Soy and cardiovascular disease: cholesterol lowering and beyond

Characterization and Identification of Isoflavonoids in the Roots of Millettia speciosa Champ. by UPLC-Q-TOF-MS/MS

Introduction:

The root of Millettia speciosa Champ. (Leguminosae) is one of the wellknown traditional Chinese medicines abundant in phenolic compounds and plays important roles in the treatment of pain or numbness of the joints, blood deficiency sallow, chronic bronchitis and chronic hepatitis.

Objective:

An ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS) based chemical profiling approach was established for the separation and characterization of isoflavonoids in the roots of Millettia speciosa Champ.

Methods:

The roots of Millettia speciosa Champ. were prepared by ethanol extraction followed by further extraction with chloroform. The extracts were analyzed by UPLC-Q-TOF-MS in positive and negative electrospray ion modes at different Collision Energy (CE) values.

Results:

A total of 48 components were simultaneously detected, of which 38 components, including 21 isoflavones, 4 phenolic acids, 4 isoflavanones, 2 phenolic aldehydes, 2 flavanones, 1 aliphatic acid, 1 chalcone, 1 flavonol, 1 isoflavane and 1 pterocarpan were unambiguously identified or tentatively assigned based on the retention time, UV spectra, characteristic molecular ions, MS/MS fragmentation data and reference standards. The isomers of isoflavonoids were distinguished using accurate mass, the diagnostic fragmentations of C-ring and UV spectra. The major diagnostic fragment ions of isoflavonoids were observed and the corresponding fragmentation pathways were proposed.

Conclusion:

This investigation provides important analysis data for further quality control, pharmacological and toxicological research on Millettia speciosa Champ.

Genistein induces macrophage polarization and systemic cytokine to ameliorate experimental colitis

Mucosal changes in Crohn’s disease (CD) and ulcerative colitis (UC), two major forms of inflammatory bowel disease (IBD), are characterized by a prominent infiltration of inflammatory cells including lymphocytes, macrophages, T cells and neutrophils. The precise etiology of IBD is unknown but it involves a complex interplay of factors associated with the immune system, environment, host genotype and enteric commensal bacteria. As there is no known safe cure for IBD, natural alternative therapeutic options without side effects are urgently needed. To this end, Soy-based foods, which have been eaten for centuries in Asian countries, have potential benefits, including lowering the incidence of coronary heart disease, atherosclerosis, type-2 diabetes, allergic response, and autoimmune diseases. This study describes the effect of Soy isoflavons 4', 5, 7 Trihydroxyisoflavone (genistein) on dextran sodium sulphate (DSS) induced experimental colitis. The extent and severity of disease was analyzed through body weight, histopathological analysis, cellular immune response, systemic cytokine levels, and inflammation score using a disease activity index. Genistein treatment significantly attenuated DSS-induced colitis severity and resulted in increase in body weight, colon length and reduction in inflammation score. Genistein also skews M1 macrophages towards the M2 phenotype. Further, gen also reduced the systemic cytokine levels as compared to vehicle control. This serves as the first detailed study towards natural soya based product that shows the polarization of M1 towards M2 macrophages, and reduction of systemic cytokine in part to attenuate the colitis symptoms. Thus, our work demonstrates that genistein, a soya compound, may be useful for the treatment of IBD.

The functional effect of soybean extract and isolated isoflavone on myocardial infarction and ventricular dysfunction: the soybean extract on myocardial infarction

BACKGROUND

Myocardial infarction is a public health problem. Functional food is an alternative treatment for cardiovascular diseases.

OBJECTIVE

The objective was to analyze the functional and anatomopathological post-myocardial-infarction effects of soybean extract (SE) and isoflavone (IF).

METHODS

Myocardial infarction was induced in adult Wistar rats. After 5 days, an echocardiogram was performed to determine heart rate (HR), ejection fraction (EF), systolic volume (LVESV) and diastolic volume (LVEDV). Animals with ventricular dysfunction (EF<45%) were selected for study. The animals were divided into three groups: control (n=14), SE (n=15) and IF (n=12). The IF group received 120 mg/kg/day isolated IF, and the SE group received 12.52 g/day. After 30 days, a new echocardiogram was performed. A histological exam was carried out to determine the collagen. Activity of biochemical markers [arginase, lactate dehydrogenase (LDH) and malate dehydrogenase] was measured.

RESULTS

The animals of the control, IF and SE groups showed a reduction in EF after the infarction (P=.432, P=.017 and P=.320, respectively). An increase of LVESV and LVEDV was observed in all groups (P=.009, P=.001 and P=.140; and P=.003, P=.008 and P=.205, respectively). A reduction of HR was found in the SE group (P=.020). There was a greater activity of LDH in the SE group. A smaller quantity of mature collagen was found in the region proximal to the myocardial infarction in the SE group.

CONCLUSION

A protective effect in the SE group was observed 30 days after the myocardial infarction.

Soy isoflavone equol perpetuates dextran sulfate sodium-induced acute colitis in mice

The effects of the soy isoflavones, genistein, daidzein and equol, on experimental colitis were examined. Equol severely perpetrated dextran sulfate sodium (DSS)-induced colitis as evaluated by the weight loss. Production of the anti-inflammatory cytokine, IL-10, from T cells was decreased in the equol-treated mice. The results show that the soy isoflavone, equol, played an important role in the inflammatory response in the gastrointestinal tract.

