected, genistein displayed higher binding affinity toward ERβ than ERα and significantly induced estrogen response element (ERE)-dependent transcription in UMR-106 cells in a dose-dependent manner. In contrast, icariin failed to bind to ERα or ERβ and did not induce ERE-dependent transcription in UMR-106 cells at 10^-10 to 10^-7 M. The effects of genistein (10 nM) and icariin (0.1 μM) on cell proliferation and differentiation in osteoblastic UMR-106 cells were abolished in the presence of ER antagonist ICI 182,780 (1 μM), MAPK inhibitor U0126 (10 μM), and PI3K inhibitor LY294002 (10 μM). Genistein at 10 nM rapidly induced ERK1/2 phosphorylation at 5–10 min in UMR-106 cells and the phosphorylation of ERα at both Ser118 and Ser167 in both MC3T3-E1 and transfected UMR-106 cells whereas icariin at 0.1 μM rapidly activated both ERK1/2 and Akt phosphorylation in UMR-106 cells and subsequent ERα phosphorylation at both Ser118 and Ser167 in MC3T3-E1 and transfected UMR-106 cells. Confocal imaging studies confirmed that the phosphorylation of ERα at Ser 118 and Ser 167 by genistein and icariin in MC3T3-E1 cells was mediated via MAPK- and PI3K-dependent pathway, respectively. Furthermore, our studies showed that icariin exerted stronger anti-apoptotic effects than genistein and 17β-estradiol (E2) and inhibited the cleavage of downstream caspase-3 in MC3T3-E1 cells induced by a potent PI3K inhibitor, PI828 (at 2 μM). These results indicated that the mechanisms that mediate the estrogenic actions of icariin in osteoblastic cells are different from those of genistein.

Effects of phytoestrogens on bone mineral density during the menopause transition: a systematic review of randomized, controlled trials

INTRODUCTION

Menopause is associated with increased bone resorption and decreased bone mineral density (BMD). Phytoestrogens are believed to prevent bone loss. This study reviewed relevant randomized, controlled trials to determine the effects of phytoestrogens on BMD in postmenopausal women.

METHODS

In order to perform this systematic review, PubMed, Science Direct, Scopus, Cochrane Library, ISI Web of Knowledge, and ProQuest databases were searched for articles published during 2005-2016. The main keywords used during the searches were "phytoestrogen" and "bone mineral density" and "menopause". The Cochrane Risk of Bias Assessment Tool was used to evaluate the quality of the selected studies and to assess the risk of bias.

RESULTS

A total of 23 eligible studies were included in this systematic review. Most selected studies used a double-blind, placebo-controlled design. In total, 3494 participants were enrolled in the selected trials. Different types of soy isoflavone extracts, including genistein extracts (either alone or in combination with daidzein), dietary products containing different amounts of phytoestrogens, and red clover extracts were used in the designed interventions. The duration of the interventions ranged from 7 weeks to 3 years. In most studies, the primary outcome was the efficacy of the designed intervention which was assessed through measuring whole body or regional BMD or bone mineral content, T-scores, and biomarkers of bone metabolism.

CONCLUSIONS

Isoflavones probably have beneficial effects on bone health in menopausal women. Nevertheless, there were controversial reports about changes in BMD. Supplementation with a phytoestrogen can probably prevent the reduction in BMD and maintain a healthy bone structure during menopause.

Effect of whole soy and purified daidzein on ambulatory blood pressure and endothelial function--a 6-month double-blind, randomized controlled trial among Chinese postmenopausal women with prehypertension

BACKGROUND/OBJECTIVES

Although observational studies suggest that soy foods or isoflavones are cardio-protective, clinical trials on whole soy or isoflavone daidzein (one major isoflavone and the precursor of equol) on blood pressure (BP) and endothelial function (EF) are few and have not been specifically conducted among equol producers, a population most likely to benefit from soy treatment.

SUBJECTS/METHODS

We performed a 6-month double-blind, randomized, placebo-controlled trial to examine the effect of whole soy (soy flour) or purified daidzein on BP and EF in prehypertensive or untreated hypertensive postmenopausal women verified to be equol producers. A total of 270 eligible women were recruited and randomized to either one of the three treatment groups, 40 g soy flour (whole soy group), 40 g low-fat milk powder+63 mg daidzein (daidzein group) or 40 g low-fat milk powder (active control group) daily, each given as a solid beverage powder for 6 months. The primary outcome measures were 24 h ambulatory BP (ABP) and EF assessed by flow-mediated dilation using brachial artery ultrasound.

RESULTS

A total of 253 subjects completed the study according to protocol. Urinary isoflavones indicated good compliance with the interventions. Intention to treat and per-protocol analysis indicated that there was no significant difference in the 6-month changes or % changes in parameters of ABP and brachial flow-mediated dilation among the three treatment groups. A further subgroup analysis among hypertensive women (n=138) did not alter the conclusions.

CONCLUSIONS

Whole soy and purified daidzein had no significant effect on BP and vascular function among equol-producing postmenopausal women with prehypertension or untreated hypertension.

Impact of equol-producing capacity and soy-isoflavone profiles of supplements on bone calcium retention in postmenopausal women: a randomized crossover trial

BACKGROUND

Postmenopausal estrogen depletion is a major contributing factor to bone loss. Soy isoflavones have variable effects on the prevention of postmenopausal bone loss, which is possibly related to the specific isoflavone content or the variable equol-producing capacity of individuals.

OBJECTIVE

We aimed to determine the effects of the content of isoflavones in a soy supplement and the equol-producing ability of the individual on postmenopausal bone calcium retention.

DESIGN

The study was a blinded, randomized, crossover intervention trial in 24 postmenopausal women who were prescreened for their ability to convert daidzein to equol. Women were equilibrated with (41)Ca before the intervention. Interventions were 5 soy isoflavone oral supplements (2 doses of a genistein-rich soy supplement and 3 doses of mixed isoflavones in various proportions) and a bisphosphonate (risedronate). Each intervention was given sequentially for 50 d followed by a 50-d washout period. The percentage of bone calcium retention was determined from the change in urinary (41)Ca:calcium.

RESULTS

Interventions that ranged from 52 to 220 mg total isoflavones/d increased bone calcium retention between 3.4% and 7.6% (P < 0.05), which was a moderate effect compared with that of risedronate at 15.3% (95% CI: 7.1%, 22.7%; P = 0.0014). The most-effective soy intervention delivered 105.23 mg total isoflavones/d as genistein, daidzein, and glycitein in their natural ratios and increased bone calcium retention by 7.6% (95% CI: 4.9%, 10.2%; P < 0.0001). Genistein, at 52.85 mg/d, increased bone calcium retention by 3.4% (95% CI: 0.5%, 6.2%; P = 0.029); but there was no benefit at higher amounts (113.52 mg/d). There was no difference (P = 0.5) in bone calcium retention between equol producers and nonproducers.

