Effects Of Soy Isoflavones Research Articles

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‐derived isoflavones inhibit the growth of adult T‐cell leukemia cells in vitro and in vivo

Adult T-cell leukemia occurs in human T-lymphotropic virus type I-infected individuals and is endemic to the south-western area of Kyushu in Japan. In this communication, we examined the effect of soy isoflavones on the growth of adult T-cell leukemia cells in vitro and in vivo. In the in vitro study, daidzein and genistein but not glycitein significantly inhibited the proliferation of ED-40515 and Hut102 cells in a dose-dependent manner. Among the isoflavones studied, genistein had the highest growth-inhibitory effect; however, genistein did not exert an apparent growth-inhibitory effect on Jurkat and Molt-4 cells, which were non-adult T-cell leukemia cells. Genistein prevented the G(1)/S or G(2)/M transition at 3 and 10 or 30 microM, respectively. Genistein upregulated p21 protein expression together with p53 accumulation. In addition, treatment with 30 microM genistein strongly induced phosphorylation of checkpoint kinase (CHK) 2 and p53 at serines 15, 20 and 37. Caffeine, an inhibitor of ataxia-telangiectasia mutated protein kinase, alleviated the genistein-induced p53 and CHK2 phosphorylation, suggesting the involvement of DNA damage at 30 microM. However, marked phosphorylation of CHK2 and p53 could not be detected at 3 and 10 microM genistein. These data indicate that genistein has biphasic growth-inhibitory properties. The in vivo studies demonstrated that soy-derived isoflavones significantly inhibit ED-40515 cell growth and infiltration into various organs in non-obese diabetic severe combined-immunodeficiency common gamma-chain knockout mice. Taken together, it is evident that soy isoflavones might serve as a promising compound for the treatment of adult T-cell leukemia.

The hype surrounding nutraceutical supplements: Do consumers get what they deserve?

g f a The general public and the media have become increasngly interested in nutraceuticals over the past two decades, nd this has coincided with a general interest in health ssues. This has resulted in increasing usage of commerially available nutraceutical products and their food ources. The market for nutraceuticals is rapidly expanding nd is projected to grow at a rate of 9.9% annually during he period 2002–2007, reaching $75 billion in 2007 [1], and t is expected to reach 5% of the total food bills in developed ountries. The large growth in demand for the wide range of comercially available nutraceuticals has come at a time when ealth-conscious consumers of all ages are also increasingly upplementing their diets with nutraceuticals, as these are ecoming “life style” treatments. The perceived health benfits mean that increasingly they are being used for prevenion or treatment of often serious and chronic health issues uch as arthritis and cardiovascular diseases. However, in ddition to promoting their use, this “hype” associated with he increase in use may expose consumers to often inherent roblems of quality and potentially increase the risk of ndividuals self-medicating for serious disease states instead f seeking the correct medical attention. Although nutraceuticals would generally appear to be afe at normal therapeutic levels, several instances of aderse effects have been reported, and minor effects such as hose seen with melatonin (drowsiness) and creatine (headches) are often reported [2]. More serious adverse effects ave been suggested for glucosamine interfering with insuin secretion, but recently shown to be ill founded, and ossible teratogenic effects of soy isoflavones, seen only in nimals [3]. A limited number of drug interactions has also een reported, such as carnitine deficiency shown with so-

Effects of Soy Isoflavone on Performance, Meat Quality and Antioxidative Property of Male Broilers Fed Oxidized Fish Oil

This study was conducted to determine the effect of dietary soy isoflavone (ISF, 0 and 20 mg/kg) on performance, meat quality and antioxidative property in male broilers. Six replicates of 45 birds (42 d old) were used for each treatment. The birds were fed soybean meal-free diets containing 3% oxidized fish oil (acid value, 6.76 mg potassium hydroxide/g; and peroxide value, 6.18 meq/kg) for 3 wk. The results showed that average daily gain, feed intake, feed conversion and carcass traits were not affected by soy 1SF. Compared with the control group, breast muscle color redness value and water holding capacity were increased (p<0.05) by ISF supplementation. The activity of plasma catalase was increased by supplementing with 20 mg ISF/kg diet. In breast muscle, Broilers fed 20 mg ISF/kg had decreased production of malondialdehyde and lactic acid. The ISF supplementation elevated total antioxidative capacity and activities of total superoxide dismutase and glutathione peroxidase. The results indicated that dietary ISF could increase redness and water holding capacity of meat, and antioxidative property of meat in male broilers fed oxidized fish oil diet.

