Effects of soy isoflavone extract supplements on blood pressure in adult humans: systematic review and meta-analysis of randomized placebo-controlled trials

Unanticipated differences in the rat plasma metabolome of genistein and daidzein

Genistein (GEN) and daidzein (DAI) are soy isoflavones known to bind to estrogen receptors. Overall health effects of GEN and DAI in humans exhibit a dual nature, presenting both health benefits and concerns related to their interaction with the estrogen receptor. The metabolomes of these isoflavones were determined in 28-day oral studies in male and female Wistar rats to elucidate (1) metabolites changes, (2) compare their metabolomes with other compounds and (3) identify toxicological modes of action (MoA). Dose levels for GEN were 1000 and 300 mg/kg bw by gavage and 1000 and 300 ppm (via diet). DAI gavage dose levels were 1000 and 100 mg/kg bw. Results were evaluated using the MetaMap®Tox data base. Both compounds demonstrated metabolome profiles which were associated with estrogenic profiles and compounds, predominantly in females. However, the metabolomes were compound specific with relatively few common metabolite changes. There were no relevant matches between any GEN and any DAI treatment group indicating that both compounds are substantially different from metabolome perspective. Ranking of the metabolome patters for GEN and DAI with ≥ 1000 compounds in the MetaMap®Tox database revealed correlations with estrogenic and other hormonally active compounds. GEN-treated females correlated best with Cabergoline, a dopamine D2 receptor agonist, DAI females with tamoxifen and diethylstilbestrol, suggesting that even their estrogenic activity may be different. Beyond estrogenic effects, the high dose (HD) DAI metabolome indicated altered fatty acid metabolism associated with PPAR-alpha activation. For GEN, there was an indication of ethanolamine-like liver effects. Dose levels without estrogenic effects for GEN were 1000 and 100 mg/kg bw for males and females respectively, there were no estrogenic effects in the feeding studies. For DAI males, the no estrogenic effect level was 300 mg/kg bw, for females < 100 mg/kg bw, suggesting that DAI may be a more potent estrogen than GEN in rats.

Screening of soybean antifungal isoflavones based on targeted metabolomics analysis

Soybean (Glycine max) is a key crop rich in bioactive compounds, particularly isoflavones, which play a significant role in plant defense against biotic stress like fungal infections. In this study, nine soybean varieties with varying susceptibility to mildew were evaluated. Isoflavone profiles in seeds and pods were analyzed using high-performance liquid chromatography-mass spectrometry (HPLC-MS), and metabolomics analysis via orthogonal signal correction partial least squares discriminant analysis (OSC-PLS-DA) identified differences between mildew-affected and unaffected samples. Results showed organ-specific changes, with isoflavone aglycones increasing in seeds, while malonylglucosides (M-type) varied in pods. β-Glucoside (G-type) and M-type isoflavones were identified as differential metabolites. Antifungal assays revealed that genistin, among six isoflavone glycosides and aglycones tested, had the strongest inhibitory effects on Aspergillus flavus. Additionally, the identification of G-type and M-type isoflavone glycosides underscores the necessity for further investigation into the roles these metabolites play in the overall antifungal activity observed.

A Mendelian Randomization Study about Causal Associations between Tofu Consumption and Stroke as well as Related Subtypes

OBJECTIVE

Consuming soy in the diet is beneficial for health, and tofu possess the richest source of dietary soy. However, the specific association with stroke and related subtypes remains controversial. In this study, the genetic causal relationship among tofu and stroke as well as the subtypes was investigated by utilizing the data in a number of genome-wide association study (GWAS) based on population.

METHODS

The tofu intake GWAS analysis is derived from the Medical Research Council (MRC) Integrative Epidemiology Unit at the University of Bristol (MRC-IEU) Consortium. The two-sample Mendelian randomization (MR) study was carried out, utilizing multiple analysis methods to analyze the associations with stroke and related subtypes. The sensitivity, heterogeneity, and potential pleiotropy could be investigated by multiple analysis method.

RESULTS

We found that tofu intake had no causal relationship with stroke. However, in stroke subtype, there is a causal relationship among tofu intake with the risk of intracerebral hemorrhage (ICH) (odds ratio, OR = 1.24 × 10-5, 95% CI: 1.54 × 10-8-9.95 × 10-3, p = 9.300 × 10-4), while tofu intake does not affect the risk of ischemic stroke (OR = 1.07 × 10-1, 95% CI: 3.84 × 10-4-2.97 × 101, p = 4.362 × 10-1) and subarachnoid hemorrhage (SAH) (OR = 3.33 × 10-3, 95% CI: 1.79 × 10-6-6.18, p = 1.373 × 10-1). Both the Mendelian randomization PRESSO (MR-PRESSO) global test and Cochran's Q test did not detect any sensitivity and heterogeneity.

CONCLUSIONS

While tofu consumption is associated with a higher risk of ICH, it does not show a significant relationship with ischemic stroke or SAH. The varying effects of tofu on different stroke subtypes underscore the need for considering potential confounding dietary and lifestyle factors in future studies.

Soy isoflavone intake and risk of cardiovascular disease in adults: A systematic review and dose-response meta-analysis of prospective cohort studies

We examined the association between soy isoflavone intake and risk of cardiovascular disease (CVD) outcomes in adults. We searched the online databases for relevant studies published up to September 2021. In total, 13 publications were included in the systematic review and 12 in the meta-analysis. We found that a high intake of soy isoflavones was significantly associated with a lower risk of coronary heart disease (CHD) among whole populations (Pooled RR: 0.92, 95% CI: 0.85-0.99, I2 = 41.0%, Pheterogeneity = 0.10) and a lower risk of overall CVD (Pooled RR: 0.91, 95% CI: 0.84-0.98, I2 = 30.7%, Pheterogeneity = 0.19) and CHD (Pooled RR: 0.89, 95% CI: 0.83-0.96, I2 = 14.4%, Pheterogeneity = 0.32) among Western population. In the linear dose-response analysis, a 3 mg/day increase in soy isoflavone intake was associated with 16% and 14% lower risks of overall CVD and CHD, respectively, among Western population. In conclusion, we found that soy isoflavone intake was associated with a lower risk of overall CVD and CHD in adults, particularly among Western population.

European soybean to benefit people and the environment

Europe imports large amounts of soybean that are predominantly used for livestock feed, mainly sourced from Brazil, USA and Argentina. In addition, the demand for GM-free soybean for human consumption is project to increase. Soybean has higher protein quality and digestibility than other legumes, along with high concentrations of isoflavones, phytosterols and minerals that enhance the nutritional value as a human food ingredient. Here, we examine the potential to increase soybean production across Europe for livestock feed and direct human consumption, and review possible effects on the environment and human health. Simulations and field data indicate rainfed soybean yields of 3.1 ± 1.2 t ha-1 from southern UK through to southern Europe (compared to a 3.5 t ha-1 average from North America). Drought-prone southern regions and cooler northern regions require breeding to incorporate stress-tolerance traits. Literature synthesized in this work evidenced soybean properties important to human nutrition, health, and traits related to food processing compared to alternative protein sources. While acknowledging the uncertainties inherent in any modelling exercise, our findings suggest that further integrating soybean into European agriculture could reduce GHG emissions by 37-291 Mt CO2e year-1 and fertiliser N use by 0.6-1.2 Mt year-1, concurrently improving human health and nutrition.

Changes in the consumption of isoflavones, omega-6, and omega-3 fatty acids in women with metastatic breast cancer adopting a whole-food, plant-based diet: post-hoc analysis of nutrient intake data from an 8-week randomized controlled trial

Background

Diets rich in minimally processed plant-based foods are recommended to breast cancer patients, and some may have an interest in whole-food, plant-based (WFPB) diets that avoid animal-based foods, added fats, and refined sugars. Within WFPB diets, the intakes of isoflavones, omega-6 polyunsaturated fatty acids (n-6 PUFAs), and omega-3 polyunsaturated FAs (n-3 PUFAs), which have been discussed in reference to breast cancer outcomes, have not been well characterized.

