Isoflavone Group Research Articles

Lycopene and Soy Isoflavones in the Treatment of Prostate Cancer

Dietary intake of lycopene and soy has been associated with a lower risk of prostate cancer. In vitro studies with lycopene and genistein, a soy isoflavone, have shown induction of apoptosis and inhibition of cell growth in androgen-sensitive (LNCaP) and androgen–independent (PC3 and VeCaP) prostate cancer cell lines. In a previous Phase II clinical trial in prostate cancer patients, we observed prostate-specific antigen (PSA) stabilization with soy isoflavone intake. In this Phase II clinical trial, we investigated the efficacy of lycopene alone or in combination with soy isoflavones on serum PSA levels in men with prostate cancer. To be eligible for the study, men with prostate cancer had to have rising serum PSA following local therapy or while on hormone therapy. Study population included 71 eligible patients who had 3 successive rising PSA levels or a minimum PSA of 10 ng/ml at 2 successive evaluations prior to starting therapy. Subjects were randomly assigned to receive a tomato extract capsule containing 15 mg of lycopene alone (n = 38) or together with a capsule containing 40 mg of a soy isoflavone mixture (n = 33) twice daily orally for a maximum of 6 mo. One patient on the lycopene arm did not receive therapy due to his inability to ingest the study pill. There was no decline in serum PSA in either group qualifying for a partial or complete response. However, 35 of 37 (95%) evaluable patients in the lycopene group and 22 of 33 (67%) evaluable patients in the lycopene plus soy isoflavone group achieved stable disease described as stabilization in serum PSA level. The data suggest that lycopene and soy isoflavones have activity in prostate cancer patients with PSA relapse disease and may delay progression of both hormone-refractory and hormone-sensitive prostate cancer. However, there may not be an additive effect between the 2 compounds when taken together. Future studies are warranted to further investigate the efficacy of lycopene and soy isoflavones in prostate cancer as well as the mechanism of potential negative interaction between them.

Possible role of equol status in the effects of isoflavone on bone and fat mass in postmenopausal Japanese women

Equol is more biologically active than its precursor daidzein, which is the principal isoflavone found in soybean. There are interindividual differences in the ability to produce equol; these may lead to differences in the effects of isoflavone intervention on human health. This study aimed to investigate whether the effects of soy isoflavones on bone and fat mass are related to an individual's equol status. We performed a 1-year double-blind, randomized trial to compare the effects of isoflavone (75 mg of isoflavone conjugates/day) with those of placebo on bone mineral density, fat mass, and serum isoflavone concentrations in early postmenopausal Japanese women who were classified based on their equol-producer phenotype. After 1 year, the isoflavone intervention significantly increased the serum equol concentration in the equol producers but not in the nonproducers. In the isoflavone group, the annualized changes in the bone mineral density of the total hip and intertrochanteric regions were -0.46% and -0.04%, respectively, in the equol producers and -2.28% and -2.61%, respectively, in the nonproducers; these values were significantly different (P<0.05 for both the regions). Significant differences were observed between the equol producers and nonproducers in the isoflavone group with regard to the annualized changes in the fat mass. No significant difference in the annualized changes in bone mineral density and fat mass was observed between the equol producers and nonproducers in the placebo group. Our data suggest that the preventive effects of isoflavones on bone loss and fat accumulation in early postmenopausal women depend on an individual's equol-producing capacity.

Soy isoflavone supplementation and fasting serum glucose and lipid profile among postmenopausal Chinese women

