Effect Of Soy Isoflavone Supplementation Research Articles

Dietary Soy Isoflavones Prevent Metabolic Disturbs Associated with a Deleterious Combination of Obesity and Menopause.

This study aimed to evaluate the effects of soy isoflavone supplementation (25 mg/kg) on insulin resistance and inflammation in adipose tissue in an experimental model of menopause-obesity. Twenty-four female Wistar rats were ovariectomized (O) and distributed among the groups: OSD-ovariectomized rats submitted to normocaloric standard diet (n = 6); OHF-ovariectomized rats submitted to high-fat diet (n = 9); and OHFI-ovariectomized rats submitted to high-fat diet with isoflavones (n = 9). Weight gain, body adiposity, food and caloric intake, blood pressure, and glucose tolerance were assessed. After 24 weeks, the rats were euthanized; the thoracic blood collected for serum insulin determination and the homeostatic model assessment-insulin resistance) (HOMA-IR) and homeostatic model assessment-β cell (HOMA-β) indices were calculated. Abdominal adipose tissues were removed, weighed, and fixed for immunohistochemical and morphometric studies. Isoflavones decreased weight gain and blood pressure without changing the food and caloric intake (P < .05). Isoflavones did not affect the weight of the abdominal adipose tissue depots (P < .05). Although they did not alter glucose tolerance, the isoflavones reduced HOMA-IR and HOMA-β, serum insulin levels, in addition to reducing adipocytes' size (P < .05). The number of macrophages, lymphocytes, and crown-like structures in adipose tissue was lower in the group treated with isoflavones (P < .05). In conclusion, our data show that dietary soy isoflavones' supplementation prevents many of well-known deleterious combination of obesity and menopause on metabolism, such as body overweight, adipocyte hypertrophy, and hypertension, as well as insulin resistance and adipose tissue inflammation.

The Impact of Soy Isoflavone Supplementation on the Menopausal Symptoms in Perimenopausal and Postmenopausal Women.

Introduction:Approximately one-third of a woman's life is spent in the menopausal phase. The unpleasant menopausal symptoms are unacceptable as a part of routine life. Indications of menopausal hormone therapy (MHT) are for alleviation of vasomotor symptoms, prevention of osteoporosis, and genitourinary symptoms associated with menopause. MHT is associated with an increased risk of breast cancer, cerebrovascular accidents, and coronary heart disease. Soy isoflavones have been extensively used as an alternative treatment in patients who cannot take MHT. The evidence of the efficacy of isoflavones in the literature is equivocal.Aim:The aim of the study was to evaluate the efficacy of soy isoflavone supplementation on menopausal symptoms in perimenopausal and postmenopausal women and to evaluate the effect on blood pressure (BP) and body mass index (BMI).Materials and Methods:A questionnaire-based prospective observational study was undertaken involving 39 perimenopausal and 61 postmenopausal women, who were prescribed 40 mg soy isoflavone supplements twice daily for 12 weeks. Menopause Rating Scale questionnaire was given to the patients before starting soy isoflavone therapy and at the end of the treatment; BP and BMI were also noted.Results:The total score of both the groups was comparable at baseline. Among perimenopausal and postmenopausal women, the highest score was noted in symptoms of somatic domain. At the completion of our study, the total scores improved significantly by 38.6% and 33.3% in perimenopausal and postmenopausal women, respectively. The greatest improvement was seen in somatic subscale (42.5%) and psychological subscale (42.5%) and the least in urogenital subscale (16.1%) for perimenopausal women. For postmenopausal women, the greatest improvement was seen in psychological subscale (40.0%) and the least in urogenital subscale (14.2%).Conclusion:Soy isoflavone supplementation is beneficial in both perimenopausal and postmenopausal women, more so in perimenopausal women. There is no beneficial effect of soy isoflavone supplementation on lowering systolic BP and BMI.

Effects of soy isoflavone supplementation on patients with diabetic nephropathy: a systematic review and meta-analysis of randomized controlled trials.

