Effect of chronic treatment with ipriflavone in postmenopausal women with low bone mass

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.

The efficacy and safety of ipriflavone in postmenopausal women with osteopenia or osteoporosis: A systematic review and meta-analysis

OBJECTIVES

Ipriflavone (IP) is one of the over-the-counter drugs and found in foods, which is available for prevention of osteoporosis (OP) since 1989 in over 22 countries. Although some clinical trials have suggested that IP is appropriate for treatment of OP, there continues to be controversy regarding the efficacy and safety due to some contradictory reports. With the wide usage of IP for osteoporotic women, there is a critical need for evaluation of the evidence for IP in clinical practice.

METHODS AND MATERIALS

We searched randomized control trials (RCTs) in PubMed, CENTRAL and CNKI which used the regimen of IP in postmenopausal women with osteopenia or OP. The efficacy referred to the absolute change and relative change in bone mineral density (BMD) and bone turnover markers. The safety profiles were associated with adverse events and the number of subject withdrawals due to adverse reactions.

RESULTS

Eleven RCTs (n = 1605) met the eligibility criteria were included. The increase of the BMD in lumbar spine of the IP group is greater than that of the placebo group (random effect model: SMD = 0.36; 95%CI= (0.09, 0.62)). For safety profile, most frequent reactions are gastrointestinal symptoms, but withdrawals due to adverse reactions are similar in both the IP group and placebo control at the same time intervals.

CONCLUSIONS

IP significantly increases BMD and has inhibitory effect on bone resorption markers in postmenopausal women with osteopenia or OP. Gastrointestinal symptoms may occur, but adverse drug withdrawal events were not statistically increased when compared with placebo group.

Ipriflavone attenuates the degeneration of cartilage by blocking the Indian hedgehog pathway

BACKGROUND

To determine if ipriflavone, a novel and safe inhibitor of Indian hedgehog (Ihh) signaling, can attenuate cartilage degeneration by blocking the Ihh pathway.

METHODS

Human chondrocytes were used to evaluate Ihh signaling, cell proliferation, apoptosis, gene, and protein expression of chondrocytes by cell proliferation and apoptosis assays, real-time qPCR, and Western blotting at 48 h after ipriflavone treatment. Human cartilage explants were further used to validate the cell culture results. The effects of ipriflavone on cartilage degeneration in vivo were assessed using the rat ACLT OA model. Two-month-old male SD rats were randomized into 3 groups (n = 75): (1) sham, (2) ACLT alone, and (3) ACLT+ ipriflavone. Ipriflavone was administered intragastrically at 24 h after ACLT for 6 weeks. The extent of OA progression was evaluated by the OARSI score and immunohistochemistry at 12 weeks after surgery. The Ihh signaling pathway and OA-related genes were quantified by real-time PCR.

RESULTS

Cell proliferation in the cells treated with ipriflavone was increased to 36.40% ± 1.32% (5 μM) and 28.54% ± 0.74% (10 μM) from 11.99% ± 0.35% (DMSO) (P < 0.001), and apoptosis was decreased to 12.64% ± 3.7% (5 μM) and 15.18% ± 3.13% (10 μM) from 25.76% ± 5.1% (DMSO) (P < 0.05). Ipriflavone blocked Runx-2 mainly through the Smo-Gli2 pathway. A similar result was found in the cartilage explant culture. Ihh signaling in vivo was inhibited in animals treated with ipriflavone. Safranin-O staining revealed a less cartilage damage with lower OARSI scores (P < 0.05) in the ipriflavone-treated animals compared with untreated animals. The gene expression of Smo and Gli2 was inhibited significantly by ipriflavone (P < 0.05). The OA-related gene and protein type X, MMP-13, and type II collagen-C fragment were reduced, while type II collagen and Agg were increased in the ipriflavone-treated animals (P < 0.05).

CONCLUSIONS

Catabolic genes were disrupted by blocking the Ihh pathway. This finding suggests that disruption of Ihh signaling with ipriflavone provides chondral protection in rat posttraumatic OA.

