The effect of soy protein isolate on bone metabolism

The Influences of Macronutrients on Bone Mineral Density, Bone Turnover Markers, and Fracture Risk in Elderly People: A Review of Human Studies

Osteoporosis is a health condition that involves weak bone mass and a deteriorated microstructure, which consequently lead to an increased risk of bone fractures with age. In elderly people, a fracture attributable to osteoporosis elevates mortality. The objective of this review was to examine the effects of macronutrients on bone mineral density (BMD), bone turnover markers (BTMs), and bone fracture in elderly people based on human studies. A systematic search was conducted in the PubMed®/MEDLINE® database. We included human studies published up to April 2023 that investigated the association between macronutrient intake and bone health outcomes. A total of 11 meta-analyses and 127 individual human studies were included after screening the records. Carbohydrate consumption seemed to have neutral effects on bone fracture in limited studies, but human studies on carbohydrates' effects on BMD or/and BTMs are needed. The human studies analyzed herein did not clearly show whether the intake of animal, vegetable, soy, or milk basic proteins has beneficial effects on bone health due to inconsistent results. Moreover, several individual human studies indicated an association between eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and osteocalcin. Further studies are required to draw a clear association between macronutrients and bone health in elderly people.

Effects of Soy Protein Containing of Isoflavones and Isoflavones Extract on Plasma Lipid Profile in Postmenopausal Women as a Potential Prevention Factor in Cardiovascular Diseases: Systematic Review and Meta-Analysis of Randomized Controlled Trials

The aim of the report was to evaluate the impact of soy protein containing isoflavones and soy isoflavones extract on lipid profile in postmenopausal women, as compared with placebo or protein of milk, casein or isolated soy protein with or without trace isoflavone content. We used the following databases: MEDLINE (PubMed), EMBASE and the Cochrane Library. Quantitative data synthesis was performed by applying a random-effects model. Subgroup analysis and meta-regression were performed to assess the modifiers of treatment response. In total, in the analysis studies, 2305 postmenopausal women took part. Changes in the lipid profile showed statistically significant decreases of total cholesterol by −0.12 (95% CI: −0.21, −0.03) mmol/L, −4.64 (95% CI: −8.12, −1.16) mg/dL, p = 0.01 and increased HDL-cholesterol by 0.03 (95% CI: 0.00, 0.06) mmol/L, 1.15 (95% CI: 0.00, 1.93) mg/dL, p = 0.05, as well as in LDL-cholesterol −0.05 (95% CI: −0.11, 0.01) mmol/L, −1.93 (95% CI: −4.25, 0.39) mg/dL, p = 0.08 and triacylglycerols −0.07 (95% CI: −0.14, 0.00) mmol/L, −6.123 (95% CI: −12.25, 0.00) mg/dL, p = 0.06. Our results suggests that soy and its isoflavones can be effective in correction changes in lipid metabolism in postmenopausal women and may favorably influence in preventing cardiovascular events.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS/AMERICAN COLLEGE OF ENDOCRINOLOGY CLINICAL PRACTICE GUIDELINES FOR THE DIAGNOSIS AND TREATMENT OF POSTMENOPAUSAL OSTEOPOROSIS-2020 UPDATE

Objective: The development of these guidelines is sponsored by the American Association of Clinical Endocrinologists (AACE) Board of Directors and American College of Endocrinology (ACE) Board of Trustees and adheres with published AACE protocols for the standardized production of clinical practice guidelines (CPGs). Methods: Recommendations are based on diligent reviews of the clinical evidence with transparent incorporation of subjective factors, according to established AACE/ACE guidelines for guidelines protocols. Results: The Executive Summary of this 2020 updated guideline contains 52 recommendations: 21 Grade A (40%), 24 Grade B (46%), 7 Grade C (14%), and no Grade D (0%). These detailed, evidence-based recommendations allow for nuance-based clinical decision-making that addresses multiple aspects of real-world care of patients. The evidence base presented in the subsequent Appendix provides relevant supporting information for the Executive Summary recommendations. This update contains 368 citations: 123 (33.5%) evidence level (EL) 1 (highest), 132 (36%) EL 2 (intermediate), 20 (5.5%) EL 3 (weak), and 93 (25%) EL 4 (lowest). New or updated topics in this CPG include: clarification of the diagnosis of osteoporosis, stratification of the patient according to high-risk and very-high-risk features, a new dual-action therapy option, and transitions from therapeutic options. Conclusion: This guideline is a practical tool for endocrinologists, physicians in general, regulatory bodies, health-related organizations, and interested laypersons regarding the diagnosis, evaluation, and treatment of post-menopausal osteoporosis. Abbreviations: 25(OH)D = 25-hydroxyvitamin D; AACE = American Association of Clinical Endocrinologists; ACE = American College of Endocrinology; AFF = atypical femoral fracture; ASBMR = American Society for Bone and Mineral Research; BEL = best evidence level; BMD = bone mineral density; BTM = bone turnover marker; CI = confidence interval; CPG = clinical practice guideline; CTX = C-terminal telopeptide type-I collagen; DXA = dual-energy X-ray absorptiometry; EL = evidence level; FDA = U.S. Food and Drug Administration; FRAX® = Fracture Risk Assessment Tool; GI = gastrointestinal; HORIZON = Health Outcomes and Reduced Incidence with Zoledronic acid ONce yearly Pivotal Fracture Trial (zoledronic acid and zoledronate are equivalent terms); ISCD = International Society for Clinical Densitometry; IU = international units; IV = intravenous; LSC = least significant change; NOF = National Osteoporosis Foundation; ONJ = osteonecrosis of the jaw; PINP = serum amino-terminal propeptide of type-I collagen; PTH = parathyroid hormone; R = recommendation; ROI = region of interest; RR = relative risk; SD = standard deviation; TBS = trabecular bone score; VFA = vertebral fracture assessment; WHO = World Health Organization.

The Effect of Dried Beancurd on Bone Mineral Density in Postmenopausal Chinese Women: A 2-Year Randomized Controlled Trial

Soy foods contain several components such as isoflavones, calcium and protein that potentially modulate bone turnover and increase bone mineral density (BMD) in postmenopausal women. The study is to evaluate the effect of dried beancurd supplementation on skeletal health in postmenopausal Chinese women. Three hundred postmenopausal women aged 50-65 years were assigned into two groups, receiving 100 g dried beancurd or rice cake a day for 2 years. BMD at the lumbar spine and right proximal femur were measured with a dual-energy X-ray absorptiometry. The bone turnover biomarkers of serum alkaline phosphatase (ALP), bone Gla protein (BGP) and urinary N-telopeptide cross-links of collagen normalized for creatinine (NTX/CRT) were also determined. Serum isoflavone concentration was analyzed by high performance liquid chromatography. The 2-year dried beancurd supplementation generated a significant increase in lumbar spine BMD. An obvious decrease was found in urinary NTX/CRT, and a significant increase was detected in serum isoflavone concentration. The dried beancurd supplementation had no effect on changes of right proximal femur BMD and concentrations of serum ALP and BGP. Daily supplementation of dried beancurd could increase BMD of lumbar spine, but does not slow bone loss at right proximal femur in postmenopausal Chinese women.

Soy isoflavones prevent bone resorption and loss, a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Osteoporosis is a common bone disease characterized by reduced bone mass resulting from continuous bone resorption.

METHODS

PubMed, Scopus, and Embase were searched to find published trials on the effect of soy isoflavones on bone mineral density (BMD) and bone turnover markers (bone-specific alkaline phosphatase, osteocalcin, osteoprotegerin, pyridinoline, deoxypyridinoline, C-telopeptide, and N-telopeptide). Random-effects inverse-variance model was used to calculate the pooled effects.