Diabetic nephropathy (DN) is a microvascular complication that is becoming a worldwide public health concern. The aim of this study was to assess the effects of dietary soy isoflavone intervention on renal function and metabolic syndrome markers in DN patients. Seven databases including Medline, the Cochrane Central Register of Controlled Trials, Science Direct, Web of Science, Embase, China National Knowledge Infrastructure, and WanFang were searched for controlled trials that assessed the effects of soy isoflavone treatment in DN patients. Finally, a total of 141 patients from 7 randomized controlled trials were included. The meta-analysis showed that dietary soy isoflavones significantly decreased 24-hour urine protein, C-reactive protein (CRP), blood urea nitrogen (BUN), total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and fasting blood glucose (FBG) in DN patients. The standard mean difference was -2.58 (95% CI: -3.94, -1.22; P = 0.0002) for 24-hour urine protein, -0.67 (95% CI: -0.94, -0.41; P < 0.00001) for BUN, -6.16 (95% CI: -9.02, -3.31; P < 0.0001) for CRP, -0.58 (95% CI: -0.83, -0.33; P < 0.00001) for TC, -0.41 (95% CI: -0.66, -0.16; P < 0.00001) for TG, -0.68 (95% CI: -0.94, -0.42; P < 0.00001) for LDL-C, and -0.39 (95% CI: -0.68, -0.10; P = 0.008) for FBG. Therefore, soy isoflavones may ameliorate DN by significantly decreasing 24-hour urine protein, BUN, CRP, TC, TG, LDL-C, and FBG.

Soy supplementation: Impact on gene expression in different tissues of ovariectomized rats and evaluation of the rat model to predict (post)menopausal health effect.

This toxicogenomic study was conducted to predict (post)menopausal human health effects of commercial soy supplementation using ovariectomized rats as a model. Different target tissues (i.e. breast, uterus and sternum) and non-target tissues (i.e. peripheral blood mononuclear cells (PBMC), adipose and liver) of ovariectomized F344 rats exposed to a commercially available soy supplement for eight weeks, were investigated. Changes in gene expression in these tissues were analysed using whole-genome microarray analysis. No correlation in changes in gene expression were observed among different tissues, indicating tissue specific effects of soy isoflavone supplementation. Out of 87 well-established estrogen responsive genes (ERGs), only 19 were found to be significantly regulated (p < 0.05) in different tissues, particularly in liver, adipose and uterus tissues. Surprisingly, no ERGs were significantly regulated in estrogen sensitive breast and sternum tissues. The changes in gene expression in PBMC and adipose tissue in rats were compared with those in (post)menopausal female volunteers who received the same supplement in a similar oral dose and exposure duration in human intervention studies. No correlation in changes in gene expression between rats and humans was observed. Although receiving a similar dose, in humans the plasma levels expressed as total free aglycones were several folds higher than in the rat. Therefore, the overall results in young ovariectomized female F344 rats indicated that using rat transcriptomic data does not provide a suitable model for human risk or benefit analysis of soy isoflavone supplementation.

The Effect of Soy Isoflavones on the Menopause Rating Scale Scoring in Perimenopausal and Postmenopausal Women: A Pilot Study.

Menopause is associated with many unpleasant symptoms which vary in different phases of menopausal transition. Although, Hormone Replacement Therapy (HRT) is considered the most effective mode of treatment for these symptoms, its use is associated with increased risk of breast cancer, endometrial cancer and thromboembolic events. Soy isoflavones are being widely used as a safer alternative to HRT, even though scientific evidence of their efficacy is poor or lacking. To study the effect of soy isoflavone supplementation on the menopausal symptoms in perimenopausal and postmenopausal women. An observational pilot study was done involving 29 perimenopausal and 21 postmenopausal women prescribed 100 mg soy isoflavones for 12 weeks. Menopause Rating Scale (MRS) questionnaire was administered to the patients before starting soy isoflavone therapy and at the end of treatment. Responses were analysed using Statistical Package for Social Sciences (SPSS) software 23.0. Total score of both the groups were comparable at baseline. Among perimenopausal women highest score was given to symptoms of psychological domain. Urogenital symptoms were the worst among postmenopausal women. After 12 weeks of treatment, total scores improved significantly by 19.55% and 12.62% in the perimenopausal and postmenopausal women respectively. The greatest improvement was seen in scores of hot flashes for both the groups and the least improvement was shown by symptoms of urogenital subscale. Soy isoflavone improves the MRS score among both the perimenopausal and postmenopausal women. As they are most effective for somatic and psychological symptoms, their use could be beneficial during perimenopause.

