Longitudinal study of soy food intake and blood pressure among middle-aged and elderly Chinese women

Preventive and Therapeutic Effects of Sericin-Derived Oligopeptides (SDOs) from Yellow Silk Cocoons on Blood Pressure Lowering in L-NAME-Induced Hypertensive Rats

Our previous research has shown that SDOs derived from yellow silk cocoons have hypotensive effects on rats in chronic toxicity testing. This study investigated the potential preventative and therapeutic benefits of SDOs on hypertensive rats induced by L-NAME. The experiment involved nine rat groups: (1) normal control, (2) normal + 200 mg kg-1 BW SDOs, (3) hypertensive (HT) control, (4) HT + 50 mg kg-1 BW SDOs, (5) HT + 100 mg kg-1 BW SDOs, (6) HT + 200 mg kg-1 BW SDOs, (7) HT + enalapril (Ena), (8) HT + soy protein isolate (SPI), and (9) HT + bovine serum albumin (BSA). In the preventative approach, rats received 40 mg kg-1 of L-NAME with the studied substances during the four-week investigation. SDOs given at doses of 100 and 200 mg kg-1 BW demonstrated a significant decrease in systolic blood pressure (SBP) without affecting heart rate (HR). In therapeutic studies, 40 mg kg-1 BW of L-NAME increased SBP in the experimental groups over the first four weeks, resulting in mean SBP values above 150 mmHg. Administering 100 and 200 mg kg-1 BW SDOs and 100 mg kg-1 BW SPI significantly reduced SBP. However, SDOs at 200 mg kg-1 BW exhibited SBP closer to the enalapril group. In functional vascular tests, rats given SDOs at a dose of 200 mg kg-1 BW had the highest relaxation and lowest contraction percentages, like the normal control groups. The research found that SDOs may inhibit and manage hypertension in both healthy and hypertensive rats by safeguarding endothelial cells.

Perspective: Isoflavones-Intriguing Molecules but Much Remains to Be Learned about These Soybean Constituents

Isoflavones are naturally occurring compounds found in a wide range of plants, but among commonly consumed foods are especially abundant in soybeans and foods derived from this legume. Much of the substantial amount of research conducted on soy protein and soy foods over the past 30 y is because of their isoflavone content. Research interest in isoflavones increased dramatically beginning in the early 1990s as evidence highlighted their possible role in the prevention of a wide range of cancers, including breast, prostate, and colon cancer. Recognition that isoflavones preferentially bind to estrogen receptor (ER)β in comparison with ERα provided a conceptual basis for classifying these diphenolic molecules as selective ER modulators (SERMs). Isoflavone research soon greatly expanded beyond cancer to include areas such as coronary artery disease, bone health, cognitive function, and vasomotor symptoms of menopause. Nevertheless, safety concerns about isoflavones, based primarily on the results of rodent studies and presumed estrogenic effects, also arose. However, recent work challenges the traditional view of the estrogenicity of isoflavones. Furthermore, safety concerns have largely been refuted by intervention and population studies. On the other hand, investigation of the proposed benefits of isoflavones has produced inconsistent data. The small sample size and short duration common to many intervention trials, combined with marked interindividual differences in isoflavone metabolism, likely contribute to the conflicting findings. Also, many different intervention products have been employed, which vary not only in the total amount, but also in the relative proportion of the 3 soybean isoflavones, and the form in which they are delivered (glycoside compared with aglycone). For those interested in exploring the proposed benefits of isoflavones, studies justify an intake recommendation of ∼50 mg/d, an amount provided by ∼2 servings of traditional Asian soy foods.

A Review of the Clinical and Epidemiologic Evidence Relevant to the Impact of Postdiagnosis Isoflavone Intake on Breast Cancer Outcomes

PURPOSE OF REVIEW

This narrative review aims to determine the impact of postdiagnosis isoflavone intake, via supplements and foods, on breast cancer outcomes. Foods derived from soybeans are uniquely rich sources of isoflavones, naturally occurring compounds that can bind to estrogen receptors although the extent to which they exert estrogen-like effects in humans is unclear. Isoflavones have been rigorously investigated for a wide range of health benefits including breast cancer prevention. However, their classification as phytoestrogens has led to concern that isoflavones and hence, soy food consumption, could worsen the prognosis of women with breast cancer and interfere with the efficacy of endocrine therapy for this disease.

RECENT FINDINGS

Research in athymic ovariectomized mice shows isoflavones stimulate the growth of existing estrogen-sensitive mammary tumors. However, extensive clinical research indicates that neither soy foods nor isolated isoflavones affect markers of breast cancer risk including mammographic density and breast cell proliferation. No effects are observed even when isoflavone exposure greatly exceeds typical intake in Asian countries. Furthermore, the results from epidemiologic studies indicate postdiagnosis isoflavone intake from soy foods reduces recurrence and possibly mortality from breast cancer. Additionally, the limited observational data do not show that isoflavones interfere with the efficacy of tamoxifen or aromatase inhibitors. Regardless of their treatment status, evidence indicates that women with breast cancer can safely consume soy foods. Limiting intake to no more than two servings of traditional Asian soy foods daily, an amount that provides approximately 50 mg isoflavones, is recommended, not because data indicate exceeding this amount is harmful, but because few population-based studies involved participants consuming more than this intake recommendation.

Perspective: Observational Studies Involving Low-Soy Intake Populations Have Limited Ability for Providing Insight into the Health Effects of Soybean Isoflavones

Isoflavones are naturally occurring plant compounds found in uniquely high amounts in soybeans and foods made from this legume. These soybean constituents have been proposed to exert several health benefits and as such they have been the subject of an enormous amount of research. This research includes randomized controlled trials (RCTs) and epidemiologic investigations. Although statistically significant associations between isoflavone intake and a wide range of health outcomes have been identified in cohorts involving low-isoflavone intake populations, we suggest that these associations are unlikely to have a causal basis because exposure is too low for isoflavones to exert physiologic effects. In cohorts involving predominantly non-Asian, non-vegetarian populations, the highest isoflavone intake category is typically ≤3 mg/d, an amount of isoflavones provided by ∼30 mL (2 tablespoons) of soymilk made from whole soybeans. In comparison, mean isoflavone intake in the upper intake categories in observational studies involving high-isoflavone intake populations is typically ≥50 mg/d. In RCTs, intervention doses of isoflavones typically range between 40 and 100 mg/d. Health professionals advising patients and clients about soy food and isoflavone intake need to be aware of the limitations of epidemiologic research involving low-isoflavone intake populations. Intake recommendations are best based on the results of RCTs using clinically relevant doses of isoflavones and epidemiologic studies involving populations for whom soy foods are a habitual part of the diet.

Benefits of Soybean in the Era of Precision Medicine: A Review of Clinical Evidence

Soybean (Glycine max) is an important ingredient of cuisines worldwide. While there is a wealth of evidence that soybean could be a good source of macronutrients and phytochemicals with health-promoting effects, concerns regarding adverse effects have been raised. In this work, we reviewed the current clinical evidence focusing on the benefits and risks of soybean ingredients. In breast, prostate, colorectal, ovarian, and lung cancer, epidemiological studies showed an inverse association between soybean food intake and cancer risks. Soybean intake was inversely correlated with risks of type 2 diabetes mellitus (T2DM), and soy isoflavones ameliorated osteoporosis and hot flashes. Notably, soybean was one of the dietary protein sources that may reduce the risk of breast cancer and T2DM. However, soybean had adverse effects on certain types of drug treatment and caused allergies. In sum, this work provides useful considerations for planning clinical soybean research and selecting dietary protein sources for human health.

