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1.
Dietary soybean isoflavones in Alzheimer's disease prevention.
Lu, Y, An, Y, Lv, C, Ma, W, Xi, Y, Xiao, R
Asia Pacific journal of clinical nutrition. 2018;(5):946-954
Abstract
Soybean isoflavone (SIF) is a type of polyphenol present extensively in legumes. Because of its unique chemical construction and the physiological activity of the phenolic hydroxyl group, SIF exhibits strong antioxidant activity in antioxidant and nonantioxidant enzyme systems. Genistein is the major isoflavone in soy foods, accounting for more than 50% of the isoflavone content. The health effects of soybean dietary isoflavones on humans have gained increased attention. Recent studies have suggested that SIF may alleviate neurodegenerative diseases such as Alzheimer's disease (AD). Despite the comprehensive research on AD, effective treatments for AD are yet to be established. The early diagnosis and prevention of mild cognitive impairment (MCI) have become crucial for delaying AD development. Several dietary polyphenols have exerted cognitive effects on AD, and the appropriate intake of dietary SIF helps reduce the risk of AD. This study reviews the possible mechanisms of AD pathogenesis and their relationships with SIF intake; the results provide useful insights for AD prevention in the future.
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2.
Soy isoflavones improve cardiovascular disease risk markers in women during the early menopause.
Sathyapalan, T, Aye, M, Rigby, AS, Thatcher, NJ, Dargham, SR, Kilpatrick, ES, Atkin, SL
Nutrition, metabolism, and cardiovascular diseases : NMCD. 2018;(7):691-697
Abstract
BACKGROUND Hormone replacement therapy may be beneficial for cardiovascular disease risk (CVR) in post-menopausal women. Soy isoflavones may act as selective estrogen receptor modulators. The aim of this study was to evaluate whether soy isoflavones had an effect on CVR markers. METHODS The expected 10-year risk of cardiovascular disease and mortality were calculated as a secondary endpoint from a double blind randomised parallel study involving 200 women (mean age 55 years, Caucasian, Hull, UK, 2012) in the early menopause who were randomised to 15 g soy protein with 66 mg isoflavone (SPI) or 15 g soy protein alone (depleted of all isoflavones; SP) given as a snack bar between meals daily for 6 months. Age, diabetes, smoking, blood pressure and lipid profiles were used to calculate CVR using the Framingham CVR engine. RESULTS SPI treatment resulted in a significant reduction in the metabolic parameters and systolic blood pressure compared to SP (p < 0.01). There were no changes in fasting lipid profile and diastolic blood pressure with either treatment. At 6 months, changes in these parameters with SPI treatment were reflected in a calculated 27% (p < 0.01) reduction in 10 year coronary heart disease risk, a 37% (p < 0.01) reduction in myocardial infarction risk, a 24% (p < 0.04) reduction in cardiovascular disease and 42% (p < 0.02) reduction in cardiovascular disease death risk. CONCLUSIONS Supplementation with soy protein with isoflavones for 6 months significantly improved CVR markers and calculated CVR at 6 months during early menopause compared to soy protein without isoflavones. ISRCTN REGISTRY ISRCTN34051237.
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Association between Dietary Isoflavones in Soy and Legumes and Endometrial Cancer: A Systematic Review and Meta-Analysis.
