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Mindy S Kurzer - One of the best experts on this subject based on the ideXlab platform.
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Isoflavones and Postmenopausal Women
Treatments in Endocrinology, 2002Co-Authors: William R Phipps, Alison M Duncan, Mindy S KurzerAbstract:Isoflavonic phytoestrogens, or Isoflavones, constitute a class of phytoestrogens that have properties similar to selective estrogen receptor modulators, and have attracted a substantial degree of attention in recent years, particularly as a possible alternative to the conventional hormone replacement therapy regimens used by postmenopausal women. Despite great promise, it is difficult to make many specific recommendations about their use at the current time, in light of the many outstanding questions that hopefully will be answered in the future by focused interventional studies involving humans. Studies to date indicate that the use of Isoflavones to address vasomotor symptoms provides at most small benefits beyond a placebo effect, and no benefit for genital atrophy. As for postmenopausal women whose primary concern is cardiovascular disease, the recommendation of the American Heart Association to include soy protein foods as part of an otherwise healthy diet is well justified, and similarly the substitution of supplements containing soy protein for animal protein can also be recommended. The use of purified isoflavone supplements not containing soy protein may have some cardiovascular benefits, but these appear to be less substantial in degree than those provided by soy protein with Isoflavones. In particular, more research is needed to assess the effects of Isoflavones on osteoporosis, for which no recommendation regarding Isoflavones can be made based on the current data. Also, Isoflavones should not be taken by postmenopausal women for the specific purpose of decreasing their risk of breast or endometrial cancer, although, at least for those without pre-existing disease or at high risk, it seems quite unlikely that isoflavone use is harmful in this regard.
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soy Isoflavones improve plasma lipids in normocholesterolemic and mildly hypercholesterolemic postmenopausal women
The American Journal of Clinical Nutrition, 2001Co-Authors: Kerry E Wangen, Xia Xu, Alison M Duncan, Mindy S KurzerAbstract:BACKGROUND: Soy-protein consumption is known to reduce plasma total and LDL cholesterol concentrations. However, the responsible soy component or components and the magnitude of effects in normocholesterolemic and mildly hypercholesterolemic subjects are unclear. OBJECTIVE: The present study examined the effects of soy isoflavone consumption on plasma concentrations of triacylglycerol, apolipoprotein (apo) A-I, apo B, lipoprotein(a), and total, LDL, and HDL cholesterol and on LDL peak particle diameter in normocholesterolemic and mildly hypercholesterolemic postmenopausal women. DESIGN: In a randomized crossover trial, fasting plasma samples were obtained from 18 postmenopausal women throughout three 93-d periods of daily isolated soy protein (ISP) consumption providing an average of 7.1 +/- 1.1 (control), 65 +/- 11 (low isoflavone), or 132 +/- 22 (high isoflavone) mg Isoflavones/d. RESULTS: Compared with values measured during the control diet, the plasma LDL cholesterol concentration was 6.5% lower (P < 0.02) during the high-isoflavone diet and the ratio of LDL to HDL cholesterol was 8.5% and 7.7% lower during the low- and high-isoflavone diets, respectively (P < 0.02). Isoflavone consumption did not significantly affect plasma concentrations of total or HDL cholesterol, triacylglycerol, apo A-I, apo B, or lipoprotein(a) or the LDL peak particle diameter. CONCLUSIONS: Consumption of Isoflavones as a constituent of ISP resulted in small but significant improvements in the lipid profile in normocholesterolemic and mildly hypercholesterolemic postmenopausal women. Although the effects were small, it is possible that Isoflavones may contribute to a lower risk of coronary heart disease if consumed over many years in conjunction with other lipid-lowering strategies.