3-Piperidylethoxypterocarpan: A potential bone anabolic agent that improves bone quality and restores trabecular micro-architecture in ovariectomized osteopenic rats

A series of new 6H-benzofuro[3, 2-c]chromenes (BFC, pterocarpans) with structure-activity relationships were investigated for their potential use in osteoporosis treatment. One of the BFCs 3-piperidylethoxypterocarpan 20 promotes osteoblast differentiation and mineralization at a dose as low as 1 pM via activation of ER/P38MAPK/BMP-2 pathway. When evaluated for in-vivo osteogenic activity in female Sprague-Dawley rats, BFC 20 increased bone mineral density and new bone formation, compared with control at 1.0 and 10.0 mg/kg/body weight by oral gavage for 30 days. The compound was devoid of any uterotrophic effect and led to the new bone formation in adult ovariectomized osteopenic rats. BFC 20 compound also inhibited bone resorption by reducing Ovx induced increase in urinary CTx, thus exhibiting both bone anabolic and anti-catabolic action. Finally, BFC 20 treatment to Ovx rats led to improved trabecular microarchitectural restoration and exhibited therapeutic potential as a dual acting anti-osteoporotic agent for the management of osteoporosis.

Women's health: selected topics

Complementary and alternative medicine (CAM) therapies have become increasingly popular for the treatment of a variety of conditions. The World Health Organization has recognized the value of traditional healing techniques, which are classified as CAM, for 30 years. In the United States nearly 50% of women use CAM for common medical conditions, significantly more than men. This pattern is frequently seen in the treatment of women's health conditions such as infertility, premenstrual syndrome, and menopause. This article provides an integrative approach for conditions commonly encountered in the primary care setting among women, discusses alternative therapies used to treat these health conditions, and provides an evidence-based summary of recommendations based on a review of the literature.

Effects of phyto-oestrogens on tissues

Recent investigations on the effects of phyto-oestrogens on various tissues have revealed that these diverse molecules may improve human health, particularly by protecting against certain chronic diseases. After a brief examination of the food sources, structures, and general cellular actions of the major phyto-oestrogens, current research findings on cardiovascular disease, skeletal tissues, and reproductive cancers are reviewed. Phyto-oestrogen concentrations in blood may be maintained at high levels in those consuming soyabean (Glycine max)-based food daily at several meals and exert their effects on target cells through either genomic effects via the classical oestrogen receptors or non-genomic effects mediated by membrane-bound oestrogen receptors or other cellular proteins. The expression of oestrogen receptor (OR) subtypes alpha (a) and beta (beta) varies across tissues, and cells that preferentially express OR-beta, which may include bone cells, are more likely to respond to phyto-oestrogens. Conversely, reproductive tissues contain relatively more OR-a and may, thus, be differently affected by phyto-oestrogens. Soyabean phyto-oestrogens appear to prevent the progression of atherosclerosis through multiple interactions, including lowering of plasma lipids and lipoproteins, increased vasodilatation and, possibly, decreased activation of blood platelets and vascular smooth muscle cells. However, a favourable impact on cardiovascular disease morbidity and mortality by a soyabean-enriched western-type diet remains to be shown, and unresolved questions remain regarding dose and form of the phyto-oestrogens in relation to risks and benefits. The isoflavones of soyabean have been shown consistently to have bone-retentive effects in animal studies by several investigators using rodent models, although intakes must be above a relatively high threshold level for a lengthy period of time, and little or no extra benefit is observed with intakes above this threshold level. The reports of modest or no effects on prevention of bone loss in human and non-human primate studies respectively, may be due to the limited doses tested so far. The relationship between soyabean-food intake and cancer risk has been more extensively investigated than for any other disease, but with less certainty about the benefits of long-term consumption of phyto-oestrogen-containing foods on prevention of cancer. The observations that breast and prostate cancer rates are lower in Asian countries, where soyabean foods are consumed at high levels, and the high isoflavone content of soyabeans have led to examination of the potential protective effects of phyto-oestrogens. Establishing diet-cancer relationships has proved difficult, in part because of the conflicting data from various studies of effects of soyabean-diets on cancer. Epidemiological evidence, though not impressive, does suggest that soyabean intake reduces breast cancer risk. The isoflavone genistein has a potent effect on breast cancer cells in vitro, and early exposure of animals to genistein has been effective in reducing later development of mammary cancer. Thus, continuous consumption of soyabean foods in early life and adulthood may help explain the low breast cancer mortality rates in Asian countries. Although the evidence for a protective effect against prostate cancer may be slightly more supportive, more research is needed before any firm conclusions can be made about the phyto-oestrogen-cancer linkages.

