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Effects on blood fat and bone density of postmenopausal women fed by soy protein with isoflavone
Abstract
To explore the effects of phytoestrogen (PE) on blood lipid and bone density in postmenopausal women.
A total of 75 menopausal women aged 50-70 years with estrogen reduction symptoms received an intake of soy protein containing 70 mg isoflavone daily in a year. Their changes of blood fat, density lumbar bone and sex hormone level were compared with control group without an intake.
The changes of blood triglyceride (TG), total cholesterol (TC) and low-density lipoprotein (LDL) in two groups before and after a year showed no statistical significance.High-density lipoprotein (HDL) decreased in control group while it had no significant change in the study group. Bone densities in two groups showed a downward trend by an annual rate of 1%-4%, the changes in two groups showed no statistical significance.E2 increased slightly over basic value in the study group. But it had no statistical significance. The changes of follicle-stimulating hormone (FSH) in two groups were also similar.
The above soy protein preparation has no effect on hypothalamic-pituitary-ovarian axis and no stimulation on endometrium of uterus. But it may improve the profile of HDL.
... None of the studies reported any relevant intergroup differences in the baseline characteristics of the intervention and control groups. Apart from 3 of the RCTs (33,39,43), all other included trials, to various degrees, described measures for blinding of participants and personnel taking part in the studies (33,39,43). Two of the aforementioned RCTs did not indicate any measures for blinding of outcome assessment (39,43). ...
... None of the studies reported any relevant intergroup differences in the baseline characteristics of the intervention and control groups. Apart from 3 of the RCTs (33,39,43), all other included trials, to various degrees, described measures for blinding of participants and personnel taking part in the studies (33,39,43). Two of the aforementioned RCTs did not indicate any measures for blinding of outcome assessment (39,43). ...
... Five assessed soy protein isolate against control (26,38,(49)(50)(51). Three administered isoflavone equivalents compared with placebo (33,34,52). Four RCTs compared intake of tablets with purified isoflavones (genistein, daidzein, and glycitein) against placebo tablets (37,40,41,53). ...
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.
... Large randomised controlled trials (RCTs) showed that oestrogen therapy (such as red clover isoflavone supplementation) was effective for preventing and treating osteoporosis in postmenopausal women. [3][4][5] However, this remains controversial because of the increased risk of cancer, including endometrial, breast and ovarian cancer. 6 Nevertheless, other antiresorptive agents are not widely used because of their side effects, high prices and poor compliance on the part of patients; these include bisphosphonates, calcitonin and raloxifene. ...
Objective
Osteoporosis is a common disease in postmenopausal women. Several studies have analysed the associations between dietary supplementation with probiotics and bone health in postmenopausal women, but the results are still controversial. We conducted this meta-analysis to assess the effects of probiotics supplement on bone mineral density (BMD) and bone turnover markers for postmenopausal women.
Design
Systematic review and meta-analysis.
Methods
We systematically searched PubMed, EMBASE and the Cochrane Library from their inception to November 2020 for randomised controlled trials (RCTs) assessing probiotic supplements and osteoporosis in postmenopausal women. Study-specific risk estimates were combined using random-effect models.
Results
Five RCTs (n=497) were included. Probiotic supplements were associated with a significantly higher BMD in the lumbar spine (standardised mean difference, SMD=0.27, 95% CI 0.09 to 0.44) than in control. There was no difference between probiotic supplements and BMD in hips (SMD=0.22, 95% CI −0.07 to 0.52). Collagen type 1 cross-linked C-telopeptide levels in the treatment groups were significantly lower than those of the placebo group (SMD=−0.34, 95% CI −0.60 to −0.09). In subgroup meta-analysis, levels of bone-specific alkaline phosphatase, osteoprotegerin, osteocalcin and tumour necrosis factor did not differ between the probiotic and placebo groups.
Conclusions
We conclude cautiously that supplementation with probiotics could increase lumbar BMD. More RCTs are recommended to validate or update these results.
Previous research has shown that underlying dietary patterns are related to the risk of many different adverse health outcomes, but the relationship of these underlying patterns to skeletal fragility is not well understood. The objective of the study was to determine whether dietary patterns in men (ages 25-49, 50+) and women (pre-menopause, post-menopause) are related to femoral neck bone mineral density (BMD) independently of other lifestyle variables, and whether this relationship is mediated by body mass index.
We performed an analysis of 1928 men and 4611 women participants in the Canadian Multicentre Osteoporosis Study, a randomly selected population-based longitudinal cohort. We determined dietary patterns based on the self-administered food frequency questionnaires in year 2 of the study (1997-99). Our primary outcome was BMD as measured by dual x-ray absorptiometry in year 5 of the study (2000-02).
We identified two underlying dietary patterns using factor analysis and then derived factor scores. The first factor (nutrient dense) was most strongly associated with intake of fruits, vegetables, and whole grains. The second factor (energy dense) was most strongly associated with intake of soft drinks, potato chips and French fries, certain meats (hamburger, hot dog, lunch meat, bacon, and sausage), and certain desserts (doughnuts, chocolate, ice cream). The energy dense factor was associated with higher body mass index independent of other demographic and lifestyle factors, and body mass index was a strong independent predictor of BMD. Surprisingly, we did not find a similar positive association between diet and BMD. In fact, when adjusted for body mass index, each standard deviation increase in the energy dense score was associated with a BMD decrease of 0.009 (95% CI: 0.002, 0.016) g/cm(2) for men 50+ years old and 0.004 (95% CI: 0.000, 0.008) g/cm(2) for postmenopausal women. In contrast, for men 25-49 years old, each standard deviation increase in the nutrient dense score, adjusted for body mass index, was associated with a BMD increase of 0.012 (95% CI: 0.002, 0.022) g/cm(2).