Zhong, XS, Ge, J, Chen, SW, Xiong, YQ, Ma, SJ, Chen, Q
Journal of the Academy of Nutrition and Dietetics. 2018;(4):637-651
Abstract
BACKGROUND Epidemiologic studies have reported conflicting findings between soy- and legume-derived dietary isoflavones and risk of endometrial cancer. OBJECTIVE The aim of the present meta-analysis was to quantitatively investigate the association between daily intake of soy- and legume-derived isoflavones and risk of endometrial cancer. DESIGN A broad search was conducted in the following electronic databases: PubMed, EMBASE, Google Scholar, the Cochrane Library, the China Knowledge Resource Integrated Database, and the Chinese Biomedical Database based on combinations of the key words endometrial cancer, isoflavone, soy, and legume for epidemiologic studies that focused on relationships between dietary isoflavones and endometrial cancer risk. A fixed-effect or random-effect model was used to pool study-specific risk estimates. RESULTS A total of 13 epidemiologic studies were included in the present meta-analysis, consisting of three prospective cohort studies and 10 population-based case-control studies. The final results indicated that higher dietary isoflavone levels from soy products and legumes were associated with a reduced risk of endometrial cancer (odds ratio [OR] 0.81, 95% CI 0.74 to 0.89). Low heterogeneous bias was observed (I2=11.7%; P=0.327). Subgroup analyses were conducted based on study design, source of dietary isoflavones, and study region. When restricted to study design, dietary isoflavones from soy and legumes played a role in prevention of endometrial cancer in case-control studies (OR 0.81, 95% CI 0.73 to 0.90). However, there did not appear to be an association between dietary isoflavones and endometrial cancer in cohort studies (OR 0.81, 95% CI 0.66 to 1.00). Significant associations were found between dietary isoflavones from soy products (OR 0.82, 95% CI 0.72 to 0.92) and legumes (OR 0.84, 95% CI 0.74 to 0.96) and endometrial cancer. Dietary isoflavones were associated with reduced incidence of endometrial cancer, both in Asian countries (OR 0.78, 95% CI 0.66 to 0.93) and non-Asian countries (OR 0.82, 95% CI 0.73 to 0.92). CONCLUSIONS The findings suggest a weak inverse association between higher consumption of dietary isoflavones from soy products and legumes and endometrial cancer risk. However, there is still a need for large, prospective epidemiologic studies that provide a higher level of evidence to verify these findings.
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4.
Effect of soy isoflavone supplementation on plasma lipoprotein(a) concentrations: A meta-analysis.
Simental-Mendía, LE, Gotto, AM, Atkin, SL, Banach, M, Pirro, M, Sahebkar, A
Journal of clinical lipidology. 2018;(1):16-24
Abstract
BACKGROUND Soy supplementation has been shown to reduce total and low-density lipoprotein cholesterol, while increasing high-density lipoprotein cholesterol. However, contradictory effects of soy isoflavone supplementation on lipoprotein(a) [Lp(a)] have been reported suggesting the need for a meta-analysis to be undertaken. OBJECTIVE The aim of the study was to investigate the impact of supplementation with soy isoflavones on plasma Lp(a) levels through a systematic review and meta-analysis of eligible randomized placebo-controlled trials. METHODS The search included PubMed-Medline, Scopus, ISI Web of Knowledge, and Google Scholar databases (by March 26, 2017), and quality of studies was evaluated according to Cochrane criteria. Quantitative data synthesis was performed using a random-effects model, with standardized mean difference and 95% confidence interval as summary statistics. Meta-regression and leave-one-out sensitivity analysis were performed to assess the modifiers of treatment response. RESULTS Ten eligible studies comprising 11 treatment arms with 973 subjects were selected for the meta-analysis. Meta-analysis did not suggest any significant alteration of plasma Lp(a) levels after supplementation with soy isoflavones (standardized mean difference: 0.08, 95% confidence interval: -0.05, 0.20, P = .228). The effect size was robust in the leave-one-out sensitivity analysis. In meta-regression analysis, neither dose nor duration of supplementation with soy isoflavones was significantly associated with the effect size. CONCLUSION This meta-analysis of the 10 available randomized placebo-controlled trials revealed no significant effect of soy isoflavones treatment on plasma Lp(a) concentrations.
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Effect of phytoestrogens on sexual function in menopausal women: a systematic review and meta-analysis.
Najaf Najafi, M, Ghazanfarpour, M
Climacteric : the journal of the International Menopause Society. 2018;(5):437-445
Abstract
OBJECTIVE This systematic review and meta-analysis aimed to critically evaluate the effectiveness of phytoestrogens on sexual disorders and severity of dyspareunia. MATERIALS AND METHODS Relevant studies were identified through a systematic search of major databases such as PubMed, Cochrane Library, ISI Web of Science, and Scopus up to 29 September 2017, without any time limit. Two independent reviewers screened all abstracts and full-text articles. The final version of Jadad scale was used for evaluating the quality of trials. RESULTS Soy did not have an effect on sexual function (standardized mean difference [SMD] = 1.099 [95% CI: -3.033 to 0.835, p = 0.265]; heterogeneity I2 = 80%; p = 0.006; random-effect model; three trials) but improved dyspareunia (p > 0.05). Red clover showed no significant effect on sexual function (SMD = -0.087 [95% CI: -0.936 to 0.763, p = 0.842]; heterogeneity I2 = 0%, p = 0.397; fixed-effect model; two trials) and sexual satisfaction (p > 0.05). Phytoestrogens isolated from Lepidium meyenii, Foeniculum vulgare, and maritime pine bark as well as Trigonella foenum-graecum L. significantly improved sexual function. In contrast, phytoestrogens isolated from Korean red ginseng and flaxseed did not lead to significant effect on sexual function. The positive effects of Trigonella foenum-graecum L. were observed on libido. CONCLUSION Phytoestrogens have various effects on sexual function. Published reports show that maritime pine bark, T. foenum-graecum L., and F. vulgare could be considered as agents to overcome sexual dysfunctions while soy, red clover, genistein, and flaxseed had no promising effects on these conditions.