Methods

Women with stage IV breast cancer on stable therapy were randomized 2:1 into (1) a WFPB intervention (N = 21) or (2) usual care (N = 11) for 8 weeks. Three meals per day were provided. Outcomes presented here include dietary intake of isoflavones, n-3 and n-6- PUFAs, which were assessed using three-day food records at baseline and 8 weeks. Baseline and 8-week mean intake within groups were compared using the Wilcoxon signed-rank test and between control and intervention groups by a two-sample t-test.

Results

The WFPB intervention participants increased their daily consumption of total isoflavones from a mean of 0.8 mg/day to 14.5 mg/day (p < 0.0001) and decreased the n-6:n-3 ratio of their diet from a mean of 9.3 to 3.7 (p < 0.0001). Within the WFPB group, linoleic acid (n-6 PUFA) consumption decreased by a mean of 3.8 g (p = 0.0095), from 12.8 g/day to 9.0 g/day; total n-3 PUFA consumption increased by a mean of 1.1 g (p = 0.0005), from 1.6 g/day to 2.7 g/day.

Conclusion

Transitioning to a WFPB diet resulted in significantly increased isoflavone intake and decreased n-6:n-3 ratio in women with breast cancer.

Effect of soy isoflavone supplementation on blood pressure: a meta-analysis of randomized controlled trials

BACKGROUND

Previous experimental studies have suggested that the consumption of soy isoflavones may have a potential impact on lowering blood pressure. Nevertheless, epidemiological studies have presented conflicting outcomes concerning the correlation between soy isoflavone consumption and blood pressure levels. Consequently, a comprehensive meta-analysis of all eligible randomized controlled trials (RCTs) was conducted to explore the influence of soy isoflavones on systolic blood pressure (SBP) and diastolic blood pressure (DBP) in adults.

METHODS

A thorough search of PubMed, Embase, and the Cochrane Library for relevant literature up to April 30, 2023 was conducted. RCTs involving adults that compared soy isoflavone supplementation with a placebo (the same matrix devoid of soy isoflavone) were included. The combined effect size was presented as the weighted mean difference (WMD) along with 95% confidence interval (CI), employing a fixed-effects model.

RESULTS

Our meta-analysis included a total of 24 studies involving 1945 participants. The results revealed a significant reduction in both SBP and DBP with soy isoflavone supplementation. Subgroup analyses suggested more pronounced reductions in SBP and DBP for interventions lasting ≥6 months, in individuals receiving mixed-type soy isoflavone, and among patients with metabolic syndrome or prehypertension. However, we did not detect significant nonlinear associations between supplementation dosage and intervention duration concerning both SBP and DBP. The overall quality of evidence was deemed moderate.

CONCLUSIONS

The current meta-analysis revealed that supplementation with soy isoflavones alone effectively reduces blood pressure. Additional high-quality studies are required to investigate the efficacy of blood pressure reduction through supplementation with an optimal quantity and proportion of soy isoflavone.

Differential Gut Microbiota, Dietary Intakes in Constipation Patients with or without Hypertension

SCOPE

Diet and gut microbiota are involved in blood pressure regulations, but few studies have focused on the constipation patients. The study seeks to identify differences in gut microbiota between hypertensive and normotensive subjects in constipation patients, analyzes the relationship between dietary patterns and blood pressure, and explores mediation effects of gut microbiota.

METHODS AND RESULTS

Gut microbial genera and dietary information of 186 functional constipation participants are characterized by 16S rRNA sequencing and a food frequency questionnaire. The hypertensive subjects shows lower α-diversity and β-diversity of gut microbiota than normotensive (p < 0.05) and 17 differential microbial genera. The dried-beans intake frequency inversely correlated with systolic and diastolic blood pressure after multivariate adjustment (r = -0.273, p-FDR < 0.01; r = -0.251, p-FDR = 0.026, respectively). Logistic regression indicates that the individuals often consumed dried-beans have a lower hypertension risk than those never consumed [OR = 0.137, 95% CI: (0.022, 0.689), p = 0.022]. A marginal mediating effect of the genus Monoglobus is observed for the association between high-fiber dietary pattern and hypertension.

CONCLUSION

In patients with functional constipation, hypertension-related gut microbial differences are identified. Dried-beans intake is inversely associated with blood pressure, and a genus may potentially mediate the association between high-fiber dietary pattern and hypertension.

Soybean Isoflavones Activating Autophagy and Improving the Chemosensitivity of Carboplatin to Ovarian Cancer Cells

Objection: To discuss soybean isoflavones activating autophagy and improving the chemosensitivity of carboplatin to ovarian cancer cells. Materials and Methods: Using SKOV3 and A2780 cell lines as research object, dividing into Normal, Carb (treated with 50 μmol/L carboplatin) and Carb+Soy (treated with 50 μmol/L carboplatin and 80 μmol/L soybean isoflavone). Evaluating cell proliferation by EdU and MTT assay; measuring cell apoptosis rate by flow cytometry; observation cells’ autophagy by transmission electron microscope (TEM); LC 3B protein expression were evaluated by cellular immunofluorescence and using WB assay to evaluate autophagy relative proteins expression. Results: Compared with Normal group, the cell proliferation were significantly depressed with cell apoptosis rates significantly increasing (P < 0.01, respectively); and autophagy enhancing; with LC 3B, LC 3II/LC 3I ratio and Beclin 1 significantly up-regulation and P62 protein significantly down-regulation (P < 0.01, respectively) in Carb and Carb+Soy groups. And there were significantly differences between Carb and Carb+Soy groups in EdU cell number, cell proliferation, apoptosis rate, autophagy, LC 3B, LC 3II/LC 3I ratio, Beclin 1 and P62 protein expression. Conclusion: Soy activating autophagy and improving the chemosensitivity of carboplatin to ovarian cancer cells.

Systematic review and meta-analysis of randomized, controlled trials on the effects of soy and soy products supplementation on serum adiponectin levels

BACKGROUND AND AIMS

Our aim in this meta-analysis was to determine the effect of soy and soy product supplementation on serum adiponectin levels.

METHOD

A systematic search was conducted using Medline (PubMed and Web of Science), Scopus, and Cochrane Library for eligible trials up to August 2020. A random-effects model was used to pool calculated effect sizes.

RESULTS

Seven trials were included in the overall analysis. Our analysis showed that soy and soy product supplementation did not significantly affect adiponectin concentrations (WMD = -0.77 μg/ml, 95% CI: -0.61, 2.15, P = 0.27) in comparison with a placebo. The between-study heterogeneity was high (I2: 68.2%, P = 0.004). Subgroup analysis, based on participants' health status and duration of the supplementation, could not detect the potential source of the observed heterogeneity. In addition, subgroup analysis showed that the effect was not statistically significant in all subgroups.

CONCLUSION

Overall, soy and soy product supplementation did not change the circulatory adiponectin levels. In addition, the results were not affected by the participant's health status and duration of supplementation. However, further studies are needed to confirm the present results.

The Association between Plasma Concentration of Phytoestrogens and Hypertension within the Korean Multicenter Cancer Cohort

In order to examine the association between plasma phytoestrogen concentration (genistein, daidzein, equol and enterolactone) and hypertension, we conducted a nested case–control study for 229 hypertension cases including 112 prehypertension and 159 healthy controls derived from the Korean Multi-center Cancer Cohort (KMCC). The concentration of plasma phytoestrogens was measured using time-resolved fluoroimmunoassay. We assessed the association between plasma phytoestrogens and hypertension using logistic regression models using odds ratio (OR) and 95% confidence interval (95%CI). The highest tertile of plasma equol and enterolactone concentration exhibited a significantly decreased risk of hypertension (equol, OR = 0.34, 95%CI 0.20–0.57; enterolactone, OR = 0.32, 95%CI 0.18–0.57), compared with the lowest tertile. Equol and enterolactone showed reduced ORs for prehypertension (the highest tertile relative to the lowest tertile, OR = 0.50, 95%CI 0.26–0.96; OR = 0.38, 95%CI 0.19–0.75, respectively) and hypertension (OR = 0.42, 95%CI 0.22–0.81; OR = 0.28, 95%CI 0.14–0.54, respectively). There was a stronger association in hypertension (the highest tertile relative to the lowest tertile in obesity vs. non-obesity; equol, OR = 0.06 vs. 0.63; enterolactone, OR = 0.07 vs. 0.46; both p-heterogeneity < 0.01). This study suggests that equol and enterolactone may contribute to prevent primarily prehypertension and hypertension, and control cardiovascular disease (CVD) based on the continuum of hypertension and CVD. Further study to assess hypertension risk based on useful biomarkers, including phytoestrogens, may contribute to primary prevention of hypertension.