CONCLUSION

Soy isoflavones, although not as potent as risedronate, are effective bone-preserving agents in postmenopausal women regardless of their equol-producing status, and mixed isoflavones in their natural ratios are more effective than enriched genistein. This trial was registered at clinicaltrials.gov as NCT00244907.

Soy isoflavone intake and bone mineral density in breast cancer survivors

PURPOSE

Low bone mineral density (BMD) is common among breast cancer survivors due to acute estrogen deprivation. Soy food is a rich source of phytoestrogens, namely isoflavones, known to have both estrogenic and anti-estrogenic effects. The objective of the study was to assess the association between soy consumption and BMD in breast cancer survivors, which has not previously been evaluated.

METHODS

Forearm BMD was evaluated using dual-energy X-ray absorptiometry at 60 months post-diagnosis for 1,587 participants of the Shanghai Breast Cancer Survival Study. Soy intakes collected at 6, 18, and 36 months post-diagnosis were averaged, and the association with BMD, osteopenia, and osteoporosis was evaluated using linear and logistic regression.

RESULTS

The mean (standard deviation) intake of isoflavones was 48.1 (28.0) mg/day. Soy intake was inversely associated with BMD and positively associated with osteoporosis. Compared with the lowest quartile, the highest quartile of soy isoflavone intake, ≥ 62.64 mg/day, was associated with a reduction of BMD by 1.95% [95% confidence interval (CI) -3.54, -0.36%] and an increased odds ratio of 1.69 for osteoporosis (95% CI 1.09, 2.61). The inverse association was predominantly seen among women who recently entered menopause (≤ 5 years).

CONCLUSION

In contrast to observations from general populations, high soy intake (≥ 62.64 mg of soy isoflavone/day) was associated with lower proximal forearm BMD among breast cancer survivors, particularly during the early years of menopause. Our finding needs to be replicated, particularly in studies with more comprehensive bone density evaluation.

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.

Effect of whole soy and purified isoflavone daidzein on renal function--a 6-month randomized controlled trial in equol-producing postmenopausal women with prehypertension

OBJECTIVES

The aim of the study was to examine the long-term effect of commonly used whole soy foods (soy flour) and purified daidzein (one major isoflavone and the precursor of equol) on renal function among prehypertensive postmenopausal women who are also equol producers, a population most likely to benefit from soy intervention.

DESIGN AND METHODS

This was a 6-month double-blind, randomized, placebo-controlled trial. Two hundred seventy eligible Chinese women were randomized to either one of the three treatments: 40 g soy flour (whole soy group), 40 g low-fat milk powder + 63 mg daidzein (daidzein group) or 40 g low-fat milk powder (placebo group) daily each for 6 months. Fasting blood and 24-h urine samples were collected at the beginning and end of trial. Serum creatinine, cystatin C, urea, angiotensin-converting enzyme, minerals and 24-h urinary creatinine and minerals were analyzed. Estimated glomerular filtration rate (eGFR) was calculated with the Cockcroft-Gault and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations.

RESULTS

Two hundred fifty-three subjects completed the study according to the protocol. Urinary isoflavones indicated good compliance of participants. No significant changes were observed in most of renal parameters, however, there was a less decrease in eGFRcockcroft in 6-month change (p=0.044) and %change (p=0.031) with whole soy intake relative to milk placebo. Subgroup analysis among women with lowered renal function suggested whole soy consumption tended to improve markers of renal function relative to control.

CONCLUSIONS

Six-month consumption of whole soy tended to have a modest improvement of renal function in prehypertensive postmenopausal women with lowered renal function. Future trials in subjects with more declined renal function are necessary.

TRIAL REGISTRATION

The trial was registered in ClinicalTrials.gov with identifier of NCT01270737. (URL: http://clinicaltrials.gov/ct2/show/NCT01270737).

Randomized controlled trial of whole soy and isoflavone daidzein on menopausal symptoms in equol-producing Chinese postmenopausal women

OBJECTIVE

Dietary supplements containing soy or isoflavones are widely used as alternatives to hormone therapy. However, their efficacy is still inconclusive, and limited data on equol producers are available. The aim of this study was to examine the effect of whole soy (soy flour) or purified daidzein (one major soy isoflavone and the precursor of equol) on menopausal symptoms in equol-producing postmenopausal women, a population most likely to benefit from soy intervention.

METHODS

This is a 6-month parallel-group, double-blind, randomized, placebo-controlled trial. Two hundred seventy equol-producing prehypertensive Chinese postmenopausal women were randomized to one of three treatment groups: 40 g of soy flour (whole soy group), 40 g of low-fat milk powder + 63 mg of daidzein (daidzein group), or 40 g of low-fat milk powder (placebo group) daily, each given as a solid beverage for 6 months. Changes in menopausal symptoms were assessed by a validated and structured symptom checklist at baseline and 6 months.

RESULTS

Two hundred fifty-three participants completed the study according to protocol. Urinary isoflavones indicated good compliance with the interventions. Baseline menopausal symptoms were comparable among the three study groups. Intention-to-treat analysis indicated that there was no significant difference in the 6-month changes or percent changes in the total number of menopausal symptoms, in the five dimensions of symptoms, and in the frequencies of individual symptoms among the three treatment groups.

CONCLUSIONS

Whole soy and purified daidzein have no significant effect on alleviation of menopausal symptoms among equol-producing postmenopausal women with prehypertension.

Hydrolysis of isoflavone glycoside by immobilization of β-glucosidase on a chitosan-carbon in two-phase system

We explored a method to examine the hydrolysis of isoflavone glycoside by immobilizing β-glucosidase on chitosan-carbon beads in an aqueous-organic two-phase system. The chitosan-carbon beads were cross-linked with glutaraldehyde to immobilize β-glucosidase from Exiguobacterium sp. DAU5. The optimal pH and temperature were 9.0 and 55 °C, respectively. Under the optimized conditions, crude and purified enzymes immobilized onto chitosan-carbon beads gave yields of 16.7% and 60%, respectively. The specific activities of immobilized crude and purified enzymes were 4.3 U/g and 6 U/g, respectively. The immobilized enzyme retained more than 80% of its maximum activity at pH 7.0-11.0, while temperature was more influential (80% activity after 40 °C for 1.5 h, but only 40% activity after 55 °C for 0.5 h, respectively. The immobilized enzyme was able to hydrolyze isoflavone glycoside in an aqueous-organic two-phase system, and the hydrolyzed products were enriched in the organic phase, making it easy to recover the products, i.e., genistein and daidein from the reaction system. These results suggest that immobilized β-glucosidase may be applicable for the industrial-scale hydrolysis of isoflavone glycoside.

Production of hydroxlated flavonoids with cytochrome P450 BM3 variant F87V and their antioxidative activities

A variant of P450 BM3 with an F87V substitution [P450 BM3 (F87V)] is a substrate-promiscuous cytochrome P450 monooxygenase. We investigated the bioconversion of various flavonoids (favanones, chalcone, and isoflavone) by using recombinant Escherichia coli cells, which expressed the gene coding for P450 BM3 (F87V), to give their corresponding hydroxylated products. Potent antioxidative activities were observed in some of the products.