In summary, we found no consistent relationship between diet and BMD despite finding a positive association between a diet high in energy dense foods and higher body mass index and a strong correlation between body mass index and BMD. Our data suggest that some factor related to the energy dense dietary pattern may partially offset the advantages of higher body mass index with regard to bone health.
We have reviewed the literature regarding the food sources, potency, population intakes, and known biological effects of phytoestrogens in humans using MEDLINE data base from the years 1975-1996. Over 600 articles pertinent to the metabolism of phytoestrogens, including female reproduction (in particular menstruation and menopause), cardiovascular disease, osteoporosis, and cancer were assessed including relevant case control or cohort studies, as well as randomized trials and review articles. Epidemiological studies regarding human data were included, as well as human cell line and animal studies when there were no relevant human data available. We conclude that phytoestrogens exhibit physiological effects in humans. Mild estrogenic changes occur in postmenopausal women. Benefits are seen regarding hypercholesterolaemia. Epidemiological, animal, and in vitro data encourage further assessment of the role of phytoestrogens in cancer prevention.
A model is described for evaluating the activity of a retinoid based on its effect on the keratinization of the vaginal epithelium that occurs on estrus (day 4) of a 4-day cycle in female rats. This keratinization process is dependent on the endogenous estradiol (E2) secreted between the evening of diestrus 2 (day 2) and that of proestrus (day 3). Various doses of all-transretinoic acid (tRA) were injected at different time points during the estrous cycle and the vaginal keratinization was assessed by microscope examination of unstained native or Papanicolaou-stained smear preparations. Additionally, the preovulatory E2 secretion was measured and ovaries were histologically examined. A single injection of 10 mg/kg tRA either on diestrus 2 (evening) or on proestrus (early morning) was able to induce a complete inhibition of the vaginal keratinization in more than 80% of the cases. This can be considered as a direct effect on the vaginal epithelial differentiation since neither the E2 secretion nor the ovulatory process were affected. The inhibition of vaginal keratinization can be used as a rapid and convenient in vivo model for screening retinoid candidates with antikeratinizing activity.
To assess the effect of a dietary soy protein supplement containing isoflavones on lipids and indices of bone resorption in postmenopausal women.
Placebo-controlled, double-blind, randomized study.
One hundred and six postmenopausal women were randomized to dietary soy supplementation (n = 51) or placebo (n = 55) for 3 months, of which 78 were included in the final analysis.
Lipid profiles including total, low-density lipoprotein (LDL) and HDL cholesterol as well as triacylglycerol were measured. Pyridinoline and deoxypyridinoline were used as markers of bone resorption. Urinary isoflavone excretion was measured to assess compliance.
There was a significantly greater increase in urinary isoflavone excretion detected in the soy group compared to placebo. Lipid profiles improved with significant decreases in LDL cholesterol (-0.60 +/- 0.10 vs.-0.29 +/- 0.09 mmol/l, P < 0.05), triacylglycerol (-0.22 +/- 0.07 vs. +0.01 +/- 0.05 mmol/l, P < 0.005) and the LDL : HDL ratio (-0.32 +/- 0.10 vs. +0.20 +/- 0.10, P < 0.005) in the soy group compared to placebo. There were no significant differences between the soy and placebo groups for urinary excretion of pyridinoline (-3.8 +/- 3.1 vs.-0.8 +/- 3.1 nmol/mmolCr, P = 0.4) or deoxypyridinoline (-0.8 +/- 0.9 vs.-0.3 +/- 0.7 nmol/mmolCr, P = 0.4).
In postmenopausal women, dietary supplementation with soy protein containing isoflavones does not appear to have oestrogenic effects on markers of bone resorption. Soy protein favourably affected lipids; however, these effects (fall in triacylglycerol and no change in HDL) differ from those observed with oral oestrogen. These findings suggest that soy may not have biologically significant oestrogenic effects on bone resorption and we hypothesize that the lipid effects may be mediated, at least in part, through nonoestrogenic mechanisms.
Soy consumption has been shown to modulate bone turnover and increase bone mineral density in postmenopausal women. To our knowledge, no published studies have directly examined the association between soy consumption and risk of fracture.
We examined the relationship between usual soy food consumption and fracture incidence in 24,403 postmenopausal women who had no history of fracture or cancer and were recruited between March 1, 1997, and May 23, 2000, in the Shanghai Women's Health Study, a cohort study of approximately 75,000 Chinese women aged 40 to 70 years. Usual soy food intake was assessed at baseline and reassessed during follow-up through in-person interviews using a validated food frequency questionnaire. Outcomes were ascertained by biennial in-person interview surveys.
During a mean follow-up of 4(1/2) years (110,243 person-years), 1770 incident fractures were identified. After adjustment for age, major risk factors of osteoporosis, socioeconomic status, and other dietary factors, the relative risks (95% confidence intervals) of fracture were 1.00, 0.72 (0.62-0.83), 0.69 (0.59-0.80), 0.64 (0.55-0.76), and 0.63 (0.53-0.76) across quintiles of soy protein intake (P<.001 for trend). The inverse association was more pronounced among women in early menopause. The multivariate relative risks (95% confidence intervals) of fracture comparing the extreme quintiles of soy protein intake were 0.52 (0.38-0.70) for women within 10 years of menopause vs 0.71 (0.56-0.89) for late postmenopausal women. Similar results were also found for intake of isoflavones.
Soy food consumption may reduce the risk of fracture in postmenopausal women, particularly among those in the early years following menopause.