Long-term effects of soy-derived isoflavones on lipids remain uncertain, and few data are available on their effects on glycemic control. We examined the effects of isolated soy germ isoflavones on the changes in fasting glucose (FG) and lipids. A double-blind, randomized, placebo-controlled trial was conducted in 203 postmenopausal Chinese women aged 48 to 62 years. They were randomly assigned to receive daily doses of 500 mg calcium, and 0 mg isoflavones (placebo, n=67), 40 mg isoflavones (n=68), and 80 mg isoflavones (n=68). Serum FG, triglycerides, high-density lipoprotein, low-density lipoprotein, total cholesterol, and lipoprotein cholesterol were measured at baseline and 1 year after treatment. The primary data analysis was performed on the 203 randomized women according to the intent-to-treat principle. The last value carried forward was used for any missing data at follow-up. We observed moderate but significant favorable effects of soy isoflavones on the changes (P=0.012) and percentage of changes (P=0.031) in FG (analysis of variance). The 1-year mean (SD) differences of FG changes were -5.2 (-9.4 to -1.0) mg/dL (P=0.010) and -3.3 (-7.5 to 0.9) mg/dL (P=0.18) in the 40- and 80-mg isoflavone groups compared with the placebo group. We also noted a significant interaction between the treatment and baseline FG on the changes in FG (P=0.004). The isoflavone effects were much more significant in women with baseline FG 100 mg/dL or more than in those with FG less than 90 mg/dL. We observed little effect of soy isoflavones on changes in serum lipids among the treatment groups. One-year of soy isoflavone supplementation might have a favorable effect on FG in women, but has no significant effect on serum lipids.

Six months of isoflavone supplement increases fat-free mass in obese–sarcopenic postmenopausal women: a randomized double-blind controlled trial

The aim of this study was to verify if six months of isoflavone supplementation could increase fat-free mass (FFM) and muscle mass index (MMI=appendicular FFM/height(2)) in obese-sarcopenic postmenopausal women. Double-blind randomized study. Eighteen sarcopenic-obese women completed the study (12 on isoflavones and six on placebo). Body composition was measured by dual-energy X-ray absorptiometry. Subjects ingested 70 mg of isoflavones per day (44 mg of diadzein, 16 mg glycitein and 10 mg genestein) or a placebo for 24 weeks. The isoflavone group increased significantly appendicular (P=0.034), leg (P=0.016) FFM and MMI (P=0.037), but not the placebo group. Six months of isoflavone supplementation increased FFM and MMI in obese-sarcopenic postmenopausal women.

Cooperative effects of isoflavones and exercise on bone and lipid metabolism in postmenopausal Japanese women: a randomized placebo-controlled trial

Cooperative effects of isoflavones and exercise on bone and lipid metabolism have been exhibited in estrogen-deficient animals; however, results from clinical trials have not been published. In this study, we determined the effects of isoflavone intake and walking and their interaction on bone and lipid metabolism in postmenopausal women over 24 weeks. The bioavailability and metabolism of isoflavones (daidzein in particular) were also examined to clarify the mechanism of their bone-protective effects in humans. One hundred twenty-eight subjects were randomly assigned to 4 groups: placebo; placebo combined with walking (3 times per week); isoflavone intake (75 mg of isoflavones conjugates per day); and isoflavone combined with walking. The subjects were classified by equol status (producers or nonproducers) as identified using production of equol from daidzein in fecal culture. Bone mineral density (BMD), body composition, and serum concentrations of isoflavones were assessed. Serum high-density lipoprotein cholesterol concentration significantly increased (6.1%, P = .03), and fat mass in the whole body significantly decreased (−4.3%, P = .0003) from the baseline in the combined intervention group. There were no significant differences in BMD between baseline and postintervention in any of the treatment groups. However, the percent changes in BMD in equol producers were −0.53% and +0.13% in the sub–whole body and total hip, respectively. This was significantly different compared with −1.35 and −1.77 for the sub–whole body and total hip, respectively, in nonproducers in the isoflavone group ( P = .049 and .040, respectively). The mean serum equol concentration was significantly higher in equol producers than in nonproducers in the isoflavone groups, but not in the placebo group. The combination of isoflavones and exercise exhibited favorable effects on serum lipid and body composition of postmenopausal women. The findings of this study suggest that the preventive effects of isoflavones on bone loss depend on the individual's intestinal flora for equol production.