The effect of soy isoflavone on bone mineral density in postmenopausal Taiwanese women with bone loss: a 2-year randomized double-blind placebo-controlled study

The treatment of 300-mg/day isoflavones (aglycone equivalents) (172.5 mg genistein + 127.5 mg daidzein) for 2 years failed to prevent lumbar spine and total proximal femur bone mineral density (BMD) from declining as compared with the placebo group in a randomized, double-blind, two-arm designed study enrolling 431 postmenopausal women 45-65 years old.

INTRODUCTION

This study evaluated the effects of soy isoflavones on bone metabolism in postmenopausal women.

METHODS

Four hundred and thirty-one women, aged 45-65 years, orally consumed 300-mg/day isoflavones (aglycone equivalents) or a placebo for 2 years in a parallel group, randomized, double-blind, two-arm study. Each participant also ingested 600 mg of calcium and 125 IU of vitamin D(3) per day. The BMD of the lumbar spine and total proximal femur were measured using dual-energy X-ray absorptiometry at baseline and every half-year thereafter. Serum bone-specific alkaline phosphatase, urinary N-telopeptide of type 1 collagen/creatinine, and other safety assessments were examined regularly.

RESULTS

Two hundred out of 217 subjects in the isoflavone group and 199 out of 214 cases in placebo group completed the treatment. Serum concentrations of isoflavone metabolites, genistein and daidzein, of the intervention group were remarkably elevated following intake of isoflavones (p < 0.001). However, differences in the mean percentage changes of BMD throughout the treatment period were not statistically significant (lumbar spine, p = 0.42; total femur, p = 0.39) between the isoflavone and placebo groups, according to the generalized estimating equation (GEE) method. A significant time trend of bone loss was observed at both sites as assessed by the GEE method following repeated measurement of BMD (p < 0.001). Differences in bone marker levels were not significant between the two treatment groups.

CONCLUSION

Treatment with 300-mg/day isoflavones (aglycone equivalents) failed to prevent a decline in BMD in the lumbar spine or total femur compared with the placebo group.

Soy milk and dairy consumption is independently associated with ultrasound attenuation of the heel bone among postmenopausal women: the Adventist Health Study-2

Soy milk has become a popular substitute for dairy milk with important health claims. We hypothesized that soy milk, based on its nutrient composition, is comparable to dairy products and, therefore, beneficial for bone health. To test this hypothesis, we examined the benefit of soy milk and dairy products intake on bone health using broadband ultrasound attenuation of the calcaneus. Postmenopausal white women (n = 337) who had completed a lifestyle and dietary questionnaire at enrollment into the Adventist Health Study-2 had their calcaneal broadband ultrasound attenuation measured 2 years later. The association between osteoporosis (defined as a T-score <-1.8) and some dietary factors (soy milk, dairy) and selected lifestyle factors was assessed using logistic regression. In a multivariable model adjusted for demographics, hormone use, and other dietary factors, osteoporosis was positively associated with age (odds ratio [OR] = 1.08; 95% confidence interval [CI], 1.06-1.12) and inversely associated with body mass index (OR = 0.91; 95% CI, 0.86-0.97) and current estrogen use (OR = 0.27; 95% CI, 0.13-0.56). Compared with women who did not drink soy milk, women drinking soy milk once a day or more had 56% lower odds of osteoporosis (OR = 0.44; 95% CI, 0.20-0.98; P(trend) = .04). Women whose dairy intake was once a day or more had a 62% reduction in the likelihood of having osteoporosis (OR = 0.38; 95% CI, 0.17-0.86; P(trend) = .02) compared with women whose dairy intake was less than twice a week. Among individual dairy products, only cheese showed an independent and significant protection (OR = 0.28; 95% CI, 0.12-0.66; P(trend) = .004) for women eating cheese more than once per week vs those who ate cheese less than once a week. We concluded that osteoporosis is inversely associated with soy milk intake to a similar degree as dairy intake after accounting for age, body mass index, and estrogen use.

A process for high-efficiency isoflavone deglycosylation using Bacillus subtilis natto NTU-18

In order to produce isoflavone aglycosides effectively, a process of isoflavone hydrolysis by Bacillus subtilis natto NTU-18 (BCRC 80390) was established. This process integrates the three stages for the production of isoflavone aglycosides in one single fermenter, including the growth of B. subtilis natto, production of β-glucosidase, deglycosylation of fed isoflavone glycosides. After 8 h of batch culture of B. subtilis natto NTU-18 in 2 L of soy medium, a total of 3 L of soy isoflavone glucoside solution containing 3.0 mg/mL of daidzin and 1.0 mg/mL of genistin was fed continuously over 34 h. The percentage deglycosylation of daidzin and genistin was 97.7% and 94.6%, respectively. The concentration of daidzein and genistein in the broth reached 1,066.8 μg/mL (4.2 mM) and 351 μg/mL (1.3 mM), respectively, and no residual daidzin or genistin was detected. The productivity of the bioconversion of daidzein and genistein over the 42 h of culture was 25.6 mg/L/h and 8.5 mg/L/h, respectively. This showed that this is an efficient bioconversion process for selective estrogen receptor modulator production.

Formula feeding alters hepatic gene expression signature, iron and cholesterol homeostasis in the neonatal pig

In the U.S. formula feeding remains more popular than breast-feeding. In the current study, neonatal piglets were breast fed and compared with those fed commercially available milk-based formula (milk) or soy-based formula (soy) from postnatal day 2 (PND2) until death at PND21 (the usual age of weaning). Liver weights were greater in formula-fed piglets ( P < 0.05) than in breast-fed piglets ( P < 0.05). Affymetrix array analysis revealed significant differences in hepatic gene expression signatures between piglets fed breast milk or formula, as well as between piglets fed milk or soy. In males, expression of 346 hepatic genes differed between formula-fed and breast-fed piglets, and soy-fed differed from milk-fed piglets in 277 genes. Furthermore, gene expression profiles of males differed from females, even when the same diet was consumed. Serum cholesterol was lower in piglets fed formula relative to breast-fed piglets ( P < 0.05), and this was associated with elevations in mRNA encoding cholesterol 7α-hydroxylase (CYP7A1). Consistent with the human literature, breast-fed piglets had lower hepatic iron accumulation than formula-fed piglets. Hepcidin, a major regulator of hepatic iron trafficking, was elevated in piglets fed formula relative to breast-fed piglets ( P < 0.05). Female piglets fed soy formula had increased expression of CYP3A enzymes ( P < 0.05), and soy formula feeding decreased expression of several hepatic genes considered estrogen inducible. These data suggest that: 1) gene expression profiles in neonates differ significantly depending on the diet consumed, 2) hepatic iron storage and cholesterol metabolism clearly differ between breast and formula feeding in piglets, 3) there is no evidence that soy is estrogenic in neonatal pig liver.