Consumption of soy products and cardiovascular mortality in people with and without cardiovascular disease: a prospective cohort study of 0.5 million individuals

PURPOSE

We sought to examine the association of soy product consumption with risk of cardiovascular death in Chinese individuals with and without a history of cardiovascular disease (CVD).

METHODS

The current analysis included 487,034 individuals free of CVD and 22,923 individuals with a history of CVD at study baseline. Data on consumption of soy products were collected by a food frequency questionnaire. The Cox regression was used to obtain the hazard ratios (HRs) of cardiovascular mortality associated with soy product consumption among people with and without a history of CVD at baseline.

RESULTS

During the period of follow-up, 12,582 and 2860 cardiovascular deaths were recorded among people without and with a history of CVD. Compared with those who never or rarely ate soy products, the multivariable HRs (95% CIs) were 1.02 (0.96, 1.08) for those who ate soy products monthly, 1.01 (0.95, 1.07) for those who ate soy products 1-3 days per week, 0.95 (0.88, 1.04) for those who ate soy products ≥ 4 days per week. For cause-specific mortality, soy product consumption was inversely associated with mortality from acute myocardial infarction (HR [95% CI] = 0.75 [0.61, 0.92]). Among people with a history of CVD, higher soy product consumption was not associated with cardiovascular mortality.

CONCLUSIONS

Soy consumption ≥ 4 days per week was associated with a significantly lower risk of mortality from acute myocardial infarction in comparison with never or rarely consumption among people without a history of CVD. Among people with a history of CVD, higher soy product consumption was not associated with cardiovascular mortality.

The Effects of Soy Products on Cardiovascular Risk Factors in Patients with Type 2 Diabetes: A Systematic Review and Meta-analysis of Clinical Trials

Previous studies have suggested that soy products may be beneficial for cardiometabolic health, but current evidence regarding their effects in type 2 diabetes mellitus (T2DM) remain unclear. The aim of this systematic review and meta-analysis was to determine the impact of soy product consumption on cardiovascular risk factors in patients with T2DM. PubMed, Scopus, Embase, and the Cochrane library were systematically searched from inception to March 2021 using relevant keywords. All randomized controlled trials (RCTs) investigating the effects of soy product consumption on cardiovascular risk factors in patients with T2DM were included. Meta-analysis was performed using random-effects models and subgroup analysis was performed to explore variations by dose and baseline risk profile. A total of 22 trials with 867 participants were included in this meta-analysis. Soy product consumption led to a significant reduction in serum concentrations of triglycerides (TG) (WMD: -24.73 mg/dL; 95% CI: -37.49, -11.97), total cholesterol (TC) (WMD: -9.84 mg/dL; 95% CI: -15.07, -4.61), low density lipoprotein (LDL) cholesterol (WMD: -6.94 mg/dL; 95% CI: -11.71, -2.17) and C-reactive protein (CRP) (WMD: -1.27 mg/L; 95% CI: -2.39, -0.16). In contrast, soy products had no effect on high density lipoprotein (HDL) cholesterol, fasting blood sugar (FBS), fasting insulin, hemoglobin A1c (HbA1c), homeostatic model assessment of insulin resistance (HOMA-IR), systolic and diastolic blood pressure (SBP/DBP) or body mass index (BMI) (all P ≥ 0.05). In subgroup analyses, there was a significant reduction in FBS after soy consumption in patients with elevated baseline FBS (>126 mg/dL) and in those who received higher doses of soy intake (>30 g/d). Moreover, soy products decreased SBP in patients with baseline hypertension (>135 mmHg). Our meta-analysis suggests that soy product consumption may improve cardiovascular parameters in patients with T2DM, particularly in individuals with poor baseline risk profiles. However, larger studies with longer durations and improved methodological quality are needed before firm conclusions can be reached.

Phytonutrient supplements and metabolic biomarkers of cardiovascular disease: An umbrella review of meta-analyses of clinical trials

Phytonutrients exert several pharmacological effects on humans. In this study, we performed an umbrella review of the association of phytonutrient supplements (PNSs) with biomarkers of cardiovascular disease. Relevant published systematic reviews and meta-analyses of clinical trials were identified by searching PubMed, Embase, and Cochrane Library until July 4, 2020. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) for summarized effects and I2 statistics of heterogeneity were extracted from individual studies or reanalyzed using a random-effects model. Of the 50 included studies, pooled effects of PNSs on blood pressure, lipid profiles, and glycemic control were reported in 16, 25, and 14 articles, respectively. The findings appeared to be highly heterogeneous among individual trials of included systematic reviews and meta-analyses. Ginger (WMD = -6.36 mmHg, 95% CI = -11.27, -1.46) and Hibiscus sabdariffa (WMD = -7.58 mmHg, 95% CI = -9.69, -5.46) were associated with lowered systolic blood pressure, whereas Aloe vera, Nigella sativa, and spirulina were associated with beneficial effects on both lipid profiles and glycemic control. In summary, this umbrella review has provided up-to-date evidence for the effect of PNSs on biomarkers related to hypertension, dyslipidemia, and diabetes. The results must be interpreted with caution due to potential heterogeneity.

Impact of functional foods and nutraceuticals on high blood pressure with a special focus on meta-analysis: review from a public health perspective

In recent times many researchers are expressing immense interest in nutraceuticals and functional foods for combating various diseases or abnormal conditions, especially against hypertension (HT). Persistent HT is medically referred to as chronic high blood pressure (BP) and considered to be one of the major risk factors for the deadliest diseases including cardiovascular disease (CVD) and cerebrovascular diseases. Hence HT poses a serious socio-economic burden worldwide, particularly to developing countries. The current treatment strategy for HT includes standard anti-hypertensive drugs, which are associated with many adverse effects and lower drug adherence rates. Therefore, an alternative or complementary natural therapy (functional foods or nutraceuticals or dietary supplements) would be the alternate choice along with a modified lifestyle pattern that might help to manage or combat HT and its related complications. During this review, the author would like to shed light on the basic science behind HT including pathophysiology and the impact of dietary salt on HT and the impact of various functional foods or nutraceuticals against HT in humans (meta-analysis and systemic review). This contribution gives a better idea (public health perspective) for choosing the best functional foods/nutraceuticals for the prevention, management or delaying the onset of HT and its associated conditions along with modified lifestyle patterns and standard anti-hypertensive drugs.

Soy protein supplementation in men following radical prostatectomy: a 2-year randomized, placebo-controlled clinical trial

BACKGROUND

Many studies have addressed effects of dietary supplementation with soy protein, but most have been inconsistent and few have been long-term studies in men.

OBJECTIVES

This study was a secondary analysis of body weight, blood pressure, thyroid hormones, iron status, and clinical chemistry in a 2-y trial of soy protein supplementation in middle-aged to older men.

METHODS

Data were analyzed as secondary outcomes of a randomized controlled trial of dietary supplementation with 20 g/d soy protein isolate, providing 41 mg/d total isoflavones and 23 mg/d genistein, in 44- to 75-y-old men who were at risk of cancer recurrence following prostatectomy randomized to soy (n = 50) or a casein-based placebo (n  = 43). Weight, blood pressure, and blood samples were collected at baseline, every 2 mo in year 1, and every 3 mo in year 2.

RESULTS

Compared with casein, soy supplementation did not affect body weight, blood pressure, serum total cholesterol, calcium, phosphorus, and thyroid hormones. Serum ferritin concentrations doubled over 2 y in both groups (117-129%), whereas hemoglobin and hematocrit increased slightly. In an exploratory subgroup analysis of soy group data, weight increased in subjects producing equol but not in nonproducers. Blood pressure was reduced in nonequol producers but not in producers. Other endpoints were not affected by equol production status.

CONCLUSIONS

Soy protein supplementation for 2 y compared with a casein-based placebo did not affect body weight, blood pressure, serum total cholesterol, iron status parameters, calcium, phosphorus, and thyroid hormones. Exploratory analysis suggests that equol production status of subjects on soy may modify effects of soy on body weight and possibly blood pressure. This trial was registered at clinicaltrials.gov as NCT00765479.