Synthesis of isoflavone aglycones and equol in soy milks fermented by food-related lactic acid bacteria and their effect on human intestinal Caco-2 cells

One hundred and three strains of lactic acid bacteria, isolated from various food ecosystems, were assayed for β-glucosidase activity toward p-nitrophenyl-β-D-glucopyranoside substrate. Lactobacillus plantarum DPPMA24W and DPPMASL33, Lactobacillus fermentum DPPMA114, and Lactobacillus rhamnosus DPPMAAZ1 showed the highest activities and were selected as the mixed starter to ferment various soy milk preparations, which mainly differed for chemical composition, protein dispersibility index, and size dimension. The soy milk made with organically farmed soybeans (OFS) was selected as the best preparation. All selected strains grew well in OFS soy milk, reaching almost the same values of cell density (ca. 8.5 log cfu/mL). After 96 h of fermentation with the selected mixed starter, OFS soy milk contained 57.0 μM daidzein, 140.3 μM genistein, 20.4 μM glycitein, and 37.3 μM equol. Fermented and nonfermented OFS soy milks were used for the in vitro assays on intestinal human Caco-2/TC7 cells. Fermented OFS soy milk markedly inhibited the inflammatory status of Caco-2/TC7 cells as induced by treatment with interferon-γ (IFN-γ) (1000 U/mL) and lipopolysaccharide (LPS) (100 ng/mL), maintained the integrity of the tight junctions, even if subjected to negative stimulation by IFN-γ, and markedly inhibited the synthesis of IL-8, after treatment with interleukin-1β (2 ng/mL). As shown by using chemical standards, these effects were due to the concomitant activities of isoflavone aglycones and, especially, equol, which were synthesized in the fermented OFS soy milk preparation.

Evaluation of soy hulls as a potential ingredient of functional foods for the prevention of obesity

The prevalence of obesity and its associated health problems is rising to epidemic proportions throughout the world. Soy hulls, an industrial waste from oil extraction, contain a high proportion of fiber--soluble and insoluble--and may be a potential ingredient of functional foods for the prevention of obesity. However, crude soybeans, as do all legumes, present challenges to their use because of intensive antitrypsin and antichimotrypsin activity that impairs normal growth in humans and other mammals, requiring inactivation. To evaluate possible antinutritional effects of soybean hulls, diets with 10 percent fiber from soybean hulls or cellulose were offered to weanling IIMb/Beta obese rats during their prepubertal timeframe. The fact that no significant differences were found in growth, blood parameters nor in fat depots' weight and lipid content plus the proven beneficial effects on obese adult rats suggest that soy hulls may be a useful ingredient of functional foods for the prevention and treatment of human obesity.

The soy isoflavone equol enhances antigen-specific IgE production in ovalbumin-immunized BALB/c mice

Although an immunomodulatory role of the soy isoflavone genistein has been demonstrated, the effects of other soy isoflavones on induction of antigen (Ag)-specific immune responses are not known. In this study, we therefore investigated the effects of daidzein and equol on ovalbumin (OVA)-specific T cell and B cell responses in BALB/c mice. Mice that had been treated with 20 mg/kg equol showed a significantly higher level of OVA-specific IgE than control mice. Levels of interferon (IFN)-gamma and interleukin (IL)-4 production were not different between the control and equol groups. However, IL-13 production level in mice administered 20 mg/kg equol was significantly higher than that in control mice. Strong induction of OVA-specific IgE production by equol was also observed in ovariectomized BALB/c mice, suggesting that the immunomodulatory effect of equol is not affected by endogenous estrogen.

Consumo alimentar e doença macrovascular em nipo-brasileiros: um estudo transversal

OBJETIVO: Descrever o hábito alimentar de nipo-brasileiros com e sem doença macrovascular (DMV). MÉTODOS: Definiu-se DMV, para 1.165 nipo-brasileiros, a partir de escores atribuídos ao histórico de saúde, eletrocardiograma e valores do índice tornozelo-braquial. Determinou-se o consumo alimentar habitual por meio de Questionário de Frequência do Consumo de Alimentos. RESULTADOS: A porcentagem de casos confirmados com DMV foi de 3,2%, sendo semelhante entre os sexos. Observou-se, de forma estatisticamente significante, maior frequência de indivíduos com DMV (confirmados ou suspeitos) entre aqueles de primeira geração, com idade > 60 anos, tabagistas, com hipertensão arterial, hipertrigliceridemia e diabetes. Nipo-brasileiros com DMV (confirmados ou suspeitos) apresentaram menor perímetro do quadril e maior idade, pressão arterial sistólica, triglicérides, glicemia, consumo de alimentos fonte de ferro e menor fonte de fibras de grãos. Encontrou-se diferença estatisticamente significante apenas para o consumo de gordura saturada (análise bruta: segundo terço versus primeiro terço). CONCLUSÕES: programas de educação nutricional devem ser incentivados neste grupo com alta prevalência de doenças crônicas não transmissíveis.

Proteomic biomarkers of peripheral blood mononuclear cells obtained from postmenopausal women undergoing an intervention with soy isoflavones

BACKGROUND

The incidence of cardiovascular diseases increases after menopause, and soy consumption is suggested to inhibit disease development.

OBJECTIVE

The objective was to identify biomarkers of response to a dietary supplementation with an isoflavone extract in postmenopausal women by proteome analysis of peripheral blood mononuclear cells.

DESIGN

The study with healthy postmenopausal woman was performed in a placebo-controlled sequential design. Peripheral mononuclear blood cells were collected from 10 volunteers after 8 wk of receiving daily 2 placebo cereal bars and after a subsequent 8 wk of intervention with 2 cereal bars each providing 25 mg of isoflavones. The proteome of the cells was visualized after 2-dimensional gel electrophoresis, and peptide mass fingerprinting served to identify proteins that by the intervention displayed altered protein concentrations.