Influence of gamma irradiation in the antioxidant potential of chestnuts (Castanea sativa Mill.) fruits and skins

As seasonal products chestnuts have to be post-harvest treated to increase their shelf-life. The most common preservation method for chestnuts is the chemical fumigation with methyl bromide, a toxic agent that is under strictly Montreal Protocol due to its adverse effects on human health and environment. Food irradiation is a possible feasible alternative to substitute the traditional quarantine chemical fumigation treatment. This preliminary study evaluated the influence of gamma irradiation in the antioxidant potential of chestnut fruits and skins, through several chemical and biochemical parameters. The bioactive compounds (phenolics and flavonoids) and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-scavenging activity, reducing power and inhibition of β-carotene bleaching capacity were determined. The obtained results seem to indicate that the storage favoured chestnuts antioxidant potential. Furthermore, the application of gamma irradiation also seems to be advantageous for antioxidant activity, independently of the dose used (0.27 ± 0.04 kGy or 0.54 ± 0.04 kGy).

Whole versus the piecemeal approach to evaluating soy

Soy has been singled out for attention among other legumes as a valuable source of nutrients, phytochemicals, and bioactive compounds. Early epidemiological studies established that whole soy and traditional soy foods were implicated in health-protective effects in Asian populations. The same benefits attributable to soy have not been consistently proven in Western populations that, for various reasons, opt to consume more processed soy foods or various soy components. Soy researchers continue to isolate soy components in search of identifying its salubrious components and whole soy remains relatively underinvestigated despite what we know of the health benefits it may confer to those regularly consuming it. Various dietary guidelines advocate the regular consumption of legumes that tend not to be included in our diets in sufficient quantities. This paper highlights the possibility that whole soy may have a more unique effect on health than a select soy component(s). It explores the rationale for focusing research on whole soy in an attempt to understand it better rather than trying to replicate the health benefits by targeting various soy components, which has been plagued by inconsistent results.

Effects of isoflavones equol and genistein on bone quality in a rat osteopenia model

Phytoestrogens might be an alternative medication in prophylaxis and treatment of osteoporosis. In this study, the osteoprotective effects of genistein (GEN) and equol (EQO) were evaluated. After ovariectomy, 44 rats received soy-free food (Control, C) and developed substantial osteoporosis over the course of two months. After that period, the rats were divided into different groups and fed estradiol (E), GEN or EQO for 35 days. To analyze the osteoprotective effects of the tested substances, bone biomechanical properties and histomorphometric changes of the lumbar vertebrae were evaluated. In analyzing the vertebral body compression strength, we found that the EQO (103.8%) and GEN (96.8%) groups reached similar levels relative to the E group, while the C group reached 77.7% of the biomechanical properties of the E group. EQO was significantly superior to C. The histomorphometric evaluation demonstrated an increased number of nodes in EQO- and E-treated rats compared to GEN- and C-treated rats. E led to an improvement of cortical as well as trabecular bone, an advantage that was only partly seen in the other groups. Treatment with phytoestrogens induced improved bone quality. EQO and GEN might be alternatives for hormone replacement therapy, although further studies are needed to elucidate possible side effects.

Tracking deposition of a 14C-radiolabeled kudzu hairy root-derived isoflavone-rich fraction into bone

Hairy roots were induced in four genotypes from three kudzu species (Pueraria montana var. lobata, P. lobata and P. phaseoloides) in vitro using Agrobacterium rhizogenes to stimulate rapid secondary metabolite synthesis. Hairy roots from P. montana var. lobata (United States Department of Agriculture no. PI 434246) yielded the highest puerarin and total isoflavone content and the greatest new biomass per growth cycle among the genotypes evaluated. Hairy roots from this genotype were selected for radiolabeling using (14)C-sucrose as a carbon source. Isoflavones from radiolabeled kudzu hairy root cultures were extracted with 80% methanol, partitioned by solvent extraction, and then subfractionated by Sephadex LH-20 gel filtration. Radiolabeled isoflavones were isolated in a highly enriched fraction, which contained predominantly puerarin, daidzin and malonyl-daidzin and had an average radioactivity of 8.614 MBq/g (232.8 μCi/g) dry fraction. The (14)C-radiolabeled, isoflavone-rich fraction was orally administered at a dose of 60 mg/kg body weight to male Sprague-Dawley rats implanted with a jugular catheter, a subcutaneous ultrafiltrate probe and a brain microdialysate probe. Serum, interstitial fluid, brain microdialysate, urine and feces were collected using a Culex(®) Automated Blood Collection System for 24 h. At the end of this period, rats were sacrificed and major tissues were collected. Analysis by a scintillation counter confirmed that a bolus dose of (14)C-radiolabeled, isoflavone-rich kudzu fraction reached bone tissues, which accumulated 0.011%, 0.09% and 0.003% of the administered dose in femur, tibia and vertebrae, respectively. Femurs extracted with 80% methanol were analyzed by high-performance liquid chromatography with electrospray ionization-mass spectrometry and were found to contain trace quantities of puerarin, daidzein and puerarin glucuronide. This study demonstrates that kudzu isoflavones and metabolites are capable of reaching bone tissues, where they may contribute to the prevention of osteoporosis and the promotion of bone health.

Bioconversion of isoflavone glycosides to aglycones, mineral bioavailability and vitamin B complex in fermented soymilk by probiotic bacteria and yeast

AIM

To study the role of β-glucosidase producing probiotic bacteria and yeast in the biotransformation of isoflavone glycosides to aglycones, mineral bioavailability and vitamin B complex in fermented soymilk.

METHODS AND RESULTS

Five isolates of probiotic lactic acid bacteria (LAB), Lactobacillus acidophilus B4496, Lactobacillus bulgaricus CFR2028, Lactobacillus casei B1922, Lactobacillus plantarum B4495 and Lactobacillus fermentum B4655 with yeast Saccharomyces boulardii were used to ferment soymilk to obtain the bioactive isoflavones, genistein and daidzein. High-performance liquid chromatography was used to analyse the concentration of isoflavones. Bioactive aglycones genistein and daidzein after 24 and 48 h of fermentation ranged from 97.49 to 98.49% and 62.71 to 92.31% respectively with different combinations of LAB with yeast. Increase in bioavailability of minerals and vitamin B complex were also observed in fermented soymilk.

CONCLUSIONS

LAB in combination with yeast S. boulardii has great potential for the enrichment of bioactive isoflavones, enhancing the viability of LAB strains, decreasing the antinutrient phytic acid and increasing the mineral bioavailability in soymilk fermentation.

SIGNIFICANCE AND IMPACT OF THE STUDY

Fermentation of soymilk with probiotic organisms improves the bioavailability of isoflavones, assists in digestion of protein, provides more soluble calcium, enhances intestinal health and supports immune system. Increased isoflavone aglycone content in fermented soymilk improves the biological functionality of soymilk.