The Vascular Effects of Isolated Isoflavones-A Focus on the Determinants of Blood Pressure Regulation

Isoflavones are phytoestrogen compounds with important biological activities, including improvement of cardiovascular health. This activity is most evident in populations with a high isoflavone dietary intake, essentially from soybean-based products. The major isoflavones known to display the most important cardiovascular effects are genistein, daidzein, glycitein, formononetin, and biochanin A, although the closely related metabolite equol is also relevant. Most clinical studies have been focused on the impact of dietary intake or supplementation with mixtures of compounds, with only a few addressing the effect of isolated compounds. This paper reviews the main actions of isolated isoflavones on the vasculature, with particular focus given to their effect on the determinants of blood pressure regulation. Isoflavones exert vasorelaxation due to a multitude of pathways in different vascular beds. They can act in the endothelium to potentiate the release of NO and endothelium-derived hyperpolarization factors. In the vascular smooth muscle, isoflavones modulate calcium and potassium channels, leading to hyperpolarization and relaxation. Some of these effects are influenced by the binding of isoflavones to estrogen receptors and to the inhibition of specific kinase enzymes. The vasorelaxation effects of isoflavones are mostly obtained with plasma concentrations in the micromolar range, which are only attained through supplementation. This paper highlights isolated isoflavones as potentially suitable alternatives to soy-based foodstuffs and supplements and which could enlarge the current therapeutic arsenal. Nonetheless, more studies are needed to better establish their safety profile and elect the most useful applications.

Habitual Miso (Fermented Soybean Paste) Consumption Is Associated with a Low Prevalence of Sarcopenia in Patients with Type 2 Diabetes: A Cross-Sectional Study

Insulin resistance is a risk of sarcopenia, and the presence of sarcopenia is high in patients with type 2 diabetes (T2DM). It has been reported that habitual miso soup consumption was associated with lower insulin resistance. However, the association between habitual miso consumption and the presence of sarcopenia in patients with T2DM, especially sex difference, was unclear. In this cross-sectional study, 192 men and 159 women with T2DM were included. Habitual miso consumption was defined as consuming miso soup regularly. Having both low skeletal muscle mass index (<28.64% for men, <24.12% for women) and low adjusted hand grip strength (<51.26% for men, <35.38% for women) was defined as sarcopenia. The proportions of sarcopenia were 8.7% in men and 22.6% in women. The proportions of habitual miso consumption were 88.0% in men and 83.6% in women. Among women, the presence of sarcopenia was lower in the group with habitual miso consumption (18.8% versus 42.3%, p = 0.018); however, there was no association between habitual miso consumption and the presence of sarcopenia in men. Habitual miso consumption was negatively associated with the presence of sarcopenia in women (adjusted odds ratio (OR), 0.20 (95% confidence interval (CI): 0.06-0.62), p = 0.005) but not in men. This study indicated that habitual miso consumption was associated with the presence of sarcopenia in women but not in men.

Association between the Intake of Fermented Soy Products and Hypertension Risk in Postmenopausal Women and Men Aged 50 Years or Older: The Korea National Health and Nutrition Examination Survey 2013-2018

Sodium intake is positively associated with hypertension risk; however, it is not clear whether there is an association between the intake of fermented soy products, a major source of salt, and blood pressure (BP). This study aimed to investigate the hypothesis that hypertension risk and BP were negatively associated with the intake of fermented soy products but not with the intake of sodium from fermented soy products. This cross-sectional study was performed using data from the Korea National Health and Nutrition Examination Survey (2013–2018). In total, 11,566 men and postmenopausal women aged ≥50 years were divided according to quintiles of sodium or fermented soy product intake. The intake of fermented soy products was negatively associated with hypertension risk (odds ratio: 0.81, 95% confidence interval: 0.66–0.98; p-trend = 0.023) and systolic BP (SBP; p-trend = 0.043) in postmenopausal women. Mediation analysis showed that the intake of fermented soy products had total and direct effects on SBP; however, there was no indirect effect because soy nutrients, such as protein, fiber, calcium, and potassium, had no significant effects on SBP. Among men, fermented soy product intake was not associated with hypertension risk and BP. Additionally, the intake of sodium from fermented soy products was not significantly associated with hypertension risk and BP in both postmenopausal women and men. This study suggests that hypertension risk and BP were not associated with the intake of sodium from fermented soy products; further, hypertension risk and BP were inversely associated with fermented soy product intake in postmenopausal women. Further clinical studies are needed to confirm the effect of fermented soy product intake on hypertension risk and BP.

Isoflavone Supplementation Does Not Potentiate the Effect of Combined Exercise Training on Resting and Ambulatory Blood Pressure in Non-Obese Postmenopausal Women: A Randomized Double-Blind Controlled Trial-A Pilot Study

Physical exercise and isoflavone supplementation are potential strategies to prevent and treat cardiovascular diseases in postmenopausal women. The aim of this study was to investigate whether there are additive effects of isoflavone supplementation when associated with combined aerobic and resistance exercise on resting and ambulatory blood pressure monitoring (ABPM) and in blood pressure variability (BPV). Thirty-one non-obese postmenopausal women were randomly allocated into two groups: placebo and exercise (Placebo n = 19); and isoflavone supplementation (100 mg/day) and exercise (isoflavone n = 19). ABPM and BPV were evaluated before and after 10 weeks of moderate combined (aerobic and resistance) exercise training. Generalized Estimating Equation (GEE) with Bonferroni correction and intention-to-treat analysis was used to compare the effects of interventions on resting BP, ABPM and BPV. Combined exercise training decreased resting systolic (SBP) and diastolic blood pressure (DBP) and reduced 24 h and awake ambulatory SBP, DBP and mean blood pressure over time, with no additional effects of isoflavone supplementation. No changes were observed in sleep period, or in BPV indexes (Standard Deviation of 24 h (SD), daytime and nighttime interval (SDdn) and average real variability (ARV) in both groups. We conclude that isoflavone supplementation does not potentiate the effects of combined training on resting and ambulatorial systolic and diastolic blood pressure in non-obese postmenopausal women.

Soy isoflavones interact with calcium and contribute to blood pressure homeostasis in women: a randomized, double-blind, placebo controlled trial

BACKGROUND

Estrogens and calcium regulate vascular health but caused adverse cardiovascular events in randomized trials.

OBJECTIVES

Whether phytoestrogenic soy isoflavones modulate the physiological effects of calcium on blood pressure was explored.

DESIGN

A double-blind, randomized study assigned 99 premenopausal women to 136.6 mg isoflavones (as aglycone equivalents) and 98 to placebo for 5 days per week for up to 2 years. Blood pressure, serum calcium and urinary excretion of daidzein (DE) and genistein (GE) were measured repeatedly before and during treatment.

RESULTS

Isoflavones did not affect blood pressure per intake dose assignment (i.e. intention-to-treat, n = 197), but significantly affected blood pressure per measured urinary excretion of isoflavones (i.e. per protocol analysis, n = 166). Isoflavones inversely moderated calcium effects on systolic blood pressure (SBP) (interaction term β-estimates: - 3.1 for DE, - 12.86 for GE, all P < 0.05), and decreased diastolic blood pressure (DBP) (β-estimates: - 0.84 for DE, - 2.82 for GE, all P < 0.05) after controlling for calcium. The net intervention effects between the maximum and no isoflavone excretion were - 17.7 and + 13.8 mmHg changes of SBP, respectively, at serum calcium of 10.61 and 8.0 mg/dL, and about 2.6 mmHg decrease of DBP.

CONCLUSIONS

Moderation by isoflavones of the physiological effect of calcium tends to normalize SBP, and this effect is most significant when calcium concentrations are at the upper and lower limits of the physiological norm. Isoflavones decrease DBP independent of calcium levels. Further studies are needed to assess the impact of this novel micronutrient effect on blood pressure homeostasis and cardiovascular health.

TRIAL REGISTRATION

www.clinicaltrials.gov identifier: NCT00204490.

Soy food intake associates with changes in the metabolome and reduced blood pressure in a gut microbiota dependent manner

BACKGROUND AND AIMS

Consumption of soy foods has been associated with protection against cardiometabolic disease, but the mechanisms are incompletely understood. We hypothesized that habitual soy food consumption associates with gut microbiome composition, metabolite production, and the interaction between diet, microbiota and metabolites.

