Ipriflavone Prevents Bone Loss 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.

Bone mineral density, polyphenols and caffeine: a reassessment

Several studies have shown beneficial associations between tea consumption and bone mineral density (BMD) and fracture risk. Current investigations into potential mechanisms of benefit are focused upon the F and polyphenol components of tea. However, previous studies have pointed towards caffeine consumption as a potential risk factor for low BMD and high fracture risk. Tea, therefore, represents an interesting paradox as a mildly caffeinated beverage that may enhance bone health. Fruit and vegetable intake has also been associated with BMD, and it is now apparent that several fruit and vegetable components, including polyphenols, may contribute positively to bone health. Evidence surrounding the function(s) of polyphenol-rich foods in bone health is examined, along with more recent studies challenging the relevance of caffeine consumption to in vivo Ca balance. Plant foods rich in polyphenols such as tea, fruit and vegetables, as significant factors in a healthy diet and lifestyle, may have positive roles in bone health, and the negative role of caffeine may have been overestimated. The present review covers evidence of dietary mediation in positive and negative aspects of bone health, in particular the roles of tea, fruit and vegetables, and of caffeine, flavonoids and polyphenols as components of these foods. Since the deleterious effects of caffeine appear to have been overstated, especially in respect of the positive effects of flavonoids, it is concluded that a reassessment of the role of caffeinated beverages may be necessary.

Complementary therapies for reducing the risk of osteoporosis in patients receiving luteinizing hormone-releasing hormone treatment/orchiectomy for prostate cancer: a review and assessment of the need for more research

Osteoporosis in women has received a substantial amount of attention, but its impact in men is also significant and noteworthy. Those men who benefit from treatment for prostate cancer with androgen deprivation therapy (ADT) may also be at a higher risk for osteoporosis. Pharmacologic approaches to reduce this risk have received some attention. For example, agents such as bisphosphonates, estrogen receptor-binding drugs (diethylstilbestrol, tamoxifen, and raloxifene), calcitonin, and fluoride are some of the more promising interventions that have been previously outlined. In addition, statin drugs, or hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, have recently been hypothesized to lower osteoporosis risk. However, complementary therapies, which may also have an impact on reducing osteoporosis risk, have not received attention. Dietary and supplemental calcium and vitamin D have been shown, in some preliminary investigations, to maintain bone density in women and men. Numerous healthy and affordable dietary sources of this mineral and vitamin exist, and large intakes can be realistically achieved through proper education. Similarly, the supplemental dosages required to impact risk have been moderate, appear to be safe, are of low cost, and thus may provide an additional route for reducing risk, especially if these interventions are initiated at the start of medical treatment. More studies in men receiving ADT are needed because the existing work has mostly focused on men without castrate levels of male hormone. Additionally, many studies with conventional and nonconventional agents have only focused on individuals with baseline osteoporosis, rather than normal bone mineral densities or osteopenia. Other promising complementary therapies, such as weight-bearing exercise and abstaining from smoking, may also be of benefit. Newer estrogenic-type supplements (eg, ipriflavone) appear interesting and have some preliminary data, but more research is desperately required to determine their actual impact and potential for adverse effects (such as lymphocytopenia from a recent trial). Simple, inexpensive, and potentially effective dietary and supplemental approaches to reduce the risk of osteoporosis in men exist, and they should be discussed with patients. Whether these approaches effectively reduce the risk of osteoporosis in men receiving androgen ablation remains to be determined. The possibility is intriguing, and future research is needed. In the meantime, it is important to keep in mind that these complementary approaches are, at the very least, an integral part of the conventional options used today to the reduce the risk of osteoporosis in men and women.