Effect of soy isoflavone supplementation on endothelial dysfunction and oxidative stress in equol-producing postmenopausal women.

Dietary isoflavones are considered to be cardioprotective because of their structural similarity to estrogen. Equol is a metabolite of daidzein that is more potent than daidzein itself. The effect of equol on endothelial function and oxidative stress remains unclear. The objective of this study was to determine the effect of 100 mg/day soy isoflavone supplementation on the following markers: vascular cell adhesion molecule-1 (VCAM-1) and nitric oxide (NO) as markers of vascular endothelial function, and malonyldialdehyde (MDA) as oxidative stress marker in equol-producing postmenopausal women. A stratified randomized double blind controlled trial was conducted among 190 postmenopausal Indonesian women aged 47 to 60 years. They were stratified into equol producers and equol nonproducers. The random allocation of intervention was carried out separately in each stratum. The intervention group received tablets consisting of 100 mg soy isoflavones and calcium carbonate 500 mg, and the control group received 500 mg calcium carbonate. The concentrations of VCAM-1, NO and MDA were measured at baseline and post-supplementation at 6 months. After 6 months of supplementation the MDA concentrations were significantly lower in the soy-isoflavone equol producers compared with equol nonproducers (p=0.021). Similar results were also found for VCAM-1 and NO concentrations, but these were statistically not significant (p = 0.413 and p= 0.724, respectively). This study demonstrates that isoflavone supplementation in postmenopausal women with equol-producer status had a more beneficial effect by decreasing the MDA concentration, but did not improve VCAM-1 and NO concentrations.

Effect of soy isoflavone supplementation on vascular endothelial function and oxidative stress in postmenopausal women: a community randomized controlled trial.

A 12-month randomized double blind controlled trial was conducted among 182 Indonesian postmenopausal women aged 47 to 60 years to determine the effect of 100 mg/day soy isoflavone supplementation on vascular endothelial function such as vascular cell adhesion molecule-1 (VCAM-1), nitric oxide (NO) and malondialdehyde (MDA) as oxidative stress marker. The subjects were randomized to the intervention group receiving tablets consisting of 100 mg soy isoflavones and calcium carbonate 500 mg, and to the control group receiving 500 mg calcium carbonate. The concentrations of VCAM-1, NO and MDA were measured at baseline, and postsupplementation at 6 months and 12 months. After supplementation, the MDA concentrations were significantly lower in the soy isoflavone group compared with the control group (p=0.001). The concentrations of VCAM-1 and NO were not affected (p=0.992 and p=0.759, respectively). In all group the MDA concentration increased compared with baseline concentrations but the relative change of MDA concentrations was significantly lower in the soy isoflavone group compared with the control group. This study demonstrates that supplemental intake of soy isoflavones for 6 months and 12 months had an effect on oxidative stress by decreasing MDA concentration, but did not improve vascular endothelial function.

Effect of soy isoflavone supplementation on menopausal quality of life

The purpose of this study was to assess the effect of soy isoflavone supplementation on quality of life in postmenopausal women. A multicenter, randomized, double-blind, placebo-controlled 24-month trial was conducted to assess the effect of 80 or 120 mg of daily aglycone hypocotyl soy isoflavone supplementation on quality of life in 403 postmenopausal women using a validated Menopause-Specific Quality of Life questionnaire. Menopause-Specific Quality of Life domain scores at 1 year and 2 years were similar to baseline. There were no differences in domain scores among treatment groups. Soy isoflavone supplementation offers no benefit to quality of life in postmenopausal women.