METHODS AND RESULTS

We analyzed dietary soy intake, plasma and stool metabolites, and gut microbiome data from two independent cross-sectional samples of healthy US individuals (N = 75 lean or overweight, and N = 29 obese). Habitual soy intake associated with several circulating metabolites. There was a significant interaction between soy intake and gut microbiome composition, as defined by gut enterotype, on metabolites in plasma and stool. Soy consumption associated with reduced systolic blood pressure, but only in a subset of individuals defined by their gut microbiome enterotype, suggesting that responsiveness to soy may be dependent on microbiome composition. Soy intake was associated with differences in specific microbial taxa, including two taxa mapping to genus Dialister and Prevotella which appeared to be suppressed by high soy intake We identified context-dependent effects of these taxa, where presence of Prevotella was associated with higher blood pressure and a worse cardiometabolic profile, but only in the absence of Dialister.

CONCLUSIONS

The gut microbiome is an important intermediate in the interplay between dietary soy intake and systemic metabolism. Consumption of soy foods may shape the microbiome by suppressing specific taxa, and may protect against hypertension only in individuals with soy-responsive microbiota.

CLINICAL TRIALS REGISTRY

NCT02010359 at clinicaltrials.gov.

The effect of soy isoflavones on arterial stiffness: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

Some but not all randomized controlled trials (RCTs) of soy isoflavones showed their beneficial effect on arterial stiffness, a predictor of cardiovascular events, dementia, and all-cause mortality, independent of traditional risk factors. To test the hypothesis that supplementation of soy isoflavones reduces arterial stiffness, we performed a systematic review and meta-analysis of RCTs of soy isoflavones on arterial stiffness.

METHODS

The protocol of this systematic review was registered with PROSPERO (CRD42019126128) and written in accordance with PRISMA. The PubMed, Embase, and clinicaltrials.gov databases were searched using the following criteria: human subjects, soy isoflavones as intervention, and arterial stiffness as primary outcome. A random-effects meta-analysis was used to pool estimates across studies. Standardized mean difference (SMD) was used to synthesize quantitative results.

RESULTS

Among 998 articles retrieved, 8 articles met our criteria. Duration of intervention was relatively short (maximum of 12 weeks). Outcome measurements extracted were pulse wave velocity (PWV), systemic arterial compliance (SAC), augmentation index (AI), and cardio-ankle vascular index (CAVI). Soy isoflavones reduced arterial stiffness compared to placebo (standardized mean difference - 0.33, 95% confidence interval - 0.47, - 0.19). Subgroup analyses showed no difference between treatment effects for intervention duration (< 6 weeks vs. ≥ 6 weeks) or gender (women only vs. men only vs. combined). Sensitivity analysis showed no difference in the effect of soy isoflavones between PWV, CAVI, SAC, and AI.

CONCLUSION

Supplementation of soy isoflavones reduced arterial stiffness. Longer duration trials with larger number of participants are warranted.

Association of soy and fermented soy product intake with total and cause specific mortality: prospective cohort study

OBJECTIVE

To investigate the association between several types of soy products and all cause and cause specific mortality.

DESIGN

Population based cohort study.

SETTING

Japan Public Health Centre-based Prospective Study, which includes 11 public health centre areas in Japan.

PARTICIPANTS

92 915 participants (42 750 men and 50 165 women) aged 45 to 74 years.

EXPOSURES

Intake of total soy products, fermented soy products (natto and miso), non-fermented soy products, and tofu from a five year survey questionnaire.

MAIN OUTCOME MEASURES

All cause and cause specific mortality (cancer, total cardiovascular disease, heart disease, cerebrovascular disease, respiratory disease, and injury) obtained from residential registries and death certificates.

RESULTS

During 14.8 years of follow-up, 13 303 deaths were identified. In the multivariable adjusted models, intake of total soy products was not significantly associated with total mortality. Compared with the lowest fifth of total soy product intake, the hazard ratios in the highest fifth were 0.98 (95% confidence interval 0.91 to 1.06, P_trend=0.43) in men and 0.98 (0.89 to 1.08, P_trend=0.46) in women. Intake of fermented soy products was inversely associated with all cause mortality in both sexes (highest versus lowest fifth: 0.90 (0.83 to 0.97), P_trend=0.05 in men, and 0.89 (0.80 to 0.98), P_trend=0.01 in women). Natto showed significant and inverse associations with total cardiovascular disease related mortality in both sexes.

CONCLUSIONS

In this study a higher intake of fermented soy was associated with a lower risk of mortality. A significant association between intake of total soy products and all cause mortality was not, however, observed. The findings should be interpreted with caution because the significant association of fermented soy products might be attenuated by unadjusted residual confounding.

Acute Soy Supplementation Improves 20-km Time Trial Performance, Power, and Speed

INTRODUCTION

Isoflavones, a chemical class of phytoestrogens found in soybeans and soy products, may have biological functions similar to estradiol. After binding with ERβ or perhaps independently of estrogen receptors, isoflavones may augment vascular endothelial relaxation, contributing to improved limb blood flow.

PURPOSE

To determine if acute fermented soy extract supplementation influences 20-km time trial cycling performance and cardiac hemodynamics compared with a placebo.

METHODS

Subjects included 25 cyclists and triathletes (31 ± 8 yr, V˙O2peak: 55.1 ± 8.4 mL·kg·min). Each subject completed a V˙O2peak assessment, familiarization, and two 20-km time trials in randomized order after ingestion of a fermented soy extract supplement or placebo. The fermented soy extract consisted of 30 g powdered supplement in 16 fl. ounces of water. The placebo contained the same quantities of organic cocoa powder and water. Each trial consisted of 60 min of rest, 30 min at 55% Wpeak, and a self-paced 20-km time trial.

RESULTS

Soy supplementation elicited a faster time to 20-km completion (-0.22 ± 0.51 min; -13 s), lower average HR (-5 ± 7 bpm), and significantly greater power (7 ± 3 W) and speed (0.42 ± 0.16 km·h) during the last 5 km of the time trial compared with placebo. Analysis of the results by relative fitness level (<57 vs ≥ 57 mL⋅kg⋅min) indicated that those with a higher level of fitness reaped the largest performance improvement alongside a reduced HR (-5 ± 7 bpm).

CONCLUSIONS

Ingestion of a fermented soy extract supplement improved sprint-distance performance through improvements in both power and speed. For those with great aerobic fitness, soy supplementation may help to decrease cardiac demand alongside performance improvement.

Legume Consumption and Cardiometabolic Health

Legumes are key components of several plant-based diets and are recognized as having a wide range of potential health benefits. Previous systematic reviews and meta-analyses have summarized the evidence regarding different cardiometabolic outcomes, such as cardiovascular disease (CVD) and type 2 diabetes (T2D), and legume consumption. However, those studies did not differentiate between nonsoy and soy legumes, which have different nutritional profiles. The aim of the present updated review, therefore, was to summarize and meta-analyze the published evidence regarding legume consumption (making a distinction between nonsoy and soy legumes) and cardiometabolic diseases. In addition, we reviewed randomized clinical trials assessing the effect of legume consumption on CVD risk factors in order to understand their associations. The results revealed a prospective, significant inverse association between total legume consumption and CVD and coronary heart disease risk, whereas a nonsignificant association was observed with T2D and stroke. In the stratified analysis by legume subtypes, only nonsoy legumes were associated with lower risk of T2D. Unfortunately, owing to the paucity of studies analyzing legumes and CVD, it was not possible to stratify the analysis for these outcomes. Because of the high degree of heterogeneity observed for most of the outcomes and the few studies included in some analyses, further prospective studies are warranted to determine the potential role of legume consumption on CVD and T2D.

