Effects of combined low dose of the isoflavone derivative ipriflavone and estrogen replacement on bone mineral density and metabolism in postmenopausal women

Isoflavone intervention and its impact on bone mineral density in postmenopausal women: a systematic review and meta-analysis of randomized controlled trials

Due to estrogen deficiency, postmenopausal women may suffer from an imbalance in bone metabolism that leads to bone fractures. Isoflavones, a type of phytoestrogen, have been suggested to improve bone metabolism and increase bone mass. Therefore, isoflavones are increasingly recognized as a promising natural alternative to hormone replacement therapy for postmenopausal women who face a heightened risk of osteoporosis and are susceptible to bone fractures.

PURPOSE

This study aimed to evaluate the efficacy of isoflavone interventions on bone mineral density (BMD) in postmenopausal women by means of systematic review and meta-analysis.

METHODS

The electronic database searches were performed on PubMed, Embase, Scopus, and Cochrane Library databases, covering literature up to April 20, 2023. A random-effects model was used to obtain the main effect estimates, with a mean difference (MD) and its 95% confidence interval (CI) as the effect size summary. The risk of bias assessment was conducted using the Risk of Bias 2 (RoB2) tool.

RESULTS

A total of 63 randomized controlled trials comparing isoflavone interventions (n = 4,754) and placebo (n = 4,272) were included. The results indicated that isoflavone interventions significantly improved BMD at the lumbar spine (MD = 0.0175 g/cm2; 95% CI, 0.0088 to 0.0263, P < 0.0001), femoral neck (MD = 0.0172 g/cm2; 95% CI, 0.0046 to 0.0298, P = 0.0073), and distal radius (MD = 0.0138 g/cm2; 95% CI, 0.0077 to 0.0198, P < 0.0001) in postmenopausal women. Subgroup analysis showed that the isoflavone intervention was effective for improving BMD when the duration was ≥ 12 months and when the intervention contained genistein of at least 50 mg/day.

CONCLUSION

This systematic review and meta-analysis suggests that isoflavone interventions, especially those containing genistein of at least 50 mg/day, can effectively enhance BMD in postmenopausal women.

Clinical Evidence of the Benefits of Phytonutrients in Human Healthcare

Phytonutrients comprise many different chemicals, including carotenoids, indoles, glucosinolates, organosulfur compounds, phytosterols, polyphenols, and saponins. This review focuses on the human healthcare benefits of seven phytochemical families and highlights the significant potential contribution of phytonutrients in the prevention and management of pathologies and symptoms in the field of family health. The structure and function of these phytochemical families and their dietary sources are presented, along with an overview of their potential activities across different health and therapeutic targets. This evaluation has enabled complementary effects of the different families of phytonutrients in the same area of health to be recognized.

The effect of Cornus mas extract consumption on bone biomarkers and inflammation in postmenopausal women: A randomized clinical trial

The drastic decrease in estrogen levels in menopausal women can elevate bone resorption and osteoporosis. Cornus mas extract (C. mas extract) is a potential candidate for treating menopausal-related bone complications because of its phytoestrogen and anti-inflammatory contents. It was an interventional double-blind placebo-controlled randomized study. Eighty-four women aged 45-60 years old were randomly allocated to either the extract group receiving 3 capsules of 300 mg C. mas extract or the placebo group receiving 3 capsules of 300 mg of starch powder per day for 8 weeks. Then, venous blood was used to measure bone-specific alkaline phosphatase (BAP), osteocalcin (OC), C-terminal telopeptide (TC) as well as serum levels of PTH and hsCRP. Our results indicated the decrease in alkaline phosphatase, PTH, and as an inflammation biomarker, hsCRP, between two groups at the end of the study. No statistically significant difference was observed in telopeptide C, osteocalcin, and calcium between the placebo and extract groups after 8 weeks of intervention. In conclusion, the results indicate that the C. mas extract supplement of 900 mg/day may decrease levels of BAP, PTH, and hsCRP. However, this intervention had no beneficial effect on OC and TC in healthy postmenopausal women.