RESULTS

A total of 5313 articles were found, screened, and assessed for eligibility, and finally 52 trials were included in the meta-analysis. Consumption of soy isoflavones caused significant improvement in BMD of lumbar spine (mean difference (MD) = 0.76%; 95% CI: 0.09, 1.42%; p = 0.03), hip (MD = 0.22%; 95% CI: 0.02, 0.42%; p = 0.04), and femoral neck (MD = 2.27%; 95% CI: 1.22, 3.31%; p < 0.001). Subgroup analysis showed that in all 3 sites, the improvement was significant in normal weight subjects and interventions longer than a year, although trial location and dosage were also factors influencing isoflavones' impact on BMD. Among markers of bone turnover, osteoprotegerin (MD = 5.79; 95% CI: 3.08, 8.51 pg/ml; p < 0.001), pyridinoline (MD = -5.13; 95% CI: -7.76, -2.50 nmol/mmol; p < 0.001), and C-telopeptides (MD = -0.08; 95% CI: -0.16, -0.00 ng/ml; p = 0.04) were favorably affected by isoflavones while osteocalcin and bone alkaline phosphatase did not change. Subgroup analysis of bone markers showed that in overweight/obese individuals and dosages <90 mg/day, isoflavones are more effective.

CONCLUSIONS

Soy isoflavones prevent osteoporosis-related bone loss in any weight status or treatment duration. They increase BMD in normal weight subjects and diminish bone resorption in overweight/obese individuals. Although bone resorption may be decelerated over short-term isoflavone consumption, periods longer than a year are probably needed to affect BMD. Isoflavones also appear benefits on bone in any dose or subjects' ethnicity.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND AMERICAN COLLEGE OF ENDOCRINOLOGY CLINICAL PRACTICE GUIDELINES FOR THE DIAGNOSIS AND TREATMENT OF POSTMENOPAUSAL OSTEOPOROSIS - 2016

ABBREVIATIONS

AACE = American Association of Clinical Endocrinologists AFF = atypical femur fracture ASBMR = American Society for Bone and Mineral Research BEL = best evidence level BMD = bone mineral density BTM = bone turnover marker CBC = complete blood count CI = confidence interval DXA = dual-energy X-ray absorptiometry EL = evidence level FDA = U.S. Food and Drug Administration FLEX = Fracture Intervention Trial (FIT) Long-term Extension FRAX_® = Fracture Risk Assessment Tool GFR = glomerular filtration rate GI = gastrointestinal HORIZON = Health Outcomes and Reduced Incidence with Zoledronic Acid Once Yearly IOF = International Osteoporosis Foundation ISCD = International Society for Clinical Densitometry IU = international units IV = intravenous LSC = least significant change NBHA = National Bone Health Alliance NOF = National Osteoporosis Foundation 25(OH)D = 25-hydroxy vitamin D ONJ = osteonecrosis of the jaw PINP = serum carboxy-terminal propeptide of type I collagen PTH = parathyroid hormone R = recommendation RANK = receptor activator of nuclear factor kappa-B RANKL = receptor activator of nuclear factor kappa-B ligand RCT = randomized controlled trial RR = relative risk S-CTX = serum C-terminal telopeptide SQ = subcutaneous VFA = vertebral fracture assessment WHO = World Health Organization.

Effect of S-equol and Soy Isoflavones on Heart and Brain

BACKGROUND

Observational studies in Asia show that dietary intake of soy isoflavones had a significant inverse association with coronary heart disease (CHD). A recent randomized controlled trial (RCT) of soy isoflavones on atherosclerosis in the US, however, failed to show their benefit. The discrepancy may be due to the much lower prevalence of S-equol producers in Westerners: Only 20-30% of Westerners produce S-equol in contrast to 50-70% in Asians. S-equol is a metabolite of dietary soy isoflavone daidzein by gut microbiome and possesses the most antiatherogenic properties among all isoflavones. Several short-duration RCTs documented that soy isoflavones improves arterial stiffness. Accumulating evidence shows that both atherosclerosis and arterial stiffness are positively associated with cognitive decline/dementia. Therefore, potentially, soy isoflavones, especially S-equol, are protective against cognitive decline/dementia.

METHODS/RESULTS

This narrative review of clinical and epidemiological studies provides an overview of the health benefits of soy isoflavones and introduces S-equol. Second, we review recent evidence on the association of soy isoflavones and S-equol with CHD, atherosclerosis, and arterial stiffness as well as the association of atherosclerosis and arterial stiffness with cognitive decline/ dementia. Third, we highlight recent studies that report the association of soy isoflavones and S-equol with cognitive decline/dementia. Lastly, we discuss the future directions of clinical and epidemiological research on the relationship of S-equol and CHD and dementia.

CONCLUSIONS

Evidence from observational studies and short-term RCTs suggests that S-equol is anti-atherogenic and improves arterial stiffness and may prevent CHD and cognitive impairment/ dementia. Well-designed long-term (≥ 2years) RCTs should be pursued.

A systematic review and meta-analysis of the effects of isoflavone formulations against estrogen-deficient bone resorption in peri- and postmenopausal women

Background: Age-related estrogen deficiency leads to accelerated bone resorption. There is evidence that, through selective estrogen receptor modulation, isoflavones may exert beneficial effects against estrogen-deficient bone loss. Isoflavone aglycones show higher bioavailability than their glycosidic counterparts and thus may have greater potency.Objective: To summarize evidence, we executed a systematic review and meta-analysis examining isoflavone therapies and bone mineral density (BMD) loss in peri- and postmenopausal women.Design: We systematically searched EMBASE and PubMed for randomized controlled trials (RCTs) evaluating isoflavone therapies for treating BMD loss at the lumbar spine and femoral neck in estrogen-deficient women. Separate meta-analyses were carried out with the use of random-effects models for the lumbar spine and femoral neck for all studies providing isoflavones as aglycones.Results: Twenty-six RCTs (n = 2652) were included in the meta-analysis. At the lumbar spine, isoflavone treatment was associated with a significantly (P < 0.00001) higher weighted mean difference (WMD) of BMD change of 0.01 (95% CI: 0.01, 0.02) than the control. For the femoral neck (18 RCTs, n = 1604), isoflavone treatment showed a significantly (P < 0.01) higher WMD of BMD change of 0.01 (95% CI: 0.00, 0.02) compared with the control. When isolating studies that provide isoflavone aglycones in their treatment arm, the average effect was further significantly increased at the spine (5 RCTs, n = 682) to 0.04 (P < 0.00001; 95% CI: 0.02, 0.05) and femoral neck (4 RCTs, n = 524) to 0.03 (P < 0.05; 95% CI: 0.00, 0.06) compared with the control. This protective effect against bone loss disappeared when only studies with formulations comprising predominantly isoflavone glycosides were included.Conclusions: Isoflavone treatments exert a moderately beneficial effect against estrogen-deficient bone loss in women. The effect appears dependent on whether isoflavone treatments are in aglycone form; we conclude that beneficial effects against bone loss may be enhanced for isoflavone aglycones.

Soybean peptide fractions inhibit human blood, breast and prostate cancer cell proliferation

In this study, we examined in vitro the bio-activity of peptide fractions obtained from soybeans against blood (CCRF-CEM and Kasumi-3), breast (MCF-7), and prostate (PC-3) cancer cell proliferation. Gastro-intestinal treated peptide fractions (<5, 5-10 and 10-50 kDa) prepared from seed proteins of two high oleic acid soybean lines-N98-4445A, S03-543CR and one high protein line-R95-1705, were tested for anticancer activity against human breast, blood and prostate cancer cell lines. Anti-proliferative cell titer assay was conducted to assess the inhibitory effects of the peptide fractions, while trypan blue dye exclusion assay was used to determine the dose response of most effective fractions. Results showed that the peptide fractions inhibited the cancer cell lines up to 68.0% and the minimum concentration to get 50% inhibitory activity (IC50) ranged between 608 and 678 µg/mL. This multiple site in vitro cancer inhibition by GI friendly peptides could have the potential use as food ingredients or nutritional supplements in an alternative cancer therapy.