The health effects of soy: A reference guide for health professionals

Soy is a hotly debated and widely discussed topic in the field of nutrition. However, health practitioners may be ill-equipped to counsel clients and patients about the use of soyfoods because of the enormous, and often contradictory, amount of research that has been published over the past 30 years. As interest in plant-based diets increases, there will be increased pressure for practitioners to gain a working knowledge of this area. The purpose of this review is to provide concise literature summaries (400-500 words) along with a short perspective on the current state of knowledge of a wide range of topics related to soy, from the cholesterol-lowering effects of soy protein to the impact of isoflavones on breast cancer risk. In addition to the literature summaries, general background information on soyfoods, soy protein, and isoflavones is provided. This analysis can serve as a tool for health professionals to be used when discussing soyfoods with their clients and patients.

Perspective: Soybeans Can Help Address the Caloric and Protein Needs of a Growing Global Population

Feeding a growing global population with projected rising socioeconomic status will require additional sources of calories and especially protein. These sources need to align with the Sustainable Development Goals established by the Food and Agriculture Organization of the United Nations. The soybean is uniquely positioned to meet this challenge based on the following criteria: (1) Global soybean production exceeds by ~4 times the production of all pulses combined (2) Soybeans are higher in protein than other legumes and soy protein quality is similar to animal protein quality (3) Soybeans are an excellent source of healthy fat, including both essential fatty acids (4) Soybeans, like other legumes, symbiotically fix atmospheric nitrogen thereby reducing the need for fertilizer inputs (5) Greenhouse gas emissions per unit protein are lower than for nearly all other foods (6) Soybeans, like other legumes, are also recognized as an affordable food that can be incorporated into diverse diets regardless of economic standing and (7) The range of foods produced from soybeans constitutes an important position in historic and contemporary cuisines, cultures and emerging consumer trends for plant-based protein. Although most soybeans are currently used for animal feed, soybean use is dictated by consumer demand. Therefore, soybeans are well positioned to meet future global needs for energy and protein. Armed with this knowledge, health professionals can feel justified in encouraging greater consumption of soyfoods for both personal and planetary reasons.

Strategies to achieve significant physiological concentrations of bioactive phytoestrogens in plasma

The benefits to health attributed to the intake of phytoestrogens (PEs) have been demonstrated in previous studies with significant physiological concentrations of bioactive PEs, such as genistein, equol, enterolignans and urolithins in plasma. However, the achievement of high bioactive PE levels in plasma is restricted to a select population group, mainly due to the low intake of plant PEs and/or the absence, or inhibition, of the microbiota capable of producing these bioactive forms. In this study, the intake of plant PEs, the concentration of bioactive PEs in plasma, the ability of the intestinal microbiota to produce bioactive PEs, as well as the different mechanisms used by GRAS bacteria to increase the level of bioactive PEs were evaluated concluding that the use of GRAS bacteria bioactive PE producers and the development of fermented foods enriched in bioactive PEs in addition to a high intake of plant PEs and taking care of the intestinal microbiota, are some of the different strategies to achieve significant physiological concentrations of bioactive PEs in the intestine and, subsequently, in plasma and targets organs which are essential to improve menopausal symptoms or reduce the risk of some pathologies such as breast and colon cancer, or cardiovascular disease.

The efficacy of soy isoflavones combined with soy protein on serum concentration of interleukin-6 and tumour necrosis factor-α among post-menopausal women? A systematic review and meta-analysis of randomized controlled trials

The post-menopausal stage in women's life is associated with the enhancement of inflammation that may be reduced using soy isoflavones or soy protein. The present study aimed to summarize the effect of soy isoflavones plus soy protein on circulating interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) in post-menopausal women. The English-language articles were identified from the databases such as Cochrane Library, clinicaltrials.gov, Web of Science, PubMed, and Scopus until December 2020. The mean change from baseline and its standard deviation (SD) for intervention and comparison groups were used to calculate the effect size. The statistical heterogeneity of the intervention effects was computing by Cochran's Q test and I² statistic. Nine and seven studies were selected for systematic review and meta-analysis, respectively. The results of our meta-analysis indicated a non-significant effect on the serum concentrations of IL-6 and TNF-α (weighted mean differences [WMD] = 0.07 pg/mL; 95% confidence interval [CI] = -0.03, 0.17 pg/mL; P = 0.190; WMD =0.05 pg/mL; 95% CI = -0.01, 0.12 pg/mL; P = 0.092; respectively). In subgroup analysis, soy isoflavones plus soy protein could increase the serum concentration of IL-6 in studies with soy isoflavones dose ≤87 mg/days, cross-over design, weak quality, and studies on participants who had health risk factors or diseases. The serum concentration of TNF-α increased in studies with cross-over design, intervention duration ≤56 days, and body mass index (BMI) >27, and in studies that were conducted on at-risk or sick participants. In conclusion, our meta-analysis did not confirm any significant effect on serum concentration of IL-6 and TNF-α among post-menopausal women.

Effect of soy protein containing isoflavones on endothelial and vascular function in postmenopausal women: a systematic review and meta-analysis of randomized controlled trials

IMPORTANCE

The beneficial role of soy protein in cardiovascular health has been well documented in observational studies. However, evidence from clinical trials on effects of soy protein on endothelial function in postmenopausal women has been conflicting.

OBJECTIVE

We aimed to systematically review and conduct a meta-analysis of randomized controlled trials (RCTs) investigating the impact of soy protein supplement containing isoflavones on endothelial function in postmenopausal women.

EVIDENCE REVIEW

We searched PubMed-Medline, SCOPUS, Embase, and Google Scholar until March 2020 to find RCTs evaluating the impact of soy protein supplementation on endothelial function parameters. Random effects model (using DerSimonian-Laird method) was applied to synthesize quantitative data. We performed the leave-one-out method for sensitivity analysis. To quantitatively assess heterogeneity, the I index was applied.

FINDINGS

From a total of 267 studies identified from the initial search 15 and 5 studies were considered appropriate for inclusion into the systematic review and meta-analysis, respectively. In the meta-analysis, an insignificant enhancement in flow-mediated dilation (FMD) after soy protein supplementation (0.882%; 95% CI: -1.059 to 2.822; P = 0.373) was found. However, subgroup analysis showed that supplementation of isolated soy protein had significant effect on FMD (3.39%; 95% CI: 0.733-6.01; P = 0.01).

CONCLUSIONS AND RELEVANCE

Our findings suggest that soy protein supplementation does not lead to meaningful improvement in FMD in postmenopausal women. However, this finding is based on a limited number of studies. Additional high-quality large-scale RCTs are warranted.