Does the Effect of Soy Phytoestrogens on Bone in Postmenopausal Women Depend on the Equol-Producing Phenotype?

Plant-derived phytoestrogens are considered to be an alternative therapy for the prevention and control of bone loss in postmenopausal women. However, there are contradictory findings among clinical studies in the efficacy of soy isoflavones on bone metabolism in postmenopausal women. Inter-individual differences in gut bacteria metabolism of isoflavones to produce equol (the equol-producing phenotype) might partly explain these discrepancies. Among several trials in this area of research, few studies took the equol-producing phenotype into consideration, and those studies support the importance of this phenotype in the effect of soy isoflavones on bone health among post-menopausal women. Greater consideration of the equol-producing phenotype in the design of studies investigating the effect of soy isoflavones on bone health of postmenopausal women may provide more useful information.

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.

Protective Effect of Soy Isoflavones and Activity Levels of Plasma Paraoxonase and Arylesterase in the Experimental Nonalcoholic Steatohepatitis Model

Nonalcoholic steatohepatitis (NASH) is characterized by diffuse fatty infiltration in the liver and ballooning degeneration and inflammation in hepatocytes. We aimed to study the protective effect of soy isoflavones on experimental NASH and their effects on plasma paraoxanese and arylesterase levels in rats. Twenty-eight male rats were divided into four groups: Group 1 (n=7) received an isocaloric normal diet for 8 weeks, Group 2 (n=7) was fed an isocaloric basal diet plus oral soy isoflavone for 8 weeks (100 mg/kg in diet), Group 3 (n=7) received a special diet that was methionine and choline deficient (MCD) and rich in fat for 8 weeks, and Group 4 (n=7) was fed a special diet that was MCD and rich in fat plus oral soy isoflavone for 8 weeks (100 mg/kg in diet). Blood samples were collected to measure plasma malondialdehyde (MDA), paraoxanese, and arylesterase and biochemical parameters. Tissue samples were duly taken for histopathological examination and measurement of tissue MDA levels. Plasma MDA levels were higher in Group 3 than in Groups 1, 2, and 4 (P <0.01, P <0.05, and P <0.05 respectively). Liver tissue MDA levels were also significantly higher in Group 3 compared to Groups 1, 2, and 4 (P <0.001, P <0.001, and P <0.05 respectively). A significant decrease was found in the plasma and liver tissue MDA levels in Group 4 compared to Group 3 (P <0.05 and P <0.05, respectively). The activity levels of plasma paraoxanase and arylesterase were significantly higher in Group 2 than in Groups 1 and 3 (P <0.05 and P <0.01, respectively). Also, the plasma paraoxanase and arylesterase levels were significantly higher in Group 4 compared to Groups 1 and 3 (P <0.05 and P <0.01, respectively). A significant reduction was observed in Group 4 in steatosis, inflammation, necrosis, and fibrosis compared to Group 3 (P <0.05 for each). We conclude that soy isoflavones seem to be effective in preventing liver damage by decreasing lipid peroxidation in the NASH model induced by a MCD diet. They stimulate and increase the activity of the antioxidative paraoxanase enyzme while decreasing the total cholesterol and triglyceride levels.

1624: The Effects of Soy Isoflavone and Curcumin on the Serum PSA Level of the Biopsy-Negative Men: A Randomized, Double-Blinded, Placebo-Controlled Study

1624: The Effects of Soy Isoflavone and Curcumin on the Serum PSA Level of the Biopsy-Negative Men: A Randomized, Double-Blinded, Placebo-Controlled Study

Soy isoflavones lower serum total and LDL cholesterol in humans: a meta-analysis of 11 randomized controlled trials