Dietary Approaches to Stop Hypertension (DASH): potential mechanisms of action against risk factors of the metabolic syndrome

The metabolic syndrome is a cluster of disorders dominated by abdominal obesity, hypertriacylglycerolaemia, low HDL-cholesterol, high blood pressure and high fasting glucose. Diet modification is a safe and effective way to treat the metabolic syndrome. Dietary Approaches to Stop Hypertension (DASH) is a dietary pattern rich in fruits, vegetables and low-fat dairy products, and low in meats and sweets. DASH provides good amounts of fibre, K, Ca and Mg, and limited quantities of total fat, saturated fat, cholesterol and Na. Although DASH was initially designed for the prevention or control of hypertension, using a DASH diet has other metabolic benefits. In the present review, the effect of each dietary component of DASH on the risk factors of the metabolic syndrome is discussed. Due to limited fat and high fibre and Ca content, individuals on the DASH diet are less prone to overweight and obesity and possess lower concentrations of total and LDL-cholesterol although changes in TAG and HDL-cholesterol have been less significant and available evidence in this regard is still inconclusive. Moreover, high amounts of fruit and vegetables in DASH provide great quantities of K, Mg and fibre, all of which have been shown to reduce blood pressure. K, Mg, fibre and antioxidants have also been effective in correcting glucose and insulin abnormalities. Evidence is provided from cross-sectional investigations, cohort studies and randomised controlled trials, and, where available, from published meta-analyses. Mechanisms are described according to human studies and, in the case of a lack of evidence, from animal and cell culture investigations.

Dietary Polyphenol Intake, Blood Pressure, and Hypertension: A Systematic Review and Meta-Analysis of Observational Studies

Background: Dietary polyphenols, including flavonoids, have been the focus of major recent attentions due to their wide content in a variety of foods commonly consumed and the findings from numerous studies showing evidence of an association with positive outcomes on human health. Methods: A systematic search using electronic databases PubMed and EMBASE was performed to retrieve English language studies published from the earliest indexing year of each database to April 2019, reporting on the association between dietary flavonoids intake and hypertension. Results: The search strategy resulted in the final selection of 20 studies including 15 cross-sectional investigations and 7 prospective cohorts (1 study reported on 3 prospective cohorts). 5 prospective cohorts, comprising 200,256 individuals and 45,732 cases of hypertension were included in the quantitative analysis. Analysis by extreme quantiles of intake of flavonoid showed a non-significant association with decreased risk of hypertension (RR (risk ratio): 0.96, 95% CI (confidence interval): 0.89, 1.03). Taking into consideration individual flavonoid subclasses, dietary anthocyanins intake was associated with 8% reduction in risk of hypertension, when comparing highest vs. lowest exposure (RR: 0.92, 95% CI: 0.88, 0.97). Conclusions: Further studies are needed to strengthen the retrieved association between anthocyanins consumption and decreased risk of hypertension and clarify whether total flavonoids or rather individual subclasses may exert beneficial effects on blood pressure.

Effect of S-equol and Soy Isoflavones on Heart and Brain

BACKGROUND

Observational studies in Asia show that dietary intake of soy isoflavones had a significant inverse association with coronary heart disease (CHD). A recent randomized controlled trial (RCT) of soy isoflavones on atherosclerosis in the US, however, failed to show their benefit. The discrepancy may be due to the much lower prevalence of S-equol producers in Westerners: Only 20-30% of Westerners produce S-equol in contrast to 50-70% in Asians. S-equol is a metabolite of dietary soy isoflavone daidzein by gut microbiome and possesses the most antiatherogenic properties among all isoflavones. Several short-duration RCTs documented that soy isoflavones improves arterial stiffness. Accumulating evidence shows that both atherosclerosis and arterial stiffness are positively associated with cognitive decline/dementia. Therefore, potentially, soy isoflavones, especially S-equol, are protective against cognitive decline/dementia.

METHODS/RESULTS

This narrative review of clinical and epidemiological studies provides an overview of the health benefits of soy isoflavones and introduces S-equol. Second, we review recent evidence on the association of soy isoflavones and S-equol with CHD, atherosclerosis, and arterial stiffness as well as the association of atherosclerosis and arterial stiffness with cognitive decline/ dementia. Third, we highlight recent studies that report the association of soy isoflavones and S-equol with cognitive decline/dementia. Lastly, we discuss the future directions of clinical and epidemiological research on the relationship of S-equol and CHD and dementia.

CONCLUSIONS

Evidence from observational studies and short-term RCTs suggests that S-equol is anti-atherogenic and improves arterial stiffness and may prevent CHD and cognitive impairment/ dementia. Well-designed long-term (≥ 2years) RCTs should be pursued.

Dietary Phytoestrogen Intake is Inversely Associated with Hypertension in a Cohort of Adults Living in the Mediterranean Area

Background: Dietary polyphenols, including phytoestrogens are abundantly present in a balanced diet. Evidence for their role in preventing non-communicable diseases is emerging. Methods: We examined the association between estimated habitual intakes of dietary phytoestrogens and hypertension in a cohort study. The baseline data included 1936 men and women aged 18 years and older. Intakes of total phytoestrogens, isoflavones, and lignans were calculated from validated food frequency questionnaire. Data on the polyphenols content in foods were retrieved from the Phenol-Explorer database. Results: Individuals in the highest quartile of dietary phytoestrogens intake were less likely to be hypertensive (OR: 0.66, 95% CI: 0.44–0.98); moreover, the association showed a significant decreasing trend. Isoflavones and lignans were not associated with lower odds of hypertension; however, some individual compounds, such as biochanin A and pinoresinol showed an independent inverse association with hypertension. Conclusions: Dietary phytoestrogens are associated with lower likelihood of hypertension in adults living in the Mediterranean area. Future studies are needed to confirm the present findings (i.e., prospective cohort studies) and to better understand the mechanisms underlying such associations.

Quantitative assessment of the effects of chitosan intervention on blood pressure control

Background

Chitosan is a popular dietary fiber often used to reduce dietary fat absorption to control weight and blood lipids. However, its effects on blood pressure (BP) have not been fully elucidated. We evaluated the effects of chitosan administration on systolic blood pressure (SBP) and diastolic blood pressure (DBP) through a pooled analysis of available randomized controlled trials (RCTs).

Materials and methods

Electronic searches were conducted in Medline, Cochrane Library, Scopus, and EMBASE to identify relevant human placebo-control RCTs. Trials that reported BP changes from baseline to study endpoint in patients receiving treatment of chitosan were included for analysis. Weighted mean difference (WMD) and 95% CIs were pooled using fixed-effects or random-effects models. Statistical heterogeneity, prespecified subgroup, publication bias, sensitivity analysis, and meta-regression assessments were also tested.

Results

Six hundred and seventeen participants from eight trials with 10 arms were included. Overall, chitosan administration did not significantly lower SBP (WMD: -1.41 mmHg, 95% CI: -3.29 to 0.47; P=0.14) and DBP (WMD: -0.61 mmHg, 95% CI: -1.75 to 0.52; P=0.29). However, our subgroup analyses indicated that chitosan consumption significantly reduced DBP in shorter-term (<12 weeks) and higher-dose (>2.4 g/day) arms. Funnel plots or Egger's tests analysis (P=0.36 and 0.43 for SBP and DBP, respectively) demonstrated that there was no significant publication bias in this study.

Conclusion

This meta-analysis indicates that chitosan consumption significantly decreases DBP at higher dosage and in shorter-term interventions, while chitosan has no significant effects on SBP. However, these results should be interpreted cautiously because of the limited eligible RCTs included in this meta-analysis; further large-scale, well-designed RCTs on this topic are urgently needed.

The history and basic science development of soy isoflavones

This review summarizes the 2016 NAMS/Pfizer-Wulf H. Utian Endowed Lecture that focused on the history and basic science of soy isoflavones. Described is a personal perspective of the background and history that led to the current interest in soy and isoflavones with a specific focus on the role that soy isoflavones play in the health of postmenopausal women. This overview covers the metabolism and physiological behavior of isoflavones, their biological properties that are of potential relevance to aging, issues related to the safety of soy isoflavones, and the role of the important intestinally derived metabolite S-(-)equol.