Neither soyfoods nor isoflavones warrant classification as endocrine disruptors: a technical review of the observational and clinical data

Soybeans are a rich source of isoflavones, which are classified as phytoestrogens. Despite numerous proposed benefits, isoflavones are often classified as endocrine disruptors, based primarily on animal studies. However, there are ample human data regarding the health effects of isoflavones. We conducted a technical review, systematically searching Medline, EMBASE, and the Cochrane Library (from inception through January 2021). We included clinical studies, observational studies, and systematic reviews and meta-analyses (SRMA) that examined the relationship between soy and/or isoflavone intake and endocrine-related endpoints. 417 reports (229 observational studies, 157 clinical studies and 32 SRMAs) met our eligibility criteria. The available evidence indicates that isoflavone intake does not adversely affect thyroid function. Adverse effects are also not seen on breast or endometrial tissue or estrogen levels in women, or testosterone or estrogen levels, or sperm or semen parameters in men. Although menstrual cycle length may be slightly increased, ovulation is not prevented. Limited insight could be gained about possible impacts of in utero isoflavone exposure, but the existing data are reassuring. Adverse effects of isoflavone intake were not identified in children, but limited research has been conducted. After extensive review, the evidence does not support classifying isoflavones as endocrine disruptors.

Effects of soy consumption on metabolic parameters in patients with metabolic syndrome: A systematic review and meta-analysis

Functional foods like soy have unique effects on health status. Although various dietary modifications have been recommended to ameliorate features of metabolic syndrome (MetS), no meta-analysis has summarized the effect of soy consumption in patients with MetS. PubMed, ISI Web of Science, and Scopus were searched for relevant articles until Jun 2020, resulting in six relevant publications that were included in our meta-analysis. Combining a total of 9 comparisons suggested a significant decrease in serum levels of triglyceride (WMD: -0.29; 95 % CI: -0.49, -0.09 mg/dL), total cholesterol (WMD: -1.46; 95 % CI: -1.70, -1.22 mg/dL), LDL-C (WMD: -0.73; 95 % CI: -0.93, -0.52 mg/dL) and no change in serum HDL-c levels. Combining a total of 7 effect sizes examining soy effects on glycemic parameters indicated that subjects who consumed soy products had lower levels of fasting blood sugar (WMD: -0.90; 95 % CI: -1.12, -0.68 mg/dL), insulin (WMD: -1.06; 95 % CI: -1.29, -0.84 pmol/ L) and HOMA-IR (WMD: -1.08; 95 % CI: -1.31, -0.85) compared with those in the control group. Soy consumption could not significantly change anthropometric measures and blood pressure. Consuming soy products in patients with MetS effectively improved lipid profile and glycemic parameters independent of affecting anthropometric measures.

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 intake is associated with lowering blood pressure in adults: A systematic review and meta-analysis of randomized double-blind placebo-controlled trials

BACKGROUND

Soy has several beneficial effects on cardiovascular disease (CVD); however, results of clinical trial studies are equivocal. Thus, the present study sought to discern the efficacy of soy intake on blood pressure.

METHODS

The search process was conducted in PubMed, Scopus, Web of Science, and Cochrane Library, to ascertain studies investigating the efficacy of soy intake on blood pressure in adults, published up to June 2020. A random-effects model was applied to pool mean difference and 95 % confidence interval (CI). Begg's and Egger's methods were conducted to assess publication bias.

RESULTS

Pooled effects from 17 effect sizes revealed a significant improvement in systolic blood pressure (SBP) (-1.70; -3.34 to -0.06 mmHg; I² = 45.4 %) and diastolic blood pressure (DBP) (-1.27; -2.36 to -0.19 mmHg, I² = 43.9 %) following soy consumption, in comparison with controls. Subgroup analysis demonstrated a reduction in both SBP and DBP in younger participants with lower baseline DBP and intervention durations of <16 weeks.

CONCLUSION

Our results suggest that soy intake is associated with an ameliorating effect on blood pressure in adults.

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.

Dose-dependent reductions in plasma ceramides after anthocyanin supplementation are associated with improvements in plasma lipids and cholesterol efflux capacity in dyslipidemia: A randomized controlled trial

BACKGROUND & AIMS

Plasma ceramides have been identified as novel risk factors for metabolic and cardiovascular diseases. We aimed to evaluate the effects of dietary anthocyanins on plasma ceramides and to disentangle whether the alterations in ceramides could be related with those in other cardiometabolic risk factors in the dyslipidemia.

METHODS

In a randomized double-blinded placebo-controlled trial, 176 eligible dyslipidemia subjects were randomly assigned into four groups receiving placebo, 40, 80, or 320 mg/day anthocyanins, respectively for 12 weeks.

RESULTS

A total of 169 subjects completed the study. After 12-week intervention, dietary anthocyanins dose-dependently reduced plasma concentrations of all six ceramide species in the dyslipidemia subjects (all P_trend values < 0.05). Specifically, 320 mg/day anthocyanins effectively lowered plasma N-palmitoylsphingosine (Cer 16:0, mean change: -28.3 ± 41.2 versus 2.9 ± 38.2, nmol/L, P = 0.018) and N-tetracosanoylsphingosine (Cer 24:0, mean change: -157.1 ± 493.9 versus 10.7 ± 439.9, nmol/L, P = 0.002) compared with the placebo. The declines in plasma Cer 16:0 and Cer 24:0 were significantly correlated with the decreases in plasma non-high-density lipoprotein cholesterol (nonHDL-C, Spearman's r = 0.32, P = 0.040 for Cer 16:0; Spearman's r = 0.35, P = 0.026 for Cer 24:0), apolipoprotein B (Spearman's r = 0.33, P = 0.031 for Cer 16:0; Spearman's r = 0.48, P = 0.002 for Cer 24:0), and total cholesterol (Spearman's r = 0.34, P = 0.026 for Cer 16:0; Spearman's r = 0.31, P = 0.042 for Cer 24:0) after 12-week 320 mg/day anthocyanin administration. Besides, we found that anthocyanins at 320 mg/day also markedly enhanced cholesterol efflux capacity in the dyslipidemia, the changes of which were positively associated with the reductions in Cer 16:0 (Spearman's r = 0.42, P = 0.006) independent of HDL-C and apolipoprotein A-I.

CONCLUSIONS

Reductions in plasma Cer 16:0 and Cer 18:0 after 12-week anthocyanin intervention were dose-dependently associated with improvements in plasma lipids and cholesterol efflux capacity in the dyslipidemia.

CLINICAL TRIAL REGISTRATION

The study was registered at ClinicalTrials.gov with the identifier No. NCT03415503.