Background:Clinical trials have reported the cholesterol-lowering effects of soy protein intake, but the components responsible are not known.Objective:This meta-analysis was primarily conducted to evaluate the precise effects of soy isoflavones on lipid profiles. The effects of soy protein that contains enriched and depleted isoflavones were also examined.Design:PUBMED was searched for English-language reports of randomized controlled trials published from 1990 to 2006 that described the effects of soy protein intake in humans. Eleven studies were selected for the meta-analysis.Results:Soy isoflavones significantly decreased serum total cholesterol by 0.10 mmol/L (3.9 mg/dL or 1.77%; P= 0.02) and LDL cholesterol by 0.13 mmol/L (5.0 mg/dL or 3.58%; P< 0.0001); no significant changes in HDL cholesterol and triacylglycerol were found. Isoflavone-depleted soy protein significantly decreased LDL cholesterol by 0.10 mmol/L (3.9 mg/dL or 2.77%; P= 0.03). Soy protein that contained enriched isoflavones significantly decreased LDL cholesterol by 0.18 mmol/L (7.0 mg/dL or 4.98%; P< 0.0001) and significantly increased HDL cholesterol by 0.04 mmol/L (1.6 mg/dL or 3.00%; P= 0.05). The reductions in LDL cholesterol were larger in the hypercholesterolemic subcategory than in the normocholesterolemic subcategory, but no significant linear correlations were observed between reductions and the starting values. No significant linear correlations were found between reductions in LDL cholesterol and soy protein ingestion or isoflavone intakes.Conclusions:Soy isoflavones significantly reduced serum total and LDL cholesterol but did not change HDL cholesterol and triacylglycerol. Soy protein that contained enriched or depleted isoflavones also significantly improved lipid profiles. Reductions in LDL cholesterol were larger in hypercholesterolemic than in normocholesterolemic subjects.

Soy isoflavones enhance radiotherapy in a metastatic prostate cancer model

We previously reported that genistein, the bioactive isoflavone of soybeans, acts as a radiosensitizer for prostate cancer. Pretreatment of tumor cells with genistein potentiated radiation-induced killing in vitro and in orthotopic models in vivo. However, pure genistein promoted increased lymph node metastasis, when administered alone in vivo. We investigated in vitro and in vivo the effects of soy isoflavones (genistein, daidzein and glycitein) as soy pills of similar composition are used in human interventions but not pure genistein. Soy isoflavones inhibited cell survival and potentiated radiation cell killing in PC-3 tumor cells, in vitro. Increased cell killing correlated with inhibition of antiapoptotic molecules Bcl-xL and survivin, upregulation of proapoptotic Bax molecule and PARP cleavage, suggesting activation of apoptotic pathways. In vivo, using the PC-3 orthotopic metastatic mouse model, soy isoflavones and prostate tumor irradiation led to enhanced control of primary tumor growth and metastasis, as observed with pure genistein and radiation. Interestingly, treatment with soy isoflavones did not increase metastasis to para-aortic lymph nodes in contrast to the consistent increase caused by pure genistein. Histologically prostate tumors, treated with soy isoflavones and radiation, showed tumor destruction and in situ tissue alterations, comparable with genistein and radiation effects. However, genistein, but not soy isoflavones, caused induction of HIF1-alpha in prostate tumors, suggesting that induction of hypoxia by pure genistein could contribute to increased metastasis. Our studies demonstrate the safety and potential role of soy isoflavones for enhancing the therapeutic effect of radiotherapy in prostate cancer.

Soy isoflavones and saponins provide modest protection from colon cancer in a mouse model

Colon cancer risk is highly correlated with dietary factors. We have systematically investigated soy protein and bioactive compounds found in soy, isoflavones (IF) and saponins (SAP), using a mouse model of colon cancer. In previous studies we found soy IF were protective of azoxymethane (AOM)-induced tumors in C57Black/J mice and that soy protein reduced tumor burden compared to casein. In two experiments we attempted to verify these findings and separate the effects of SAP from soy protein and IF. In study 1, female, ovariectomized C57B/J mice were fed diets containing soy protein depleted of IF and SAP, soy+IF, soy+SAP, or soy+IF+SAP. In study 2, similar mice were fed diets containing soy flour prepared from soybeans that were high, moderate or low in naturally occurring IF and SAP. All mice were treated once per wk for 6 wks with IP injection of 10 mg AOM/kg body weight and continued on the study for 35 wks. At termination all organs were removed and weighed and colon examined for tumors. Tumor incidence in study 1 was 46, 46, 30 and 45% for mice fed soy, soy+IF, soy+SAP and soy+IF+SAP, hence a slight decrease in mice fed SAP but not IF. In study 2, tumor incidence was 33, 29 and 21% in mice fed soy flour with low, moderate and high IF+SAP, hence a slight negative correlation with IF+SAP concentration. Overall, the protective effects of soy IF and SAP on colon tumor incidence were modest in this animal model. However, preliminary evidence suggests IF may inhibit cyclooxygenase-2 expression in mouse colon thereby providing a potential protective mechanism. Funding provided by USDA-CSREES.