Effects of Dietary Phytoestrogens on Hormones throughout a Human Lifespan: A Review

Dietary phytoestrogens are bioactive compounds with estrogenic activity. With the growing popularity of plant-based diets, the intake of phytoestrogen-rich legumes (especially soy) and legume-derived foods has increased. Evidence from preclinical studies suggests these compounds may have an effect on hormones and health, although the results of human trials are unclear. The effects of dietary phytoestrogens depend on the exposure (phytoestrogen type, matrix, concentration, and bioavailability), ethnicity, hormone levels (related to age, sex, and physiological condition), and health status of the consumer. In this review, we have summarized the results of human studies on dietary phytoestrogens with the aim of assessing the possible hormone-dependent outcomes and health effects of their consumption throughout a lifespan, focusing on pregnancy, childhood, adulthood, and the premenopausal and postmenopausal stages. In pregnant women, an improvement of insulin metabolism has been reported in only one study. Sex hormone alterations have been found in the late stages of childhood, and goitrogenic effects in children with hypothyroidism. In premenopausal and postmenopausal women, the reported impacts on hormones are inconsistent, although beneficial goitrogenic effects and improved glycemic control and cardiovascular risk markers have been described in postmenopausal individuals. In adult men, different authors report goitrogenic effects and a reduction of insulin in non-alcoholic fatty liver patients. Further carefully designed studies are warranted to better elucidate the impact of phytoestrogen consumption on the endocrine system at different life stages.

Impact of calcium, vitamin D, vitamin K, oestrogen, isoflavone and exercise on bone mineral density for osteoporosis prevention in postmenopausal women: a network meta-analysis

The aim of this network meta-analysis is to compare bone mineral density (BMD) changes among different osteoporosis prevention interventions in postmenopausal women. We searched MEDLINE, Embase and Cochrane Library from inception to 24 February 2019. Included studies were randomised controlled trials (RCT) comparing the effects of different treatments on BMD in postmenopausal women. Studies were independently screened by six authors in three pairs. Data were extracted independently by two authors and synthesised using Bayesian random-effects network meta-analysis. The results were summarised as mean difference in BMD and surface under the cumulative ranking (SUCRA) of different interventions. A total of ninety RCT (10 777 participants) were included. Ca, vitamin D, vitamin K, oestrogen, exercise, Ca + vitamin D, vitamin D + vitamin K and vitamin D + oestrogen were associated with significantly beneficial effects relative to no treatment or placebo for lumbar spine (LS). For femoral neck (FN), Ca, exercise and vitamin D + oestrogen were associated with significantly beneficial intervention effects relative to no treatment. Ranking probabilities indicated that oestrogen + vitamin D is the best strategy in LS, with a SUCRA of 97·29 % (mean difference: +0·072 g/cm2 compared with no treatment, 95 % credible interval (CrI) 0·045, 0·100 g/cm2), and Ca + exercise is the best strategy in FN, with a SUCRA of 79·71 % (mean difference: +0·029 g/cm2 compared with placebo, 95 % CrI –0·00093, 0·060 g/cm2). In conclusion, in postmenopausal women, many interventions are valuable for improving BMD in LS and FN. Different intervention combinations can affect BMD at different sites diversely.

Comparative anti-osteoporotic properties of the leaves and roots of Marantodes pumilum var. alata in postmenopausal rat model

Background

Marantodes pumilum var. alata (MPva), popularly known as Kacip Fatimah, is widely used to maintain female reproductive health, facilitate post-partum recovery and manage symptoms of menopause and osteoporosis in South-East Asia. This study aims to further evaluate the osteoprotective potential of MPva in view of reports of its bone-protective properties in postmenopausal condition.

Methods

Thirty female Sprague-Dawley rats were sorted into 5 groups (n = 6) namely: MPv (leaf treatment); MPr (root treatment); ERT (estrogen treatment); OVXC (untreated ovariectomized control) and Sham (untreated sham-operated control). All rats (except the Sham) were ovariectomized to induce a state of estrogen deficiency that simulates menopause. Two weeks after ovariectomy, the rats were treated for 8 weeks with oral gavages of estrogen and plant extracts. The ERT group received 64.5 μg/kg/day dose of estrogen while MPv and MPr groups received 20 mg/kg/day dose of leaf and root extracts, respectively. At the end of treatment, left femora were excised from euthanized rats and investigated for changes in bone micro-architecture, mineral density, and biomechanical properties.