Comprehensive evaluation of the role of soy and isoflavone supplementation in humans and animals over the past two decades

Soy and soy-based foods are considered healthy, particularly in many Asia-Pacific countries, where soy products have long been consumed. Soy and soy-related products have been found to help prevent the occurrence of cardiovascular diseases and certain types of cancer, such as breast and prostate cancer. These products can also have antioxidative effects that alleviate hot flashes during menopause and bone loss. These biological and therapeutic functions are primarily due to the isoflavones derived from soy, whose structure is similar to the structure of 17-β-oestradiol. Despite the many health benefits for humans and animals, the application of isoflavones remains controversial because of their anti-oestrogenic properties. We focused on general information regarding isoflavones, as well as their structure, function, and application. We summarized evidence showing that dietary or supplemental isoflavones exert protective effects on the health of humans and animals. Based on the literature, we conclude that soy foods and isoflavones may be effective and safe; however, more high-quality trials are needed to fully substantiate their potential use.

Effect of soybean protein on blood pressure in postmenopausal women: a meta-analysis of randomized controlled trials

The effect of soybean protein on blood pressure (BP) in postmenopausal women is controversial, so we aimed to conduct a systematic review and a meta-analysis of published randomized controlled trials (RCTs) to investigate whether supplementation with soy protein improves their blood pressure. PubMed and Embase were searched up to February 2016. Weighted mean differences were calculated for net changes in BP by using fixed-effect or random-effect models. Subgroup and meta-regression analyses were performed to clarify heterogeneity among the trials. A total of twelve trials (1551 postmenopausal women participants) were included in the present meta-analysis. The overall pooled estimates of the effect of soy protein indicated a significant effect on systolic blood pressure (SBP) (mean difference: -3.03 mmHg; 95% CI: -5.03, -1.02; P = 0.003) and diastolic blood pressure (DBP) (mean difference: -0.71 mmHg; 95% CI: -1.26, -0.16; P = 0.012). Subgroup analyses further demonstrated that soy protein intake ≥25 g d-1 significantly reduced BP, and the mean difference in SBP and DBP was -4.62 mmHg (95% CI: -8.42, -0.81; P = 0.04) and -1.63 mmHg (95% CI: -2.85, -0.41; P = 0.009), respectively. Soy isoflavone intake ≥100 mg d-1 had a better reduction effect both in SBP (-5.47 mmHg; 95% CI: -8.42, -2.51; P = 0.00) and DBP (-2.03 mmHg; 95% CI: -3.35, -0.72; P = 0.002). However, soy protein intake <25 g d-1 or soy isoflavone intake <100 mg d-1 had no such effects (P > 0.05). This meta-analysis suggests that ingestion of ≥25 g soy protein per day has BP-lowering effects, and the improvements in BP may be due to the isoflavones component of soy protein. More high-quality RCTs need to be carried out to confirm the present findings.

Significant inverse association of equol-producer status with coronary artery calcification but not dietary isoflavones in healthy Japanese men

Equol, a metabolite of the dietary isoflavone daidzein, is produced by the action of gut bacteria in some individuals who are termed as equol-producers. It is proposed to have stronger atheroprotective properties than dietary isoflavones. We examined a cross-sectional association of dietary isoflavones and equol-producer status with coronary artery calcification (CAC), a biomarker of coronary atherosclerosis, among men in Japan. A population-based sample of 272 Japanese men aged 40-49 years recruited from 2004 to 2007 was examined for serum isoflavones, serum equol, CAC and other factors. Equol-producers were classified as individuals having a serum level of equol >83 nm. The presence of CAC was defined as a coronary Ca score ≥10 Agatston units. The associations of dietary isoflavones and equol-producers with CAC were analysed using multiple logistic regression. The median of dietary isoflavones, equol and CAC were 512·7 (interquartile range (IQR) 194·1, 1170·0), 9·1 (IQR 0·10, 33·1) and 0·0 (IQR 0·0, 1·0) nm, respectively. Prevalence of CAC and equol-producers was 9·6 and 16·0 %, respectively. Dietary isoflavones were not significantly associated with CAC. After multivariable adjustment, the OR for the presence of CAC in equol-producers compared with equol non-producers was 0·10 (95 % CI 0·01, 0·90, P<0·04). Equol-producers had significantly lower CAC than equol non-producers, but there was no significant association between dietary isoflavones and CAC, suggesting that equol may be a key factor for atheroprotective properties of isoflavones in Japanese men. This finding must be confirmed in larger studies or clinical trials of equol that is now available as a dietary supplement.

Beyond the Cholesterol-Lowering Effect of Soy Protein: A Review of the Effects of Dietary Soy and Its Constituents on Risk Factors for Cardiovascular Disease

The hypocholesterolemic effect of soy is well-documented and this has led to the regulatory approval of a health claim relating soy protein to a reduced risk of cardiovascular disease (CVD). However, soybeans contain additional components, such as isoflavones, lecithins, saponins and fiber that may improve cardiovascular health through independent mechanisms. This review summarizes the evidence on the cardiovascular benefits of non-protein soy components in relation to known CVD risk factors such as hypertension, hyperglycemia, inflammation, and obesity beyond cholesterol lowering. Overall, the available evidence suggests non-protein soy constituents improve markers of cardiovascular health; however, additional carefully designed studies are required to independently elucidate these effects. Further, work is also needed to clarify the role of isoflavone-metabolizing phenotype and gut microbiota composition on biological effect.

Dietary tofu intake and long-term risk of death from stroke in a general population

BACKGROUND & AIM

Although dietary soy intake is linked with health benefits, a relation with stroke has not been established. The present study examined the association between the intake of tofu, the richest source of dietary soy, with stroke mortality in a general population cohort of Japanese men and women.

METHODS

Data comprise 9244 Japanese enrolled in the National Nutrition Survey of Japan in 1980. Participants were free of cardiovascular disease and followed for 24 years. Dietary intake was estimated from 3-day weighed food records. Multivariable Cox regression models were used to estimate hazard ratios across levels of tofu intake.

RESULTS

During follow-up, there were 417 deaths due to stroke (88 cerebral hemorrhage [CH], 245 cerebral infarction [CI], and 84 of other subtypes). Among all men, and in women aged 65 years or more, tofu intake was unrelated to each form of stroke. For young women (<65 years of age), a significantly lower risk of CH in the top versus bottom quartile of tofu intake was observed (Multivariable-adjusted HR = 0.26, 95% CI: 0.08-0.85).

CONCLUSIONS

In this large prospective study with long follow-up of Japanese men and women, consumption of tofu was unrelated to the risk of stroke except for CH in women <65 years of age. Whether the association in younger women is real or due to chance alone warrants further study.

Soy and Health Update: Evaluation of the Clinical and Epidemiologic Literature

Soyfoods have long been recognized as sources of high-quality protein and healthful fat, but over the past 25 years these foods have been rigorously investigated for their role in chronic disease prevention and treatment. There is evidence, for example, that they reduce risk of coronary heart disease and breast and prostate cancer. In addition, soy alleviates hot flashes and may favorably affect renal function, alleviate depressive symptoms and improve skin health. Much of the focus on soyfoods is because they are uniquely-rich sources of isoflavones. Isoflavones are classified as both phytoestrogens and selective estrogen receptor modulators. Despite the many proposed benefits, the presence of isoflavones has led to concerns that soy may exert untoward effects in some individuals. However, these concerns are based primarily on animal studies, whereas the human research supports the safety and benefits of soyfoods. In support of safety is the recent conclusion of the European Food Safety Authority that isoflavones do not adversely affect the breast, thyroid or uterus of postmenopausal women. This review covers each of the major research areas involving soy focusing primarily on the clinical and epidemiologic research. Background information on Asian soy intake, isoflavones, and nutrient content is also provided.

Polyphenol-based nutraceuticals for the prevention and treatment of cardiovascular disease: Review of human evidence

BACKGROUND

In addition to prescription drugs, nutraceuticals/functional foods/medical foods are being increasingly added as adjunct treatment of cardiovascular disease (CVD), even though most of them have been exclusively studied in vitro.

HYPOTHESIS/PURPOSE

We review the available evidence (focusing on when the amount of polyphenols' intake was measured) coming from randomized controlled trials (RCTs) of (poly)phenol-based supplements.

CONCLUSION

We conclude that (poly)phenol-based nutraceuticals and functional foods might be indeed used as adjunct therapy of CVD, but additional long-term RCTs with adequate numerosity and with clinically relevant end points are needed to provide unequivocal evidence of their clinical usefulness.