Antioxidant potential of chestnut (Castanea sativa L.) and almond (Prunus dulcis L.) by-products

The antioxidant properties of almond green husks (Cvs. Duro Italiano, Ferraduel, Ferranhês, Ferrastar and Orelha de Mula), chestnut skins and chestnut leaves (Cvs. Aveleira, Boa Ventura, Judia and Longal) were evaluated through several chemical and biochemical assays in order to provide a novel strategy to stimulate the application of waste products as new suppliers of useful bioactive compounds, namely antioxidants. All the assayed by-products revealed good antioxidant properties, with very low EC(50) values (lower than 380 μg/mL), particularly for lipid peroxidation inhibition (lower than 140 μg/mL). The total phenols and flavonoids contents were also determined. The correlation between these bioactive compounds and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, reducing power, inhibition of β-carotene bleaching and inhibition of lipid peroxidation in pig brain tissue through formation of thiobarbituric acid reactive substances, was also obtained. Although, all the assayed by-products proved to have a high potential of application in new antioxidants formulations, chestnut skins and leaves demonstrated better results.

Serum markers of bone turnover are increased by modest weight loss with or without weight-bearing exercise in overweight premenopausal women

Weight loss improves metabolic fitness and reduces morbidity and mortality; however, weight reduction also reduces bone mineral density (BMD) and increases bone turnover. Weight-bearing aerobic exercise may preserve bone mass and maintain normal bone turnover during weight reduction. We investigated the impact of weight-bearing and nonweight-bearing exercise on serum markers of bone formation and breakdown during short-term, modest weight loss in overweight premenopausal women. Subjects (n = 36) were assigned to 1 of 3 weight-loss interventions designed to produce a 5% reduction in body weight over 6 weeks: (i) energy restriction only (n = 11; DIET); (ii) energy restriction plus nonweight-bearing exercise (n = 12, CYCLE); or (iii) energy restriction plus weight-bearing exercise (n = 13, RUN). Bone turnover markers were measured in serum collected at baseline and after weight loss. All groups achieved a ~5% reduction in body weight (DIET = 5.2%; CYCLE = 5.0%; RUN = 4.7%). Osteocalcin (OC) and C-terminal telopeptide of type I collagen (CTX) increased with weight loss in all 3 groups (p < 0.05), whereas bone alkaline phosphatase was unaltered by the weight-loss interventions. At baseline, OC and CTX were positively correlated (r = 0.36, p = 0.03), but the strength of this association was diminished (r = 0.30, p = 0.06) after weight loss. Modest weight loss, regardless of method, resulted in a significant increase in both OC and CTX. Low-impact, weight-bearing exercise had no effect on serum markers of bone formation or resorption in premenopausal women during weight loss. Future studies that examine the effects of high-impact, weight-bearing activity on bone turnover and BMD during weight loss are warranted.

Hydrolysis of soy isoflavone glycosides by recombinant beta-glucosidase from hyperthermophile Thermotoga maritima

A recombinant Thermotoga maritima beta-glucosidase A (BglA) was purified to homogeneity for performing enzymatic hydrolysis of isoflavone glycosides from soy flour. The kinetic properties K(m), k(cat), and k(cat)/K(m) of BglA towards isoflavone glycosides, determined using high-performance liquid chromatography, confirmed the higher efficiency of BglA in hydrolyzing malonylglycosides than non-conjugated glycosides (daidzin and genistin). During hydrolysis of soy flour by BglA at 80 degrees C, the isoflavone glycosides (soluble form) were extracted from soy flour (solid state) into the solution (liquid state) in thermal condition and converted to their aglycones (insoluble form), which mostly existed in the pellet to be separated from BglA in the reaction solution. The enzymatic hydrolysis in one-step and two-step approaches yielded 0.38 and 0.35 mg genistein and daidzein per gram of soy flour, respectively. The optimum conditions for conversion of isoflavone aglycones were 100 U per gram of soy flour, substrate concentration 25% (w/v), and incubation time 3 h for 80 degrees C.

A longitudinal study of the effect of genistein on bone in two different murine models of diminished estrogen-producing capacity

This experiment was designed to assess the capacity of dietary genistein (GEN), to attenuate bone loss in ovariectomized (OVX) and ovary-intact VCD-treated mice. Pretreatment of mice with 4-vinylcyclohexene diepoxide (VCD) gradually and selectively destroys ovarian follicles whilst leaving ovarian androgen-producing cells largely intact. VCD induces a perimenopause-like condition prior to the onset of reproductive acyclicity. Sixteen-week-old C57BL/6J mice were randomized to five treatment groups: sham(SHM), OVX, SHM + VCD, OVX + GEN, and SHM + VCD + GEN. In vivo, blood samples were drawn for hormone and isoflavone analyses, estrous cycles were monitored, and X-ray imaging was performed to assess changes in bone parameters. Following sacrifice, ovaries were assessed histologically, bone microarchitecture was evaluated via microcomputed tomography, and bone mechanical properties were measured. Some effects of GEN were observed in OVX mice, but GEN effects were not able to be evaluated in VCD-treated mice due to the subtle diminution of bone during the 4 months of this experiment.

The health implications of soy infant formula

Soy formula (SF) has been fed to millions of infants worldwide. It has been shown to promote growth and development as well as milk-based formula (MF). Controversy has developed over the adequacy and safety of SF. Most concerns are based on in vivo and in vitro data that raise the possibility of estrogenic effects of isoflavones contained in SF. There are few studies of children who were fed SF, and thus insufficient data are available to judge if SF feeding results in clinically significant developmental effects and if there are any long-term health consequences (adverse or beneficial). However, the Arkansas Children's Nutrition Center is conducting a prospective longitudinal study comparing growth, development, and health of breastfed children with formula-fed (SF and MF) children from birth through age 6 y. After 5 y of study, children in all 3 groups (n > 300) are growing and developing within normal limits, and there are no indications of adverse effects in the soy-fed children. Neonatal pig studies comparing SF, MF, and breast milk (BM) have shown diet-specific gene expression profiles in various target tissues. Therefore, although SF differed significantly from BM, MF also differed from BM, and SF differed from MF. Nonetheless, these animals grew and developed normally, and SF piglets had several health benefits (eg, increased bone quality) and no observable adverse effects. Thus, to date, our results suggest that SF supports normal growth and may have advantages in promoting bone development.