RESULTS

Twenty-nine proteins were identified that showed significantly altered expression in the mononuclear blood cells under the soy-isoflavone intervention, including a variety of proteins involved in an antiinflammatory response. Heat shock protein 70 or a lymphocyte-specific protein phosphatase and proteins that promote increased fibrinolysis, such as alpha-enolase, were found at increased intensities, whereas those that mediate adhesion, migration, and proliferation of vascular smooth muscle cells, such as galectin-1, were found at reduced intensities after soy extract consumption.

CONCLUSION

Proteome analysis identified in vivo markers that respond to a dietary intervention with isoflavone-enriched soy extract in postmenopausal women. The nature of the proteins identified suggests that soy isoflavones may increase the antiinflammatory response in blood mononuclear cells that might contribute to the atherosclerosis-preventive activities of a soy-rich diet.

Antiatherogenic effect of isoflavones in ovariectomized apolipoprotein e-deficient mice

The consumption of isoflavone-containing foods such as soybean and soybean products has been reported to have beneficial effects on the cardiovascular system in postmenopausal women. The present study was carried out to examine the mechanism underlying the beneficial effects of isoflavones in apolipoprotein (apo) E-deficient mice subjected to ovarian resection. Compared with sham-operated mice, ovariectomized mice had a larger arterial lesion area in the aortic root. Feeding the ovariectomized mice an isoflavone-containing diet (0.055 mg/kJ of total isoflavones/cal of diet) reduced the size of these lesions more than did feeding them with an isoflavone-free diet. Neither ovariectomy nor diet had a significant effect on the concentration of cholesterol in serum and urinary levels of isoprostanes, which are biomarkers for oxidative stress in vivo. The ovariectomized mice showed a greater increase in mRNA abundance for monocyte chemoattractant protein (MCP)-I in the aorta and in the level of nitric oxide (NO) secreted by peritoneal macrophages in culture than did the sham-operated mice. The isoflavone-containing diet lowered the MCP-I expression and the NO secretion more than did the isoflavone-free diet. These results suggest that dietary isoflavones confer an antiatherogenic effect by preventing the activation of macrophages due to the removal of ovaries.

Warfarin and its interactions with foods, herbs and other dietary supplements

Despite its complex pharmacokinetic and pharmacodynamic profile, warfarin is still one of the most widely used oral anticoagulant agents. Attaining optimal anticoagulation with this agent is clinically challenging in view of its many food and drug interactions. Inappropriate anticoagulation control can expose patients to an increased risk of bleeding or thromboembolic complications, due to over and underanticoagulation, respectively. Fluctuations in dietary vitamin K intake can have a significant effect on the degree of anticoagulation in patients treated with warfarin. In addition, the explosion in use of various dietary supplements and herbal products can lead to undesired outcomes on anticoagulant levels. The aim of this review is to discuss the scope and the potential clinical impact of the most commonly reported food, dietary supplement and herbal interactions with warfarin therapy. Practical steps for patients and providers to minimise these interactions are highlighted.

Human and murine hepatic sterol-12-alpha-hydroxylase and other xenobiotic metabolism mRNA are upregulated by soy isoflavones

The transport and metabolism of xenobiotics is controlled by the drug transporters and drug-metabolizing enzymes in the liver and small intestine. Expression of these genes is 1 factor affecting the half-life of drugs and xenobiotics. Isoflavone-containing soyfood products and supplements are promoted to treat several different health conditions, including improvement of blood lipid profiles. Because relatively high isoflavone intake may be possible via use of supplements, we tested the hypothesis that isoflavones regulate the expression of genes critical to drug transport and metabolism. Using a gene array screening method, 2 drug transporters, Multidrug restistant-1 and Multidrug-related protein-2; 3 phase I enzymes, cytochrome 1A1, 3A4, and 8B1; and 2 phase II enzymes, carbohydrate sulfotransferase-5 and glutathione-sulfotransferase-2, were upregulated 3-fold or more of the initial expression levels in primary human hepatocytes exposed to soy isoflavones for 48 h. Isoflavone-related induction of 12-alpha-hydroxylase (CYP8B1) was further studied in other in vitro and murine in vivo models. Transfection studies suggest that isoflavones may act as a weak activating ligand for hepatocyte nuclear factor 4alpha, which in turn may activate the transcription of CYP8B1. The action of soy isoflavones on CYP8B1 may increase the conversion of cholesterol into bile acids and enhance synthesis of cholic acid. These isoflavone-induced changes in gene expression may help explain how isoflavones modulate cholesterol metabolism.

Cardiovascular Actions of Selective Estrogen Receptor Modulators and Phytoestrogens

Cardiovascular disease is the leading cause of death among men and women in Western societies. Over the past decade, interest in a better understanding of gender differences in cardiovascular disease has heightened. Concomitantly, the use of hormone therapy for cardiovascular risk reduction in postmenopausal women has come into question in light of recent landmark clinical studies casting doubt on the benefits of this therapy. As a consequence, alternatives to conventional hormone replacement, including selective estrogen receptor modulators and phytoestrogens, have attracted considerable attention. The authors provide an up-to-date review of the clinical actions of selective estrogen receptor modulators on cardiovascular disease. The actions of tamoxifen, raloxifene, droloxifene, and soy phytoestrogens are discussed in the context of cardiovascular disease epidemiology, coronary events, clinical markers of cardiovascular risk, and vascular function. In addition, the authors' current understanding of the mechanism of action of these agents is discussed and recommendations for clinical practice are reviewed.