One-year soy isoflavone supplementation prevents early postmenopausal bone loss but without a dose-dependent effect

It is believed that soy isoflavone has much potential effectiveness on the postmenopausal status; however, the optimal dose for preventing postmenopausal bone loss still remains unclear. This open-labeled, self-controlled pilot study was undertaken to determine the effect of 1-year supplementation of different high dosages of soy isoflavone in postmenopausal Taiwanese women. Forty-three women aged 45–67 years were enrolled and randomly assigned into a control (C), 100 mg/day isoflavone (IF100) and 200 mg/day isoflavone (IF200) groups for 1 year. Dual-energy X-ray absorptiometry and other related biochemical markers of bone metabolism were measured. Results indicated that the decrease in bone mineral density (BMD) was significant for lumbar vertebrae L1–3, L1–4 and the femur neck in the C group; surprisingly, the BMD of L1–3 was significantly elevated in the IF100 group; however, there were no consistent responses in the IF200 group. No significant change except loss of the bone mineral content of Ward's triangle ( P=.003) was found in the IF200 group after treatment. The percentage change at L1–3 was less ( P=.04) in the IF200 group when compared to the IF100 group. A relatively uniform direction of bone formation in expanding the weight and area with different rates of change resulted in different BMD changes. Both indicated a change of bone formation patterns with the higher-dose supplement. A protective effect of IF100 on estrogen-related bone loss was observed. A lack of a benefit such as high safety in the IF200 group for 1-year administration was ensured and lacked undesirable side effects.

Inhibition of .ALPHA.-Glucosidase and .ALPHA.-Amylase by Flavonoids

The inhibitory activity of six groups of flavonoids against yeast and rat small intestinal alpha-glucosidases and porcine pancreatic alpha-amylase was compared, and chemical structures of flavonoids responsible for the inhibitory activity were evaluated. Yeast alpha-glucosidase was potently inhibited by the anthocyanidin, isoflavone and flavonol groups with the IC50 values less than 15 microM. The following structures enhanced the inhibitory activity: the unsaturated C ring, 3-OH, 4-CO, the linkage of the B ring at the 3 position, and the hydroxyl substitution on the B ring. Rat small intestinal alpha-glucosidase was weakly inhibited by many flavonoids, and slightly by the anthocyanidin and isoflavone groups. 3-OH and the hydroxyl substitution on the B ring increased the inhibitory activity. In porcine pancreatic alpha-amylase, luteolin, myricetin and quercetin were potent inhibitors with the IC50 values less than 500 microM. The 2,3-double bond, 5-OH, the linkage of the B ring at the 3 position, and the hydroxyl substitution on the B ring enhanced the inhibitory activity, while 3-OH reduced it.

Possible Adverse Effects of Soy Isoflavone Mixture on Pregnant and Lactating Rats and their Suckling Pups

There is general agreement that soy isoflavones can be beneficial to health in adults. However, isoflavones are well known as endocrine-disrupting chemicals. The possibility that soy foods might adversely affect the reproductive system of mothers and infants should be considered. The aim of this study was to evaluate the adverse effects of a soy isoflavone mixture on rat dams and their offspring. The rat dams were fed diets containing the isoflavone mixture (commercial name: Soyact, aglycone type) at 0, 0.25, 0.5 and 1.0 g/kg as total isoflavones from pregnancy day 5 to postnatal day 13. We found that the dietary soy isoflavone mixture decreased the dam body weights in a dose-dependent manner and that the number of pups also tended to decrease. Genistein and daidzein were detected in the blood of the dams and the stomach contents of the suckling pups. The concentrations of daidzein were higher than those of genistein. We also found the transfer of isoflavones to the fetus. The reproductive output and fetus numbers were not significantly different in the isoflavone groups compared with the control group. The number of absorbed fetuses tended to increase though not significant. Our experiments suggested that soy isoflavones have the possibility of inducing adverse effects on endocrinic functions and others in animal studies at very high doses.