Reduced mammary tumor progression in a transgenic mouse model fed an isoflavone-poor soy protein concentrate

Dietary exposure to soy has been associated with reduced breast cancer incidence. Soy isoflavones and protein components, such as protease inhibitors and the lunasin peptide, have been indicated as potential agents reducing carcinogenesis. In this study, the effect of soy-based diets was evaluated in a transgenic mouse model of breast carcinoma, overexpressing the neu oncogene. Neu female mice were fed for 20 wk a soy- and isoflavone-free diet (IFD), 4RF21 laboratory mouse diet, soy-based, thus isoflavone-rich (STD), or AIN-76-based semisynthetic diets with a soy protein isolate (SPI) or an isoflavone-poor soy protein concentrate (IPSP) as protein source. Mice were then sacrificed and tumors removed. Mammary tumor weights were not different in SPI versus IFD and STD fed mice. In contrast, mice fed IPSP showed reduced tumor progression versus IFD and STD groups (p < 0.05). Moreover, IPSP fed mice showed lower bromo-2'-deoxyuridine (BrdU) incorporation into breast tumor cells compared to STD and SPI fed animals (p < 0.02). Lung metastases were detected in 80% of IFD fed mice, in 70% of mice fed STD and SPI, and only in 50% of the IPSP fed animals. These results indicate that a diet containing an isoflavone-poor soy protein concentrate may inhibit breast tumor progression and metastasis development.

Short term effects on bone quality associated with consumption of soy protein isolate and other dietary protein sources in rapidly growing female rats

Beneficial effects of soy protein consumption on bone quality have been reported. The effects of other dietary protein sources such as whey protein hydrolysate (WPH) and rice protein isolate (RPI) on bone growth have been less well examined. The current study compared effects of feeding soy protein isolate (SPI), WPH and RPI for 14 d on tibial bone mineral density (BMD) and bone mineral content (BMC) in intact and ovariectomized (OVX) rapidly growing female rats relative to animals fed casein (CAS). The effects of estrogenic status on responses to SPI were also explored. Tibial peripheral quantitative computerized tomography (pQCT) showed all three protein sources had positive effects on either BMD or BMC relative to CAS (P < 0.05), but SPI had greater effects in both intact and OVX female rats. SPI and E2 had positive effects on BMD and BMC in OVX rats (P < 0.05). However, trabecular BMD was lower in a SPI + E2 group compared to a CAS + E2 group. In OVX rats, SPI increased serum bone formation markers, and serum from SPI-fed rats stimulated osteoblastogenesis in ex vivo. SPI also suppressed the bone resorption marker RatLaps (P < 0.05). Both SPI and E2 increased alkaline phosphatase gene expression in bone, but only SPI decreased receptor activator of nuclear factor-kappaB ligand (RANKL) and estrogen receptor gene expression (P < 0.05). These data suggest beneficial bone effects of a soy diet in rapidly growing animals and the potential for early soy consumption to increase peak bone mass.

Effect of estrogenic compounds (estrogen or phytoestrogens) combined with exercise on bone and muscle mass in older individuals

Exercise has a beneficial effect on bone, possibly by stimulating estrogen receptor alpha. Because estrogen up-regulates this receptor, estrogen therapy combined with exercise training may be optimal for increasing bone mineral density. Studies combining estrogen therapy and exercise training in postmenopausal women show mixed results, but indicate that the combination of interventions may be more effective for increasing bone mass than either intervention alone. Plant-like estrogens (i.e phytoestrogens such as soy isoflavones) may act as weak estrogen agonists or antagonists, have small beneficial effects on bone, and may interact with exercise for increasing bone mineral density. Phytoestrogen derived from flaxseed (flax lignans) has not been evaluated as extensively as soy isoflavones and thus its effect on bone is difficult to determine. Estrogen or soy isoflavones given to postmenopausal women results in a small increase in lean tissue mass that may be mediated through estrogen receptor alpha on muscle or through decreased inflammation.

Phyto-oestrogens and bone health

As oestrogen deficiency is the main cause in the pathogenesis of osteoporosis hormone-replacement therapy remains the mainstay for prevention. However, prophylaxis by hormone-replacement therapy is limited. Phyto-oestrogens, which are weakly-oestrogenic compounds present in plants, deserve particular mention because emerging data support the suggestion that they may prevent bone loss associated with the menopause. In the past few years extensive research using animal models has provided convincing data to indicate a significant improvement in bone mass or other end points following feeding with soyabean. Moreover, observational studies relate the lower incidence of osteoporosis among women in the Eastern world to a diet rich in phyto-oestrogens. However, it is not valid to extrapolate to the Western situation. The varied clinical trials that have been published suggest that isoflavones reduce bone loss in women in the early period post menopause, but a definitive result requires more investigations of the effect of phyto-oestrogens on bone health that have substantial sample size and are of long duration. In addition, the clinical efficacy of soya foods in preventing osteopenia depends on their intestinal metabolism. Thus, phyto-oestrogens are a source for putative innovative dietary health intervention for post-menopausal women. However, more data are necessary, particularly in relation to their effect on the risk of fracture.

Long-term consumption of isoflavone-enriched foods does not affect bone mineral density, bone metabolism, or hormonal status in early postmenopausal women: a randomized, double-blind, placebo controlled study

BACKGROUND

Osteoporosis is a major health problem. It was hypothesized that isoflavone-containing products may be a potential alternative to hormone replacement therapy for preventing bone loss during the menopausal transition.

OBJECTIVE

The objective was to investigate whether the consumption of isoflavone-enriched foods for 1 y affects bone mineral density, bone metabolism, and hormonal status in early postmenopausal women.

DESIGN

This was a randomized, double-blind, placebo-controlled, parallel, multicenter trial. Two hundred thirty-seven healthy early postmenopausal women [mean (+/-SD) age of 53 +/- 3 y and time since last menses of 33 +/- 15 mo] consumed isoflavone-enriched foods providing a mean daily intake of 110 mg isoflavone aglycones or control products for 1 y while continuing their habitual diet and lifestyle. Outcome measures included bone mineral density of the lumbar spine and total body, markers of bone formation and bone resorption, hormones, isoflavones in plasma and urine, safety variables, and adverse events.

RESULTS

Consumption of isoflavone-enriched products did not alter bone mineral density of the lumbar spine and total body or markers of bone formation and bone resorption. Hormone concentrations did not differ between the isoflavone and control groups. Consumption of isoflavone-enriched products resulted in increased isoflavone concentrations in plasma and urine, whereas control products did not. This finding indicated good compliance with treatment. Subgroup analysis did not support an effect of equol phenotype on bone density. The intervention had no effect on a range of safety variables and reported adverse events.

CONCLUSION

Consumption of foods containing 110 mg/d of soy isoflavone aglycone equivalents for 1 y did not prevent postmenopausal bone loss and did not affect bone turnover in apparently healthy early postmenopausal white women. This trial was registered at clinicaltrials.gov as NCT00301353.