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modest hormonal effects of soy Isoflavones in postmenopausal women
The Journal of Clinical Endocrinology and Metabolism, 1999Co-Authors: Alison M Duncan, Xia Xu, Kerry E W Underhill, June Lavalleur, William R Phipps, Mindy S KurzerAbstract:Soy Isoflavones have been hypothesized to exert hormonal effects in postmenopausal women. To test this hypothesis, we studied the effects of three soy powders containing different levels of Isoflavones in 18 postmenopausal women. Isoflavones were consumed relative to body weight[ control: 0.11 ± 0.01; low isoflavone (low-iso): 1.00 ± 0.01; high isoflavone (high-iso): 2.00 ± 0.02 mg/kg/day] for 93 days each in a randomized crossover design. Blood was collected on day 1 of the study (baseline) and days 36–38, 64–66, and 92–94 of each diet period, for analysis of estrogens, androgens, gonadotropins, sex hormone binding globulin (SHBG), prolactin, insulin, cortisol, and thyroid hormones. Vaginal cytology specimens were obtained at baseline and at the end of each diet period, and endometrial biopsies were performed at baseline and at the end of the high-iso diet period, to provide additional measures of estrogen action. Overall, compared with the control diet, the effects of the low-iso and high-iso diets were...
Kenneth D R Setchell - One of the best experts on this subject based on the ideXlab platform.
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factors affecting the bioavailability of soy Isoflavones in humans after ingestion of physiologically relevant levels from different soy foods
Journal of Nutrition, 2006Co-Authors: Aedin Cassidy, Linda Zimmernechemias, Jonathan E Brown, Anne Hawdon, Marian S Faughnan, Laurence J King, Joe Millward, Brian Wolfe, Kenneth D R SetchellAbstract:: The precise role that Isoflavones play in the health-related effects of soy foods, and their potential for adverse effects are controversial. This may be due in part to a lack of basic knowledge regarding their bioavailability and metabolism, particularly as it relates to the soy source. To date, there is little information concerning possible differences in the bioavailability of Isoflavones derived from natural soy foods consumed at physiologically relevant intakes and whether age- or gender-related differences influence that bioavailability. In the current study of healthy adults [premenopausal (n = 21) and postmenopausal (n = 17) women and a group of men (n = 21)], we examined the effect of age, gender, and the food matrix on the bioavailability of Isoflavones for both the aglycon and glucoside forms that are naturally present in 3 different soy foods, soy milk, textured vegetable protein, and tempeh. The study was designed as a random crossover trial so that all individuals received each of the 3 foods. The dose of Isoflavones administered to each individual as a single bolus dose was 0.44 mg/kg body weight. Pharmacokinetic parameters were normalized to mg of each isoflavone ingested per kilogram body weight to account for differences in daidzein and genistein content between the diets. Serum isoflavone concentrations in all individuals and groups increased rapidly after the ingestion of each soy food; as expected, genistein concentrations exceeded daidzein concentrations in serum. In this small study, gender differences in peak concentrations of daidzein were observed, with higher levels attained in women. Consumption of tempeh (mainly isoflavone aglycon) resulted in higher serum peak levels of both daidzein (P < 0.001) and genistein (P < 0.01) and the associated area under the curve (P < 0.001 and P < 0.03, respectively) compared with textured vegetable protein (predominantly isoflavone glucosides). However, soy milk was absorbed faster and peak levels of Isoflavones were attained earlier than with the other soy foods. Only 30% of the subjects were equol producers and no differences in equol production with age or gender were observed.
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Animal Models Impacted by Phytoestrogens in Commercial Chow: Implications for Pathways Influenced by Hormones
Laboratory Investigation, 2001Co-Authors: Nadine M Brown, Kenneth D R SetchellAbstract:It is generally not known that most commercial rodent diets are formulated with soy protein and deliver large daily doses of Isoflavones to animals throughout their lifespan, including the in utero period. Here, we demonstrate that Isoflavones are bioavailable and show that commercial rodent diets universally used by animal facilities lead to very high steady-state serum isoflavone concentrations in adult rats (2613 ± 873 ng/mL) and mice (2338 ± 531 ng/mL), exceeding the animal's endogenous estrogen level by 30,000- to 60,000-fold. We demonstrate the maternal-fetal intrauterine transfer of Isoflavones in animals fed a standard Purina 5001 soy-containing diet and show that newborn rat pups have high serum Isoflavones levels (540 ± 174 ng/mL) that are maintained throughout the suckling period by passage of Isoflavones into maternal milk. These findings have profound implications for all animal experiments, including multigenerational studies and studies of transgenic animals, especially if biochemical or morphological end-points are influenced by the hormonal or nonhormonal properties of phytoestrogens. These compounds have the potential to modulate genotypic and phenotypic expression in general, and therefore, all investigators should be vigilant to the phytoestrogen composition of commercial rodent diets because there is a history of potent biological effects in larger animals and in humans from high circulating isoflavone concentrations.