Possible Link Between NO Concentrations and COX‐2 Expression in Systems Treated with Soy‐Isoflavones

The production of nitric oxide (NO) emerges as an essential determinant in auto- and paracrine signaling. NO is known to be generated under inflammatory conditions, carcinogenesis, and circulatory shock. The large amount of NO produced in response to cytokines plays an important role in inflammatory conditions. Cyclooxygenase (COX), the central enzyme in prostanoid biosynthesis, is involved in the first step of prostanoid synthesis from arachidonic acid. The reported studies to evaluate the relationship between NO and COX-2 have revealed both inhibitory and stimulatory effects of NO on COX-2 expression. Genistein, one of soy-isoflavones, is a polyphenolic flavonoid and a potent antioxidant and anti-inflammatory agent. In the present article, the effect of soy-isoflavones on NO production and COX-2 gene expression was examined. NO production by soy-isoflavones was greatly increased even though eNOS and iNOS expression were not different from nontreated control. The increment of NO was accompanied with the elevated expression of COX-2 and the concentrations of PGE2. The COX-2 stimulatory effect of soy-isoflavones appeared to be modulated by ERK-1 and -2 and p38. In mammalian cancer system, incubation with the NO donor sodium nitroprusside (SNP) resulted in a slight upregulation of COX-2, and cotreatment with genistein decreased COX-2 expression possibly by the activation of AMP-activated protein kinase (AMPK).

Suppressive effects of soy isoflavones on aberrant crypt foci formation and expression of cyclooxygenase‐2 are not dose‐dependent in colonic cancer model rats fed fructooligosaccharide

Suppressive effects of soy isoflavones on aberrant crypt foci formation and expression of cyclooxygenase‐2 are not dose‐dependent in colonic cancer model rats fed fructooligosaccharide

Regulatory Behavior and Skin Temperature in Mid-Aged Male Rats on Three Different Isoflavone-Containing Diets

Soy isoflavones, the most abundant phytoestrogens, are known as endocrine modulators and appear to be an effective treatment in some women during perimenopause when symptoms such as hot flashes may be reduced. This study examined the effects of dietary soy isoflavones on regulatory behaviors such as body weight, food and water intake, and skin tail temperature by feeding male Long-Evans rats one of the three standard chows (Phyto-free, Phyto-200, and Phyto-600) containing approximately 10-15 ppm, 200 ppm, and 600 ppm of isoflavones, respectively. In an apparent dose-dependent manner, body weight was decreased as a function of increasing isoflavone levels in the diets. The average skin tail temperature of Phyto-600-fed rats (25.5 degrees C) was significantly lower than Phyto-free (27.5 degrees C) values by approximately 2 degrees C. The rats on the Phyto-200 diet (26.6 degrees C) displayed a temperature in between the Phyto-free and Phyto-600 values. Similar to the body weight results, skin tail temperature was decreased in an apparent dose-dependent manner as a function of increasing isoflavone concentrations in the diets. These results suggest that consumption of soy isoflavones alters regulatory behaviors (such as body weight and food and water intake) and skin temperature regulation that may help explain, in part, the beneficial effects of soy isoflavones on obesity and hot flashes in humans.

Enhanced estrogenic responses and sensitivity to azoxymethane following dietary soy isoflavone supplementation in older female rats

Soy isoflavones are popular supplements among middle-aged and older women based on their potential protection against cancer and their use as alternative hormone replacement therapy. The purpose of this study was to investigate the effects of dietary soy isoflavones on early stage colon cancer in various ages of female rats. Young (1 month), mature (11 month) and old (22 month) female Fisher 344 rats were fed either the control diet or a diet containing 0.4% soy isoflavone isolate for 1 week, injected once with 20 mg/kg azoxymethane (AOM) and maintained on the diets for another 15 weeks. The concentration of isoflavones in the diet was 2 g/kg diet, composed of 1.2 g/kg genistin, 0.7 g/kg daidzin and 0.1 g/kg other isoflavones including glycitin, acetylgenistin, acetyldaidzin, genistein, daidzein, and glycitein. There was no difference over all ages in the development of preneoplastic colonic aberrant crypt foci between rats fed the soy compared to the control diet, indicating that the soy diet did not provide protection against early stage colonic carcinogenesis. On the contrary, several adverse effects of soy supplementation in female AOM-treated rats were observed. Soy-supplemented rats had greater weight loss and a slower recovery of body weight following the AOM injection compared to rats fed the control diet and these changes increased with age. Five of the 21 rats fed the soy supplement died before the end of the experiment while all animals on the control diet survived to term. The density of normal crypts lining the colonic mucosa was reduced in rats fed the soy compared to control diet, indicating gastrointestinal damage. Uterine weights, serum estradiol and serum isoflavone levels were increased in mature and old female rats fed the soy-supplemented diets compared to age-matched controls, suggesting an increasing estrogenic response with age to isoflavone supplementation. These adverse effects of soy isoflavones in aged female animals need further examination because women, and particularly older women, are the prime target population for consumption of soy supplements.