[Treatment with isoflavones replaces estradiol effect on the tissue fat accumulation from ovariectomized rats]

OBJECTIVE

Isoflavones (ISO) present in soybean are named phytoestrogens because they show estrogen effect. The use of isoflavones has beneficial effect in disturbance of post-menopause, which is characterized by ovarian function suppression. Decreasing of estrogen secretion and consequent morphologic and metabolic disarrangements are observed in female hormonal decline. The aim of present work was to investigate the effect of ISO on the fat accretion of uterine endometric tissue, and HDL and glucose blood concentration from ovariectomized rats (OVX).

METHODS

Female Wistar rats with 60 days-old were submitted a surgery to remove bilaterally the ovarium. After 8-day recovery period the animals were distributed into three groups: sham operate (GC); OVX ISO untreated (GI) and OVX supplemented with ISO (G II). Total uterus mass, uterus fat and retroperitoneal fat pad, were removed, washed and weighted. Samples of uterus were histological processed to measure endometrium thickness. Blood samples were also collected to analyze the concentration of HDL and glucose. The OVX caused endometric atrophy, decrease of uterus weight and HDL reduction. The treatment with ISO provoked decrease of uterine and retroperitoneal fat pad. HDL increase and glycemia reduction were also observed. However, there was no uterotrophic effect.

CONCLUSIONS

ISO treatment causes decrease in tissue fat accretion from ovariectomized rats.

The effect of soy protein and soy isoflavones on calcium metabolism in postmenopausal women: a randomized crossover study

BACKGROUND

Evidence suggests that soy isoflavones act as estrogen agonists and have beneficial skeletal effects, but the effects on calcium metabolism in humans are not known.

OBJECTIVE

This study tested whether soybean isoflavones, soy protein, or both alter calcium metabolism in postmenopausal women.

DESIGN

Calcium metabolism in 15 postmenopausal women was studied by using metabolic balance and kinetic modeling in a randomized, crossover design of three 1-mo controlled dietary interventions: soy protein isolate enriched with isoflavones (soy-plus diet), soy protein isolate devoid of isoflavones (soy-minus diet), and a casein-whey protein isolate (control diet).

RESULTS

There was no significant difference between the diets in net acid excretion (P = 0.12). Urinary calcium excretion was significantly (P < 0.01) less with consumption of either of the soy diets (soy-plus diet: 85 +/- 34 mg/d; soy-minus diet: 80 +/- 34 mg/d) than with consumption of the control diet (121 +/- 63 mg/d), but fractional calcium absorption was unaffected by treatment. Endogenous fecal calcium was significantly (P < 0.01) greater with consumption of the soy-minus diet than with consumption of the other diets. Total fecal calcium excretion, bone deposition and resorption, and calcium retention were not significantly affected by the dietary regimens.

CONCLUSIONS

The lower urinary calcium seen with the consumption of an isolated soy protein than with that of an isolated milk protein was not associated with improved calcium retention. This finding reinforces the importance of evaluating all aspects of calcium metabolism. Soy isoflavones did not significantly affect calcium metabolism.

Biochanin A Stimulates Osteoblastic Differentiation and Inhibits Hydrogen Peroxide-Induced Production of Inflammatory Mediators in MC3T3-E1 Cells

Phytoestrogens are plant chemicals that are structurally analogous to estrogen and are known to affect estrogenic activity. Biochanin A, a naturally occurring isoflavone, has been identified and detected in various diets and plant species. We examined the effects of biochanin A on the differentiation of osteoblastic MC3T3-E1 cells and the production of local factors in osteoblasts. Biochanin A (1-50 microM) caused a significant elevation of cell growth, alkaline phosphatase (ALP) activity, collagen content, and osteocalcin secretion in osteoblastic MC3T3-E1 cells (p<0.05). The effect of biochanin A (10 microM) in increasing ALP activity and collagen content was completely prevented by the presence of 10(-6) M cycloheximide and 10(-6) M tamoxifen, suggesting that biochanin A's effect results from a newly synthesized protein component and might be partly involved in estrogen action. We then examined the effect of biochanin A on the H2O2-induced production of inflammatory mediators in osteoblasts. Biochanin A (1-10 microM) decreased the 0.2 mM H2O2-induced production of TNF-alpha, IL-6 and NO in osteoblasts. These results suggest that biochanin A may be useful as potential phytoestrogens, which play important physiological roles in the prevention of postmenopausal osteoporosis.

Alternatives to estrogen

For many years, women have sought alternative therapies for menopausal symptoms and for general health overall. The highly publicized findings from the Women's Health Initiative have led to an increased pressure on the medical community to find safe and alternative medications for female health. This article reviews the challenges and problems with the use of alternative medicines, and the clinical trials that prove their efficacy, and discusses the safety issues that may occur with these types of products.