Cloning, expression, and characterization of two beta-glucosidases from isoflavone glycoside-hydrolyzing Bacillus subtilis natto

On the basis of the genomic sequence of Bacillus subtilis 168, two beta-glucosidase genes (bglH and yckE) from B. subtilis natto, which has been reported to have high isoflavone glucoside-hydrolyzing activity, were cloned and overexpressed in E. coli M15. The temperature for the optimal p-nitrophenyl-beta-D-glucoside hydrolyzing activity of both enzymes was between 37 and 45 degrees C, but BglH had a higher thermal stability than YckE. Both showed high activity at pH 6.0, but YckE was stable over a wider pH range than BglH. Recombinant BglH was inhibited 73%, 63%, and 43% by 1.0 mM Cd(2+), Fe(2+), or Cu(2+), respectively, while other divalent metal ions resulted in 0-23% inhibition, whereas YckE was inhibited by less than 20% by any of the divalent metal ions we tested. Among the substrate we used, BglH showed the highest affinity for genistin and YckE showed the highest affinity for p-nitrophenyl-beta-D-fructopyranoside. Both BglH and YckE hydrolyzed genistin and daidzin into their isoflavone aglycones, genistein and daidzein, but BglH was more efficient than YckE in isoflavone glucoside hydrolysis (20-fold higher kcat). Our results suggest that recombinant BglH may be applicable in the process of isoflavones deglycosylation.

WHI and WHIMS follow-up and human studies of soy isoflavones on cognition

Recent follow-up analyses of the previous findings from the Women's Health Initiative and the Women's Health Initiative Memory Study confirmed some health benefits of estrogen-containing hormone therapy (HT) in women within 10 years from the onset of menopause. However, the potential risks associated with long-term administration of HT, such as breast cancer and stroke, remain a concern for therapy recipients, underlying the need for an alternative treatment that is functionally equivalent but with a greater safety profile. Owing to their structural and functional resemblance to mammalian estrogens and lack of evident adverse effects, research interest in plant-derived phytoestrogens has increased in the past decade. While multiple health-promoting benefits of phytoestrogens have been proposed from basic science, the clinical data remain inconclusive. This review provides a comparative analysis of human studies on the effects of soy-based isoflavones on cognition. Of the eight studies published in 2000-2007, seven were conducted in postmenopausal women, four of which revealed a positive impact of isoflavones on cognitive function. Multiple factors could have contributed to the discrepant outcomes across studies, such as variation in the composition of phytoestrogen interventions and the heterogeneous characteristics of the study population. Thus, a well-designed clinical study based on a standardized stable formulation in a well-characterized study population is required in order to reach a clinical consensus. A formulation composed of select estrogen receptor beta-selective phytoestrogens with a rationally designed composition would avoid the potential antagonism present in a mixture and thus enhance therapeutic efficacy. In addition, inclusion of equol in a study formulation offers a potential synergistic effect from equol in both equol-producing and nonproducing individuals, as well as added benefits for men. With respect to the design of study population, a clinically consistent effect could potentially be achieved by stratifying populations based on genotype, age, hormonal history and even diets. Development of an effective phytoestrogen formulation would benefit both women and men to prevent or treat hormone-dependent conditions and, most of all, to improve neurological health and reduce the risk of Alzheimer's disease.

Effects of genistein on vertebral trabecular bone microstructure, bone mineral density, microcracks, osteocyte density, and bone strength in ovariectomized rats

Until now, the effects of phytoestrogen on bone in both women and ovarian hormone-deficient animal models of osteoporosis have remained uncertain. We have aimed here to investigate the effect of genistein (GEN) on trabecular bone quality in ovariectomized (OVX) rats. Forty 7-month-old female Sprague-Dawley rats were randomly divided into the following four groups: OVX, sham-operated (SHAM), treated with 17beta-estradiol (EST, 10 microg x kg(-1) x day(-1)), and GEN (5 mg x kg(-1) x day(-1)). At 15 weeks postoperation, the compressive test was performed on the L5 vertebral body; additionally, microcomputed tomography (micro-CT) assessment was performed to estimate the bone mineral density (BMD) and microstructure parameters of the L6 vertebral body. After fatigue damage testing, the L6 vertebral body was bulk-stained in 1% basic fuchsin and embedded in methylmethacrylate. The L4 vertebral body was embedded in methylmethacrylate for dynamic histomorphometry analysis without staining. Mounted bone slices were used to measure microcrack parameters, empty osteocyte lacuna density (e.Lc.Dn), and osteocyte density (Ot.N/T.Ar). Maximum loading (ML) and Ot.N/T.Ar were significantly lower in the OVX group than in the other groups. E.Lc.Dn was significantly decreased in GEN and EST groups compared to the OVX group. ML was significantly decreased in the GEN group compared to the SHAM group. Microcrack density, microcrack surface density, and microcrack length were significantly increased in the OVX group compared to the other groups. Mineral apposition rate was significantly decreased in the OVX group compared to the SHAM and GEN groups. Bone formation rate was significantly decreased in the OVX group compared to other groups. There were no significant differences with regard to mineralizing surface among the four groups. Volumetric BMD at organ was significantly lower in OVX, EST, and GEN groups than in the SHAM group. Bone mineral content was significantly lower in the OVX group than in the SHAM group. Bone volume fraction and trabecular number were significantly decreased in OVX, EST, and GEN groups compared to the SHAM group. Structure model index was significantly lower in the SHAM group than in OVX, EST, and GEN groups. Trabecular separation was significantly increased in the OVX group compared to SHAM and EST groups. There were no significant differences with regard to the trabecular thickness (Tb,Th) between SHAM, GEN, and OVX groups. Tb.Th was significantly lower in the EST group than in the SHAM group. Connectivity density (Conn.D) was significantly lower in the OVX group than in SHAM and GEN groups, and Conn. D was significantly lower in the EST group than in GEN. In conclusion, the present study demonstrates that GEN preserved the biomechanical quality of the trabecular bone regardless of the microstructure and BMD.

Soybean and soy isoflavone intake indicate a positive change in bone mineral density for 2 years in young Korean women

Many studies have shown that soybean and isoflavones have a favorable effect on bone mass for postmenopausal women, but few data are available on young Asian women. To investigate the effect of soybean and isoflavone intake on bone mineral density (BMD) and its change among young Korean women over 2 years, we conducted a longitudinal study for 34 women. The BMD was measured 3 times with 1-year intervals by dual x-ray absorptiometry at the lumbar spine and femur (neck, Ward's triangle [WT], and trochanter). Dietary intake was assessed up to 8 times by 24-hour recall with average 4-month interval. During the study period, BMD increased significantly for lumber spine and WT (2.5% and 5.2%). The average daily intake of soybeans and isoflavones was 39 g and 8 mg, respectively. Soybean intake and total isoflavone intake had positive correlation on femoral neck (FN) and WT. By longitudinal mixed-model regression analysis, BMD increased 0.26% per 1 mg of isoflavone intake per year in the FN and 0.31% for WT (P = .05 and .008). In conclusion, soybean and isoflavone intake have a positive effect on the change of BMD on the FN and WT among young Korean women. Because soybean and isoflavone intakes could be confounded by other nutrients, the positive effects of isoflavones on bone should be further investigated.