Using of Lactobacillus and Bifidobacterium to product the isoflavone aglycones in fermented soymilk

The study determined isoflavone aglycone contents in soymilk and sugar-soymilk fermented with a single culture of two strains of Lactobacillus paracasei, two strains of Lactobacillus acidophilus, and one strain of Bifidobacterium longum respectively at 37 degrees C for 24 h. Isoflavone concentration was analyzed by HPLC. The viable count of bacteria in all of the fermented soymilk ranged from 7 to 9 log CFU/ml. The isoflavone aglycone had a significant increase of 62%-96% of isoflavone in all of the fermented soymilk compared to 17% in non-fermented soymilk (P<0.05). The five strains of microorganisms produced lesser amount of isoflavone aglycones in fermented sucrose-soymilk than in other fermented soymilk.

Can stevioside in combination with a soy-based dietary supplement be a new useful treatment of type 2 diabetes? An in vivo study in the diabetic goto-kakizaki rat

The diterpene glycoside stevioside (SVS) and soy bean protein isolate have both been shown to have beneficial effects in diabetes treatment. As they each show different benefits we investigated whether the combination of both substances shows an improvement in the treatment of diabetes in Goto-Kakizaki (GK) rats. Over the course of 4 wk, the rats were fed with the following four test diets (n = 12 per group): 1. Standard carbohydrate-rich laboratory diet (chow), 2. chow + SVS (0.03 g/kg BW/day), 3. 80% SPI + 20% chow and 4. 80% SPI + 20 % chow + SVS (0.03 g/kg BW/day). At the end of the course conscious rats underwent an intra-arterial glucose tolerance test (IAGTT) (2.0 g glucose/kg BW). Compared to normal chow diet, stevioside in combination with SPI shows the following beneficial effects in GK rats with mild type 2 diabetes: 1. a 56% reduction in plasma glucose (p < 0.001), 2. a 118% increase in first-phase insulin (p < 0.005), 3. a 20% reduction in glucagons (p < 0.05), 4. a 28% reduction in total cholesterol (p < 0.001), 5. a 13% reduction in FFA (p < 0.01), 6. a 49% reduction in TG (p < 0.001) and 7. a 11% reduction in the systolic blood pressure (p < 0.001). In conclusion, the combination of stevioside and SPI has synergistic positive effects on the characteristic features of the metabolic syndrome, i.e. hyperglycemia, hypertension and dyslipidemia.

Lowering effect of an isoflavone-rich fermented soybean extract on the serum cholesterol concentrations in female rats, with or without ovariectomy, but not in male rats

We examined the effect of administering an isoflavone-rich fermented soybean extract (FSBE) on the serum cholesterol concentrations in male rats and in intact and ovariectomized (OVX) female rats. Dietary FSBE decreased the serum cholesterol concentrations in intact female and OVX rats, but did not affect the concentrations in male rats. Dietary FSBE increased the hepatic total and esterified cholesterol contents in the intact female rats, but decreased them in the OVX rats. This hypocholesterolemic effect was not a simple estrogenic effect because it has appeared in some reports that estrogen administration decreased serum cholesterol both male and female rats. Dietary FSBE increased the hepatic low-density lipoprotein receptor (LDLR) gene expression in the intact female rats as has previously been reported from many studies, but did not affect that of the OVX rats. Further investigation is needed into the hypocholesterolemic mechanism of FSBE.

Effects of soy protein and genistein on blood glucose, antioxidant enzyme activities, and lipid profile in streptozotocin-induced diabetic rats

In the current study, the effect of soy protein and genistein, one of the main isoflavones in soybeans, on blood glucose, lipid profile, and antioxidant enzyme activities in streptozotocin (STZ)-induced diabetic rats was investigated. Male Sprague-Dawley rats were divided into nondiabetic control, STZ, STZ-genistein supplemented group (STZ-G; 600 mg/kg diet), and STZ-isolated soy protein supplemented group (STZ-ISP; 200 g/kg diet). Diabetes was induced by a single injection of STZ (50 mg/kg BW) freshly dissolved in 0.1 mol/L citrate buffer (pH 4.5) into the intraperitonium. Diabetes was confirmed by measuring the fasting blood glucose concentration 48-h post-injection. The rats with blood glucose level above 350 mg/dL were considered to be diabetic. Genistein and ISP were supplemented in the diet for 3 weeks. The supplementation of genistein and ISP increased the plasma insulin level but decreased the HbA(IC) level of the STZ-induced diabetic rats. The supplementation of genistein and ISP increased the glucokinase level of the STZ-induced diabetic rats. A significant reduction in glucose-6-phosphatase was observed in the groups treated with genistein and ISP in comparison with the diabetic control group. Hepatic superoxide dismutase, catalase, and glutathione peroxidase activities of the STZ-induced diabetic rats were significantly decreased in comparison with the control rats. Administering genistein and ISP to the STZ-induced diabetic rats significantly increased those enzyme activities. The concentration of thiobarbituric acid reactive substances in the STZ-induced diabetic rats was significantly elevated, while the genistein and ISP supplement decreased it to the control concentration. Genistein and ISP supplements seem to be beneficial for correcting the hyperglycemia and preventing diabetic complications.