Legume consumption and risk of hypertension in a prospective cohort of Chinese men and women

Prior data on long-term association between legume consumption and hypertension risk are sparse. We aimed to evaluate whether total legume and subtype intakes prospectively associate with hypertension incidence among 8758 participants (≥30 years) from the China Health and Nutrition Survey 2004-2011. Diet was assessed by interviews combining 3-d 24-h food recalls and household food inventory weighing at each survey round. Incident hypertension was identified by self-reports or blood pressure measurements. We applied multivariable Cox regressions to estimate hazard ratios (HR) with corresponding 95 % CI for hypertension across increasing categories of cumulatively averaged legume intakes. For 35 990 person-years (median 6·0 years apiece), we documented 944 hypertension cases. After covariate adjustment, higher total legume intakes were significantly associated with lower hypertension risks, with HR comparing extreme categories being 0·56 (95 % CI 0·43, 0·71; Ptrend < 0·001). Then we found that intakes of dried legumes (HR 0·53 (95 % CI 0·43, 0·65); Ptrend < 0·001) and fresh legumes (HR 0·67 (95 % CI 0·55, 0·81); Ptrend < 0·001) were both related to decreased hypertension hazards. However, further dried legume classification revealed that negative association with hypertension substantially held for soyabean (HR 0·51 (95 % CI 0·41, 0·62); Ptrend < 0·001) but not non-soyabean intakes. In stratified analyses, the association of interest remained similar within strata by sex, BMI, physical activity, smoking and drinking status; rather, significant heterogeneity showed across age strata (Pinteraction = 0·02). Total legume consumption among the over-65s was related to a more markedly reduced hypertension risk (HR 0·47 (95 % CI 0·30, 0·73); Ptrend < 0·001). Our findings suggest an inverse association of all kinds of legume (except non-soyabean) intakes with hypertension risks.

Phytoestrogens: Dietary Intake, Bioavailability, and Protective Mechanisms against Colorectal Neoproliferative Lesions

Phytoestrogens are natural substances that have been extensively studied for their beneficial effect on human health. Herein, we analyzed the data of the literature on the role of phytoestrogens in the prevention of colorectal neoproliferative lesions (CNL). Both in vitro and in vivo studies suggest that the beneficial effects of phytoestrogens on CNL mainly depend on their ability to bind estrogen receptor beta (ERβ) in the intestinal mucosa and counter ER-alpha (ERα) activity. Epidemiological data demonstrate a correlation between the low prevalence of CNL in Eastern populations and the consumption of soy products (phytoestrogen-enriched diet). However, both observational and interventional studies have produced inconclusive results. In our opinion, these discrepancies depend on an inadequate evaluation of phytoestrogen intake (dietary questionnaires were not aimed at establishing phytoestrogen intake) and absorption (depending mainly on the intestinal microbiota of the analyzed subjects). For this reason, in the present review, we performed an overview of phytoestrogen dietary intake and metabolism to offer the reader the opportunity for a better interpretation of the literature. Future prospective trials focusing on the protective effect of phytoestrogens against CNL should take into account both their dietary intake and absorption, considering the effective role of the intestinal microbiota.

Habitual consumption of soy protein and isoflavones and risk of metabolic syndrome in adults ≥ 40 years old: a prospective analysis of the Korean Multi-Rural Communities Cohort Study (MRCohort)

PURPOSE

Although considerable attention has been paid to the potential benefits of soy protein and isoflavones for preventing metabolic syndrome (MetS) and its components, findings linking habitual consumption of these factors to MetS are limited. This study aimed to evaluate the association of MetS incidence with habitual intake of soy protein/isoflavones among Korean men and women aged ≥ 40 years old who did not have MetS at baseline (n = 5509; 2204 men and 3305 women).

METHODS

Dietary intake of soy protein/isoflavones at baseline and average consumption during follow-up were used.

RESULTS

A significant inverse association between dietary intake and incidence of MetS was found in women (incidence rate ratios, IRR = 0.60, 95% CI = 0.46-0.78, P for trend = 0.0094 for the highest quintile of average soy protein intake compared with the lowest quintile; IRR = 0.57, 95% CI = 0.44-0.74, P for trend = 0.0048 for the highest quintile of average isoflavones intake compared with the lowest quintile). A tendency towards an inverse association was also found in men, although it was not significant for the highest quintile (IRR = 0.80, 95% CI = 0.58-1.11, P for trend = 0.9759, comparing the lowest to the highest quintile of average soy protein intake; IRR = 0.73, 95% CI = 0.53-1.01, P for trend = 0.8956, comparing the lowest to the highest quintile of average isoflavones intake). In terms of individual abnormalities, a significant inverse association was found between soy protein and isoflavones and the incidence of low-high-density lipoprotein cholesterol in both men and women. Abdominal obesity and elevated blood pressure were inversely related to soy protein/isoflavones only in women, and an inverse association of elevated triglyceride appeared only in men.

CONCLUSION

Our findings suggest that habitual intake of soy protein and isoflavones is inversely associated with the risk of MetS and its components. There is likely to be a reverse J-shaped association of average intake with MetS.

The associations between plasma phytoestrogens concentration and metabolic syndrome risks in Chinese population

Metabolic syndrome (MetS) has become an important issue in the healthcare systems of both developed and developing countries. Phytoestrogens have shown estrogenic effects, which may involve in the etiology of MetS. The current study consisted of 293 MetS cases and 264 healthy controls. The concentrations of seven plasma phytoestrogens (daidzein, genistein, glycitein, equol, enterolactone, enterodiol and coumestrol) were detected by UPLC-MS/MS. Adjusted unconditional logistic regression was used to assess the associations between plasma phytoestrogens concentration and risks of MetS, as well as the associations between plasma phytoestrogens concentration and MetS components. Linear regression was used to evaluate the associations between equol concentration in equol-producers and MetS components. Higher concentrations of total isoflavone and equol were associated with decreased risk of MetS. The equol concentration was negatively associated with waist circumference and positively associated with HDL-C level. Increased daidzein was associated with both lower waist circumference and lower fasting blood glucose levels. Our results suggested that higher plasma total isoflavone, equol and daidzein might decrease MetS risk.

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.

Fermented Soy Product Intake Is Inversely Associated with the Development of High Blood Pressure: The Japan Public Health Center-Based Prospective Study

Background: Randomized controlled studies have investigated the short-term effect of soy product intake on blood pressure (BP) in normotensive people. To our knowledge, no prospective studies exist on the effect of habitual intake of fermented soy products, separate from total soy products, on BP in the general population.Objective: We examined the association between the habitual intake of soy products, including fermented soy products, and the development of high BP during a 5-y period among participants in a population-based prospective cohort study in Japan.Methods: The study included normotensive participants aged 40-69 y at baseline (926 men and 3239 women) who completed 2 questionnaires and whose BP was measured at the baseline survey between 1993 and 1994 and the 5-y follow-up in the Japan Public Health Center-Based Prospective Study Cohort II. The intake of soy products was assessed with a food-frequency questionnaire. High BP was defined as systolic blood pressure ≥130 mm Hg, diastolic blood pressure ≥85 mm Hg, or antihypertensive medication use. ORs and 95% CIs of high BP by frequency of soy products (miso, natto, and tofu) consumption, intake of total and fermented soy products, and intake of isoflavones from total and fermented soy products were estimated with the use of multiple logistic regression analysis.Results: Multivariable-adjusted ORs of high BP for the highest compared with the lowest tertile of total and fermented soy product intake were 1.03 (95% CI: 0.84, 1.25; P-trend = 0.786) and 0.72 (95% CI: 0.56, 0.92; P-trend = 0.009), respectively. The frequency of nonfermented soy product (tofu) intake was not associated with the development of high BP (P-trend = 0.597).Conclusions: The intake of fermented soy products, but not total or nonfermented soy products, was inversely associated with developing high BP in men and women with normal BP.

Association of Animal and Plant Proteins Intake with Hypertension in Iranian Adult Population: Isfahan Healthy Heart Program

Background:

There is evidence regarding the relationship between dietary proteins intake and blood pressure (BP), but they had inconsistent results. Therefore, this study was designed to assess the association between different kinds of protein intake (animal and plant protein) and BP.