The impact of equol-producing status in modifying the effect of soya isoflavones on risk factors for CHD: a systematic review of randomised controlled trials

Recent studies suggest that the ability to produce equol, a metabolite of the soya isoflavone daidzein, is beneficial to coronary health. Equol, generated by bacterial action on isoflavones in the human gut, is biologically more potent than dietary sources of isoflavones. Not all humans are equol producers. We investigated whether equol-producing status is favourably associated with risk factors for CHD following an intervention by dietary soya isoflavones. We systematically reviewed randomised controlled trials (RCT) that evaluated the effect of soya isoflavones on risk factors for CHD and that reported equol-producing status. We searched PubMed, EMBASE, Ovid Medline and the Cochrane Central Register for Controlled Trials published up to April 2015 and hand-searched bibliographies to identify the RCT. Characteristics of participants and outcomes measurements were extracted and qualitatively analysed. From a total of 1671 studies, we identified forty-two articles that satisfied our search criteria. The effects of equol on risk factors for CHD were mainly based on secondary analyses in these studies, thus with inadequate statistical power. Although fourteen out of the forty-two studies found that equol production after a soya isoflavone intervention significantly improved a range of risk factors including cholesterol and other lipids, inflammation and blood pressure variables, these results need further verification by sufficiently powered studies. The other twenty-eight studies primarily reported null results. RCT of equol, which has recently become available as a dietary supplement, on CHD and its risk factors are awaited.

Alveolar bone loss: mechanisms, potential therapeutic targets, and interventions

This article reviews recent research into mechanisms underlying bone resorption and highlights avenues of investigation that may generate new therapies to combat alveolar bone loss in periodontitis. Several proteins, signaling pathways, stem cells, and dietary supplements are discussed as they relate to periodontal bone loss and regeneration. RGS12 is a crucial protein that mediates osteoclastogenesis and bone destruction, and a potential therapeutic target. RGS12 likely regulates osteoclast differentiation through regulating calcium influx to control the calcium oscillation-NFATc1 pathway. A working model for RGS10 and RGS12 in the regulation of Ca(2+) oscillations during osteoclast differentiation is proposed. Initiation of inflammation depends on host cell-microbe interactions, including the p38 mitogen-activated protein kinase (MAPK) signaling pathway. Oral p38 inhibitors reduced lipopolysaccharide (LPS)-induced bone destruction in a rat periodontitis model but showed unsatisfactory safety profiles. The p38 substrate MK2 is a more specific therapeutic target with potentially superior tolerability. Furthermore, MKP-1 shows anti-inflammatory activity, reducing inflammatory cytokine biosynthesis and bone resorption. Multipotent skeletal stem cell (SSC) populations exist within the bone marrow and periosteum of long bones. These bone-marrow-derived SSCs and periosteum-derived SSCs have shown therapeutic potential in several applications, including bone and periodontal regeneration. The existence of craniofacial bone-specific SSCs is suggested based on existing studies. The effects of calcium, vitamin D, and soy isoflavone supplementation on alveolar and skeletal bone loss in post-menopausal women were investigated. Supplementation resulted in stabilization of forearm bone mass density and a reduced rate of alveolar bone loss over 1 yr, compared with placebo. Periodontal attachment levels were also well-maintained and alveolar bone loss suppressed during 24 wk of supplementation.

Soy Isoflavones and Osteoporotic Bone Loss: A Review with an Emphasis on Modulation of Bone Remodeling

Osteoporosis is an age-related disorder that affects both women and men, although estrogen deficiency induced by menopause accelerates bone loss in older women. As the demographic shifts to a more aged population, a growing number of men and women will be afflicted with osteoporosis. Since the current drug therapies available have multiple side effects, including increased risk of developing certain types of cancer or complications, a search for potential nonpharmacologic alternative therapies for osteoporosis is of prime interest. Soy isoflavones (SI) have demonstrated potential bone-specific effects in a number of studies. This article provides a systematic review of studies on osteoporotic bone loss in relation to SI intake from diet or supplements to comprehensively explain how SI affect the modulation of bone remodeling. Evidence from epidemiologic studies supports that dietary SI attenuate menopause-induced osteoporotic bone loss by decreasing bone resorption and stimulating bone formation. Other studies have also illustrated that bone site-specific trophic and synergistic effects combined with exercise intervention might contribute to improve the bioavailability of SI or strengthen the bone-specific effects. To date, however, the effects of dietary SI on osteoporotic bone loss remain inconclusive, and study results vary from study to study. The current review will discuss the potential factors that result in the conflicting outcomes of these studies, including dosages, intervention materials, study duration, race, and genetic differences. Further well-designed studies are needed to fully understand the underlying mechanism and evaluate the effects of SI on osteoporosis in humans.

Effects of different doses of soy isoflavones on bone tissue of ovariectomized rats

AIM

Studies report that hormone replacement prevents osteoporosis, but there are doubts whether isoflavones are really efficient in this process. The aim of this study was to evaluate the effects of different doses of soy isoflavones on bone tissue of ovariectomized rats.

METHODS

Forty female rats at the age of 6 months were ovariectomized and, after 3 months, the animals were divided into four groups: GI - Control (treated with drug vehicle); GII - treated with isoflavones (80 mg/kg per day); GIII - treated with isoflavones (200 mg/kg per day) and GIV - treated with isoflavones (350 mg/kg per day). Soy isoflavones were administered by gavage for 90 consecutive days. After treatment, the rats were euthanized and their distal femurs were removed for histological routine, histochemistry and biochemical study. Histological sections were stained with hematoxylin-eosin or subjected to picrosirius red and alcian blue methods. Shafts of femurs were submitted to biochemical assay and tibias were subjected to biophysical and biomechanical tests.

RESULTS

In distal femurs, the trabecular bone volume was higher in the groups treated with isoflavones, being higher in GIV, while the cortical bone width and the presence of mature type I collagen fibers were higher in GII. At the trabecular bone region, the percentage of total glycosaminoglycans (GAGs) was higher in GII and the percentage of only sulfated GAGs was higher in GIII, while the higher content of chondroitin sulfate in shafts of femurs was seen in GIV. Biophysical and biomechanical tests in tibias did not differ among the groups.

CONCLUSION

Our data indicate that soy isoflavones improve bone quality in femurs of rats by increasing histomorphometric parameters, the content of GAGs and mature type I collagen fibers. These positive effects are dose-dependent and it was different in cortical and trabecular bone.