Biological activity of Bifidobacterium longum in response to environmental pH

The influence of environmental pH on biological activity of Bifidobacterium longum CRL 849 grown in MRS-raffinose was evaluated. At pH 6.0, 5.5 and 5.0, raffinose was completely consumed by this microorganism, showing different consumption rates at each pH value (between 3.03 and 0.76 mmol l(-1) h(-1)). At pH 4.5, the growth was lowest. The removal of raffinose was due to the alpha-galactosidase (alpha-gal) activity of this bifidobacteria, which was highest at pH 6.0-5.5 (1,280-1,223 mU ml(-1)). The production of beta-glucosidase (beta-glu) showed a similar pattern to alpha-gal activity with major values. The yield of organic acids produced during raffinose consumption was also highest at pH 6.0-5.5. The results of this study will allow the selection of the optimum growth conditions of B. longum CRL 849, with elevated levels of alpha-gal to be used in the reduction of nondigestible alpha-oligosaccharide in soy products and beta-glu activities involved in isoflavone conversion to bioactive forms when used as starter culture.

Soybean Foods and Their Benefits: Potential Mechanisms of Action

Isoflavones have been proposed to be the active component responsible for the beneficial effects of soybean foods, and appear to work in conjunction with the proteins to protect against cancer, cardiovascular disease, and osteoporosis. Most of the research activities on the benefits of soybean foods have focused on the role these isoflavones play in disease prevention or treatment; however, there is also some evidence that the benefits are attributable to certain peptides or protein fractions from soybeans. This review will focus on some of the potential mechanisms whereby soybeans exert their protective effects against heart disease, cancer, and osteoporosis.

Effect of a soybean product on serum lipid levels in female university students

1. A dietary intervention study targeting female students by using cake containing soybean protein and isoflavone was conducted. Female students (n = 120) were divided into three Groups (A, 6.26 g of soybean protein and isoflavone at 50 mg/day; B, 1.36 g soybean protein and isoflavone 50 mg; and C, a wheat puff as placebo). Intervention period was 4 weeks. The ratio of hypercholesterol in each group indicated a high value; A: 25%, B: 17.9% and C: 24.4%. 2. Total cholesterol as well as the rate of hypercholesterolemia decreased in Group A. The average total cholesterol significantly reduced (P < 0.001) from 242 +/- 17 to 220 +/- 25 mg/dL in Group A. 3. Dietary intake of soy protein for 4 weeks could be effective in reducing CHD risk among Japanese female students with a high plasma cholesterol level.

Endocrine and cognitive effects of short-time soybean consumption in women

BACKGROUND

Soy phytoestrogens are known to influence the hormonal status acting as partial estrogen agonists. Soy-derived food supplements are advised for hormone replacement therapy, prevention of atherosclerosis, age-related cognitive decline and even hormone-dependent cancer, although results from clinical studies are controversial. Whether increased soybean intake can affect the endocrine status and cognitive abilities is largely unknown.

AIM

To observe the effects of 1 week of increased soybean intake on sex hormone levels and spatial cognitive abilities in women.

SUBJECTS AND METHODS

16 young healthy female volunteers were asked to eat 900 g of soybeans within 1 week. Salivary testosterone (T), free and total plasma T, salivary and plasma estradiol (E) were measured by radioimmunoassay before and after the study period. Mental rotation (MR) and spatial visualization (SV) psychological tests were done at the days of sampling.

RESULTS

Soybean intake increased total plasma T levels (p < 0.02) while decreasing salivary T (p < 0.01) and not altering free plasma T levels. Salivary and plasma E levels were not changed. The results of MR and SV tests were improved after the study period.

CONCLUSION

Short-time increased soybean intake alters the level of total plasma and salivary T and improves spatial cognition in women. Whether this effect is mediated by modulation of estrogen receptors, changes in sex hormone-binding globulin production or changes in activity of steroid-competent enzymes needs further study.

Soy isoflavones affect sterol regulatory element binding proteins (SREBPs) and SREBP-regulated genes in HepG2 cells

Soy intake reduces cholesterol levels. However, both the identity of the soy component or components that contribute to this reduction and the cellular mechanism producing this reduction are unknown. Soy consists of protein, lipids, fiber, and phytochemicals including isoflavones. We propose that the isoflavone component of soy mediates this effect, at least in part, by affecting cellular sterol homeostasis. We investigated the effects of an isoflavone-containing soy extract and the individual isoflavones on the maturation of the sterol regulatory element binding proteins (SREBP) and the expression of SRE-regulated genes controlling lipid metabolism. We found a corresponding increase in the mature form of SREBP-2 in both soy extract- and isoflavone-treated HepG2 cells, whereas there was no significant change in the levels of SREBP-1. 3-Hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase protein and HMG CoA synthase mRNA levels also increased. When HepG2 cells were transiently transfected with HMG CoA synthase and LDL receptor reporter plasmids there was an increase in expression in response to soy extract or isoflavone treatment from both of these promoters, but this induction was blunted in the presence of sterols (P < 0.05). The mechanism responsible for this effect may be via a statin-like inhibition of HMG CoA reductase enzyme activity or by enhanced SREBP processing via the SREBP cleavage activating protein. We hypothesize that maturation of SREBP and induction of SRE-regulated genes produce an increase in surface LDL receptor expression that increases the clearance of plasma cholesterol, thus decreasing plasma cholesterol levels.

Quantitative analysis of phytoestrogens in kudzu-root, soy and spiked serum samples by high-pressure liquid chromatography

A sensitive and reliable HPLC method that allows simultaneous quantification of phytoestrogens extracted from kudzu-root and soy preparations, and serum samples has been developed. Kudzu-root and soy preparations were mixed with 5 microg flavone and 15 microg rutin (internal standards) and the phytoestrogens were extracted by using solid-phase (C18) extraction cartridges. Blank or spiked serum samples were extracted by using either C18 cartridges or trichloroacetic acid-methanol extraction. The extracts were analyzed by the HPLC equipped with a reverse-phase (250 x 4 mm, C18) column and UV, diode-array or MS detector. A linear gradient of acetic acid and acetonitrile provided excellent separation of glycoside and aglycone-phytoestrogens from kudzu root and soy preparations. The C18 cartridge extraction of serum yielded excellent recovery of both glycoside- and aglycone-phytoestrogens, while the trichloroacetic acid-methanol extraction yielded excellent recovery of glycoside but poor recovery of aglycone compounds. UV and MS detectors were suitable for phytoestrogen analysis in plant and serum samples, while the diode-array detector was suitable for generating the UV absorbance curve for phytoestrogens.