Results

Bone volume fraction, degree of anisotropy and structure-model-index of bone were significantly improved (p < 0.05) in the MPv group compared to OVXC. Breaking force and maximum stress of bone were also significantly higher (p < 0.05) in the MPv group compared to the OVXC.

Conclusion

Treatment with MPva leaf protected bone microarchitecture and density against osteoporosis-related changes in postmenopausal rats. Similar to estrogen, the protective effects of MPva leaf translated into better-enhanced bone mechanical properties compared to the root treatment.

Adiponectin receptors in energy homeostasis and obesity pathogenesis

Adipokines, that is factors secreted by adipose tissue, act through a network of autocrine, paracrine, and endocrine pathways to regulate several aspects of physiology, including glucose and lipid metabolism, neuroendocrine function, reproduction, and cardiovascular function. In particular, adiponectin, a 30-kDa protein, is associated with the regulation of insulin sensitivity, and its levels in serum are affected by altered metabolic homeostasis. Adiponectin effects are mediated by adiponectin receptors, which occur as two isoforms (AdipoR1 and AdipoR2). Transcriptional regulation of adiponectin is by the peroxisome proliferator-activated receptor-gamma (PPAR-γ). However, acting through AdipoR1 and AdipoR2, adiponectin enhances 5' adenosine monophosphate-activated protein kinase (AMPK) and the PPARα-mediated pathways in the liver and skeletal muscles. Adiponectin receptors mediate a wide spectrum of metabolic reactions, including gluconeogenesis and fatty-acid oxidation. Altogether, adiponectin deficiency and/or decreased adiponectin receptor-mediated activity possibly contribute to insulin resistance in metabolic syndromes, coronary heart disease, and liver disease.

Expression of CYP19 and CYP17 is associated with leg length, weight, and BMI

This study investigates associations between gene expressions of aromatase (CYP19), 17α hydroxylase (CYP17), and estrogen receptors α and β and anthropometric measurements in offspring of the Michigan fish eater cohort. Leg and trunk length, height, weight, and BMI and gene expression in peripheral blood cells were measured in offspring of the Michigan fish eater cohort. The parental generation was followed between 1973 and 1991, and maternal age, height, and weight data were collected. Female offspring were contacted in 2001/2002 and followed up in 2006/2007; offspring information included age, education, reproductive history, smoking, and exercise. Gene expression was standardized against 18S ribosomal ribonucleic acid (18SrRNA) and RNA polymerase II (RNA PolII) expressions. Mixed models assessed the statistical effect of gene expression on anthropometric outcomes, accounting for multiple offspring from one mother. Anthropometric measurements and gene expression were measured in 139 female offspring. The two length and the height measurements were correlated, as were BMI and weight. CYP19 expression was correlated with the other gene expressions and both estrogen receptor expressions were associated. For every 1 unit of ΔC(t) (18SrRNA - CYP19) or ΔC(t) (RNA PolII - CYP19), BMI was increased by 0.9 (P = 0.03) and 0.87 kg/m(2) (P = 0.04), respectively, and weight by 2.35 kg (P = 0.03) and 2.1 kg (P = 0.03), respectively. For every 1 unit of ΔC(t) (18SrRNA - CYP17), leg length was increased by 0.84 cm (P = 0.04). The results suggest that CYP17 gene expression may influence growth during childhood and adolescence while CYP19 may be associated with the concurrent measures of weight and BMI.

Soy isoflavone intake inhibits bone resorption and stimulates bone formation in menopausal women: meta-analysis of randomized controlled trials

OBJECTIVE

To clarify the effects of isoflavone intake on bone resorption and bone formation.

METHODS

We identified randomized controlled trials related to urinary deoxypyridinoline (Dpyr, a bone resorption marker) and serum bone-specific alkaline phosphatase (BAP, a bone formation marker) listed on MEDLINE (January 1966-April 2006), the Cochrane Controlled Trials Register, EMBASE (1985-January 2006), Science Citation Index and PUBMED (updated till April 2006).