Materials and Methods:

Data were collected from Isfahan Healthy Heart Program. We performed a cross-sectional study among 9660 randomly selected Iranian adults aged ≥19-year-old that they were selected from three large Iranian regions in 2007. A simplified validated 48-item-food frequency questionnaire was used to assess dietary intake including all kinds of protein. Systolic and diastolic BPs were measured in duplicate by trained personnel using a standard protocol. Multivariable regressions were applied to assess the relationship between protein intake and BP levels and the presence of hypertension (HTN).

Results:

More frequent consumption of animal, plant, and total protein intake were inversely associated with BP in a crude model (P < 0.001); however, after adjustment for potential confounders this relationship remained only for plant protein (P = 0.04). The risk of HTN occurrence decreased in the highest quintile of total and plant protein consumption by 19% (odds ratio [OR] = 0.81; confidence interval [CI]: [0.65–0.96]; P for trend = 0.004) and 18% (OR = 0.82; [CI: (0.67–0.94]; P for trend = 0.03), respectively.

Conclusions:

More frequent protein intake, especially plant protein consumption was inversely associated with BP and risk of HTN among Iranian adults.

Does soy protein affect circulating levels of unbound IGF-1?

INTRODUCTION

Despite the enormous amount of research that has been conducted on the role of soyfoods in the prevention and treatment of chronic disease, the mechanisms by which soy exerts its physiological effects are not fully understood. The clinical data show that neither soyfoods nor soy protein nor isoflavones affect circulating levels of reproductive hormones in men or women. However, some research suggests that soy protein, but not isoflavones, affects insulin-like growth factor I (IGF-1).

METHODS

Since IGF-1 may have wide-ranging physiological effects, we sought to determine the effect of soy protein on IGF-1 and its major binding protein insulin-like growth factor-binding protein (IGFBP-3). Six clinical studies were identified that compared soy protein with a control protein, albeit only two studies measured IGFBP-3 in addition to IGF-1.

RESULTS

Although the data are difficult to interpret because of the different experimental designs employed, there is some evidence that large amounts of soy protein (>25 g/day) modestly increase IGF-1 levels above levels observed with the control protein.

CONCLUSION

The clinical data suggest that a decision to incorporate soy into the diet should not be based on its possible effects on IGF-1.

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.

Randomised controlled trial of effect of whole soy replacement diet on features of metabolic syndrome in postmenopausal women: study protocol

INTRODUCTION

Metabolic syndrome (MetS) is a public health problem in postmenopausal women. Whole soy foods are rich in unsaturated fats, high quality plant protein and various bioactive phytochemicals that may have a beneficial role in the management of MetS. The aim of the study is to examine the effect of whole soy replacement diet on the features of MetS among postmenopausal women.

METHODS AND ANALYSIS

This will be a 12-month, randomised, single-blind, parallel controlled trial among 208 postmenopausal women at risk of MetS or with early MetS. After 4 weeks' run-in, subjects will be randomly allocated to one of two intervention groups, whole soy replacement group or control group, each for 12 months. Subjects in the whole soy group will be required to include four servings of whole soy foods (containing 25 g soy protein) into their daily diet iso-calorically, replacing red or processed meat and high fat dairy products. Subjects in the control group will remain on a usual diet. The outcome measures will include metabolic parameters as well as a 10-year risk for ischaemic cardiovascular disease. We hypothesise that the whole soy substitution diet will notably improve features of MetS in postmenopausal women at risk of MetS or with early MetS. The study will have both theoretical and practical significance. If proven effective, the application of the whole soy replacement diet model will be a safe, practical and economical strategy for MetS prevention and treatment.

ETHICS AND DISSEMINATION

Ethics approval has been obtained from the Ethics Committee of the Chinese University of Hong Kong. The results will be disseminated via conference presentations and papers in academic peer reviewed journals. Data files will be deposited in an accessible repository.

TRIAL REGISTRATION NUMBER

NCT02610322.

Research protocol: effect of natural S-equol on blood pressure and vascular function--a six-month randomized controlled trial among equol non-producers of postmenopausal women with prehypertension or untreated stage 1 hypertension

BACKGROUND

Although higher habitual soy intake is associated with lower blood pressure (BP) and stroke incidence, clinical trials using soy protein or isoflavones on cardiovascular risks yielded inconsistent results. The discrepancies are hypothesized to be due to the individuals' intestinal bacterial capacity to metabolite isoflavones daidzein into equol. Animal and in vitro studies have revealed that equol has stronger estrogen-like and anti-oxidative activity than isoflavones and possesses natriuretic and vasorelaxant properties which may play an important role in the prevention of hypertension. However, no clinical trial has examined the effect of equol on BP. We thus propose a 24-week randomized controlled trial to test the effectiveness of natural S-equol on BP and vascular function among equol non-producers.

METHODS/DESIGN

This will be a 6-month double-blind, randomized, placebo-controlled trial among 207 non-equol producing postmenopausal women with prehypertension or early untreated hypertension. Eligible participants who have completed a 2-week run-in will be randomized to either one of the 3 groups: placebo group, low-equol group (10 mg/d) and high equol group (20 mg/d). The outcome measures will be conducted at baseline and at the end of the trial including 24 h ambulatory BP, endothelial function (by ultrasound determined brachial flow mediated dilation), arterial stiffness (by pulse wave analysis) and other cardiovascular risk factors (lipid profile, glycemic control and inflammatory biomarkers). Urinary isoflavones will be tested for compliance assessment. One way analysis of variance will be applied to compare the 6-month changes in ambulatory BP or parameters of vascular function among the 3 treatment groups.

DISCUSSION

This study will be performed in community subjects. If the antihypertensive effect of equol is proven, the provision of natural equol to those high risk adults who are unable to produce equol will have enormous public health implications for the primary and secondary prevention of hypertension and cardiovascular diseases on a population basis. The research efforts will also have significant implications for industry in the provision of suitable soy products for the prevention of hypertension and its related complications.

TRIAL REGISTRATION

The trial was registered in ClinicalTrials.gov with identifier of NCT02515682 .

Effect of whole soy and purified daidzein on ambulatory blood pressure and endothelial function--a 6-month double-blind, randomized controlled trial among Chinese postmenopausal women with prehypertension

BACKGROUND/OBJECTIVES

Although observational studies suggest that soy foods or isoflavones are cardio-protective, clinical trials on whole soy or isoflavone daidzein (one major isoflavone and the precursor of equol) on blood pressure (BP) and endothelial function (EF) are few and have not been specifically conducted among equol producers, a population most likely to benefit from soy treatment.

SUBJECTS/METHODS

We performed a 6-month double-blind, randomized, placebo-controlled trial to examine the effect of whole soy (soy flour) or purified daidzein on BP and EF in prehypertensive or untreated hypertensive postmenopausal women verified to be equol producers. A total of 270 eligible women were recruited and randomized to either one of the three treatment groups, 40 g soy flour (whole soy group), 40 g low-fat milk powder+63 mg daidzein (daidzein group) or 40 g low-fat milk powder (active control group) daily, each given as a solid beverage powder for 6 months. The primary outcome measures were 24 h ambulatory BP (ABP) and EF assessed by flow-mediated dilation using brachial artery ultrasound.