Soy isoflavone supplementation could reduce body weight and improve glucose metabolism in non-Asian postmenopausal women—A meta-analysis

ObjectiveThe objective of this study was to conduct a systematic review and a meta-analysis to confirm the effects of soy isoflavone supplementation on body weight, fasting glucose, and insulin level in non-Asian postmenopausal women. MethodsWe searched the PubMed, EMBASE, and Cochrane databases up to October 2010 for randomized controlled trials regarding the effects of isoflavone supplementation on body weight, fasting glucose, and insulin level. Pooled estimates and 95% confidence intervals (CIs) were calculated by the fixed-and-random-effects model. ResultsNine studies with 528 participants for body weight, 11 studies with 1182 participants for fasting glucose, and 11 studies with 1142 participants for fasting insulin were included, respectively. Significant reductions were found in body weight [weighted mean difference (WMD), −0.515; 95%CI: −0.895 to −0.134; P = 0.008), glucose level (WMD, −0.189; 95%CI: −0.344 to −0.033), and fasting insulin level (WMD, −0.940; 95%CI: −1.721 to −0.159) with soy isoflavone supplementation compared with placebo control group in non-Asian postmenopausal women after adjusted by unpublished studies. Furthermore, isoflavone supplementation in shorter duration (<6 mo) could significantly reduce body weight (WMD, −0.506; 95%CI: −0.888 to −0.124; P = 0.009) and longer duration (≥6 mo) could significantly reduce blood glucose in postmenopausal women (WMD, −0.270; 95%CI: −0.430 to −0.110; P = 0.001). Meanwhile, more reduction in body weight was observed in the lower dose subgroup (dose < 100 mg). Moreover, it is more effective to reduce body weight and fasting insulin level with soy isoflavone supplementation in normal weight (body mass index < 30) than obese (body mass index ≥ 30) women. ConclusionsThis meta-analysis showed soy isoflavone supplementation could be beneficial for body weight reduction, glucose, and insulin control in plasma. Large and well-designed studies are recommended to confirm this conclusion.

Effect of soy isoflavone supplementation on nitric oxide metabolism and blood pressure in menopausal women

Isoflavones, having chemical structures similar to estrogens, are believed to stimulate nitric oxide production and thus lower blood pressure. The efficacy of soy isoflavone supplementation to stimulate nitric oxide production and lower blood pressure in menopausal women with high normal blood pressure remains unknown. The objective was to test the effect of soy isoflavone supplementation on nitric oxide production and blood pressure in menopausal women with high normal blood pressure. A randomized, double-blind, parallel, placebo-controlled 6-wk trial was conducted to assess the effects of daily supplementation with 80 mg soy hypocotyl isoflavones (in aglycone units) on nitric oxide metabolism and blood pressure in 24 menopausal women with 12 women per group. Changes in nitric oxide metabolism were assessed via a primed, constant-infusion protocol with [15N]arginine and [13C]- and [2H]citrulline. Changes in blood pressure and associated vascular hemodynamics were assessed via office and 24-h ambulatory blood pressure monitoring, forearm blood flow, and indexes of arterial compliance. When compared with placebo and after control for pretreatment values, soy isoflavone supplementation had no effect on arginine flux, citrulline flux, nitric oxide synthesis, blood pressure, forearm blood flow, or estimates of arterial stiffness. Daily supplementation with 80 mg soy hypocotyl isoflavones over a 6-wk period had no effect on nitric oxide metabolism or blood pressure and associated vascular hemodynamics in menopausal women with high normal blood pressure.