RESULTS

Nine studies with a total of 432 subjects were selected for meta-analysis. The urinary Dpyr concentration in subjects who consumed isoflavones decreased significantly by -2.08 nmol/mmol (95% confidence interval (CI): -3.82 to -0.34 nmol/mmol) in comparison with that in subjects who did not consume isoflavones. Isoflavone intake vs placebo intake significantly increased serum BAP by 1.48 microg/l (95% CI: 0.22-2.75 mug/l). Decreases in the urinary Dpyr concentration with isoflavone intake of <90 mg/day and with treatment lasting less than 12 weeks were -2.34 nmol/mmol (95% CI: -4.46 to -0.22 nmol/mmol) and -2.03 nmol/mmol (95% CI: -3.20 to -0.85 nmol/mmol), respectively.

CONCLUSIONS

Isoflavone intervention significantly inhibits bone resorption and stimulates bone formation. These favorable effects occur even if <90 mg/day of isoflavones are consumed or the intervention lasts less than 12 weeks.

Urinary phytoestrogen concentrations in the U.S. population (1999-2000)

We report population-based urinary concentrations of phytoestrogens stratified by age, sex, and composite racial/ethnic variables. We measured the isoflavones - genistein, daidzein, equol, and O-desmethylangolensin (O-DMA) - and the lignans - enterolactone and enterodiol - in approximately 2500 urine samples from individuals aged 6 years and older who participated in the National Health and Nutrition Examination Survey (NHANES) in 1999 and 2000. We detected all phytoestrogens in over 70% of the samples analyzed; enterolactone was detected in the highest concentrations, and daidzein was detected with the highest frequency. The geometric means for each phytoestrogen were as follows: genistein, 22.3 microg/g; daidzein, 68.6 microg/g; equol, 7.65 microg/g; O-DMA, 3.95 microg/g; enterolactone, 217 microg/g; and enterodiol, 24.3 microg/g creatinine. The 95th percentiles for each phytoestrogen were as follows: genistein, 380 microg/g; daidzein, 944 microg/g; equol, 50.3 microg/g; O-DMA, 217 microg/g; enterolactone, 2240 microg/g; and enterodiol, 240 microg/g creatinine. Multivariate analyses showed statistically significant differences among many of the demographic subgroups. Adolescents had higher concentrations of genistein and equol than adults. Non-Hispanic whites had higher concentrations of enterodiol and equol than Mexican Americans or non-Hispanic blacks. Non-Hispanic whites also had higher concentrations of enterolactone and O-DMA than Mexican Americans. Mexican Americans had higher concentrations of genistein than non-Hispanic blacks; however, the opposite was found for O-DMA. Determination of phytoestrogen exposure in the US population will help us to better understand phytoestrogen consumption in the US and will assist us in elucidating the potential role of phytoestrogens in protecting against cancer and heart disease.

Design and baseline characteristics of a trial on health effects of soy protein with isoflavones in postmenopausal women

This study is a double-blind, randomized, placebo-controlled trial to assess the effects of high amounts of phytoestrogens on bone mineral density, cardiovascular diseases, cognitive function, performance in activities of daily life and well being. Participants were healthy postmenopausal women, aged 60-75 years. Between March and September 2000, 202 women were recruited, and, after completion of the baseline measurements, randomized to either soy protein, containing 99 mg naturally occurring isoflavones or placebo (milk protein) daily for 1 year. Analysis of the endpoints will be based on the difference between baseline measurements and measurements at the end of the intervention period with group allocation as independent variable.

Androgen receptor regulation by physiological concentrations of the isoflavonoid genistein in androgen-dependent LNCaP cells is mediated by estrogen receptor beta

OBJECTIVES

Isoflavonoids are discussed for use in chemoprevention and treatment of prostate cancer. We investigated the potential of genistein to modulate androgen receptor (AR) expression and transcriptional activity in the human androgen-sensitive prostate cancer cell line LNCaP.

MATERIALS AND METHODS

AR expression at mRNA and protein level was analyzed by real-time RT-PCR and immunoblot, respectively. In conditioned media PSA was measured by a microparticle enzyme immunoassay (MEIA). Binding of genistein to the AR was tested in a radioligand-binding assay and reporter gene co-transfection assay was employed to investigate AR activity.