Lack of Estrogenic or Antiestrogenic Actions of Soy Isoflavones in an Avian Model: The Japanese Quail

Isoflavones are soy compounds that possess weak estrogenic and antiestrogenic activities. In addition, phytochemicals, including isoflavones, may play a role in regulating seasonal reproductive cycles. As soy is a common constituent in poultry diets, the effect of these compounds on the reproductive system of production birds may be of concern. The present study examined the putative effects of soy isoflavones supplemented into the diet at 1 and 5% using endpoints of growth and reproduction in the Japanese quail. Isoflavones did not exert an effect on growth, feed intake, growth:feed, or the weight of the estrogen-sensitive immature oviduct in female quail. Furthermore, isoflavones did not influence the growth of the oviduct stimulated by exogenous estradiol. Similarly, isoflavones did not influence growth, feed intake, or growth:feed in male quail. However, isoflavones at 1%, but not 5%, in the diet reduced photoperiod-induced testis development 40% vs. control. In contrast, isoflavones did not influence testis regression stimulated by exogenous estradiol in sexually maturing male quail. The present results suggest that isoflavones may exert modest endocrine disruptor-like effects on reproduction in male, but not female, quail.

Effects of soy isoflavones and phytate on homocysteine, C-reactive protein, and iron status in postmenopausal women

Soy protein or its components may protect against the atherosclerotic cardiovascular disease (CVD) risk factors total homocysteine (tHcy), C-reactive protein (CRP), and excess body iron, which generally increase with menopause. The primary objective of this study was to determine the independent effect of the soy protein components isoflavones and phytate on CVD risk factors in postmenopausal women. The secondary objective was to identify factors [blood lipids, oxidative stress indexes, serum ferritin, plasma folate, plasma vitamin B-12, and body mass index (BMI)] contributing to tHcy and CRP concentrations. In a double-blind, 6-wk study, 55 postmenopausal women aged 47-72 y were randomly assigned to 1 of 4 soy protein (40 g/d) isolate treatments: native phytate and native isoflavone (n = 14), native phytate and low isoflavone (n = 13), low phytate and native isoflavone (n = 14), or low phytate and low isoflavone (n = 14). We measured iron indexes, tHcy, CRP, and BMI. Soy protein with native phytate significantly reduced tHcy (P = 0.017), transferrin saturation (P = 0.027), and ferritin (P = 0.029), whereas soy protein with native isoflavones had no effect on any variables. At baseline, BMI was highly correlated with tHcy (r = 0.39, P = 0.003) and CRP (r = 0.55, P < 0.0001), whereas HDL cholesterol was correlated with CRP (r = -0.30, P = 0.02). Multiple regression analysis showed that LDL cholesterol and BMI contributed significantly (R2= 19.9%, P = 0.003) to the overall variance in tHcy. Consuming phytate-rich foods and maintaining a healthy weight may reduce atherosclerotic CVD risk factors in postmenopausal women.

Soy isoflavones with supplemental calcium provide protection against the loss of bone mass and influence insulin-like growth factor (IGF)-I after ovariectomy in rat