Effects of the amount and source of dietary protein on bone status in rats

This study examined the effects of the dietary amount and source of protein on bone status in rats. 140 male Wistar rats aged 8 weeks were randomly allocated to 4 groups (n = 35) fed normal-protein (NP, 10% richness) or high-protein (HP, 45% richness) diets based on whey protein (WP) or soy protein (SP) sources for 12 weeks. Plasma urea was 46% higher for the HP compared to the NP diet (p < 0.001). Urinary calcium was 65% higher for the HP compared to the NP and 60% higher for the WP compared to the SP diets (all, p < 0.001). Urinary pH was 8% more acidic in the HP compared to the NP diet (p < 0.001) and 4% in the WP compared to the SP diet (p < 0.01). The plasma osteocalcin concentration was 19% higher for the NP compared to the HP (p < 0.05) and 25% for the SP compared to the WP diets (p < 0.01). Femur ash, metaphyseal and diaphyseal cross-sectional, trabecular and cortical areas were 3% higher in the HP compared to the NP diet (all, p < 0.05). Femur diaphyseal periosteal and endocortical perimeters were also 3% higher in the HP compared to the NP diet (both, p < 0.01). Groups fed the SP diet showed 2% higher femur ash percentage, 7% higher calcium content (both, p < 0.001), and 3% higher diaphyseal cortical area and thickness (both, p < 0.05) than those fed the WP diet. Some interactions were found, such as the greater effects of the SP diet on decreasing the higher plasma urea concentration promoted by the intake of the HP diet (p < 0.001). Under adequate Ca intake, HP diets could better maintain bone properties than NP diets, even with increasing some acidity markers, which could be reduced by the intake of SP sources.

Phytoestrogens for menopausal bone loss and climacteric symptoms

Women have always looked for non-hormonal options to alleviate menopausal vasomotor symptoms and prevent menopausal bone loss. The use of complementary and alternative medicine for these purposes has particularly increased after the publication of the Women's Health Initiative's results suggesting that there might be more risks than benefits with hormone replacement. Phytoestrogens are plant-derived estrogens that, although less potent than estradiol, bind to the estrogen receptor and can function as estrogen agonists or antagonists. Soy isoflavones extracted from soy are the phytoestrogens most commonly used by menopausal women. Because typical Western diets are low in phytoestrogens and taking into account the general difficulty in changing dietary habits, most clinical trials in Western women have used isoflavone-fortified foods or isoflavone tablets. Although some women might experience a reduction in the frequency or severity of hot flashes, most studies point towards the lack of effectiveness of isoflavones derived from soy or red clover, even in large doses, in the prevention of hot flashes and menopausal bone loss. This article is part of a Special Issue entitled 'Phytoestrogens'.

Phytoestrogens in the prevention of postmenopausal bone loss

Postmenopausal osteoporosis is a condition associated with low bone mass resulting from the increased bone resorption that occurs following a decline in estrogen levels. Phytoestrogens are plant-derived compounds that have affinity to the estrogen receptor and are able to act as either estrogen agonists or antagonists. Because of their structural similarity to 17-beta-estradiol, they have been studied extensively for their role in the prevention of postmenopausal bone loss. An extensive number of studies employing different types of isoflavone preparations (including soy foods, soy-enriched foods, and soy isoflavone tablets) have been conducted in a wide range of populations, including Western and Asian women. Although there is considerable variability in study design and duration, study population, type of soy isoflavone employed in the intervention, and study outcomes, the evidence points to a lack of a protective role of soy isoflavones in the prevention of postmenopausal bone loss.

Isoflavones for hypercholesterolaemia in adults

BACKGROUND

Hypercholesterolaemia is a significant risk factor for cardiovascular diseases. Isoflavones may be effective in improving hypercholesterolaemia.

OBJECTIVES

To assess the effects of isoflavones for hypercholesterolaemia.

SEARCH METHODS

We searched the following databases: The Cochrane Library (Issue 9, 2012), MEDLINE, EMBASE, Chinese BioMedical Database and China National Knowledge Infrastructure (all to September 2012).

SELECTION CRITERIA

We considered randomized controlled clinical trials in hypercholesterolaemic participants comparing isoflavones versus placebo, or soy isolated protein added with isoflavones versus soy isolated protein alone.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted relevant population and intervention characteristics. We resolved any disagreements through discussion, or if required by a third party. We assessed the risk of bias of trials against key criteria: random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective reporting and other sources of bias.

MAIN RESULTS

We included five randomized trials (208 participants, 104 in the intervention group and 104 in the control group). Interventions ranged from three to six months. Four trials reported results in non-Asian populations published in English. One trial reported results in Chinese people published in Chinese. Overall, the risk of bias of included trials was high or unclear. There were no outcome data on death from any cause, morbidity, complications, health-related quality of life and costs. Two trials reported adverse effects, including gastrointestinal discomfort (bloating and constipation) and an increased number of hot flushes. None of the trials found serious adverse events. There was a slight significant effect on triglycerides in favour of isoflavones when compared with placebo (mean difference (MD) -0.46 mmol/L (95% confidence interval (CI) -0.84 to -0.09; P = 0.02; 52 participants; 2 trials). No statistically significant effects on total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol were shown in favour of isoflavones.

AUTHORS' CONCLUSIONS

We found no evidence for effects of isoflavones on patient-important outcomes or lowering of cholesterol levels in people with hypercholesterolaemia. Our findings have to be interpreted with caution due to high or unclear risk of bias in several risk of bias domains, and low number of participants in trials.

Isoformononetin, a methoxydaidzein present in medicinal plants, reverses bone loss in osteopenic rats and exerts bone anabolic action by preventing osteoblast apoptosis

PURPOSE

Daidzein (Daid) has been implicated in bone health for its estrogen-'like' effects but low bioavailability, unfavorable metabolism and uterine estrogenicity impede its clinical potential. This study was aimed at assessing isoformononetin (Isoformo), a naturally occurring methoxydaidzein, for bone anabolic effect by overcoming the pitfalls associated with Daid.

METHODS

Sprague-Dawley ovariectomized (OVx) rats with established osteopenia were administered Isoformo, 17β-oestradiol (E2) or human parathyroid hormone. Efficacy was evaluated by bone microarchitecture using microcomputed tomography and determination of new bone formation by fluorescent labeling of bone. Osteoblast apoptosis was measured by co-labeling of bone sections with Runx-2 and TUNEL. Biochemical markers of bone metabolism were measured by ELISA. Plasma and bone marrow levels of Isoformo and Daid were determined by LC-MS-MS. Rat bone marrow stromal cells were harvested to study osteoblastic differentiation by Isoformo and Daid. New born rat pups were injected with Isoformo and Daid to study the effect of the compounds on the expression of osteogenic genes in the calvaria by real time PCR.

RESULTS

In osteopenic rats, Isoformo treatment restored trabecular microarchitecture, increased new bone formation, increased the serum osteogenic marker (procollagen N-terminal propeptide), decreased resorptive marker (urinary C-terminal teleopeptide of type I collagen) and diminished osteoblast apoptosis in bone. At the most effective osteogenic dose of Isoformo, plasma and bone marrow levels were comprised of ~90% Isoformo and the rest, Daid. Isoformo at the concentration reaching the bone marrow achieved out of its most effective oral dosing induced stromal cell mineralization and osteogenic gene expression in the calvaria of neonatal rats. Isoformo exhibited uterine safety.

CONCLUSIONS

Our study demonstrates that Isoformo reverses established osteopenia in adult OVx rats likely via its pro-survival effect on osteoblasts. Given its bone anabolic and anti-catabolic effects accompanied with safety at uterine level we propose its potential in the management of postmenopausal osteoporosis.

Positive skeletal effects of cladrin, a naturally occurring dimethoxydaidzein, in osteopenic rats that were maintained after treatment discontinuation

Effects of cladrin treatment and withdrawal in osteopenic rats were studied. Cladrin improved trabecular microarchitecture, increased lumbar vertebral compressive strength, augmented coupled remodeling, and increased bone osteogenic genes. A significant skeletal gain was maintained 4 weeks after cladrin withdrawal. Findings suggest that cladrin has significant positive skeletal effects.

INTRODUCTION

We showed that a standardized extract of Butea monosperma preserved trabecular bone mass in ovariectomized (OVx) rats. Cladrin, the most abundant bioactive compound of the extract, promoted peak bone mass achievement in growing rats by stimulating osteoblast function. Here, we studied the effects of cladrin treatment and withdrawal on the osteopenic bones.