Randomized clinical trial comparing conjugated equine estrogens and isoflavones in postmenopausal women: a pilot study

Objective The aim of this study was to evaluate the effects of isoflavone on the climacteric symptoms (Kupperman Menopausal index), vaginal pH, vaginal cytology (vaginal maturation index) and endometrium (evaluated by ultrasound and biopsy) in postmenopausal women. Methods It was a single-center, 6-month, randomized, double-blind, estrogen-controlled trial. Seventy-nine women were randomly assigned to one of the two treatment groups: isoflavone ( n = 40): 300 mg of the standardized soy extract with a medium dose of 120 mg isoflavones/day as glycoside and aglycone (60 mg twice a day), or estrogen ( n = 39): one capsule of 0.625 mg conjugated equine estrogens and other capsule with glucose 0.625 mg (placebo). Results After treatment, there was a decrease in the symptomatology in both estrogen and isoflavone groups. There was a significant decrease in vaginal pH, an increase in superficial vaginal cells and endometrium proliferation after 3 and 6 months of treatment in the estrogen group, but no differences were observed in the isoflavone group for these variables. Conclusions We concluded that the daily standardized soy extract with 120 mg isoflavones’ effect on symptoms was similar to that from estrogen. Soy isoflavone has no effect on endometrium and vaginal mucosa during the treatment.

‘Grasslands HF1’ red clover (Trifolium pratense L.)—a cultivar bred for isoflavone content

‘Grasslands HF1’ red clover was bred from the tetraploid cultivar ‘Grasslands Pawera’, with selection aimed at increasing the concentration of the isoflavone group, formononetin plus its glyco‐side ononin. Selection for two generations resulted in the concentration in leaves being raised to about 50% above that of ‘Pawera’, when harvested from sown rows. The level of total isoflavones increased by about 17%. The levels of three other isoflavone groups were not changed significantly during the selection of ‘HF1’ from ‘Pawera’. However, comparisons with the cultivar ‘Grasslands G27’ bred earlier from ‘Pawera’ for decreased level of formononetin, showed larger and more significant differences between these two extreme cultivars in the levels of most isoflavones.

Preparative column chromatography of four groups of isoflavones from soybean cake

Various adsorbents and solvent systems were compared with respect to the separation efficiency of four classes of isoflavones, malonylglucosides, acetylglucosides, glucosides and aglycones, in soybean cake by preparative column chromatography. The various fractions of isoflavones collected from column were monitored by HPLC. Soybean cake was found to contain malonylglucosides (803.70 μg/ml), acetylglucosides (85.57 μg/ml), glucosides (728.25 μg/ml) and aglycones (53.02 μg/ml). Both malonylglucosides and glucosides were separated using Diaion HP-20 as adsorbent and a solvent system of deionized water-ethanol with a ratio of 85:15 (v/v) and 73:27 (v/v), respectively. Whereas, both acetylglucosides and aglycones were separated using silica gel as adsorbent and a solvent system of n-hexane-isopropanol-ethanol (8:9:1, v/v/v). A total amount of 244.26, 21.25, 179.04 and 11.88 μg/mg were obtained for malonylglucosides, acetylglucosides, glucosides and aglycones, respectively.

Effects of soy isoflavones on endothelial function in healthy postmenopausal women

To evaluate the effects of soy isoflavone administration on endothelial function in healthy postmenopausal women. Sixty naturally postmenopausal women were randomly assigned to receive isoflavone or placebo tablets for 6 months. Endothelium-dependent vasodilatation was measured by brachial reactivity technique along with levels of plasma soluble intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, P-selectin and soluble thrombomodulin, von Willebrand factor, and tissue plasminogen activator. Differences between endothelium-dependent and endothelium-independent vasodilatation were assessed by evaluating brachial reactivity parameters after reactive hyperemia and after sublingual administration of nitroglycerin; furthermore, in the active group, the effect of isoflavones was also evaluated during the intra-arterial infusion of N-monomethyl-L-arginine. Serum levels of lipids [high-density lipoprotein and low-density lipoprotein cholesterol, triglycerides and lipoprotein(a)] and hemostatic factors (prothrombin, fibrinogen, plasminogen activator inhibitor-1, and fibrin D-dimer) were also measured. To confirm the absorption of isoflavones, their blood concentrations were determined. Isoflavone treatment versus placebo was associated with a significant improvement in endothelium-dependent vasodilatation but had no impact on endothelial-independent arterial diameter and flow. Intra-arterial infusion of N-monomethyl-L-arginine inhibited the significant effect of isoflavones on endothelium-mediated vasodilatation. Furthermore, isoflavone group experienced statistically significant reductions in plasma concentrations of ICAM-1, VCAM-1, and E-selectin. Levels of soluble thrombomodulin, von Willebrand factor, tissue plasminogen activator, lipids, and hemostatic factors did not change significantly throughout the study in both groups. Our findings suggest a positive influence of soy isoflavones on endothelial function in healthy postmenopausal women as evidenced by an improvement in endothelium-dependent vasodilatation and a reduction in plasma adhesion molecule levels.