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isoflavone content of infant formulas and the metabolic fate of these phytoestrogens in early life
The American Journal of Clinical Nutrition, 1998Co-Authors: Kenneth D R Setchell, Linda Zimmernechemias, James E HeubiAbstract:Soy-based infant formulas have been in use for >30 y. These formulas are manufactured from soy protein isolates and contain significant amounts of phytoestrogens of the isoflavone class. As determined by HPLC, the isoflavone compositions of commercially available formulas are similar qualitatively and quantitatively and are consistent with the isoflavone composition of soy protein isolates. Genistein, found predominantly in the form of glycosidic conjugates, accounts for >65% of the Isoflavones in soy-based formulas. Total isoflavone concentrations of soy-based formulas prepared for infant feeding range from 32 to 47 mg/L, whereas isoflavone concentrations in human breast milk are only 5.6 ± 4.4 μg/L (x ± SD, n = 9). Infants fed soy-based formulas are therefore exposed to 22-45 mg Isoflavones/d (6-11 mg.kg body wt -1 .d -1 ), whereas the intake of these phytoestrogens from human milk is negligible (<0.01 mg/d). The metabolic fate of Isoflavones from soy-based infant formula is described. Plasma isoflavone concentrations reported previously for 4-mo-old infants fed soy-based formula were 654-1775 μg/L (x: 979.7 μg/L; Lancet 1997:350:23-7). significantly higher than plasma concentrations of infants fed either cow-milk formula (x ± SD: 9.4 ± 1.2 μg/L) or human breast milk (4.7 ± 1.3 μg/L). The high steady state plasma concentration of Isoflavones in infants fed soy-based formula is explained by reduced intestinal biotransformation, as evidenced by low or undetectable concentrations of equol and other metabolites, and is maintained by constant daily exposure from frequent feeding. Isoflavones circulate at concentrations that are 13000-22000-fold higher than plasma estradiol concentrations in early life. Exposure to these phytoestrogens early in life may have long-term health benefits for hormone-dependent diseases.
Filippo Drago - One of the best experts on this subject based on the ideXlab platform.
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Influence of inulin on plasma isoflavone concentrations in healthy postmenopausal women
American Journal of Clinical Nutrition, 2007Co-Authors: Cateno Piazza, Barbara Melilli, Maria Giovanna Privitera, Tiziana Incognito, Matilde Amico Roxas, Gian Marco Leggio, Maria Rosa Marano, Filippo DragoAbstract:BACKGROUND: Bacterial intestinal glucosidases exert an important role in isoflavone absorption. Insoluble dietary fibers such as inulin may stimulate the growth of these bacteria in the colon and, hence, stimulate the absorption of these substances in subjects who may need isoflavone supplementation. OBJECTIVE: The objective was to assess the influence of inulin on plasma isoflavone concentrations after intake of soybean Isoflavones in healthy postmenopausal women. DESIGN: Twelve healthy postmenopausal women participated in a randomized, double-blind, crossover study. They consumed 40 mg of a conjugated form of soybean Isoflavones (6 mg daidzein and 18 mg genistein as free form) with or without 3.66 g inulin twice daily in two 21-d experimental phases. Blood samples were collected 0, 1, 2, 3, 4, 6, 10, 12, and 24 h after intake of Isoflavones with breakfast and dinner at the end of each 21-d experimental phase. Plasma concentrations of Isoflavones were assessed by HPLC with an electrochemical detector. RESULTS: Plasma 24-h areas under the curve indicated that the intake of soybean Isoflavones with inulin for 21 d was followed by higher plasma concentrations of daidzein and genistein (38% and 91%, respectively) compared with the formulation without inulin. Furthermore, the time for the maximum concentration of daidzein and genistein appeared to be lower after the 21-d intake of soybean Isoflavones, with or without inulin. However, the time for the maximum concentration of daidzein and genistein after supplementation with the inulin-containing formulation on day 21 was not significantly different from that after supplementation with the formulation without inulin. CONCLUSIONS: Inulin may increase the apparent plasma concentrations of the soybean Isoflavones daidzein and genistein in postmenopausal women. The higher plasma concentrations of the 2 Isoflavones suggests that the absorption of each was facilitated by the presence of inulin.