Phytoœstrogènes chez la femme ménopausée

Many women seek alternatives to hormone replacement therapy (HRT). Phytoestrogens are nonsteroidal compounds with estrogenic or antiestrogenic properties. Six of the 16 clinical trials suggest a significant reduction in alleviating symptoms but to a lesser degree than HRT. A meta-analysis showed that phytoestrogens improve lipid profile. The 14 recent clinical trials led, however, to divergent findings. Small clinical trials suggested a protective effect of phytoestrogens on bone metabolism. High concentration of phytoestrogens was associated with a reduction in breast cancer risk in case-control studies.

Soy food consumption is associated with lower risk of coronary heart disease in Chinese women

Soy food intake has been shown to have beneficial effects on cardiovascular disease risk factors. Data directly linking soy food intake to clinical outcomes of cardiovascular disease, however, are sparse. We examined the relationship between soy food intake and incidence of coronary heart disease (CHD) among participants in the Shanghai Women's Health Study, a population-based prospective cohort study of approximately 75000 Chinese women aged 40-70 y at the baseline survey that was conducted from 1997 to 2000. Included in this study were 64915 women without previously diagnosed CHD, stroke, cancer and diabetes at baseline. Information on usual intake of soy foods was obtained at baseline through an in-person interview using a validated food-frequency questionnaire. Cohort members were followed biennially through in-person interviews. After a mean of 2.5 y (162277 person-years) of follow-up, 62 incident cases of CHD (43 nonfatal myocardial infarctions and 19 CHD deaths) were documented. There was a clear monotonic dose-response relationship between soy food intake and risk of total CHD (P for trend = 0.003) with an adjusted relative risk (RR) of 0.25 (95% CI, 0.10-0.63) observed for women in the highest vs. the lowest quartile of total soy protein intake. The inverse association was more pronounced for nonfatal myocardial infarction (RR = 0.14; 95% CI, 0.04-0.48 for the highest vs. the lowest quartile of intake; P for trend = 0.001). This study provides, for the first time, direct evidence that soy food consumption may reduce the risk of CHD in women.

Dietary supplementation of fermented soybean, natto, suppresses intimal thickening and modulates the lysis of mural thrombi after endothelial injury in rat femoral artery

We have previously demonstrated that natto-extracts containing nattokinase (NK) inactivates plasminogen activator inhibitor type 1 and then potentiates fibrinolytic activity. In the present study, we investigated the effects of dietary supplementation with natto-extracts on neointima formation and on thrombolysis at the site of endothelial injury. Endothelial damage in the rat femoral artery was induced by intravenous injection of rose bengal followed by focal irradiation by transluminal green light. Dietary natto-extracts supplementation containing NK of 50 or 100 CU/body was started 3 weeks before endothelial injury and then continued for another 3 weeks. Intimal thickening in animals given supplementation was significantly (P<0.01) suppressed compared with controls and the intima/media ratio in animals with 50 and 100 CU/body NK and control group was 0.09 +/- 0.03, 0.09 +/- 0.06 and 0.16 +/- 0.12, respectively. Although femoral arteries were reopened both in control animals and those treated with NK within 8 hours after endothelial injury, mural thrombi were histologically observed at the site of endothelial injury. In the control group, the center of vessel lumen was reopened and mural thrombi were attached on the surface of vessel walls. In contrast, in NK-treated groups, thrombi near the vessel wall showed lysis and most of them detached from the surface of vessel walls. In conclusion, dietary natto-extracts supplementation suppressed intimal thickening produced by endothelial injury in rat femoral artery. These effects may partially be attributable to NK, which showed enhanced thrombolysis near the vessel wall.

Soy isoflavones exert antidiabetic and hypolipidemic effects through the PPAR pathways in obese Zucker rats and murine RAW 264.7 cells

The hypocholesterolemic and anti-atherosclerotic mechanism by which soy may exert a beneficial effect remains unclear. Peroxisome-proliferator activated receptors (PPAR) are promiscuous nuclear receptors that regulate the transcription of genes involved in lipid and glucose homeostasis and lipid metabolism within the cell. We hypothesize that the isoflavones improve lipid and glucose metabolism by acting as an antidiabetic PPAR agonist. Male and female obese Zucker rats (OZR) were used as a model of Type 2 diabetes, and OZR fed a high isoflavone soy protein diet displayed improvements in lipid metabolism consistent with results in humans treated with antidiabetic PPAR agonists such as the fibrates or glitazones. Liver triglyceride and cholesterol concentrations were lower in all OZR fed high-isoflavone soy protein diets than in rats fed low-isoflavone and casein diets (P < 0.05). Concurrently, PPAR-directed gene expression was evaluated in a cell culture model. An isoflavone-containing soy extract doubled PPAR-directed gene expression (P < 0.05) in RAW 264.7 cells containing either a PPARalpha or PPARgamma expression plasmid. A similar induction was observed when the soy isoflavones genistein or daidzein were used to treat cells. Both isoflavones doubled PPARalpha-directed gene expression (P < 0.05), whereas they increased PPARgamma-directed gene expression 200-400% (P < 0.05). This study suggests that soy isoflavones improve lipid metabolism, produce an antidiabetic effect, and activate PPAR receptors.