Tea drinking is associated with benefits on bone density in older women

BACKGROUND

Impaired hip structure assessed by dual-energy X-ray absorptiometry (DXA) areal bone mineral density (aBMD) is an independent predictor for osteoporotic hip fracture. Some studies suggest that tea intake may protect against bone loss.

OBJECTIVE

Using both cross-sectional and longitudinal study designs, we examined the relation of tea consumption with hip structure.

DESIGN

Randomly selected women (n = 1500) aged 70-85 y participated in a 5-y prospective trial to evaluate whether oral calcium supplements prevent osteoporotic fractures. aBMD at the hip was measured at years 1 and 5 with DXA. A cross-sectional analysis of 1027 of these women at 5 y assessed the relation of usual tea intake, measured by using a questionnaire, with aBMD. A prospective analysis of 164 women assessed the relation of tea intake at baseline, measured by using a 24-h dietary recall, with change in aBMD from years 1 to 5.

RESULTS

In the cross-sectional analysis, total hip aBMD was 2.8% greater in tea drinkers (x: 806; 95% CI: 797, 815 mg/cm(2)) than in non-tea drinkers (784; 764, 803 mg/cm(2)) (P < 0.05). In the prospective analysis over 4 y, tea drinkers lost an average of 1.6% of their total hip aBMD (-32; -45, -19 mg/cm(2)), but non-tea drinkers lost 4.0% (-13; -20, -5 mg/cm(2)) (P < 0.05). Adjustment for covariates did not influence the interpretation of results.

CONCLUSION

Tea drinking is associated with preservation of hip structure in elderly women. This finding provides further evidence of the beneficial effects of tea consumption on the skeleton.

Soy isoflavones avert chronic inflammation-induced bone loss and vascular disease

Background

Evidence from epidemiological, clinical and animal studies suggests a link may exist between low bone density and cardiovascular disease, with inflammatory mediators implicated in the pathophysiology of both conditions. This project examined whether supplementation with soy isoflavones (IF), shown to have anti-inflammatory properties, could prevent tissue expression of TNF-α and the development of skeletal pathology in an animal model of chronic inflammation.

Methods

Eight-week old, intact, female C57BL/6J mice were used. In Phase 1, a lipopolysaccharide (LPS)-dose response study (0, 0.133, 1.33 and 13.3 μg/d) was conducted to determine the LPS dose to use in Phase 2. The results indicated the 1.33 μg LPS/d dose produced the greatest decrease in lymphocytes and increase in neutrophils. Subsequently, in Phase 2, mice were randomly assigned to one of six groups (n = 12–13 per group): 0 or 1.33 μg LPS/d (placebo or LPS) in combination with 0, 126 or 504 mg aglycone equivalents of soy IF/kg diet (Control, Low or High dose IF). Mice were fed IF beginning 2 wks prior to the 30-d LPS study period.

Results

At the end of the study, no differences were detected in final body weights or uterine weights. In terms of trabecular bone microarchitecture, μCT analyses of the distal femur metaphysis indicated that LPS significantly decreased trabecular bone volume (BV/TV) and number (TbN), and increased separation (TbSp). Trabecular bone strength (i.e. total force) and stiffness were also compromised in response to LPS. The High IF dose provided protection against these detrimental effects on microarchitecture, but not biomechanical properties. No alterations in trabecular thickness (TbTh), or cortical bone parameters were observed in response to the LPS or IF. Immunohistomchemical staining showed that tumor necrosis factor (TNF)-α was up-regulated by LPS in the endothelium of small myocardial arteries and arterioles as well as the tibial metaphysis and down-regulated by IF.

Conclusion

These results suggest IF may attenuate the negative effects of chronic inflammation on bone and cardiovascular health. Additional research is warranted to examine the anti-inflammatory properties of the soy isoflavones and the mechanisms underlying their prevention of chronic inflammation-induced bone loss.

Effects of soy protein isolate and moderate exercise on bone turnover and bone mineral density in postmenopausal women

OBJECTIVE

The aim of this study was to assess the independent and additive effects of soy protein isolate (SPI) and moderate-intensity exercise (EX) on bone turnover and bone mineral density (BMD).

DESIGN

This study used a placebo-controlled, double-blind (soy), randomized 2 (SPI vs milk protein isolate [MPI]) x 2 (EX vs no EX) design. Sixty-one postmenopausal women were randomized, and 43 (62 +/- 5 y) completed the 9-month intervention (SPI, n = 10; MPI, n = 12; SPI + EX, n = 11; MPI + EX, n = 10). Serum C-terminal cross-linked telopeptides of type I collagen and serum bone-specific alkaline phosphatase were measured as markers of bone resorption and formation, respectively. BMD was measured by dual-energy x-ray absorptiometry.

RESULTS

At 9 months, SPI reduced serum C-terminal cross-linked telopeptides (-13.3% +/- 15.3% vs -1.5% +/- 21.0%; P = 0.02) and serum bone-specific alkaline phosphatase (-4.7% +/- 14.7% vs 6.5% +/- 17.7%; P = 0.02) compared to milk protein isolate. EX attenuated the reduction in serum C-terminal cross-linked telopeptides (-1.9% +/- 21.6% vs -12.4% +/- 15.3%; P = 0.04); however, no EX effects were apparent in serum bone-specific alkaline phosphatase at 9 months (2.8% +/- 16.1% vs -1.0% +/- 18.3%; P = 0.28). Neither SPI nor EX affected BMD at any site; however, change in BMD was related to change in fat mass (r = 0.40, P < 0.05).

CONCLUSIONS

In postmenopausal women (1) SPI reduces bone turnover with no impact on BMD over 9 months; (2) moderate-intensity endurance exercise training did not favorably alter bone turnover and had no impact on BMD; and (3) there were no additive effects of soy and exercise on bone turnover or BMD.

Soy isoflavones and fatty acids: effects on bone tissue postovariectomy in mice

Osteoporosis is a silent disease that leads to fragility fractures that can diminish quality of life and contribute to death. With no ideal drug treatment available to manage osteoporosis, soy isoflavones (ISO), and omega-3 long chain PUFAs in fish oil (FO) may be integral in a dietary strategy that prevents bone loss. The overall objective of this study was to determine if combining ISO with omega-3 long chain PUFAs resulted in greater protection against the loss of bone mineral and skeletal weakening in ovariectomized mice. Ovariectomized CD-1 mice were randomized to control diet or a diet containing ISO alone (250 mg of genistein + 250 mg of daidzein/kg diet), FO alone (7% menhaden oil), or ISO + FO. Each dietary intervention prevented the loss of bone mineral density (BMD) in the femur and preserved femur strength, but only FO, either alone or combined with ISO, resulted in a higher BMD of lumbar vertebra (LV). Most notably, FO + ISO resulted in a higher peak load of LV4, indicating that vertebra were more resistant to fracture. Whether a dietary strategy providing FO in combination with ISO attenuates bone loss in postmenopausal women awaits investigation.