Phytoestrogen genistein acts as an estrogen agonist on human osteoblastic cells through estrogen receptors alpha and beta

Genistein, a soybean isoflavone, has estrogen-like activity in mammals, including the prevention of bone loss. However, whether its mechanism of action on bone turnover is distinct from that of estrogen or raloxifene is unknown. Although genistein has been reported to bind both estrogen receptor (ER) isoforms (alpha and beta), little is known concerning differential activation of gene expression via these ER isoforms. To examine this question, comparison of the responses of normal fetal osteoblast (hFOB) cells stably expressing either ERalpha (hFOB/ERalpha9) or ERbeta (hFOB/ERbeta6), to treatment with genistein, 17beta-estradiol (E(2)) or raloxifene were conducted. In hFOB/ERalpha9 cells, both genistein and E(2) increased the endogenous gene expression of the progesterone receptor (PR), the proteoglycan versican, and alkaline phosphatase (AP), but inhibited osteopontin (OP) gene expression and interleukin-6 (IL-6) protein levels. Raloxifene had no effect on these bone markers. Genistein, but not raloxifene, also mimicked E(2) action in the hFOB/ERbeta6 cells increasing PR gene expression and inhibiting IL-6 production. To determine whether the gene regulatory actions of genistein in human osteoblast cells occur at the level of transcription, its action on the transcriptional activity of a PR-A promoter-reporter construct was assessed. Both genistein and E(2) were found to stimulate the PR promoter in the hFOB cell line when transiently co-transfected with either ERalpha or ERbeta. Whereas hFOB cell proliferation was unaffected by E(2), raloxifene or genistein at low concentrations, higher concentrations of genistein, displayed significant inhibition. Together, these findings demonstrate that genistein behaves as a weak E(2) agonist in osteoblasts and can utilize both ERalpha and ERbeta.

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.

Phytoestrogens--mechanism of action and effect on bone markers and bone mineral density

Dietary supplements, especially those containing phytoestrogens, frequently are used to either promote health or prevent disease. An estimated 20 billion dollars was spent on dietary supplements in the year 2000. Approximately 40% to 55% of Americans use supplements on a regular basis and 24% of these supplements contain herbs. Phytoestrogens are defined as any compound that is structurally or functionally related to ovarian or placental estrogens and their active metabolites. These compounds are widely used for various disorders related to women's health.

Phytoestrogens in the management of the menopause: up-to-date

Despite the benefits of conventional hormone replacement therapy, some women are not candidates for this treatment and many others choose not to take it. As a result, there is growing interest among patients about natural alternatives. There is some evidence that phytoestrogens may offer protection against a wide range of human conditions, including breast cancer, cardiovascular disease, brain dysfunction, osteoporosis, and menopausal symptoms. The literature on the possible health benefits of phytoestrogens has expanded exponentially since the 1980s, mainly in response to funding initiatives by the U.S. government and soybean industries, and more lately by European and UK Ministries of Food. The physiological effects of phytoestrogens also have created a marketing opportunity that has been used by industry, particularly in soybean-producing countries such as the U.S. and Australia. Nevertheless, clinical applications for phytoestrogens are still in their infancy, and more interventional trials are required to reach definitive conclusions regarding their efficacy and safety, although they appear to represent a promising group of compounds, which may be useful in the future for the treatment of the menopausal syndrome. Also, the lack of clinical data presently available must signal caution in relation to the possible risk of adverse effects.

TARGET AUDIENCE

Obstetricians and Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader will be able to identify the various types of phytoestrogens, list the sources of phytoestrogens, and summarize the various effects of phytoestrogens.