RESULTS

A total of 253 subjects completed the study according to protocol. Urinary isoflavones indicated good compliance with the interventions. Intention to treat and per-protocol analysis indicated that there was no significant difference in the 6-month changes or % changes in parameters of ABP and brachial flow-mediated dilation among the three treatment groups. A further subgroup analysis among hypertensive women (n=138) did not alter the conclusions.

CONCLUSIONS

Whole soy and purified daidzein had no significant effect on BP and vascular function among equol-producing postmenopausal women with prehypertension or untreated hypertension.

Exposure to Bisphenol A From Drinking Canned Beverages Increases Blood Pressure

Bisphenol A (BPA) is a chemical used in plastic bottles and inner coating of beverage cans, and its exposure is almost ubiquitous. BPA has been associated with hypertension and decreased heart rate variability in the previous studies. The aim of the present study was to determine whether increased BPA exposure from consumption of canned beverage actually affects blood pressure and heart rate variability. We conducted a randomized crossover trial with noninstitutionalized adults, who were aged ≥60 years and recruited from a local community center. A total of 60 participants visited the study site 3 times, and they were provided the same beverage in 2 glass bottles, 2 cans, or 1 can and 1 glass bottle at a time. The sequence of the beverage was randomized. We then measured urinary BPA concentration, blood pressure, and heart rate variability 2 hours after the consumption of each beverage. The paired t test and mixed model were used to compare the differences. The urinary BPA concentration increased after consuming canned beverages by >1600% compared with that after consuming glass bottled beverages. Systolic blood pressure adjusted for daily variance increased by ≈4.5 mm Hg after consuming 2 canned beverages compared with that after consuming 2 glass bottled beverages, and the difference was statistically significant. The parameters of the heart rate variability did not show statistically significant differences.The present study demonstrated that consuming canned beverage and consequent increase of BPA exposure increase blood pressure acutely.

Effect of soy nuts and equol status on blood pressure, lipids and inflammation in postmenopausal women stratified by metabolic syndrome status

OBJECTIVE

Soy has been associated with lower risk of cardiovascular disease in Asian countries which consume daily soy. Our study examined whether production of equol, an estrogen metabolite, affected the ability of soy nuts to improve cardiovascular risk factors.

MATERIALS/METHODS

Sixty postmenopausal women participated in a randomized, controlled, crossover trial of a Therapeutic Lifestyle Changes (TLC) diet alone and a TLC diet in which 0.5 cup of soy nuts (25 g of soy protein and 101 mg of aglycone isoflavones) replaced 25 g of nonsoy protein daily. Each diet was followed for 8 weeks at the end of which blood pressure (BP), lipid levels, adhesion molecules and inflammatory markers were measured.

RESULTS

Women with MetS had significantly higher baseline body mass index (BMI), BP, triglycerides (TG), and soluble intercellular adhesion molecule (sICAM) than women without MetS. In women with MetS on the soy diet, significant reductions in diastolic BP (7.7%; P=0.02), TG (22.9%; P=0.02), C-reactive protein (CRP) (21.4%; P=0.01) and sICAM (7.3%; P=0.03) were noted among equol producers compared to levels on the TLC diet. No significant changes were noted in equol nonproducers. Similarly, in women without MetS, only equol producers had significant reductions in diastolic BP (3.3%, P=0.02) and CRP (30%, P=0.04). In contrast to women with MetS, TG and sICAM levels were not affected in women without MetS, a finding possibly related to lower baseline levels.

CONCLUSIONS

Cardiovascular risk reduction with soy nuts is not uniform and may be greater among producers of equol.

Soy food consumption, cardiometabolic alterations and carotid intima-media thickness in Chinese adults

BACKGROUND AND AIM

The associations between soy food consumption, cardiometabolic disturbances and subclinical atherosclerosis remain controversial due to limited evidence. We examined the associations of habitual soy food consumption with cardiometabolic disturbances and carotid intima-media thickness (CIMT).

METHODS AND RESULTS

We included 2939 subjects (2135 women and 804 men) aged 50-75 years in this community-based cross-sectional study. Dietary data and other covariates were collected using interviewer-administered questionnaires. We determined CIMT in relation to each subject's common carotid artery, internal carotid artery, carotid bifurcation, blood lipids, glucose and urine acid, blood pressure and waist circumference. A logistic regression model was applied to estimate the odd ratios (ORs) and 95% confidence intervals (CIs), and linear regression was used to estimate the regression coefficient and 95% CIs. After adjusting for potential confounders, we found that greater consumption of soy protein (6.1 vs. 0.5 g/d) was inverse associated with the presence of elevated total cholesterol (TC), dyslipidemia, abdominal obesity and hyperuricemia in women, and with abdominal obesity in men, although no significant sex-soy interactions were observed (P: 0.145-0.985). The consumption of soy protein and isoflavones was inversely associated with the number of cardiometabolic disturbances among women, but not men. There were no significant associations of soy protein and isoflavones with CIMT thickening and other cardiometabolic disturbances.

CONCLUSION

Greater soy consumption was associated with a lower presence of elevated TC, dyslipidemia, hyperuricemia and less number of cardiometabolic disturbances components in women.

Higher erythrocyte n-3 PUFAs are associated with decreased blood pressure in middle-aged and elderly Chinese adults

Previous studies suggested that blood fatty acids (FAs) might affect blood pressure (BP), but the findings have been inconclusive. This study evaluated the cross-sectional and prospective associations of erythrocyte FAs with BP in middle-aged and elderly Chinese individuals. Between 2008 and 2010, 1834 participants (1364 women and 470 men) aged 57 ± 5 y had baseline measurements taken of their erythrocyte FAs and BP. A total of 1477 participants (1103 women and 374 men) had their BP measured again after 3.09 ± 0.32 y (range: 2.91-3.26 y). In the cross-sectional analyses (n = 1834), the erythrocyte saturated FA (SFA) content was positively associated with BP, whereas total cis polyunsaturated FAs (PUFAs), their subtypes cis n-3 (ω-3) PUFAs and cis n-6 (ω-6) PUFAs, and the PUFA-to-SFA ratio were inversely associated with BP (all P-trends < 0.05). The longitudinal results (n = 1477) showed marginally inverse associations between cis n-3 PUFAs and the n-3:n-6 PUFA ratio and BP. For individual cis n-3 PUFAs, higher contents of 20:5n-3, 22:5n-3, and 22:6n-3 were significantly associated with reduced increases in SBP over time (the mean change range between quartile 4 and quartile 1 was -0.917 to -0.749 mm Hg for SBP; all P-trends < 0.01), and 20:5n-3 was inversely associated with DBP change (the mean change between quartile 4 and quartile 1 was -0.631; P-trend < 0.001). Path analyses suggested that the associations between cis n-3 PUFAs and BP might be mediated by decreasing serum triglycerides (TGs) and body mass index (BMI). Our findings revealed that a higher content of cis n-3 PUFAs (mainly very long-chain cis n-3 PUFAs) may benefit BP progress, probably mediated by decreasing serum TGs and BMI.