James E Simon - One of the best experts on this subject based on the ideXlab platform.
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determination of Isoflavones in red clover and related species by high performance liquid chromatography combined with ultraviolet and mass spectrometric detection
Journal of Chromatography A, 2003Co-Authors: Qingli Wu, Mingfu Wang, James E SimonAbstract:Abstract High-performance liquid chromatography–UV–electrospray ionization-mass spectrometric detector (HPLC–UV–ESI-MSD) method for determination of Isoflavones in red clover (Trifolium pratense L.) and related species has been developed. The separated Isoflavones including aglycones, glycosides and glycoside malonates, were individually analyzed and identified by their molecular ions and characteristic fragment ion peaks using LC–MSD under MS and MS–MS mode, and in comparison with the standard Isoflavones. A total of 31 Isoflavones were detected in red clover. Several Isoflavones were also identified for the first time in related species, T. repense L. (white clover), T. hybridum L. (alsike clover) and T. campestre Schreber (hop trefoil). Based on reversed phase HPLC, all 10 isoflavone aglycones, daidzein, formononetin, genistein, pseudobaptigenin, glycitein, calycosin, prunetin, biochanin A, irilone and pratensein in acidic hydrolyzed extracts were successfully separated within 40 min and quantified individually by UV and MS detectors. For the 10 target compounds, the investigated concentrations ranged from ∼24 to ∼12500 ng/ml for UV detection and ∼6 to ∼3125 ng/ml for MS detection, and good linearities (r2>0.999 for UV and r2>0.99 for MS) for standard curves were achieved for each isoflavone. The accuracy and repeatability (n=10) were within 15% for these 10 compounds. This is the first method reported that enables the simultaneous quantitation of all 10 isoflavone aglycones in red clover and related species.
Mark W Collison - One of the best experts on this subject based on the ideXlab platform.
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improved methods for the extraction and analysis of Isoflavones from soy containing foods and nutritional supplements by reversed phase high performance liquid chromatography and liquid chromatography mass spectrometry
Journal of Chromatography A, 2001Co-Authors: Aaron P Griffith, Mark W CollisonAbstract:Abstract An improved method for extraction and analysis of Isoflavones from soy protein, soy foods and nutritional supplements is presented. The method uses acetonitrile extraction without acidification, with apigenin as internal standard. Samples extracted in acetonitrile–water are diluted to 50% acetonitrile and directly injected for gradient HPLC separation on a C18 reversed-phase column. This method saves significant time during sample preparation and improves accuracy and precision. Conventional and rapid HPLC analysis methods compatible with the extraction scheme were developed. During development of the methods, unexpected minor forms of malonyl and acetyl Isoflavones were discovered in extracts of soy proteins and in pure isoflavone standard preparations. By LC–triple MS, these peaks have identical composition to the respective 6″-O-malonyl- and 6″-O-acetyl-Isoflavones from which they form. These minor forms are believed to be malonyl and acetyl Isoflavones where the site of attachment is a hydroxyl other than the 6′-OH of the glucose. These compounds can represent significant minor isoflavone components of foods, which contain high concentrations of malonyl or acetyl Isoflavones.