Dietary supplementation with fermented soybeans suppresses intimal thickening

Although soy foods have been consumed for more than 1000 y, it is only in the past 20 y that they have made inroads into Western diets. We investigated the effect of dietary supplementation with natto extracts produced from fermented soybeans on intimal thickening of arteries after vessel endothelial denudation. Natto extracts include nattokinase, a potent fibrinolytic enzyme having four times greater fibrinolytic activity than plasmin. Intimal thickening was induced in the femoral arteries by intravenous infusion of rose bengal followed by focal irradiation with a transluminal green light. Dietary natto extract supplementation was started 3 wk before endothelial injury and continued for another 3 wk after. In ex vivo studies, euglobulin clot lysis times were measured 3 wk after the initial supplementation. Neointima formation and thickening were also initiated successfully. The intima media ratio 3 wk after endothelial injury was 0.15 +/- 0.03 in the control group. Dietary natto extract supplementation suppressed intimal thickening (0.06 +/- 0.01; P < 0.05) compared with the control group. Natto extracts shortened euglobulin clot lysis time, suggesting that their thrombolytic activities were enhanced. These findings suggest that natto extracts, because of their thrombolytic activity, suppress intimal thickening after vascular injury as a result of the inhibition of mural thrombi formation.

Local (gut) and systemic metabolism of rats is altered by consumption of raw bean (Phaseolus vulgaris L var athropurpurea)

The composition of the raw legume Phaseolus vulgaris L. var. athropurpurea (PhVa) and its effects on the metabolism of young growing rats have been evaluated. The levels of protein, unsaturated fatty acids, carbohydrate, fibre and bioactive factors present in PhVa were comparable with those in other Phaseolus vulgaris varieties. However, the lectins of PhVa were predominantly of the leucoagglutinating type, and concentrated in the albumin protein fraction. Rats fed a diet (110 g total protein, 16.0 MJ/kg) in which PhVa meal provided about half of the protein excreted high levels of N in faeces and urine, and grew more slowly, than rats fed a high-quality control diet (ad libitum or pair-fed). Small intestine, large intestine and pancreas weights were increased (by almost 100 %, P<0.05), whilst skeletal muscle, thymus and spleen weights were reduced. Blood insulin (16.20 v. 0.50 mU/l, P<0.05, thyroxine, glucose, protein (60.5 v. 48.3 g/l, P<0.05) and LDL-cholesterol were lowered, whilst glucagon (155.3 v. 185.4 ng/l, P<0.05), triiodothyronine and urea were elevated, as were urinary urea, creatinine and glucose. These changes in the local (gut) and systemic metabolism of rats were probably mediated primarily by lectins in PhVa, which were concentrated in the albumin protein fraction, whereas in many other Phaseolus vulgaris lines they are distributed across the globulin and albumin fractions.

The atheroprotective effect of dietary soy isoflavones in apolipoprotein E-/- mice requires the presence of estrogen receptor-alpha

OBJECTIVE

Although the mechanisms by which dietary soy inhibits atherosclerosis are unclear, one line of evidence implicates an important role for its phytoestrogenic isoflavones. We sought to determine whether soy isoflavones exert atheroprotective effects through estrogen receptor-dependent processes and, if so, which estrogen receptor subtype (ie, alpha or beta) is involved.

METHODS AND RESULTS

We compared the effects of diets rich in soy protein that were either isoflavone depleted (0.04 mg/g protein isolate) or isoflavone-replete, or Soy(+IF) (1.72 mg/g protein isolate) in apolipoprotein E-deficient (ee) mice that had been crossed with estrogen receptor-alpha- and -beta-deficient mice to produce double-knockout alphaalphaee and betabetaee mice and (estrogen receptor) wild-type controls (AAee and BBee). Both male and ovariectomized female mice were studied (n=10 to 17 per treatment group; total n=201). After 16 weeks, atherosclerosis was assessed by quantifying the aortic content of esterified cholesterol. Atherosclerosis was reduced 20% to 27% (P<0.05) by Soy(+IF) in betabetaee, BBee, and AAee mice but was unaffected in alphaalphaee mice. The inhibitory effect of Soy(+IF) was unrelated to sex, total plasma cholesterol, VLDL, LDL, and HDL cholesterol.

CONCLUSIONS

The results indicate a necessary role for estrogen receptor-alpha-dependent processes in mediating the atheroprotective effects of dietary soy isoflavones.

Risks and benefits of soy phytoestrogens in cardiovascular diseases, cancer, climacteric symptoms and osteoporosis

Phytoestrogens, plant chemicals classified as isoflavones, coumestans and lignans, display estrogen-like activity because of their structural similarity to human estrogens and exhibit high affinity binding for the estrogen receptor beta. They are common components of food items such as grains, beans, fruits and nuts. Isoflavones are primarily found in soybeans and foods made from soy. In particular, significant therapeutic properties have been generally attributed to soy isoflavones, but most of the claims have been poorly, or not at all, confirmed by well designed clinical trials. Such is the case of the purported role of soy isoflavones in reducing plasma cholesterol levels. This link is now not supported by many authors or by appropriately designed clinical studies. The role of isoflavones in cancer prevention, particularly of tumours under endocrine control (breast, prostate and others) is again only supported by weak to nonexisting clinical evidence. A similarcase is that of the prevention/treatment of postmenopausal symptoms and osteoporosis. Disturbing data have been reported on potential negative effects of soy isoflavones on cognitive function in the aged, particularly relating to tofu intake. Recent studies have finally indicated a potential role for soy isoflavones in inducing chromosomal changes in cells exposed in vitro and potentiating chemical carcinogens. These findings may not, however, be extrapolated to clinical conditions. Available data do not appear to unequivocally support beneficial effects of soy isoflavones, and warn against their wide use, in the absence of satisfactory clinical findings.