METHODS

Adult female Sprague-Dawley rats were OVx and left untreated for 12 weeks to allow for significant estrogen deficiency-induced bone loss, at which point cladrin (1 and 10 mg/kg/day) was administered orally for another 12 weeks. Half of the rats were killed at the end of the treatments and the other half at 4 weeks after treatment withdrawal. Sham-operated rats and OVx rats treated with PTH or 17β-estradiol (E2) served as various controls. Efficacy was evaluated by bone microarchitecture using microcomputed tomographic analysis and fluorescent labeling of bone. qPCR and western blotting measured mRNA and protein levels in bone and uterus. Specific ELISA was used for measuring levels of serum PINP and urinary CTx.

RESULTS

In osteopenic rats, cladrin treatment dose dependently improved trabecular microarchitecture, increased lumbar vertebral compression strength, bone formation rate (BFR), cortical thickness (Cs.Th), serum PINP levels, and expression of osteogenic genes in bones; and reduced expression of bone osteoclastogenic genes and urinary CTx levels. Cladrin had no uterine estrogenicity. Cladrin at 10 mg/kg maintained acquired skeletal gains 4 weeks after withdrawal.

CONCLUSION

Cladrin had positive skeletal effects in osteopenic rats that were maintained after treatment withdrawal.

Dietary isoflavone intake, urinary isoflavone level, and their relationship with metabolic syndrome diagnostic components in korean postmenopausal women

Recent studies have suggested that natural agents such as isoflavones, resveratrol, and anthocyanin have beneficial effects on metabolic syndrome-related disorders. The objective of this study was to evaluate dietary isoflavone intake, urinary isoflavone level, and their relationship with the risk of metabolic syndrome (MetS) among Korean postmenopausal women. The subjects included 46 MetS and 60 controls. The MetS risk score was determined by adding the number of risk factors such as waist circumference, blood pressure (BP) and levels of triglyceride (TG), HDL-cholesterol, and glucose. Dietary isoflavone intake was not significantly different between the MetS and control groups; however, the urinary daidzein level was significantly higher in the MetS subjects compared to that of the controls. Subjects with high TG had higher urinary daidzein and isoflavone (daidzein + genistein) levels than those without such abnormalities. But, the MetS risk score showed no significant correlation with urinary daidzein, genistein, and isoflavone excretions.

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.

Bone mineral density in postmenopausal Chinese women treated with calcium fortification in soymilk and cow's milk

Eighteen months of daily consumption of milk containing 250 mg calcium prevented bone mineral density (BMD) loss at the hip and the femoral neck in postmenopausal Chinese women aged 45 to 65.

INTRODUCTION

Estrogen-related bone loss in postmenopausal women can be prevented by the consumption of milk with high doses of calcium and soymilk with high doses of isoflavones. However, high doses of calcium and isoflavones may not be necessary to attain a beneficial effect of milk and soymilk on BMD. We hypothesized that BMD will increase in postmenopausal Chinese women who consume daily 250 mg calcium in milk or soymilk. Milk prevented bone loss at the hip and the femoral neck in postmenopausal Chinese women.

METHODS

A total of 141 eligible Chinese women without osteoporosis, aged 45-65, and postmenopausal for more than 2 years were randomized into groups receiving for 18 months (A) milk with 250 mg calcium daily, (B) soymilk with 250 mg calcium daily, or (C) neither milk nor soymilk. Dual-energy X-ray absorptiometry measured the BMD of the spine and hip at 0, 6, 12, and 18 months.

RESULTS

The BMD in the hip (2.52%) and the femoral neck (2.82%) of the women consuming milk was significantly higher (hip, P = 0.01; femoral neck, P < 0.0000001). The women in the control group experienced a reduction in BMD at all sites; the reduction in BMD was only significant at the hip during 12 months (P = 0.008) and at the femoral neck during 18 months (P = 0.005).

CONCLUSIONS

Daily consumption of milk containing 250 mg calcium over 18 months prevents BMD loss at the hip and the femoral neck in postmenopausal Chinese women.

Effects of a safflower tea supplement on antioxidative status and bone markers in postmenopausal women

We conducted this study to examine the effects of safflower seed granular tea containing physiologically active polyphenols on antioxidative activities and bone metabolism. Forty postmenopausal women ages 49 to 64-years were recruited from Daegu and Gyeongbuk and were randomly assigned to either a safflower tea supplement (Saf-tea) group (n = 27) or a placebo group (n = 13). The Saf-tea group received 20 g of safflower seed granule tea per day containing a 13% ethanol extract of defatted safflower seeds, whereas the placebo group received a similar type of tea that lacked the ethanol extract. No significant changes in nutrient intake for either the placebo or Saf-tea groups were observed before or after the study period, except vitamin A intake increased after 6 months in the Saf-tea group. Dietary phytoestrogen intakes were similar in the Saf-tea group (60.3 mg) and placebo group (52.5 mg). Significant increases in plasma genistein and enterolactone were observed in the Saf-tea group. After 6 months of supplementation, serum levels of antioxidant vitamins such as α-tocopherol and ascorbic acid increased significantly, and TBARS levels decreased in the Saf-tea group compared to the placebo group. Serum osteocalcin levels were reduced (P < 0.05) in the Saf-tea group after 6 months, whereas serum osteocalcin did not change in the placebo group. Urinary deoxypyridinoline/creatinine excretion was not different between the two groups at baseline, and did not change in either group after 6 months. Bone mineral density decreased significantly in the placebo group (P < 0.01) but not in the supplemented group. It was concluded that polyphenols (72 mg/day), including serotonin derivatives, in the Saf-tea had both antioxidant and potential bone protecting effects in postmenopausal women without liver toxicity.

Addition of fructooligosaccharides and dried plum to soy-based diets reverses bone loss in the ovariectomized rat

Dietary bioactive components that play a role in improving skeletal health have received considerable attention in complementary and alternative medicine practices as a result of their increased efficacy to combat chronic diseases. The objectives of this study were to evaluate the additive or synergistic effects of dried plum and fructooligosaccharides (FOS) and to determine whether dried plum and FOS or their combination in a soy protein-based diet can restore bone mass in ovarian hormone deficient rats. For this purpose, 72 3-month-old female Sprague-Dawley rats were divided into six groups (n = 12) and either ovariectomized (Ovx, five groups) or sham-operated (sham, one group). The rats were maintained on a semipurified standard diet for 45 days after surgery to establish bone loss. Thereafter, the rats were placed on one of the following dietary treatments for 60 days: casein-based diet (Sham and Ovx), soy-based diet (Ovx + soy) or soy-based diet with dried plum (Ovx + soy + plum), FOS (Ovx + soy + FOS) and combination of dried plum and FOS (Ovx + soy + plum + FOS). Soy protein in combination with the test compounds significantly improved whole-body bone mineral density (BMD). All test compounds in combination with soy protein significantly increased femoral BMD but the combination of soy protein, dried plum and FOS had the most pronounced effect in increasing lumbar BMD. Similarly, all of the test compounds increased ultimate load, indicating improved biomechanical properties. The positive effects of these test compounds on bone may be due to their ability to modulate bone resorption and formation, as shown by suppressed urinary deoxypyridinoline excretion and enhanced alkaline phosphatase activity.