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Effects of red clover on perimenopausal and postmenopausal women's blood lipid profile: A meta-analysis.
Luís, Â, Domingues, F, Pereira, L
Climacteric : the journal of the International Menopause Society. 2018;(5):446-453
Abstract
The study aimed to perform a systematic review with meta-analysis of randomized controlled trials (RCTs) to access the effects of red clover isoflavones on the blood lipid profile of both perimenopausal and postmenopausal women. PubMed, Web of Science, Scopus, SciELO, and Cochrane Library were searched for the terms 'red clover', 'Trifolium pratense', and 'randomized controlled trial' during November 2017. Summary measures were reported as weighted mean differences (WMD) with 95% confidence interval (CI). Fixed or random effects models were used for meta-analyses, according to heterogeneity. Risk of bias was measured with the Cochrane tool. Twelve RCTs (totalizing 1284 perimenopausal and postmenopausal women receiving red clover isoflavones for 4 weeks-18 months) resulted in a significant decrease in total cholesterol (WMD = -12.34 mg/dl; 95% CI: -18.21, -6.48), low-density lipoprotein cholesterol (WMD = -10.61 mg/dl; 95% CI: -15.51, -5.72), and triglycerides (WMD = -10.18 mg/dl; 95% CI: -16.23, -4.13) together with a significant increase in high-density lipoprotein cholesterol (WMD = 1.60 mg/dl; 95% CI: 0.17, 3.03). In conclusion, the results demonstrate that the ingestion of red clover may have a beneficial effect on the lipid profile of perimenopausal and postmenopausal women.
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The association between dietary isoflavones intake and gastric cancer risk: a meta-analysis of epidemiological studies.
You, J, Sun, Y, Bo, Y, Zhu, Y, Duan, D, Cui, H, Lu, Q
BMC public health. 2018;(1):510
Abstract
BACKGROUND Isoflavones, a class of phytoestrogenic compounds, are abundant in soybeans. A number of epidemiological studies have investigated the association between dietary isoflavones intake and the risk of gastric cancer. However, the results are inconclusive. Therefore, the meta-analysis was conducted to evaluate the effect of dietary isoflavones intake on the risk of gastric cancer. METHODS Relevant studies from May 1992 to May 2017 were identified through searching PubMed and Web of Science. Additional articles were identified from the reference lists of relevant review articles. Pooled risk ratios (RRs) or odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a fixed-effects model. Funnel plot and Egger's test were used to evaluate publication bias. RESULTS Seven articles reporting 12 studies were included in the current meta-analysis. We found no significant association between dietary isoflavones intake and gastric cancer risk with the highest versus the lowest categories of dietary isoflavones intake (OR = 0.97, 95% CI = 0.87-1.09, I2 = 27.5%). Subgroup analyses generally yield similar results. CONCLUSIONS Higher dietary isoflavones intake is not associated with a decline in the risk of gastric cancer.
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Dietary intake of isoflavones and coumestrol and the risk of prostate cancer in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial.