Soy food consumption and lung cancer risk: a meta-analysis using a common measure across studies

A published meta-analysis pooled individual studies by using the study-specific odds ratio (OR) or relative risk (RR) for the highest vs. lowest category of soy or isoflavone intake from each study, but it should be problematic to make comparison between studies/populations for lung cancer risk as the quantiles are so different from different studies/populations. Therefore, we conducted a meta-analysis to explore the association between exposure of estimated daily soy protein intake in grams and lung cancer risk. We extracted ORs or RRs and 95% confidence intervals (CIs), converted them to the estimated ones for daily soy protein intake and pooled them using fixed or random effects models from 11 epidemiologic studies. Overall, the inverse association between daily grams of soy protein intake and risk of lung cancer was borderline statistically significant (OR = 0.98, 95% CI = 0.96 to 1.00); the inverse association was statistically significant in nonsmokers (OR = 0.96; 95% CI = 0.93 to 0.99) and stronger than in smokers (P for difference <0.05). No statistical significance for the associations was observed between genders, the origin of the participants, study design and types of soy intake. This study suggests a borderline reduction in risk of lung cancer with daily soy protein intake in grams, and a significant inverse association in nonsmokers.

Phytoestrogens for menopausal bone loss and climacteric symptoms

Women have always looked for non-hormonal options to alleviate menopausal vasomotor symptoms and prevent menopausal bone loss. The use of complementary and alternative medicine for these purposes has particularly increased after the publication of the Women's Health Initiative's results suggesting that there might be more risks than benefits with hormone replacement. Phytoestrogens are plant-derived estrogens that, although less potent than estradiol, bind to the estrogen receptor and can function as estrogen agonists or antagonists. Soy isoflavones extracted from soy are the phytoestrogens most commonly used by menopausal women. Because typical Western diets are low in phytoestrogens and taking into account the general difficulty in changing dietary habits, most clinical trials in Western women have used isoflavone-fortified foods or isoflavone tablets. Although some women might experience a reduction in the frequency or severity of hot flashes, most studies point towards the lack of effectiveness of isoflavones derived from soy or red clover, even in large doses, in the prevention of hot flashes and menopausal bone loss. This article is part of a Special Issue entitled 'Phytoestrogens'.

Nutrition and nutraceutical supplements for the treatment of hypertension: part II

Vascular biology, endothelial and vascular smooth muscle, and cardiac dysfunction play a primary role in the initiation and perpetuation of hypertension, cardiovascular disease, and target organ damage. Nutrient-gene interactions and epigenetics are predominant factors in promoting beneficial or detrimental effects in cardiovascular health and hypertension. Macronutrients and micronutrients can prevent, control, and treat hypertension through numerous mechanisms related to vascular biology. Oxidative stress, inflammation, and autoimmune dysfunction initiate and propagate hypertension and cardiovascular disease. There is a role for the select use of single and component nutraceutical supplements, vitamins, antioxidants, and minerals in the treatment of hypertension based on scientifically controlled studies, which complement optimal nutrition, coupled with other lifestyle modifications.

Soy food intake and circulating levels of inflammatory markers in Chinese women

BACKGROUND

Soy and some of its constituents, such as isoflavones, have been shown to affect the inflammatory process in animal studies. The association between soy food intake and inflammatory markers has not been evaluated adequately in humans.

OBJECTIVE

Our aim was to evaluate whether higher intake of soy foods was inversely associated with inflammatory markers in 1,005 middle-aged Chinese women.

DESIGN

In this cross-sectional study, dietary intake of soy foods was assessed by a validated food frequency questionnaire and by a 24-hour recall when biospecimens were procured. A general linear model was used to estimate the geometric means of selected inflammatory markers, including interleukin-6 (IL-6), IL-1β, tumor necrosis factor-α (TNFα), soluble IL-6 receptor, soluble GP130, soluble TNF receptors 1 and 2, and C-reactive protein, across categories of soy food intake after adjusting for age, lifestyle and dietary factors, and history of infectious or inflammation-related diseases.

RESULTS

We found that multivariable-adjusted geometric mean concentrations of IL-6 and TNFα were inversely associated with quintiles of soy food intake, with a difference between the highest and lowest quintiles of 25.5% for IL-6 (P for trend=0.008) and 14% for TNFα (P for trend=0.04). Similar inverse associations were found for TNFα (P for trend=0.003), soluble TNF receptor 1 (P for trend=0.01), soluble TNF receptor 2 (P for trend=0.02), IL-1β (P for trend=0.05), and IL-6 (P for trend=0.04) when soy food consumption was assessed by the frequency of consumption in the preceding 24 hours. No significant associations were found for other markers studied.

CONCLUSIONS

This study suggests that soy food consumption is related to lower circulating levels of IL-6, TNFα, and soluble TNF receptors 1 and 2 in Chinese women.

Antihypertensive effects of dietary protein and its mechanism

Hypertension is a leading cause of morbidity and mortality worldwide. Individuals with hypertension are at increased risk of stroke, heart disease and kidney failure. Both genetic and lifestyle factors, particularly diet, have been attributed an important role in the development of hypertension. Reducing dietary sugar and salt intake can help lower blood pressure; similarly, adequate protein intake may also attenuate hypertension. Observational, cross-sectional and longitudinal epidemiological studies, and controlled clinical trials, have documented significant inverse associations between protein intake and blood pressure. Human and animal studies have shown that specific amino acids within proteins may have antihypertensive effects. Cysteine, glutathione (a tripeptide), glutamate and arginine attenuate and prevent alterations that cause hypertension including insulin resistance, decreased nitric oxide bioavailability, altered renin angiotensin system function, increased oxidative stress and formation of advanced glycation end products. Leucine increases protein synthesis in skeletal muscle and improves insulin resistance by modulating hepatic gluconeogenesis. Taurine and tryptophan attenuate sympathetic nervous system activity. Soy protein helps lower blood pressure through its high arginine content and antioxidant activity exhibited by isoflavones. A diet containing an ample amount of protein may be a beneficial lifestyle choice for individuals with hypertension; one example is the Dietary Approaches to Stop Hypertension (DASH) diet, which is low in salt and saturated fat; includes whole grains, lean meat, poultry, fish and nuts; and is rich in vegetables, fruits and low-fat dairy products, which are good sources of antioxidant vitamins, minerals and fibre. Including an adequate supply of soy in the diet should also be encouraged.

Blood pressure decrease with ingestion of a soya product (kinako) or fish oil in women with the metabolic syndrome: role of adiponectin and nitric oxide

The aim of the present study was to verify the effects of fish oil and a soya-based product on inflammatory markers and endothelial function measured by NO in women with the metabolic syndrome (MetS). A total of sixty-five women (mean age: 47·9 (sd9·98) years) were studied in a 90-d parallel, randomised design. A control group maintained their usual diet; the second group received 29 g/d of soyabean (kinako); the third group received 3 g/d of fish oiln-3 fatty acids; and the fourth group received fish oil (3 g/d) and kinako (29 g/d). Anthropometric, blood pressure (BP), inflammatory markers, anti-inflammatory marker (adiponectin) and NO concentrations were evaluated. In relation to the baseline values, the group that received fish oil and kinako concomitantly presented a statistically significant decrease in systolic BP (SBP;P < 0·05), whereas there was a significant decrease in diastolic BP (DBP) in the control group (P < 0·05), kinako group (P < 0·01) and fish oil group (P < 0·01) after 90 d. There was a significant increase in adiponectin (P < 0·01) and NO values (P < 0·05) after 90 d in the kinako and fish oil groups. Differences between treatment groups verified a significant decrease (P < 0·05) in DBP in the kinako group after 90 d when compared to the results obtained from the fish oil and kinako groups. In conclusion, the findings of increased serum adiponectin and NO metabolite levels after 90 d, both in the fish oil and soya groups, reinforce the importance of the influence of adiponectin and NO levels on BP decrease in patients with the MetS.