Effects of soy protein containing isoflavones on women's lipid profile: a meta-analysis

This study evaluated the effects of soy protein containing isoflavones on the lipid profile of women. A meta-analysis including 13 eligible randomized controlled trials was carried out. The literature was systematically searched for randomized controlled trials on the effects of soy protein containing isoflavones on the serum lipids of adult women. The main searched databases were PubMed, Cochrane Library, MedLine, Lilacs and Web of Science. Randomized controlled trials were included if they met the following criteria: published from 1966 to 2005, the study population consisted of women only, had either a crossover or a parallel design and the amounts of soy protein and isoflavones consumed were provided. Weighted mean effect sizes were calculated for net changes in serum lipid concentrations using fixed-effects and random-effects models. Prespecified subgroup analyses were performed to explore the influence of covariates on net lipid change. Soy protein with isoflavones was associated with a significant decrease in total serum cholesterol (by 5.34mg/dL, or 2.4%, p=0.03). No significant associations were detected for low density lipoprotein-cholesterol, triacylglycerols and high density lipoprotein-cholesterol. Amounts of soy protein greater than 40g decreased total cholesterol by 6.56mg/dL (95% CI: -12.35 to -0.39, p=0.04). Soy protein supplementation had small statistically significant effects on the total serum cholesterol of women, but they were clinically insignificant. Furthermore, there were no statistically significant effects on serum low density lipoprotein-cholesterol, high density lipoprotein-cholesterol or triglycerides.

The interaction between dietary protein and bone health

The role of dietary protein in bone health has been controversial. On the one hand, a plentiful supply of dietary amino acids has been considered important to support bone remodeling while on the other hand there have been concerns that the dietary acid load associated with protein consumption promotes hypercalciuria and loss of bone calcium stores. This article reviews the effect of dietary protein on bone mass and bone density, and the effect on markers of bone resorption and formation and also on fracture risk, looking at both cross-sectional and longitudinal studies and examining both meat and vegetable protein including soy and milk basic protein. The results are not entirely consistent and suggest that the interaction between dietary protein and other components in a mixed diet, such as calcium intake and vegetables and fruit to neutralize acid, are important and may determine whether high-protein diets are beneficial to bone health. Overall the results suggest that dietary protein has a modest beneficial effect on bone markers and bone density. This effect has yet to be consistently linked to reduced fracture risk, probably because of the role of other etiological factors such as the risk of falls. There is not enough evidence currently to suggest that animal protein is superior or inferior to vegetable protein, or that milk or soy protein, respectively, is more favorable than other protein sources.

Acute effects of 17 β-estradiol and genistein on insulin sensitivity and spatial memory in aged ovariectomized female rats

Aging is characterized by decline in metabolic function and insulin resistance, and both seem to be in the basis of neurodegenerative diseases and cognitive dysfunction. Estrogens prevent age-related changes, and phytoestrogens influence learning and memory. Our hypothesis was that estradiol and genistein, using rapid-action mechanisms, are able to modify insulin sensitivity, process of learning, and spatial memory. Young and aged ovariectomized rats received acute treatment with estradiol or genistein. Aged animals were more insulin-resistant than young. In each age, estradiol and genistein-treated animals were less insulin-resistant than the others, except in the case of young animals treated with high doses of genistein. In aged rats, no differences between groups were found in spatial memory test, showing a poor performance in the water maze task. However, young females treated with estradiol or high doses of genistein performed well in spatial memory task like the control group. Only rats treated with high doses of genistein showed an optimal spatial memory similar to the control group. Conversely, acute treatment with high doses of phytoestrogens improved spatial memory consolidation only in young rats, supporting the critical period hypothesis for the beneficial effects of estrogens on memory. Therefore, genistein treatment seems to be suitable treatment in aged rats in order to prevent insulin resistance but not memory decline associated with aging. Acute genistein treatment is not effective to restore insulin resistance associated to the early loss of ovarian function, although it can be useful to improve memory deficits in this condition.

Phytoestrogens and bone health

PURPOSE OF REVIEW

The present review summarizes the results of epidemiological studies and clinical trials assessing the skeletal effects of soy foods and soy dietary supplements.

RECENT FINDINGS

Results from epidemiological studies suggest a beneficial skeletal effect in Asian women consuming typical Asian diets, but clinical trials are conflictive regarding the effects of phytoestrogens on bone mineral density and bone turnover markers in premenopausal and postmenopausal women. Much of the controversy lies in differences in study design, reporting of results, participants' age and menopausal status, and type and dose of phytoestrogen used.

SUMMARY

Although western women will likely continue to incorporate soy foods and soy supplements into their diets with the increased availability of these products, published data are inconsistent and do not support soy's protective effect against bone loss. This conflicting evidence should be taken into account when considering using isoflavones in the prevention of bone loss and consequently fractures.

Effects of soy isoflavone supplements on bone turnover markers in menopausal women: systematic review and meta-analysis of randomized controlled trials

INTRODUCTION

Effects of soy isoflavone supplements on bone turnover markers remain unclear. This up-to-date systematic review and meta-analysis of randomized controlled trials (RCTs) was performed primarily to more completely and precisely clarify the effects on urinary deoxypyridinoline (DPD) and serum bone alkaline phosphatase (BAP) and secondarily to evaluate the effects on other bone turnover markers, compared with placebo in menopausal women.

METHODS

PubMed, CENTRAL, ICHUSHI, and CNKI were searched in June 2009 for relevant studies of RCTs. Data on study design, participants, interventions, and outcomes were extracted and methodological quality of each included trial was assessed.

RESULTS

From 3740 identified relevant articles, 10 (887 participants), 10 (1210 participants), and 8 (380 participants) RCTs were selected for meta-analysis of effects on DPD, BAP, and serum osteocalcin (OC), respectively, using Review Manager 5.0.22. Daily ingestion of an average 56 mg soy isoflavones (aglycone equivalents) for 10 weeks to 12 months significantly decreased DPD by 14.1% (95% CI: -26.8% to -1.5%; P=0.03) compared to baseline (heterogeneity: P<0.00001; I(2)=93%; random effects model). The overall effect of soy isoflavones on DPD compared with placebo was a significant decrease of -18.0% (95% CI: -28.4% to -7.7%, P=0.0007; heterogeneity: P=0.0001; I(2)=73%; random effects model). Subgroup analyses and meta-regressions revealed that isoflavone dose and intervention duration did not significantly relate to the variable effects on DPD. Daily supplementation of about 84 mg and 73 mg of soy isoflavones for up to 12 months insignificantly increased BAP by 8.0% (95% CI: -4.2% to 20.2%, P=0.20; heterogeneity: P<0.00001; I(2)=98%) and OC by 10.3% (95% CI: -3.1% to 23.7%, P=0.13; heterogeneity: P=0.002; I(2)=69%) compared with placebo (random effects model), respectively.

CONCLUSIONS

Soy isoflavone supplements moderately decreased the bone resorption marker DPD, but did not affect bone formation markers BAP and OC in menopausal women. The effects varied between studies, and further studies are needed to address factors relating to the observed effects of soy isoflavones on DPD and to verify effects on other bone turnover markers.

Equol, via dietary sources or intestinal production, may ameliorate estrogen deficiency-induced bone loss

Equol, a product of intestinal metabolism of daidzein, is chemically similar to estrogen (without the lipophilic moiety) and has higher estrogen receptor-beta binding affinity than its parent precursor. In 2004, a long-term, randomized controlled trial that characterized postmenopausal women by their equol-producing status showed stronger advantages to lumbar spine bone mineral density (BMD) in equol- compared with nonequol-producers. Subsequent studies have related equol status of participants to change in bone turnover markers or BMD in response to soy isoflavone interventions. To our knowledge, we are the first to prescreen women for equol-producing status prior to initiating an intervention. In menopausal Western women, equol status did not affect the modest, but significant, reduction in bone resorption achieved with a soy isoflavone intervention.