Reger, MK, Zollinger, TW, Liu, Z, Jones, JF, Zhang, J
International journal of cancer. 2018;(4):719-728
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Abstract
Experimental studies have revealed that phytoestrogens may modulate the risk of certain sites of cancer due to their structural similarity to 17β-estradiol. The present study investigates whether intake of these compounds may influence prostate cancer risk in human populations. During a median follow up of 11.5 years, 2,598 cases of prostate cancer (including 287 advanced cases) have been identified among 27,004 men in the intervention arm of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Dietary intake of phytoestrogens (excluding lignans) was assessed with a food frequency questionnaire. Cox proportional hazards regression analysis was performed to estimate hazard ratios (HRs) and 95% confidence intervals (CI) for dietary isoflavones and coumestrol in relation to prostate cancer risk. After adjustment for confounders, an increased risk of advanced prostate cancer [HR (95% CI) for quintile (Q) 5 vs. Q1] was found for the dietary intake of total isoflavones [1.91 (1.25-2.92)], genistein [1.51 (1.02-2.22), daidzein [1.80 (1.18-2.75) and glycitein [1.67 (1.15-2.43)] (p-trend for all associations ≤0.05). For example, HR (95% CI) for comparing the Q2, Q3, Q4 and Q5 with Q1 of daidzein intake was 1.45 (0.93-2.25), 1.65 (1.07-2.54), 1.73 (1.13-2.66) and 1.80 (1.18-2.75), respectively (p-trend: 0.013). No statistically significant associations were observed between the intake of total isoflavones and individual phytoestrogens and non-advanced and total prostate cancer after adjustment for confounders. This study revealed that dietary intake of isoflavones was associated with an elevated risk of advanced prostate cancer.
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Circulating isoflavone and lignan concentrations and prostate cancer risk: a meta-analysis of individual participant data from seven prospective studies including 2,828 cases and 5,593 controls.
Perez-Cornago, A, Appleby, PN, Boeing, H, Gil, L, Kyrø, C, Ricceri, F, Murphy, N, Trichopoulou, A, Tsilidis, KK, Khaw, KT, et al
International journal of cancer. 2018;(11):2677-2686
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Abstract
Phytoestrogens may influence prostate cancer development. This study aimed to examine the association between prediagnostic circulating concentrations of isoflavones (genistein, daidzein, equol) and lignans (enterolactone and enterodiol) and the risk of prostate cancer. Individual participant data were available from seven prospective studies (two studies from Japan with 241 cases and 503 controls and five studies from Europe with 2,828 cases and 5,593 controls). Because of the large difference in circulating isoflavone concentrations between Japan and Europe, analyses of the associations of isoflavone concentrations and prostate cancer risk were evaluated separately. Prostate cancer risk by study-specific fourths of circulating concentrations of each phytoestrogen was estimated using multivariable-adjusted conditional logistic regression. In men from Japan, those with high compared to low circulating equol concentrations had a lower risk of prostate cancer (multivariable-adjusted OR for upper quartile [Q4] vs. Q1 = 0.61, 95% confidence interval [CI] = 0.39-0.97), although there was no significant trend (OR per 75 percentile increase = 0.69, 95 CI = 0.46-1.05, ptrend = 0.085); Genistein and daidzein concentrations were not significantly associated with risk (ORs for Q4 vs. Q1 = 0.70, 0.45-1.10 and 0.71, 0.45-1.12, respectively). In men from Europe, circulating concentrations of genistein, daidzein and equol were not associated with risk. Circulating lignan concentrations were not associated with the risk of prostate cancer, overall or by disease aggressiveness or time to diagnosis. There was no strong evidence that prediagnostic circulating concentrations of isoflavones or lignans are associated with prostate cancer risk, although further research is warranted in populations where isoflavone intakes are high.
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Isoflavones and bone health in perimenopausal and postmenopausal women.
Lambert, MNT, Jeppesen, PB
Current opinion in clinical nutrition and metabolic care. 2018;(6):475-480
Abstract
PURPOSE OF REVIEW Isoflavones exert estrogenic activity distinct from estrogen, they have the potential to treat diseases and symptoms related to estrogen deficiency with minimal side effects and risks. Isoflavone supplementation, in general, is shown to exert beneficial effects against estrogen-deficient bone loss in women, however, some clinical trials still produce conflicting findings. The purpose of this review is to highlight and summarize the most recent and up-to-date research in the field and to bring attention to factors that play a major role in the outcomes of clinical trials that investigate phytoestrogens. Here, we also discuss the latest and most relevant data regarding the clinical safety of these substances. RECENT FINDINGS Isoflavones are naturally occurring secondary metabolites found in the Fabacaea plant family. Clinical data from isoflavone interventions support that aglycones (abundant in fermented products) exert enhanced beneficial effects against estrogen-deficient bone loss in women compared with isoflavone glycosides. Studies that employ methods to determine isoflavone content and form of treatments are more likely detect beneficial effects on bone. EFSA have confirmed the safety of isoflavones for women in the most comprehensive report to date. SUMMARY Isoflavone aglycones exert greater effects against bone loss than glycosides. Isoflavones show promise as a first-line prophylactic/treatment for bone loss in women.