Soy Isoflavones in Conjunction With Radiation Therapy in Patients With Prostate Cancer

Soy isoflavones sensitize prostate cancer cells to radiation therapy by inhibiting cell survival pathways activated by radiation. At the same time, soy isoflavones have significant antioxidant and anti-inflammatory activity, which may help prevent the side effects of radiation. Therefore, we hypothesized that soy isoflavones could be useful when given in conjunction with curative radiation therapy in patients with localized prostate cancer. In addition to enhancing the efficacy of radiation therapy, soy isoflavones could prevent the adverse effects of radiation. We conducted a pilot study to investigate the effects of soy isoflavone supplementation on acute and subacute toxicity (≤6 mo) of external beam radiation therapy in patients with localized prostate cancer. Forty-two patients with prostate cancer were randomly assigned to receive 200 mg soy isoflavone (Group 1) or placebo (Group 2) daily for 6 mo beginning with the first day of radiation therapy, which was administered in 1.8 to 2.5 Gy fractions for a total of 73.8 to 77.5 Gy. Adverse effects of radiation therapy on bladder, bowel, and sexual function were assessed by a self-administered quality of life questionnaire at 3 and 6 mo. Only 26 and 27 patients returned completed questionnaires at 3 and 6 mo, respectively. At each time point, urinary, bowel, and sexual adverse symptoms induced by radiation therapy were decreased in the soy isoflavone group compared to placebo group. At 3 mo, soy-treated patients had less urinary incontinence, less urgency, and better erectile function as compared to the placebo group. At 6 mo, the symptoms in soy-treated patients were further improved as compared to the placebo group. These patients had less dripping/leakage of urine (7.7% in Group 1 vs. 28.4% in Group 2), less rectal cramping/diarrhea (7.7% vs. 21.4%), and less pain with bowel movements (0% vs. 14.8%) than placebo-treated patients. There was also a higher overall ability to have erections (77% vs. 57.1%). The results suggest that soy isoflavones taken in conjunction with radiation therapy could reduce the urinary, intestinal, and sexual adverse effects in patients with prostate cancer.

Soy isoflavone supplementation and bone mineral density in menopausal women: a 2-y multicenter clinical trial

BackgroundIsoflavones are naturally occurring plant estrogens that are abundant in soy. Although purported to protect against bone loss, the efficacy of soy isoflavone supplementation in the prevention of osteoporosis in postmenopausal women remains controversial. ObjectiveOur aim was to test the effect of soy isoflavone supplementation on bone health. DesignA multicenter, randomized, double-blind, placebo-controlled 24-mo trial was conducted to assess the effects of daily supplementation with 80 or 120 mg of soy hypocotyl aglycone isoflavones plus calcium and vitamin D on bone changes in 403 postmenopausal women. Study subjects were tested annually and changes in whole-body and regional bone mineral density (BMD), bone mineral content (BMC), and T scores were assessed. Changes in serum biochemical markers of bone metabolism were also assessed. ResultsAfter study site, soy intake, and pretreatment values were controlled for, subjects receiving a daily supplement with 120 mg soy isoflavones had a statistically significant smaller reduction in whole-body BMD than did the placebo group both at 1 y (P < 0.03) and at 2 y (P < 0.05) of treatment. Smaller decreases in whole-body BMD T score were observed among this group of women at 1 y (P < 0.03) but not at 2 y of treatment. When compared with the placebo, soy isoflavone supplementation had no effect on changes in regional BMD, BMC, T scores, or biochemical markers of bone metabolism. ConclusionDaily supplementation with 120 mg soy hypocotyl isoflavones reduces whole-body bone loss but does not slow bone loss at common fracture sites in healthy postmenopausal women. This trial was registered at clinicaltrials.gov as NCT00665860.