Antioxidant Properties of Soybean Isoflavone Extract and Tofu in Vitro and in Vivo

Isoflavones in soybean were extracted in the crude form using 80% food-grade ethanol at 80 degrees C for 6 h and followed by concentration and dehydration. The soy extract contained isoflavones primarily in the forms of glucosides. In vitro antioxidant activities of the soy extract containing 20-500 ppm isoflavones were conducted using a Rancimat method. The results showed that soy isoflavone extract had strong in vitro antioxidant activity. There was a dose-dependent response for the in vitro antioxidant activity at the lower concentrations but not at the higher concentrations. In vivo antioxidant property was determined by measuring the antioxidant enzymes, superoxide dismutase, and catalase in various organs of rats that were fed with diets containing partially oxidized oil and various levels of isoflavones for up to 24 weeks. Neither short-term (8 weeks) feeding nor low isoflavone content (50 ppm) induced changes in superoxide dismutase or catalase activities in rats. Only diets containing high isoflavone contents (150 and 250 ppm) showed obvious elevated enzymatic levels in various organs. In addition, a laboratory-prepared tofu containing approximately 50 ppm isoflavones had better effects than the soy extract with the 250 ppm isoflavone group, which indicated that molecules other than isoflavones may have a synergistic effect on in vivo antioxidant enzyme inductions of tofu.

Soy Isoflavone Supplementation Alleviates Oxidative Stress and Improves Systolic Blood Pressure in Male Spontaneously Hypertensive Rats

The aim of this study was to investigate the protective effect of isoflavone against hypertension, via the mitigation of oxidative stress and prevention of nitric oxide (NO, a potent vasodilator) reduction, in spontaneously hypertensive rats (SHR). The 8 wk-old male SHR were divided into two groups, and fed a casein-based high fat diet (120 g fat, 1 g cholesterol/kg diet) for 30 d, either with or without 10 g of soy powder (containing 31.2% of isoflavones)/kg. During the 30-d study period, tail systolic blood pressures (BP) in the control SHR group increased, from 162.4 +/- 2.3 to 177.9 +/- 5.4 mmHg (p<0.05), while the isoflavone-supplemented group benefited from a clear antihypertensive effect (160.1 +/- 1.8 to 160.2 +/- 4.9 mmHg). The serum NO and total radical trapping antioxidant potential (TRAP) were elevated in the isoflavone group. The isoflavone group also experienced a significant decrease in oxidative DNA damage in leukocytes, using comet assay. DNA damage correlated positively with incremental BP during the study, and systolic BP at the end of the study (p<0.01). Our results indicate that soy isoflavone has an antihypertensive effect, possibly through the amelioration of oxidative stress, and the augmentation of NO production, in SHR.