The inhibitory effect of soy protein isolate on atherosclerosis in mice does not require the presence of LDL receptors or alteration of plasma lipoproteins

The mechanisms by which dietary soy favorably influences lipoprotein metabolism and inhibits atherosclerosis are uncertain. Studies of blood mononuclear cells and cultured hepatocytes have indicated that certain soy peptides (i.e., 7S globulins) stimulate expression of LDL receptors. This pathway represents a hypothetical mechanism by which soy's hypocholesterolemic and antiatherosclerotic effects may be mediated. However, direct evidence supporting this hypothesis is lacking. To address this, we compared effects of dietary soy protein isolate in two genetically engineered mouse models of atherosclerosis. One mouse [LDL receptor -/- + apolipoprotein (apo) B transgenic] is devoid of LDL receptors and overproduces apolipoprotein B, whereas the other (apoE -/-) has a normal complement of LDL receptors but does not produce apolipoprotein E. Male (n = 10-12/group) and ovariectomized female (n = 10-12/group) mice were studied. There were three treatment groups, which differed principally by the source of the protein component of the diet: 1) casein/lactalbumin (no isoflavones), 2) alcohol-washed soy protein isolate (total isoflavones = 0.04 mg/g), and 3) intact soy protein isolate (total isoflavones = 1.72 mg/g). Atherosclerosis was assessed by quantifying the aortic content of esterified cholesterol. Atherosclerosis was inhibited (relative to the casein/lactalbumin group) by both alcohol-washed (45 and 31%) (P < 0.05) and intact (65 and 41%) (P < 0.05) soy protein isolate in LDL receptor -/- and apoE -/- mice, respectively. There was no sex difference. In a two-way analysis, there were significant effects of type of soy isolate and type of mouse. The antiatherosclerosis effect was enhanced in LDL receptor -/- mice (P < 0.001) and diminished in mice fed alcohol-washed soy protein isolate (P < 0.001). Furthermore, inhibitory effects of soy on atherosclerosis were unrelated to plasma LDL, VLDL or HDL cholesterol concentrations. The results represent direct evidence for the existence of LDL receptor- and plasma lipoprotein-independent pathways by which dietary soy protein isolate inhibits atherosclerosis.

Thermal treatment improves nutritional quality of pea seeds (Pisum sativum L.) without reducing their hypocholesterolemic properties

The effects of isoproteic isoenergetic diets containing raw (RP) or extruded (EP) pea (Pisum sativum, cv. Ballet) seed meal on nutritional performance and serum lipids, amino acids and enzyme levels in growing rats were studied in two 15 d feeding experiments. Food intake and growth were greatly reduced in animals fed unsupplemented RP or EP. Both parameters were improved by addition of amino acids to the diets. Growth, apparent N digestibility, biological value and net protein utilisation values for supplemented (SRP) raw peas were however inferior to those for controls whilst with supplemented (SEP) extruded peas the values were similar to control levels. SRP and SEP also greatly reduced serum total cholesterol, LDL (VLDL) and cholesterol/HDL ratio. This may have been linked to the lower plasma lysine:arginine ratio. SRP and SEP increased kidney and adrenal weights and reduced liver weight. SRP stimulate pancreatic growth but SEP did not. Analysis of serum proteins and enzymes suggested these tissue changes did not lead to chronic disruption to gut or systemic metabolism. Extrusion treatment of peas improved their nutritional quality but did not reduce their hypocholesterolemic properties.

Lack of effect of isoflavonic phytoestrogen intake on leptin concentrations in premenopausal and postmenopausal women

OBJECTIVE

To assess the effect of soy isoflavone ingestion on plasma leptin concentrations in premenopausal and postmenopausal women.

DESIGN

Randomized, crossover studies, with blinding of participants and laboratory personnel.

SETTING

Procedures involving free-living individuals were carried out at the University of Minnesota General Clinical Research Center.

PATIENT(S)

Fourteen regularly cycling premenopausal women, and 18 postmenopausal women.

INTERVENTION(S)

Each premenopausal participant consumed, on a daily basis, each of three soy protein powders containing different levels of isoflavones for three menstrual cycles plus 9 days, with plasma samples collected every other day the last 6 weeks of each diet period. Similarly, each postmenopausal participant consumed each of the three powders for 93 days, with plasma samples collected daily on days 64 to 66 and 92 to 94 of each diet period. The powders, dosed on a per-kilogram body weight basis, provided mean isoflavone intakes of 8, 65, and 130 mg/day, for the control, low-isoflavone, and high-isoflavone diet periods, respectively.

MAIN OUTCOME MEASURE(S)

Plasma leptin concentrations.

RESULT(S)

Isoflavone intake had essentially no effect on leptin concentrations in either premenopausal or postmenopausal participants. Concentrations in the premenopausal women were higher during the periovulatory and midluteal phases as compared to the early follicular and midfollicular phases.

CONCLUSION(S)

Despite the well-documented effect of estrogens to enhance leptin production, even high levels of isoflavone consumption do not alter leptin concentrations in women. Further studies are needed to more precisely delineate the nature of estrogenic and/or antiestrogenic effects of isoflavones in humans.