Lack of effects of isoflavones on the lipid profile of Brazilian postmenopausal women

Objective To evaluate the effects of soy isoflavone supplementation on profile lipid and endogenous hormone levels. Methods In this double-blind, placebo-controlled study, 47 postmenopausal women 47–66 y of age received 40 mg of isoflavone ( n = 25) or 40 mg of casein placebo ( n = 22). Cardiovascular risk factors were assessed by evaluating lipid profile at baseline and after 6 mo of treatment. To examine the effects of this regime on endogenous hormone levels, follicle-stimulating hormone and β-estradiol were measured. Urinary isoflavone concentrations (genistein and daidzein) were measured as markers of both compliance and absorption using high performance liquid chromatography. Baseline characteristics were compared by the unpaired Student's t-test. Within-group changes were determined by paired Student's t-test and comparison between the isoflavone and casein placebo groups were determined by analysis of variance. Results Lipid levels (low-density lipoprotein and total cholesterol) similarly decreased in both groups. High-density lipoprotein increased significantly in both groups and cannot thus be attributable to treatment; the reason for such variation is unknown and can be attributed to chance or to bias (even that of a real placebo effect in both groups or perhaps in spontaneous changes in exercise and dietary habits of patients after their inclusion). Furthermore, in both groups very low-density lipoprotein and triacylglycerol levels increased in a non-significant manner. Conclusion The results of the present study do not support any biologically significant estrogenic effects of isoflavone on the parameters assessed. Further research will be necessary to definitively assess the safety and efficacy of isoflavone.

Effect of Soy Isoflavone Supplementation on Menopausal Quality of Life

Recent clinical trials have found an increased risk of health problems in women using menopausal hormone therapy. As a result, women are in search of alternative strategies to improve their quality of life. The purpose of this study was to assess the effect of soy isoflavone supplementation on quality of life in postmenopausal women. 403 healthy postmenopausal women (54.0+4.0 yrs) were enrolled in a 2 year multicenter, randomized, controlled trial designed to evaluate the effect of soy isoflavone supplementiation on the prevention of osteoporosis. Quality of life was assessed as a secondary outcome and was measured using the validated Menopause‐Specific Quality of Life Questionnaire (MENQOL) administered at baseline and at annual intervals. Participants were randomly assigned to receive soy isoflavones 80 mg/d, soy isoflavones 120 mg/d, or placebo. Data were analyzed using an analysis of variance (ANOVA). Baseline characteristics were similar among the three groups. There was a non‐significant decrease i.e. improvement, in the vasomotor domain score at one and two years compared to baseline in all three groups. However, there were no differences among groups. In conclusion, soy isoflavones provide no added benefit over placebo in terms of qualifty of life as measured by the MENQOL. Supported by IFAFS 2001‐52102‐11255 USDA CSREES.

Effects of isoflavones on the coagulation and fibrinolytic system of postmenopausal women

Objective We evaluated the effects of soy isoflavone supplementation on hemostasis in healthy postmenopausal women. Methods In this double-blinded, placebo-controlled study, 47 postmenopausal women 47–66 y of age received 40 mg of soy isoflavone ( n = 25) or 40 mg of casein placebo ( n = 22) once a day for 6 mo. Levels of factors VII and X, fibrinogen, thrombin–antithrombin complex, prothrombin fragments 1 plus 2, antithrombin, protein C, total and free protein S, plasminogen, plasminogen activator inhibitor-1, and D-dimers were measured at baseline and 6 mo. Urinary isoflavone concentrations (genistein and daidzein) were measured as a marker of compliance and absorption using high-performance liquid chromatography. Baseline characteristics were compared by unpaired Student’s t test. Within-group changes and comparison between the isoflavone and casein placebo groups were determined by a mixed effects model. Results The levels of hemostatic variables did not change significantly throughout the study in the isoflavone group; however, the isoflavone group showed a statistically significant reduction in plasma concentration of prothrombin fragments 1 plus 2; both groups showed a statistically significant reduction in antithrombin, protein C, and free protein S levels. A significant increase in D-dimers was observed only in the isoflavone group. Plasminogen activator inhibitor-1 levels increased significantly in the placebo group. However, these changes were not statistically different between groups. Conclusion The results of the present study do not support a biologically significant estrogenic effect of soy isoflavone on coagulation and fibrinolysis in postmenopausal women. However, further research will be necessary to definitively assess the safety and efficacy of isoflavone.