RESULTS

Using concentrations of genistein that have been detected in sera of Asian men on regular soy-diet we found down-regulation of androgen receptor at both mRNA and protein level. The relative binding affinity to the AR was below 4% when compared to methyltrienologe (R1881) and there was no modulation of AR transcriptional activity by genistein concentrations up to 1 microM. We also demonstrated inhibition of PSA secretion after genistein treatment. As the anti-estrogen ICI 164 384 abolished the inhibitory effect of genistein and ER-beta, but not ER-alpha is expressed in LNCaP cells we postulate that the mechanism of genistein action on androgen receptor is mediated through ER-beta.

CONCLUSION

Using physiological concentrations of genistein we showed AR down-regulation by genistein in prostate cancer cells occurring via ER-beta. This likely results in a modified response to hormonal stimuli and may help to explain the low incidence of prostate cancer in the Asian population.

Soy protein isolate with isoflavones does not prevent estradiol-induced endometrial hyperplasia in postmenopausal women: a pilot trial

OBJECTIVE

To test the hypothesis that soy protein isolate (SPI) with isoflavones opposes the proliferative effects of exogenous estradiol (E2) on the endometrium after menopause.

DESIGN

Thirty-nine postmenopausal women were randomized to receive daily for 6 months either 0.5 mg E2 + placebo, 1.0 mg E2 + placebo, 0.5 mg E2 + 25 g SPI with 120 mg isoflavones, or 1.0 mg E2 + 25 g SPI with 120 mg isoflavones. Primary outcome measures were endometrial histology, ultrasound endometrial thickness, and Ki67 staining quantification, a marker of cellular proliferation. Secondary outcome measures were serum lipids and markers of bone resorption.

RESULTS

Endometrial hyperplasia, endometrial stromal and epithelial cellular proliferation, and sonographically measured endometrial thickness were similarly affected in all groups. SPI did not lessen the beneficial effects of E2 on lipids and markers of bone resorption.

CONCLUSION

In this pilot study, SPI with isoflavones did not protect the endometrium from E2-induced hyperplasia in postmenopausal women. If higher, long-term doses of isoflavone supplementation are found to be safe for postmenopausal women, then future studies combining E2 with isoflavones may be feasible as an alternative to traditional hormone replacement therapy.

Low-Dose Estrogen Therapy for Menopausal Women: A Review of Efficacy and Safety

BACKGROUND

Recent adverse events involving research of traditional estrogen therapy have led to interest in lower-than-standard doses of menopausal estrogen therapy.

METHOD

The Medline (1966-present) database was searched for randomized controlled trials (keywords: low-dose estrogen, minimum dose AND estrogen, menopause, and osteoporosis) regarding hot flashes, endometrial hyperplasia, vaginal bleeding, breast tenderness, and bone density. Studies are only a few years in duration.

RESULTS

The decrease in hot flashes with half-strength estrogens, range 60%-70%, is less than the 80%-90% reduction with standard dosing. Some low-dose preparations preserve lumbar and femoral bone density (although the degree of effect and quality of evidence vary among preparations). Bone density effects are dose dependent for conjugated equine estrogen (CEE), transdermal estradiol ethinyl (E(2)), norethindrone acetate (E(2)/NETA), oral E(2), and esterified estrogens. Bone preservation is likely to be less efficacious with low-dose estrogens than with traditional doses. Low-dose estrogen alone may not protect bone unless adequate calcium is given. Breast tenderness and skeletal effects are likely dose dependent. The longest endometrial safety data are 2-year data, reported for 5 microg/1 mg EE(2)/NETA and for 0.3 mg/day esterified estrogens. Some low-dose preparations have better vaginal bleeding profiles than do higher dose preparations. Breast tenderness is not totally averted with new lower-dose preparations. There are no fracture, breast cancer, or cardiovascular outcome data and a general lack of direct head-to-head comparisons involving low-dose preparations.

CONCLUSIONS

Serious adverse effects linked with traditional doses of estrogens may not be averted with lower-dose preparations, and low-dose preparations should not yet be emphasized as being safer than traditional (e.g., 0.625 mg/day CEE doses).