Management of osteoporosis in postmenopausal women: 2010 position statement of The North American Menopause Society

OBJECTIVE

To update the evidence-based position statement published by The North American Menopause Society (NAMS) in 2006 regarding the management of osteoporosis in postmenopausal women.

METHODS

NAMS followed the general principles established for evidence-based guidelines to create this updated document. A panel of clinicians and researchers expert in the field of metabolic bone diseases and/or women's health was enlisted to review the 2006 NAMS position statement, compile supporting statements, and reach consensus on recommendations. The panel's recommendations were reviewed and approved by the NAMS Board of Trustees.

RESULTS

Osteoporosis, which is especially prevalent among older postmenopausal women, increases the risk of fractures. Hip and spine fractures are associated with particularly high morbidity and mortality in this population. Given the health implications of osteoporotic fractures, the primary goal of osteoporosis therapy is to prevent fractures, which is accomplished by slowing or stopping bone loss, maintaining bone strength, and minimizing or eliminating factors that may contribute to fractures. The evaluation of postmenopausal women for osteoporosis risk requires a medical history, physical examination, and diagnostic tests. Major risk factors for postmenopausal osteoporosis (as defined by bone mineral density) include advanced age, genetics, lifestyle factors (such as low calcium and vitamin D intake, smoking), thinness, and menopause status. The most common risk factors for osteoporotic fracture are advanced age, low bone mineral density, and previous fracture as an adult. Management focuses first on nonpharmacologic measures, such as a balanced diet, adequate calcium and vitamin D intake, adequate exercise, smoking cessation, avoidance of excessive alcohol intake, and fall prevention. If pharmacologic therapy is indicated, government-approved options are bisphosphonates, selective estrogen-receptor modulators, parathyroid hormone, estrogens, and calcitonin.

CONCLUSIONS

Management strategies for postmenopausal women involve identifying those at risk for fracture, followed by instituting measures that focus on reducing modifiable risk factors through dietary and lifestyle changes and, if indicated, pharmacologic therapy.

Phytoestrogens and post reproductive health

The use of phytoestrogens for various perceived health benefits is widespread. Despite 20 years of research the evidence for any significant health benefits remains inconclusive. Pre clinical trials have demonstrated both non-genomic and genomic actions of constituents of phytoestrogens including selective, but weak, binding to estrogen receptors, with a preference for ER B over ER A. Evidence of clinically relevant biological effects from observational studies and randomized trials has, in general, been lacking. Despite many trials there remains little evidence that phytoestrogens, whether dietary or supplemented, significantly relieve menopausal vasomotor symptoms or cognition. Several potential mechanisms for a positive effect on bone and cardiovascular health have been demonstrated however no fracture prevention data or cardiovascular end point benefit has yet been demonstrated. In vitro effects of phytoestrogens on breast cells have been both stimulatory and inhibitory however net effects appear neutral with observational studies finding no change in breast cancer risk. No effect has been seen on endometrial or other cancers and side effect profiles have, in general, been mild.

Neonatal administration of isoflavones attenuates deterioration of bone tissue in female but not male mice

Neonatal exposure to soy isoflavones at levels similar to that of infants fed soy protein formula resulted in higher bone mineral density (BMD), improved bone structure, and greater bone strength at young adulthood in female CD-1 mice (1,2). Our objective in this study was to determine whether these improvements in bone quantity and quality at 4 mo of age provide protection against the deterioration of bone tissue that occurs after a decline in endogenous sex steroid production. Male and female CD-1 mice (n = 8-18 pups per group per gender) were randomized to subcutaneous injections of corn oil [negative control (CON)], daidzein + genistein (DG; 7 mg x kg body weight(-1) x d(-1)), or diethylstilbestrol [(DES); positive control, 2 mg x kg body weight(-1) x d(-1)) from postnatal d 1 to 5. At 4 mo of age, mice were ovariectomized (females) or orchidectomized (males) and studied to 8 mo of age. Females treated with DG had higher (P < 0.05) femur and vertebral bone mineral content (BMC) and BMD compared with the CON group. Microstructural analysis revealed that improvements in BMD induced by DG and DES were coupled with greater trabecular thickness at the lumbar spine. Importantly, structural improvements resulted in bones that were more resistant to fracture, as the peak load of the femoral midpoint and lumbar vertebra 2 were higher (P < 0.05) with DG compared with CON. Effects in males were not significant. In conclusion, short-term neonatal exposure to isoflavones provides protection against the deterioration of bone tissue in females but not males after a decline of endogenous sex steroid production.

Design and baseline characteristics of the soy phytoestrogens as replacement estrogen (SPARE) study--a clinical trial of the effects of soy isoflavones in menopausal women

Following the results of the Women's Health Initiative, many women now decline estrogen replacement at the time of menopause and seek natural remedies that would treat menopausal symptoms and prevent bone loss and other long-term consequences of estrogen deficiency, but without adverse effects on the breast, uterus, and cardiovascular system. The results of most soy studies in this population have had limitations because of poor design, small sample size, or short duration. This report describes the study rationale, design, and procedures of the Soy Phytoestrogens As Replacement Estrogen (SPARE) study, which was designed to determine the efficacy of soy isoflavones in preventing spinal bone loss and menopausal symptoms in the initial years of menopause. Women ages 45 to 60 without osteoporosis and within 5 years from menopause were randomized to receive soy isoflavones 200mg daily or placebo for 2 years. Participants have yearly measurements of spine and hip bone density, urinary phytoestrogens, and serum lipids, thyroid stimulating hormone, and estradiol. Menopausal symptoms, mood changes, depression, and quality of life are assessed annually. The SPARE study recruited 283 women, 66.1% were Hispanic white. With a large cohort, long duration, and large isoflavone dose, this trial will provide important, relevant, and currently unavailable information on the benefits of purified soy isoflavones in the prevention of bone loss and menopausal symptoms in the first 5 years of menopause. Given the high proportion of Hispanics participating in the study, the results of this trial will also be applicable to this minority group.

The soy isoflavones for reducing bone loss (SIRBL) study: a 3-y randomized controlled trial in postmenopausal women

BACKGROUND

Our previous study indicated that soy protein with isoflavones lessened lumbar spine bone loss in midlife women.

OBJECTIVE

We examined the efficacy of isoflavones (extracted from soy protein) on bone mineral density (BMD) in nonosteoporotic postmenopausal women. We hypothesized that isoflavone tablets would spare BMD, with biological (age, body weight, serum 25-hydroxyvitamin D) and lifestyle (physical activity, dietary intake) factors modulating BMD loss.

DESIGN

Our double-blind, randomized controlled trial (36 mo) included healthy postmenopausal women (aged 45.8-65.0 y) with intent-to-treat (n = 224) and compliant (n = 208) analyses. Treatment groups consisted of a placebo control group and 2 soy isoflavone groups (80 compared with 120 mg/d); women received 500 mg calcium and 600 IU vitamin D(3). Outcomes included lumbar spine, total proximal femur, femoral neck, and whole-body BMD.

RESULTS

Analysis of variance for intent-to-treat and compliant (> or =80%) models, respectively, showed no treatment effect for spine (P = 0.46, P = 0.21), femur (P = 0.86, P = 0.46), neck (P = 0.17, P = 0.14), or whole-body (P = 0.86, P = 0.78) BMD. From baseline to 36 mo, BMD declined regardless of treatment. In intent-to-treat and compliant models, respectively, BMD decreases were as follows: spine (-2.08%, -1.99%), femur (-1.43%, -1.38%), neck (-2.56%, -2.51%), and whole body (-1.66%, -1.62%). Regression analysis (compliant model) indicated that age, whole-body fat mass, and bone resorption were common predictors of BMD change. After adjustment for these factors, 120 mg (compared with placebo) was protective (P = 0.024) for neck BMD. We observed no treatment effect on adverse events, endometrial thickness, or bone markers.