Soy intake and the maintenance of peak bone mass in Hong Kong Chinese women

Our previous study on bone health among premenopausal women showed that bone mass consolidation is attained by the early 30s, and small loss of spinal bone mineral density (SBMD) occurs soon after peak bone mass attainment. Recent interest has been shown in the potential beneficial effects of phytoestrogens on bone health. However, data are lacking, particularly in Asian women. This study aims to investigate the effect of soy isoflavones intake on the maintenance of peak bone mass in a cohort of 132 women aged 30-40 years who were followed up for 3 years. Baseline measurements of SBMD (L2-L4) were obtained using dual-energy X-ray densitometry, and dietary intake of soy foods and other key nutrients, including dietary calcium, were obtained through a quantitative food frequency method. Information on body measurements; physical activity (PA), weight-bearing activity in particular; age of menarche; and number of pregnancies were obtained at baseline. Repeated measurements of SBMD were obtained yearly for a further 3 years with an average follow-up time of 38 months. Analyses were performed on 116 subjects with at least three SBMD measurements (at baseline, 3-year follow-up, and at least one measurement during follow-up). The individual SBMD regression slope was computed for each of the subjects. Soy isoflavones consumption was categorized as quartiles of intake. We observed a significant difference in the SBMD individual regression slopes between women belonging to the fourth and first soy isoflavones intake quartiles. The positive effect of soy isoflavones on SBMD remained after adjusting for age and body size (height, weight, and bone area). Multiple linear regression analysis including the other known covariates (lean body mass, PA, energy adjusted calcium, and follow-up time) showed that soy isoflavones, together with these variables, accounted for 24% of the variances of the SBMD individual regression slope. This longitudinal study shows that soy intake had a significant effect on the maintenance of SBMD in women aged 30-40 years. The effects of phytoestrogens on bone health should be explored further in a population with habitual dietary soy but low calcium intake.

The effect of an ipriflavone-containing supplement on urinary N-linked telopeptide levels in postmenopausal women

Osteoporosis is a significant health concern to our aging population. We report here the results of a pilot placebo-controlled trial of a dietary supplement containing ipriflavone, calcium, and vitamin D on a urinary marker of bone breakdown in postmenopausal women. Seven postmenopausal women not currently receiving hormone replacement therapy received either an ipriflavone-containing supplement or placebo for 3 months. Urinary N-linked telopeptides, a marker of bone breakdown, declined by 29% in those receiving the supplement, whereas an increase in this marker was observed in the group receiving the placebo. No changes were observed in salivary hormone measurements. Although our sample size was small, to the best of our knowledge, this is the first report that demonstrates changes in N-linked telopeptide levels as a result of consuming an ipriflavone-containing product. Our findings confirm those of other researchers that demonstrate the usefulness of ipriflavone at slowing the progression of bone loss and suggest that measuring N-linked telopeptides may be a useful tool to assess therapeutic efficacy.

Effects of soy isoflavones on markers of bone turnover in premenopausal and postmenopausal women

Soy isoflavones are hypothesized to exert hormonal effects in women and thus may play a role in bone metabolism throughout life. In 2 randomized, cross-over studies, 14 pre- and 17 postmenopausal women were given 3 soy protein isolates containing different amounts of isoflavones [control, 0.13; low isoflavone (low-iso), 1.00; and high-iso, 2.01 mg/kg body wt/day, averaging 8, 65, and 130 mg/day, respectively], for over 3 months each. Food records, blood samples, and 24-h urine collections were obtained throughout the studies. The endpoints evaluated included plasma or serum concentrations of bone-specific alkaline phosphatase, osteocalcin, insulin-like growth factor-I (IGFI), IGF binding protein-3 (IGFBP3), and urine concentrations of deoxypyridinoline cross-links and carboxy-terminal telopeptide of type I collagen. In premenopausal women, IGFI and IGFBP3 concentrations were increased by the low-iso diet, and deoxypyridinoline cross-links was increased by both the low- and high-iso diets during certain phases of the menstrual cycle. In postmenopausal women, bone-specific alkaline phosphatase was decreased by both the low- and high-iso diets, and there were trends toward decreased osteocalcin, IGFI, and IGFBP3 concentrations with increasing isoflavone consumption. Although soy isoflavones do affect markers of bone turnover, the changes observed were of small magnitude and not likely to be clinically relevant. These data do not support the hypothesis that dietary isoflavones per se exert beneficial effects on bone turnover in women.

Drug-induced lymphopenia: focus on CD4+ and CD8+ cells

Drug-induced lymphopenia is a common adverse event. Some drugs, in particular those used in the treatment of malignancies and autoimmune diseases, inevitably affect the percentages and proportions of lymphocytes in the peripheral blood. Some other drugs exert only minor effects and their clinical relevance cannot be established with certainty. Most cytotoxic and immunosuppressive drugs affect CD4+ T cells more profoundly. Since their regeneration seems to be slower than that of CD8+ T cells, the frequent occurrence of CD4+ lymphopenia may merely reflect this phenomenon. As in HIV infection, critically low numbers of CD4+ cells, irrespective of the cause, predisposes to opportunistic infections. There is no such critically low value for CD8+ cells, and their essential role in various pathological conditions should also be established.