Usual dietary isoflavone intake, bone mineral density, and bone metabolism in postmenopausal women

Clinical trials of isoflavone supplementation and bone density have been of relatively short duration and yielded inconsistent results. Few studies examined the effects of usual dietary isoflavone intake on bone density, and none examined the effects on markers of bone turnover. This cross-sectional study examines the association of usual, unsupplemented dietary soy intake with bone density at the lumbar spine and hip and markers of bone turnover in postmenopausal women. Participants were 208 postmenopausal Southern California women aged 45-74 years. Information on behavioral and lifestyle factors was obtained, and dietary intake of isoflavones over the past year was assessed with a standardized questionnaire. Bone density was measured at the spine and hip with dual energy x-ray absorptiometry (DEXA). Urinary type I collagen cross-linked N-telopeptides (N-Tx) and pyridinium cross-links (PYR), both markers of bone resorption, and bone alkaline phosphatase (BAP), a marker of bone formation, were assayed. After adjustment for age and obesity, women with the highest daily intake of dietary genistein had N-Tx concentrations 18% lower than those of women who reported no daily genistein consumption (mean 37.29 vs. 45.44, respectively, p = 0.01). After adjustment for all covariates, there were trends toward significant differences in N-Tx (p = 0.09) and spine bone density (p = 0.07), whereby women with the highest level of isoflavone consumption had greater bone density at the spine. These results suggest that usual, unsupplemented dietary isoflavone consumption may be protective against bone loss in postmenopausal women through a reduction in bone resorption.

Treatment of bone loss in oophorectomized women with a combination of ipriflavone and conjugated equine estrogen

OBJECTIVE

We previously reported that 0.625 mg/day of conjugated equine estrogen (CEE) could not prevent acute bone loss in the first year after oophorectomy. The effect of additional administration of ipriflavone on bone mineral density (BMD) and biochemical indices of bone remodeling were studied to investigate whether concurrent use of CEE and ipriflavone prevent acute bone loss in the early stages following surgical menopause.

METHODS

One-hundred and sixteen oophorectomized women were randomly divided into four groups according to treatment; group 1: placebo, n = 30; group 2: CEE (0.625 mg/day), n = 29; group 3: ipriflavone (600 mg/day), n = 30; group 4: CEE (0.625 mg/day) plus ipriflavone (600 mg/day), n = 27. Vertebral BMD was measured using dual energy X-ray absorptiometry (DEXA) and two biochemical indices of bone metabolism, urinary pyridinoline (Pyr) and serum intact human osteocalcin (hOC), were also measured before, 24 weeks, and 48 weeks after initiation of treatment.

RESULTS

BMD was reduced 48 weeks after treatment by 6.1, 3.9 and 5.1% in groups 1-3, respectively, but by only 1.2% in group 4. Pyr decreased by 49.5, 32.0 and 41.5% in groups 2-4, respectively. hOC also decreased by 45.2 and 21.6% in groups 2 and 4, but increased by 40.5% in group 3, suggesting an inhibitory action of CEE and ipriflavone on the turnover of bone metabolism and stimulatory action of ipriflavone on bone formation.

CONCLUSION

Concomitant use of ipriflavone with CEE from an early stage after oophorectomy inhibited bone loss and was considered to be effective in maintaining bone mass after oophorectomy.

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

We present the results of two multicenter, double-blind, placebo-controlled, 2-year studies to evaluate the efficacy and tolerability of ipriflavone in postmenopausal women (PMW) with low bone mass. 453 PMW (aged 50-65 years) with a vertebral (VMD) or radial (RMD) mineral density value 1 SD lower compared with age-matched controls, were randomly selected to receive oral ipriflavone (200 mg T.I.D. at meals) or matching placebo, plus 1 g oral calcium daily. Vertebral (study A, by dual X-ray absorptiometry-DXA) and radial (study B, by dual photon absorptiometry-DPA) bone density, serum bone Gla-protein (BGP), and urinary hydroxyproline/creatinine (HOP/Cr) were measured every 6 months. In both studies, the Valid Completers (VC) analysis showed a maintenance of bone mass in ipriflavone-treated women, whereas in the placebo group, bone mineral density (BMD) was significantly decreased. The final outcome was a bone-sparing effect of 1.6% in study A, and of 3.5% in study B after 2 years. The Intention to Treat (ITT) analysis confirmed the decrease in the placebo group, with no changes in ipriflavone-treated women. A significant (P < 0.05) between-treatment difference was found in both studies. Biochemical markers of bone turnover decreased in patients treated with ipriflavone, thus suggesting a reduction of bone turnover rate. Twenty-six women treated with ipriflavone and 28 receiving the placebo dropped out because of side effects, mainly gastrointestinal. The compliance to the oral long-term treatment was good. The results of these studies show that ipriflavone is able to prevent both axial and peripheral bone loss in PMW with low bone mass, and is well tolerated.