Investigating the role of natural phyto-oestrogens on bone health in postmenopausal women

Research on the bone effects of natural phyto-oestrogens after menopause is at a relatively early stage. Published studies are few, difficult to compare and often inconclusive, due in part to design weaknesses. Currently, many questions remain to be answered including to what extent a safe daily intake may prevent postmenopausal bone loss. These questions can only be addressed by conducting well-planned, randomised clinical trials that take into consideration present knowledge in the oestrogen, phyto-oestrogen and bone fields. This review is intended to provide hints for critical decision-making about the selection of subjects, type of intervention, suitable outcome measures and variables that need to be controlled.

Fitoestrogênios: posicionamento do Departamento de Endocrinologia Feminina da Sociedade Brasileira de Endocrinologia e Metabologia (SBEM)

Para avaliar a utilidade dos fitoestrogênios (FE) na terapia de reposição hormonal da menopausa (TRHM), o Departamento de Endocrinologia Feminina da SBEM reuniu um grupo de especialistas para fazer uma revisão bibliográfica e selecionar trabalhos nos quais a metodologia adotada demonstrasse rigor científico. Os FE têm ações estrogênicas e antiestrogênicas, predominantemente sobre os receptores de estrogênios (E) beta, com potência estrogênica muito inferior à do estradiol. O conteúdo de FE nas suas fontes vegetais é variável, dependendo da forma de cultivo, safra, armazenamento e industrialização. Também a conversão dos precursores em fitormônios ativos no organismo humano tem grande variabilidade individual. A maior parte das pesquisas com FE é realizada in vitro ou com animais de laboratório, nem sempre podendo ser extrapoladas para humanos. Com relação à síndrome do climatério, alguns estudos sugerem discreta melhora dos fogachos, sem modificação do ressecamento vaginal ou das alterações do humor. No metabolismo lipídico, alimentação rica em soja, mas não isoflavonas isoladamente, promove redução do colesterol total, do LDL-col e dos triglicerídeos, mas não elevam o HDL-col, como os E, e podem causar aumento da lipoproteína (a), que os E contribuem para diminuir. Embora alguns estudos de curta duração sugiram aumento da densidade mineral óssea com uso de isoflavonas, não há demonstração de redução de fraturas. Conclui-se que não há evidências convincentes que justifiquem o uso de FE ou alimentação rica em soja como alternativa para a TRHM.

Meta-analyses of therapies for postmenopausal osteoporosis. V. Meta-analysis of the efficacy of hormone replacement therapy in treating and preventing osteoporosis in postmenopausal women

OBJECTIVE

To review the effect of hormone replacement therapy (HRT) on bone density and fractures in postmenopausal women.

DATA SOURCE

We searched MEDLINE and EMBASE from 1966 to 1999, the Cochrane Controlled Register, citations of relevant articles, and proceedings of international meetings for eligible randomized controlled trials. We contacted osteoporosis investigators to identify additional studies, and primary authors for unpublished data.

STUDY SELECTION

We included 57 studies that randomized postmenopausal women to HRT or a control (placebo or calcium/vitamin D) and were of at least 1 yr in duration. Seven of these studies reported fractures.

DATA ABSTRACTION

For each study, three independent reviewers assessed the methodological quality and abstracted the data.

DATA SYNTHESIS

HRT showed a trend toward reduced incidence of vertebral fractures [relative risk (RR) 0.66, 95% confidence interval (CI) 0.41-1.07; 5 trials] and nonvertebral fractures (RR 0.87, 95% CI 0.71-1.08; 6 trials). HRT had a consistent effect on bone mineral density (BMD) at all sites. The difference between HRT and control in the percent change in bone density at 2 yr was 6.76 (5.83, 7.89; 21 trials) at the lumbar spine and 4.53 (3.68, 5.36; 14 trials) and 4.12 (3.45, 4.80; 9 trials) at the forearm and femoral neck, respectively.

CONCLUSIONS

HRT has a consistent, favorable and large effect on bone density at all sites. The data show a nonsignificant trend toward a reduced incidence in vertebral and nonvertebral fractures.