Effects of phytoestrogens genistein and daidzein on production of human chorionic gonadotropin in term trophoblast cells in vitro

Background. Phytoestrogens are a diverse group of non-steroidal compounds that occur naturally in many plants. Because they possess a ring system similar to estrogens they are able to bind to estrogen receptors in humans. In the present study we tested the effects of the phytoestrogens genistein and daidzein on the production of human chorionic gondaotropin (hCG) in isolated trophoblast cells of term placentas in vitro.Methods. Genistein and daidzein were incubated at different concentrations with trophoblast cells. Untreated cells were used as controls. At designated times aliquots were removed and tested for hCG production.Results. Production of the protein hormone hCG was influenced by the phytoestrogens genistein and daidzein in trophoblast cells. We found a significant decrease of hCG production in genistein- and daidzein-treated trophoblast cells that was concentration-dependent. Compared with daidzein, genistein seems to be a more efficient inhibitor of the production of hCG.Conclusion. The phytoestrogens genistein and daidzein can reduce hCG production in human term trophoblasts. Both phytoestrogens belong to the group of isoflavones, which are enriched in soy-containing foods and are widely consumed by humans for putative beneficial health effects. Because both phytoestrogens have inhibitory effects on hCG production during pregnancy, exposure to these estrogen-like compounds during sensitive periods of development may have the capacity to alter the function of the reproductive system and thereby influence fertility.

Morphogenesis-dependent accumulation of phytoestrogenes in Genista tinctoria in vitro cultures

Liquid root, shoot, embryo and suspension cultures of Genista tinctoria were established in SH-modified media to accumulate large amounts of isoflavones of phytoestrogenic activity. In comparison with the herb of G. tinctoria, shoot, embryo and suspension cultures had much higher isoflavone content (six to nine times). The isoflavone group accumulated by the above cultures was composed of 14 compounds with the clear domination of genistin. None of the cultures produced simple flavones; possible causes are discussed. The relations between the compounds, which belong to the metabolic pathway of genistein and daidzein during the growth of all culture types are presented. Root cultures accumulated large amounts of a single metabolite, isoliquiritigenin (978.4 mg/100 g DW), an isoflavone precursor, which is absent in the intact plant. In all culture types, isoflavones were accumulated as intracellular metabolites. The ratio of isoflavone accumulation was influenced greatly by tissue differentiation. Shoot, embryo and suspension cultures showed a negative relation between the process of organogenesis and the accumulation of aglycones and glucosides. The highest isoflavone accumulation was observed in suspension cultures in which HPLC analysis identified 9414.7 mg of genistin per 100 g DW. However, there was a positive relation between the amount of genistin esters produced and the process of morphogenesis. The highest concentration of genistin malonate (1008.2 mg/100 g DW) and genistin acetate (118.95 mg/100 g DW) was observed in shoot cultures.

SOY ISOFLAVONE TABLETS REDUCE OSTEOPOROSIS RISK FACTORS AND OBESITY IN MIDDLE‐AGED JAPANESE WOMEN

1. This study examines whether the supplementation of isoflavones (ISO) exerts beneficial effects on the bone mineral density (BMD) measured by dual energy X-ray absorptiometry (DEXA). 2. Eighty-one healthy Japanese pre- and postmenopausal women were randomly assigned to the following two groups taking either ISO (100 mg) tablets (ISO group) or placebo tablets (P group) containing vitamins C (25 mg) and E (5 mg) daily for 24 weeks in a double-blind placebo controlled parallel design. 3. Seventy women completed the intervention study (34 on ISO, 36 on P), only ISO group was proven to increase significantly BMD (P < 0.05 vs before) and to significantly decrease body fat measured by the DEXA (P < 0.0001 vs before and P < 0.05 vs P group), while BMI was maintained in ISO group despite significant BMI increase in P group. Thus, percent changes in BMI were significantly different between ISO and P groups (P < 0.05) 24 weeks after the intervention. 4. This prospective DEXA study confirmed a long-term ISO supplementation, 100 mg/day could not only prevent menopausal bone resorption but also increase BMD and decrease body fat concomitantly with BMI reduction. Enough ISO supplementation may contribute to the risk reduction of osteoporosis and obesity and, thus to overall health promotion in menopausal women.