To compare the effects of soy isoflavone with supplemental calcium to soy isoflavone or Ca alone on preservation of bone mineral density (BMD) and the expression of insulin-like growth factor (IGF)-I. Sprague-Dawley (SD) female Rats, 6 months old, were ovariectomized and randomized into five groups: sham-operated group (n = 10) or ovx (n = 40) group. Shams were fed a 3.272 g/kg Ca diet. Ovx rats were randomized to a 3.272 g/kg Ca diet alone (OVX) or with soy isoflavone (SI) extract (37.95 mg/kg.bw) or to a supplemental Ca diet (Ca, 4.676 g/kg) alone or a supplemental Ca diet with the isoflavone extract (SI + Ca) for 12 weeks. BMD of femur was measured by scanner of bone mineral density. The level of IGF-1 mRNA expression was measured by reverse transcriptase-polymerase chain reaction (RT-PCR), respectively. There was no significant difference between group Sham (0.267 +/- 0.008) and group SI + Ca (0.263 +/- 0.007) g/cm(2) (P > 0.05) on femur BMD of distal end. Femur BMD of distal end in group Sham and group SI + Ca was greater (P < 0.05) as compared to group OVX (0.245 +/- 0.005) g/cm(2), SI (0.258 +/- 0.011) g/cm(2) or Ca (0.255 +/- 0.004) g/cm(2), P < 0.05. The liver tissue IGF-1 mRNA contents (IGF-1 cDNA/B-actin cDNA) were significantly decreased in group Sham (0.200 +/- 0.023) g/cm(2), SI (0.278 +/- 0.019) g/cm(2), Ca (0.302 +/- 0.026) g/cm(2) or SI + Ca (0.231 +/- 0.025) g/cm(2) as compared to group OVX (0.362 +/- 0.031) g/cm(2), P < 0.05; The liver tissue IGF-1 mRNA contents (IGF-1 cDNA/B-actin cDNA) were significantly decreased in group SI + Ca (0.231 +/- 0.025) g/cm(2) compared to group SI (0.278 +/- 0.019) g/cm(2) and Ca (0.302 +/- 0.026) g/cm(2), P < 0.05. Soy isoflavones combined with supplemental Ca are more protective against the loss of femur BMD than soy isoflavones or supplemental Ca diet alone. The dose of SI (37.95 mg/kg.bw) might significantly restrain the rising of the liver tissue IGF-1 mRNA contents caused by ovariectomy.

Soy Protein, Isoflavones, and Cardiovascular Health

This editorial summarizes the recent American Heart Association (AHA) Science Advisory on soy protein and isoflavones (phytoestrogens) published in the February 21, 2006, issue of Circulation .1 Soy protein and isoflavones have gained considerable attention for their potential role in improving risk factors for cardiovascular disease. This scientific advisory report assesses the more recent work published on soy protein and its component isoflavones. In 22 randomized trials, isolated soy protein with isoflavones compared with milk or other proteins decreased LDL cholesterol concentrations in most studies; the average effect was approximately 3%. This reduction is very small compared with the large amount of soy protein tested in these studies, averaging 50 g, approximately half the usual total daily protein intake. No significant effects were evident on HDL cholesterol, triglycerides, lipoprotein(a), or blood pressure. Among 19 studies of soy isoflavones, the average effect on LDL cholesterol and other lipid risk factors was nil. Soy protein or isoflavones have not been shown to lessen vasomotor symptoms of menopause, and results are mixed regarding slowing of postmenopausal bone loss. The efficacy and safety of soy isoflavones for preventing or treating cancer of the breast, endometrium, and prostate are not established; evidence from clinical trials is meager and cautionary as regards a possible adverse effect. For this reason, use of isoflavone supplements in food or pills is not recommended. Thus, earlier research indicating that soy protein compared with other proteins has clinically important favorable effects has not enjoyed confirmation. In contrast, many soy products should be beneficial to cardiovascular and overall health because of their high content of polyunsaturated fats, fiber, vitamins, and minerals and low content of saturated fat. In October 1999, the US Food and Drug Administration (FDA) approved labeling for foods containing soy protein as protective against coronary heart disease.2 …

Mammary Gland Tumor Promotion in F1 Generation Offspring from Male and Female Rats Exposed to Soy Isoflavones for a Lifetime

The effect of dietary isoflavones in the form of NOVASOY (NS) was investigated on methylnitrosourea-initiated mammary gland cancer in F1 generation female Sprague Dawley rats from parents who had undergone lifetime exposure to variable levels of dietary NS. In comparison to NS-free dietary groups, lifetime exposure of F1 rats to 40 and 1000 mg/kg diets of NS reduced tumor latency, but did not significantly affect tumor incidence, tumor size, or tumor multiplicity. A significantly lower tumor multiplicity was, however, observed in rats fed the soy-based, NS-free diet compared to the casein-based, NS-free diet. An evaluation of a dose-response relationship pointed towards a biphasic effect, with a trend showing lower tumor incidence, lower tumor multiplicity, and lower tumor size in rats fed 1000 mg/kg diet NS compared to 40 mg/kg diet NS; however, the data failed to achieve statistical significance. Histologically, tumor type significantly differed according to the administered basal diet variety and NS dose. Our data and that of others provide conflicting evidence for chemopreventive effects of soy isoflavones on mammary gland tumor induction. We suggest standardization of interlaboratory experimental approaches for establishing low dose-response relationships for soy and its isoflavones to aid in risk assessment.