CONCLUSION

Our results do not show a bone-sparing effect of extracted soy isoflavones, except for a modest effect at the femoral neck. This trial was registered at clinicaltrials.gov as NCT00043745.

Dietary phyto-oestrogens: molecular mechanisms, bioavailability and importance to menopausal health

Following the high-profile studies on hormone replacement therapy which provided little evidence in support of the drug therapy improving future health, there remains a growing demand for dietary solutions for maintaining health and preventing disease as women age. Although interest in the relative importance of phyto-oestrogens to human health has increased dramatically over the last decade, the effective dose for health benefits and hypothetical issues on safety remain to be resolved. Plausible mechanisms and epidemiological data are available to support the concept that phyto-oestrogen-rich diets exert physiological effects, but optimal doses and sources of these compounds have still not been elucidated for specific health benefits. In addition, much of the current mechanistic data are difficult to interpret as the experiments have incorporated levels of phyto-oestrogens that may not be achievable in vivo and have to date only used aglycones and glycosides of the pure compounds rather than examining the biological effects of gut and liver metabolites. The present review will concentrate on the isoflavone subclass of phyto-oestrogens, as, to date, these compounds have received most attention from both a commercial and research perspective.

Antiresorptive effects of phytoestrogen supplements compared with estradiol or risedronate in postmenopausal women using (41)Ca methodology

INTRODUCTION

Reduction of ovarian estrogen secretion at menopause increases net bone resorption and leads to bone loss. Isoflavones have been reported to protect bone from estrogen deficiency, but their modest effects on bone resorption have been difficult to measure with traditional analytical methods.

METHODS

In this randomized-order, crossover, blinded trial in 11 healthy postmenopausal women, we compared four commercial sources of isoflavones from soy cotyledon, soy germ, kudzu, and red clover and a positive control of oral 1 mg estradiol combined with 2.5 mg medroxyprogesterone or 5 mg/d oral risedronate (Actonel) for their antiresorptive effects on bone using novel (41)Ca methodology.

RESULTS

Risedronate and estrogen plus progesterone decreased net bone resorption measured by urinary (41)Ca by 22 and 24%, respectively (P < 0.0001). Despite serum isoflavone profiles indicating bioavailability of the phytoestrogens, only soy isoflavones from the cotyledon and germ significantly decreased net bone resorption by 9% (P = 0.0002) and 5% (P = 0.03), respectively. Calcium absorption and biochemical markers of bone turnover were not influenced by interventions.

CONCLUSIONS

Dietary supplements containing genistein-like isoflavones demonstrated a significant but modest ability to suppress net bone resorption in postmenopausal women at the doses supplied in this study over a 50-d intervention period.

Side effects of phytoestrogens: a meta-analysis of randomized trials

BACKGROUND

Phytoestrogens are widely used by postmenopausal women for the treatment of the climacteric syndrome. The risk of adverse effects of this treatment, however, is unknown.

METHODS

Using a fixed-effects model, we performed a meta-analysis of side effects comparing phytoestrogen treatment with placebo or no treatment in randomized controlled trials.

RESULTS

We identified 174 randomized controlled trials. Side effects were reported in 92/174 randomized controlled trials with 9629 participants. The overall incidence of side effects in the phytoestrogen and control groups was 2019/5502 (36.7%) and 1824/4806 (38.0%), respectively (P=.2; incidence rate ratio [IRR] 1.01; 95% confidence interval [CI], 0.95-1.08). Comparing various side effect categories, we found significantly higher rates of gastrointestinal side effects among phytoestrogen users (P=.003; IRR 1.28; 95% CI, 1.08-1.50). Gynecological (IRR 0.94; 95% CI, 0.74-1.20), musculoskeletal (IRR 1.20; 95% CI, 0.94-1.53), neurological (IRR 0.91; 95% CI, 0.70-1.19), and unspecific side effects (IRR 0.95; 95% CI, 0.88-1.03) were not significantly different between groups. Within side effect categories, we found no significantly higher rates of side effects in women using phytoestrogens. Specifically, the rates of hormone-related side effects such as endometrial hyperplasia, endometrial cancer, and breast cancer were not significantly different between groups.

CONCLUSIONS

Based on the available evidence, phytoestrogen supplements have a safe side-effect profile with moderately elevated rates of gastrointestinal side effects. Rates of vaginal bleeding, endometrial hyperplasia, endometrial cancer, and breast cancer were not significantly increased among phytoestrogen users in the investigated studies.

Soy proteins and isoflavones affect bone mineral density in older women: a randomized controlled trial

BACKGROUND

Soy foods contain several components (isoflavones and amino acids) that potentially affect bone. Few long-term, large clinical trials of soy as a means of improving bone mineral density (BMD) in late postmenopausal women have been conducted.

OBJECTIVE

Our goal was to evaluate the long-term effect of dietary soy protein and/or soy isoflavone consumption on skeletal health in late postmenopausal women.

DESIGN

We conducted a randomized, double-blind, placebo-controlled clinical trial in 131 healthy ambulatory women aged >60 y. Ninety-seven women completed the trial. After a 1-mo baseline period, subjects were randomly assigned into 1 of 4 intervention groups: soy protein (18 g) + isoflavone tablets (105 mg isoflavone aglycone equivalents), soy protein + placebo tablets, control protein + isoflavone tablets, and control protein + placebo tablets.

RESULTS

Consumption of protein powder and isoflavone pills did not differ between groups, and compliance with the study powder and pills was 80-90%. No significant differences in BMD were observed between groups from baseline to 1 y after the intervention or in BMD change between equol and non-equol producers. However, there were significant negative correlations between total dietary protein (per kg) and markers of bone turnover (P < 0.05).

CONCLUSIONS

Because soy protein and isoflavones (either alone or together) did not affect BMD, they should not be considered as effective interventions for preserving skeletal health in older women. The negative correlation between dietary protein and bone turnover suggests that increasing protein intakes may suppress skeletal turnover. This trial was registered at ClinicalTrials.gov as NCT00668447.

Effect of long-term intervention of soy isoflavones on bone mineral density in women: a meta-analysis of randomized controlled trials

INTRODUCTION

A number of RCTs have examined the role of soy isoflavones on bone mineral density (BMD) and yielded inconsistent results. This meta-analyses aims to assess the overall effect of soy isoflavones on BMD.

METHODS

We searched for all articles published in English from January 1990 to March, 2008. We included RCTs of soy isoflavone supplementation in women of at least one year duration. The main outcomes were BMD changes from baseline at the lumbar spine, total hip and femoral neck.

RESULTS

We identified 10 eligible RCTs containing 896 women. A mean dose of 87 mg soy isoflavones for at least one year did not significantly affect BMD changes. The mean (95%CI) differences in BMD changes (in mg/cm(2)/year) were 4.1 (-1.6, 9.8) (0.4%) at the lumbar spine, -1.5 (-7.2, 4.3) (-0.3%) at the femoral neck under random-effects model, and 2.5 (-0.5, 5.4) (0.2%) at the total hip by fix-effects model, respectively. Similar results were obtained in subgroup analyses by isoflavone sources (soy protein vs. isoflavone extract), ethnic differences (Asian vs. Western). Larger dose (>or=80 mg/d), but not lower dose (<80 mg/d), of isoflavone intervention tended to have a weak beneficial effect on spine BMD (p=0.08 vs. p=0.94).

CONCLUSIONS

Soy isoflavone supplementation is unlikely to have significant favorable on BMD at the lumbar spine and hip in women.