SOY ISOFLAVONES IMPROVE BONE METABOLISM IN POSTMENOPAUSAL JAPANESE WOMEN

1. This study examines whether the supplementation of isoflavones (ISO) exerts beneficial effects on serum and urinary biomarkers of bone metabolism. 2. A total of 102 women were randomly assigned to three groups taking either ISO (40 mg) tablets, tablets containing vitamins C (25 mg) and E (5 mg) (V) or placebo tablets (vehicle only) (P) daily for 4 weeks, in a double-blind parallel placebo controlled design. 3. Among the 67 women who completed the study (24 on ISO, 24 on V, 19 on P), only ISO tablets were proven to decrease significantly urinary deoxypyridinoline (Dpd) excretion (P < 0.05 vs before), a specific biomarker of bone resorption, but there was no significant difference in serum bone gamma-carboxyglutamic acid-containing protein (BGP), a specific serum biomarker of bone formation. 4. Among the 67, 25 women were postmenopausal (8 on ISO, 12 on V, 8 on P) and only ISO tablets decreased significantly urinary Dpd excretion (P < 0.05 vs before) in them. The reduction rate of Dpd in ISO group was also significantly greater than that in P group (P < 0.01). 5. Dietary supplementation of vitamins C 25 mg and E 5 mg did not affect urinary Dpd.

The Hypoglycemic Effects of Soy Isoflavones on Postmenopausal Women

Soy isoflavones have many effects similar to those of estrogen and have become popular among postmenopausal women as an alternative for hormone replacement therapy (HRT). The purpose of this study was to determine the effects of soy isoflavones on glucose, insulin, and lipid profiles in postmenopausal Taiwanese women. We conducted a randomized, double-blind, active placebo-controlled clinical trial to compare the effects of isoflavones with estrogen replacement therapy (ERT) on blood glucose, insulin, and lipid profiles in postmenopausal Taiwanese women. Thirty postmenopausal Taiwanese women were randomly assigned to two groups, and each received treatment for 6 months. The isoflavone group received 100 mg isoflavone soft capsules, 300 mg calcium, and a blank vitamin capsule per day. The estrogen active control group received 0.625 mg conjugated estrogen, 300 mg calcium, and blank isoflavone soft capsules per day. We measured baseline levels of fasting blood sugar, insulin, lipid profiles, and isoflavone concentrations prior to the study and repeated the same measurements every 3 months for a total duration of 6 months. Two-way ANOVA revealed that fasting glucose (p < 0.001) and insulin (p < 0.005) levels were significantly affected by estrogen and isoflavone treatments after 6 months. For the isoflavone group, the average blood genistein concentration was 6-10 times higher than those of the estrogen group. Within the same periods, the fasting blood glucose was reduced to 83% and 85% of the baseline levels, and insulin was reduced to 56% and 67% of the baseline levels, respectively, in the estrogen and isoflavone groups. Soy isoflavones (100 mg) and 0.625 mg conjugated estrogen equally lower fasting blood glucose and insulin levels in postmenopausal women.

Effect of oral chronic isoflavones supplementation on male rat sexual performances and sexual hormone plasma levels

The aim of our study was to evaluate how a chronic isoflavones oral supplementation could affect male rat sexual behavior in relationship to cause eventual change in plasma sexual hormone concentrations. Isoflavones were administered in the form of a standardized dry extract of soybeans. Three groups of 20 sexually experienced male rats were consecutively treated with saline 2 ml, or isoflavones 0.4 mg/kg(-1) or 0.8 mg/kg(-1) soybean dried extract via gastric tube for 40 days. No significant differences were found as regards sexual performances of the three studied groups at the baseline levels nor at the end of the study: in relationship to the base-line value, only mount frequency increased in the control group (z = -2.047, p = 0.041), while intromission frequency in the high dosage isoflavones group (z = -2.484, p = 0.13). At the base-line test 23.08% of rats in each group were not able to conclude their performance in the standard time, while at the end of the study only 15.38% of the control group rats were not able to do this. No significant difference has been observed as regards FSH, progesterone, androstenedione plasma levels, either between groups or between baseline and study end. Slight differences were found regards LH and testosterone plasma level.