Dietary Total Isoflavone Intake Is Associated With Lower Systolic Blood Pressure: The Coronary Artery Risk Development in Young Adults (CARDIA) Study

The effect of dietary isoflavone intake on systolic blood pressure (SBP) has not been studied in a large community-based cohort inclusive of African Americans. The authors analyzed data from the year 20 examination of the Coronary Artery Risk Development in Young Adults (CARDIA) study, including medical history, physical examination, and dietary intake surveys for 3142 participants. Multivariable linear regression models controlled for age, sex, body mass index, smoking, physical activity, and intakes of alcohol and total energy. Effect modification by race was tested. Overall, patients with hypertension had a lower daily intake of total dietary isoflavones (2.2±5.2 mg/d vs 4.1±11.7 mg/d; P<.001). In fully adjusted models, the highest quartile of dietary isoflavone intake was associated with a 4.4 mm Hg lower SBP on average compared with SBP for the lowest quartile. The relationship between dietary isoflavone intake and SBP was more pronounced among African Americans compared with Caucasians (P for interaction <.001). Greater dietary intake of isoflavones was independently associated with a lower SBP.

The Mediterranean diet, its components, and cardiovascular disease

One of the best-studied diets for cardiovascular health is the Mediterranean diet. This consists of fish, monounsaturated fats from olive oil, fruits, vegetables, whole grains, legumes/nuts, and moderate alcohol consumption. The Mediterranean diet has been shown to reduce the burden, or even prevent the development, of cardiovascular disease, breast cancer, depression, colorectal cancer, diabetes, obesity, asthma, erectile dysfunction, and cognitive decline. This diet is also known to improve surrogates of cardiovascular disease, such as waist-to-hip ratio, lipids, and markers of inflammation, as well as primary cardiovascular disease outcomes such as death and events in both observational and randomized controlled trial data. These enhancements easily rival those seen with more established tools used to fight cardiovascular disease such as aspirin, beta-blockers, angiotensin-converting enzyme inhibitors, and exercise. However, it is unclear if the Mediterranean diet offers cardiovascular disease benefit from its individual constituents or in aggregate. Furthermore, the potential benefit of the Mediterranean diet or its components is not yet validated by concrete cardiovascular disease endpoints in randomized trials or observational studies. This review will focus on the effects of the whole and parts of the Mediterranean diet with regard to both population-based and experimental data highlighting cardiovascular disease morbidity or mortality and cardiovascular disease surrogates when hard outcomes are not available. Our synthesis will highlight the potential for the Mediterranean diet to act as a key player in cardiovascular disease prevention, and attempt to identify certain aspects of the diet that are particularly beneficial for cardioprotection.

Effects of vitamin E, vitamin C and polyphenols on the rate of blood pressure variation: results of two randomised controlled trials

High blood pressure (BP) variability, which may be an important determinant of hypertensive end-organ damage, is emerging as an important predictor of cardiovascular health. Dietary antioxidants can influence BP, but their effects on variability are yet to be investigated. The aim of the present study was to assess the effects of vitamin E, vitamin C and polyphenols on the rate of daytime and night-time ambulatory BP variation. To assess these effects, two randomised, double-blind, placebo-controlled trials were performed. In the first trial (vitamin E), fifty-eight individuals with type 2 diabetes were given 500 mg/d of RRR-α-tocopherol, 500 mg/d of mixed tocopherols or placebo for 6 weeks. In the second trial (vitamin C-polyphenols), sixty-nine treated hypertensive individuals were given 500 mg/d of vitamin C, 1000 mg/d of grape-seed polyphenols, both vitamin C and polyphenols, or neither (placebo) for 6 weeks. At baseline and at the end of the 6-week intervention, 24 h ambulatory BP and rate of measurement-to-measurement BP variation were assessed. Compared with placebo, treatment with α-tocopherol, mixed tocopherols, vitamin C and polyphenols did not significantly alter the rate of daytime or night-time systolic BP, diastolic BP or pulse pressure variation (P>0·05). Treatment with the vitamin C and polyphenol combination resulted in higher BP variation: the rate of night-time systolic BP variation (P= 0·022) and pulse pressure variation (P= 0·0036) were higher and the rate of daytime systolic BP variation was higher (P= 0·056). Vitamin E, vitamin C or grape-seed polyphenols did not significantly alter the rate of BP variation. However, the increase in the rate of BP variation suggests that the combination of high doses of vitamin C and polyphenols could be detrimental to treated hypertensive individuals.

Ameliorative effects of Monascus pilosus-fermented black soybean (Glycine max L. Merrill) on high-fat diet-induced obesity

The purpose of this study was to examine the antiobesity effects of Monascus pilosus-fermented black soybean (F-BS) in C57BL/6 mice with high-fat diet (HFD)-induced obesity. F-BS (oral, 0.5 and 1.0 g/kg per body weight, twice per day) ameliorated obesity by reducing body and liver weight increases, and regulating blood glucose and cholesterol levels in C57BL/6 mice fed a control or HFD with oral administration of F-BS for 12 weeks. F-BS suppressed the growth of epididymal, retroperitoneal, and perirenal fat pads by preventing increases in the adipocyte size. Moreover, the levels of blood glucose, total cholesterol, and leptin were significantly lowered by F-BS administration in a dose-dependent manner. These results indicated that F-BS is a beneficial food supplement for preventing obesity, controlling blood glucose, and lowering cholesterol. Future research strategies should address the mechanisms that selectively regulate obesity, including hyperglycemia and hypercholesterolemia.

Polyphenols and the human brain: plant “secondary metabolite” ecologic roles and endogenous signaling functions drive benefits

Flavonoids and other polyphenols are ubiquitous plant chemicals that fulfill a range of ecologic roles for their home plant, including protection from a range of biotic and abiotic stressors and a pivotal role in the management of pathogenic and symbiotic soil bacteria and fungi. They form a natural part of the human diet, and evidence suggests that their consumption is associated with the beneficial modulation of a number of health-related variables, including those related to cardiovascular and brain function. Over recent years, the consensus as to the mechanisms responsible for these effects in humans has shifted away from polyphenols having direct antioxidant effects and toward their modulation of cellular signal transduction pathways. To date, little consideration has been given to the question of why, rather than how, these plant-derived chemicals might exert these effects. Therefore, this review summarizes the evidence suggesting that polyphenols beneficially affect human brain function and describes the current mechanistic hypotheses explaining these effects. It then goes on to describe the ecologic roles and potential endogenous signaling functions that these ubiquitous phytochemicals play within their home plant and discusses whether these functions drive their beneficial effects in humans via a process of “cross-kingdom” signaling predicated on the many conserved similarities in plant, microbial, and human cellular signal transduction pathways.

Soy foods, isoflavones, and the health of postmenopausal women

Over the past 2 decades, soy foods have been the subject of a vast amount of research, primarily because they are uniquely rich sources of isoflavones. Isoflavones are classified as both phytoestrogens and selective estrogen receptor modulators. The phytoestrogenic effects of isoflavones have led some to view soy foods and isoflavone supplements as alternatives to conventional hormone therapy. However, clinical research shows that isoflavones and estrogen exert differing effects on a variety of health outcomes. Nevertheless, there is substantial evidence that soy foods have the potential to address several conditions and diseases associated with the menopausal transition. For example, data suggest that soy foods can potentially reduce ischemic heart disease through multiple mechanisms. Soy protein directly lowers blood low-density lipoprotein-cholesterol concentrations, and the soybean is low in saturated fat and a source of both essential fatty acids, the omega-6 fatty acid linoleic acid and the omega-3 fatty acid alpha-linolenic acid. In addition, soflavones improve endothelial function and possibly slow the progression of subclinical atherosclerosis. Isoflavone supplements also consistently alleviate menopausal hot flashes provided they contain sufficient amounts of the predominant soybean isoflavone genistein. In contrast, the evidence that isoflavones reduce bone loss in postmenopausal women is unimpressive. Whether adult soy food intake reduces breast cancer risk is unclear. Considerable evidence suggests that for soy to reduce risk, consumption during childhood and/or adolescence is required. Although concerns have been raised that soy food consumption may be harmful to breast cancer patients, an analysis in 9514 breast cancer survivors who were followed for 7.4 y found that higher postdiagnosis soy intake was associated with a significant 25% reduction in tumor recurrence. In summary, the clinical and epidemiologic data indicate that adding soy foods to the diet can contribute to the health of postmenopausal women.