The effect of soy isoflavones on egg quality and bone mineralisation during the late laying period of quail

1. Soy isoflavones play a role in calcium and bone metabolism. Poor egg quality, skeletal abnormalities and architectural deterioration of bone tissue are common problems under hot climate conditions and with increased age in poultry. 2. In this study, we investigated the effects of soy isoflavone supplementation on egg production, egg quality, bone mineral density (BMD), levels of osteocalcin (OC), vitamin D, calcium (Ca), phosphorus (P) and alkaline phosphatase (ALP) activity in quail (Coturnix coturnix japonica) during the late laying period. 3. The birds (n = 180; 28 weeks old) were randomly assigned to 6 treatment groups consisting of 6 replicates of 5 birds each in a 2 × 3 factorial arrangement of treatments (temperatures, soy isoflavone concentration). Birds were kept in wire cages in a temperature-controlled room at either 22°C (thermo-neutral, TN) or 34°C (heat stress, HS) for 8 h/d (09:00 to 17:00 h; until the end of the study) and fed either on a basal (control) diet or on the basal diet supplemented with either 400 or 800 mg of soy isoflavones/kg of diet. 4. Heat exposure reduced feed intake, egg production, egg quality, BMD, OC, vitamin D, Ca, P and ALP when the basal diet was given. Feed intake, egg production and egg weight were not affected, while eggshell thickness and eggshell weight increased in soy isoflavone-supplemented quails reared under TN conditions. However, feed intake, egg production, egg weight, eggshell thickness, eggshell weight and Haugh units were positively influenced by soy isoflavone supplementation in HS groups for quail during the late laying period. Bone mineral density, serum OC, vitamin D, Ca, P levels and ALP activity were significantly improved by soy isoflavone supplementation in both the TN and HS groups in quail during the late laying period. 5. Soy isoflavone supplementation of basal diet significantly improved egg quality and bone mineralisation in quail during the late laying period.

Effects of soy isoflavone supplementation on cognitive function in Chinese postmenopausal women

To investigate whether soy-derived isoflavone extract improves performance in cognitive function and quality of life in Chinese postmenopausal women. The study was a 6-month double-blind, randomized, placebo-controlled, parallel group trial. Participants were community-dwelling women aged 55 to 76 years; 191 eligible women were randomly assigned to receive a daily oral intake of 80 mg soy-derived isoflavones or an identical-appearing placebo for 6 months. Standardized neuropsychological tests of memory, executive function, attention, motor control, language, and visual perception and a global cognitive function assessment were administered face-to-face individually at baseline and at 6-months posttreatment. The validated Chinese version of the Short Form-36 was used for quality of life measurements. Of the participants, 88% (168 women: 80 among the supplementation group and 88 among the placebo group) completed the trial. Intention-to-treat analysis, conducted for 176 participants with 6-month assessment results, revealed no significant differences in outcome measures between treatment groups. Subgroup analysis among the good compliers only (consumed at least 80% of the supplements or placebo; n = 168) and among the age groups younger or older than 65 years also indicated no significant differences for any outcome measures. Types of complaints of adverse events were similar in both treatment groups and included mainly gastrointestinal and musculoskeletal problems. This 6-month trial indicates that 80-mg soy-derived isoflavone supplementation did not improve performance on standard neuropsychological tests and overall quality of life in generally healthy Chinese postmenopausal women.

Alternative Therapies for Osteoporosis

A variety of common complementary and alternative medicine therapies are now being examined for effectiveness in the management of osteoporosis. Short-term studies in postmenopausal women show beneficial effects of soy isoflavone supplementation on bone density, but its long-term effects require clarification. Prospective controlled trials have shown that physical training can increase bone density to varying degrees. Other therapies that have been examined include herbal formulae, essential fatty acids and vitamins A, C, and K, but few data regarding their effectiveness, mechanisms and safety have been published. Further randomized controlled trials are needed.