Hormone replacement therapy: the benefits in tailoring the regimen and dose

Despite the clear benefits of long-term hormone replacement therapy (HRT), the majority of patients tend to undergo short-term treatment. The cyclical bleedings induced by the sequential progestogen administration are often unacceptable namely in the elderly postmenopausal women. At the standard doses HRT preparations can also induce annoying hormone-related side effects, both in sequential and continuous combined regimens. Lower HRT schedules are reported to be highly effective in the relief of climacteric symptoms, inducing minimal endometrial stimulation with high rates of amenorrhea. Continuous administration of low doses of progestins is safe for endometrium protection and minimizes progestin-related side effects. Indeed, it has been demonstrated that low dose HRT can prevent the increase in bone turnover and the consequent bone loss in postmenopausal women. The choice of lower HRT dosages can also be useful for the number of potential disadvantages of standard HRT doses, mainly for long-term treatments. Low dose regimens should be considered as a starting dose to minimize the occurrence of side effects, improving compliance and, therefore, HRT effects on the prevention of long-term consequences of estrogen deprivation.

The therapeutic potential of phytoestrogens

Phytoestrogens, such as the soya isoflavones genistein and daidzein, are currently being extensively investigated through both molecular, preclinical and clinical studies to determine their potential health benefits. Phytoestrogens may protect against chronic diseases such as hormone-dependent cancer (e.g., breast and prostate cancer), cardiovascular disease and osteoporosis. Investigations of phytoestrogen metabolism and bioavailability are also of great relevance. Conversion by gut microflora of daizein to its isoflavan metabolite equol, which is a more potent oestrogen and anti-oxidant, occurs only in some individuals (about 35% of subjects tested are equol excretors). This has considerable implications for daidzein bioavailability and also for cancer risk. Oxidative damage has been implicated in the development of heart disease and cancer and soya phytoestrogens have been reported to decrease plasma F(2)-isoprostane concentrations (biomarker for in vivo lipid peroxidation) and increase low density lipoprotein oxidation resistance. This anti-oxidant action of phytoestrogens could potentially contribute to their therapeutic efficacy. The findings from the current ongoing studies are all likely to contribute to determining the potential use of phytoestrogens as therapeutic agents.

Prevention and treatment of osteoporosis in women with breast cancer

Women who have had breast cancer may be at higher risk for osteoporosis than other women. First, they are more likely to undergo early menopause, due to chemotherapy-induced ovarian failure or oopherectomy. In addition, chemotherapy may have a direct adverse effect on bone mineral density (BMD), and osteoclastic activity may increase from the breast cancer itself. While estrogen therapy is considered standard for the prevention and treatment of osteoporosis, use of estrogen in women with a history of breast cancer is usually contraindicated. The approach to osteoporosis in women with breast cancer is also affected by the use of tamoxifen in many, as this drug appears to have opposite effects on BMD in premenopausal and postmenopausal women. We have reviewed therapeutic alternatives for the prevention and treatment of osteoporosis, focusing on patients with a history of breast cancer. Alendronate and raloxifene are currently approved in the United States for the prevention of osteoporosis; alendronate, raloxifene, and calcitonin are approved for treatment. Alendronate has the greatest positive effect on BMD and reduces the incidence of vertebral and nonvertebral fractures. Raloxifene and calcitonin appear to reduce the incidence of vertebral fractures; their effects on the incidence of nonvertebral fractures are not yet proven. Although no published studies specifically address the use of these approved agents for osteoporosis in women with breast cancer, understanding their relative effects on BMD in postmenopausal women in general will facilitate therapy selection in this population. Postmenopausal women with a history of breast cancer should undergo bone mineral analysis. Normal results and absence of other risk factors ensure that calcium and vitamin D intake are adequate. If osteopenia or other risk factors are present, preventive therapy with alendronate or raloxifene should be considered. For osteoporosis, treatment with alendronate should be strongly considered. Raloxifene and calcitonin are alternatives when alendronate is contraindicated. Further studies are needed to evaluate the optimal timing of initial bone mineral analysis in premenopausal women after breast cancer diagnosis and to determine the value of preventive treatment in women scheduled to undergo chemotherapy.