Decreased Bone Resorption with Soy Isoflavone Supplementation in Postmenopausal Women

To investigate the effect of soy isoflavone supplementation on bone mineral density (BMD) and markers of bone turnover in postmenopausal women. In this randomized, placebo-controlled clinical trial, we used a crossover design to test the effect of soy isoflavone (110 mg/day) (1.3:1.0:0.22 ratio of genistein/daidzein/ glycitein) on bone formation, bone resorption, bone mineral content (BMC), and BMD for 6 months. Postmenopausal women (n = 19), mean age 70.6 +/- 6.3 years and mean time since menopause 19.1 +/- 5.5 years, were given isoflavone supplements for 6 months. There was a 37% decrease in urinary concentrations of type 1 collagen alpha1-chain helical peptide (HP), a marker of bone resorption, during the isoflavone supplementation compared with baseline (p < 0.05) and a significant difference in mean (SE) HP excretion levels when isoflavone was compared with placebo (43.4 +/- 5.2 vs. 56.3 +/- 7.2 microg/mmol creatinine [cr], p < 0.05). With isoflavone supplementation, mean spine BMD at L2 and L3 was significantly greater when treatment was compared with control, with a difference between means of 0.03 +/- 0.04 g and 0.03 +/- 0.04 g (p < 0.05), respectively. There were nonsignificant increases from baseline for total spine BMC (3.5%), total spine BMD (1%), total hip BMC (3.6%), and total hip BMD (1.3%) with the isoflavone treatment. Soy isoflavone, in isolated form, was effective in this study to significantly decrease bone resorption in postmenopausal women. Further investigation needs to be done to evaluate the long-term effects of soy isoflavone on bone mass and fracture risk.

Effects of soy isoflavone supplementation on plasma glucose, lipids, and antioxidant enzyme activities in streptozotocin-induced diabetic rats

This study was designed to examine the effects of feeding diets containing different levels of isoflavone on plasma glucose, insulin concentrations, and lipid profiles as well as tissue antioxidant enzyme activities in diabetic rats. Diabetes was induced in the rats with streptozotocin. Diabetic rats were further assigned to 1 control group and 3 experimental groups (ISO-1, ISO-2, and ISO-8). The control group received a casein-based diet without isoflavone, whereas the ISO-1, ISO-2, and ISO-8 groups received a similar diet but supplemented with 1, 2 and 8 times of isoflavone equivalent of normal human consumption as suggested by the manufacturer. All diets were adjusted to contain identical nutrients and were maintained for 24 days. Fasted and non-fasted blood was drawn after feeding for 21 and 24 days, respectively, and blood chemistry was analyzed. The liver, lung, and kidney were excised after sacrifice, and antioxdiant enzyme activities and lipid peroxidation products were measured. The results demonstrate that there were no differences in plasma glucose or insulin levels among groups, irregardless of whether rats had fasted or not. However, hemoglobin A 1c tended to be lower in the ISO-2 group than in the control and the ISO-1 groups. Plasma total cholesterol and low-density lipoprotein-cholesterol were significantly lower in the ISO-8 group than in the other groups. No differences in plasma triglyceride or high-density lipoprotein-cholesterol were observed among groups in the non-fasting state. There were no significant differences in superoxide dismutase, glutathione peroxidase activities, and malondialdehyde concentrations in liver, lung, and kidney homogenates among groups. These results suggest that 3 doses of isoflavone supplementation had no favorable effect on plasma glucose or insulin concentrations, nor had any influence on attenuating oxidative stress in diabetic rats. However, the ISO-2 group tended to have better chronic glycemic control than did the control and the ISO-1 group. In addition, a larger amount of isoflavone supplementation had beneficial effects on reducing plasma total cholesterol and low-density lipoprotein-cholesterol levels.