Effect of soya protein on blood pressure: a meta-analysis of randomised controlled trials

Observational studies have indicated that soya food consumption is inversely associated with blood pressure (BP). Evidence from randomised controlled trials (RCT) on the BP-lowering effects of soya protein intake is inconclusive. We aimed to evaluate the effectiveness of soya protein intake in lowering BP. The PubMed database was searched for published RCT in the English language through to April 2010, which compared a soya protein diet with a control diet. We conducted a random-effects meta-analysis to examine the effects of soya protein on BP. Subgroup and meta-regression analyses were performed to explore possible explanations for heterogeneity among trials. Meta-analyses of twenty-seven RCT showed a mean decrease of 2·21 mmHg (95 % CI - 4·10, - 0·33; P = 0·021) for systolic BP (SBP) and 1·44 mmHg (95 % CI - 2·56, - 0·31; P = 0·012) for diastolic BP (DBP), comparing the participants in the soya protein group with those in the control group. Soya protein consumption significantly reduced SBP and DBP in both hypertensive and normotensive subjects, and the reductions were markedly greater in hypertensive subjects. Significant and greater BP reductions were also observed in trials using carbohydrate, but not milk products, as the control diet. Meta-regression analyses further revealed a significantly inverse association between pre-treatment BP and the level of BP reductions. In conclusion, soya protein intake, compared with a control diet, significantly reduces both SBP and DBP, but the BP reductions are related to pre-treatment BP levels of subjects and the type of control diet used as comparison.

The role of soy isoflavones in menopausal health: report of The North American Menopause Society/Wulf H. Utian Translational Science Symposium in Chicago, IL (October 2010)

OBJECTIVES

If and to what extent soy protein, soy isoflavones, and their metabolites, including S(--)-equol, have beneficial effects on women's health is currently unclear. The North American Menopause Society (NAMS)/Utian Translational Science Symposium on Soy and Soy Isoflavones convened October 9-10, 2010, to clarify basic and clinical research findings as they relate to the risk and benefits of soy products for peri- and postmenopausal women.

METHODS

A working group of faculty and panelists composed of clinical and research experts in the fields of women's health and botanicals met during a 2-day translational symposium to cover the latest evidence-based science on isoflavones as they affect menopausal symptoms, breast and endometrial cancer, atherosclerosis, bone loss, and cognition. Full descriptions of the bioavailability and pharmacokinetics of isoflavones were also presented. Subspecialty groups then broke off with the goal of translating the information into a report for general medical practice and identifying further research areas. All faculty and panelists reviewed the final report, which was then approved by the NAMS Board of Trustees.

RESULTS

From the hundreds of studies reviewed in this report, there are mixed results of the effects on midlife women. Soy-based isoflavones are modestly effective in relieving menopausal symptoms; supplements providing higher proportions of genistein or increased in S(--)-equol may provide more benefits. Soy food consumption is associated with lower risk of breast and endometrial cancer in observational studies. The efficacy of isoflavones on bone has not been proven, and the clinical picture of whether soy has cardiovascular benefits is still evolving. Preliminary findings on cognitive benefit from isoflavone therapy support a "critical window" hypothesis wherein younger postmenopausal women derive more than older women.

CONCLUSIONS

Several areas for further research have been identified on soy and midlife women. More clinical studies are needed that compare outcomes among women whose intestinal bacteria have the ability to convert daidzein to equol (equol producers) with those that lack that ability (equol nonproducers) in order to determine if equol producers derive greater benefits from soy supplementation. Larger studies are needed in younger postmenopausal women, and more research is needed to understand the modes of use of soy isoflavone supplements in women. The interrelations of other dietary components on soy isoflavones consumed as a part of diet or by supplement on equol production also require further study, as do potential interactions with prescription and over-the-counter medications. And finally, greater standardization and documentation of clinical trial data of soy are needed.

Lifestyle Intervention Strategies for the Prevention and Treatment of Hypertension: A Review

Hypertension (HTN) is an extraordinarily common progressive cardiovascular syndrome in the United States, afflicting approximately one third of the adult population. HTN is a powerful and unequivocal independent risk factor for cardiovascular and renal diseases, including coronary heart disease, stroke, and renal failure. Despite major advances in the understanding and treatment of HTN over the past several decades, the disease remains the most common primary diagnosis in the United States and is a major public health concern. Adoption of healthy lifestyle modifications has proven to be highly effective in both the prevention of new-onset HTN and in the treatment of those diagnosed with HTN. In view of the continuing epidemic of HTN and blood pressure (BP)—related diseases and the invaluable role of applying nonpharmacological therapy in the prevention and management of HTN, a review of current therapeutic lifestyle strategies appears warranted. This review will define 6 well-established nonpharmacological lifestyle modifications for preventing and managing HTN in addition to 3 novel lifestyle interventions that show promise as effective adjunct strategies for lowering BP. A healthy lifestyle prescription ideally comprising a number of these BP-lowering lifestyle intervention strategies should be dispensed by all primary care physicians for both the prevention and treatment of elevated BP, an action that would have major, positive public health ramifications.

The effects of heated vegetable oils on blood pressure in rats

OBJECTIVES

The goal of this study was to determine the possible mechanism that is involved in the blood pressure-raising effect of heated vegetable oils.

METHODS

Adult male Sprague-Dawley rats were divided into 11 groups; the control group was fed with rat chow, and the other groups were fed with chow that was mixed with 15% weight/weight palm or soy oils, which were either in a fresh form or heated once, twice, five, or ten times. Blood pressures were measured at the baseline and throughout the 24-week study. Plasma nitric oxide levels were assessed prior to treatment and at the end of the study. Following 24 weeks, the rats were sacrificed to investigate their vascular reactivity using the thoracic aorta.

RESULTS

Palm and soy oils had no detrimental effects on blood pressure, and they significantly elevated the nitric oxide contents and reduced the contractile responses to phenylephrine. However, trials using palm and soy oils that were repeatedly heated showed an increase in blood pressure, enhanced phenylephrine-induced contractions, reduced acetylcholine- and sodium nitroprusside-induced relaxations relative to the control and rats that were fed fresh vegetable oils.

CONCLUSIONS

The blood pressure-raising effect of the heated vegetable cooking oils is associated with increased vascular reactivity and a reduction in nitric oxide levels. The chronic consumption of heated vegetable oils leads to disturbances in endogenous vascular regulatory substances, such as nitric oxide. The thermal oxidation of the cooking oils promotes the generation of free radicals and may play an important contributory role in the pathogenesis of hypertension in rats.

Dietary protein and blood pressure: a systematic review

BACKGROUND

Elevated blood pressure (BP), which is a major risk factor for cardiovascular disease, is highly prevalent worldwide. Recently, interest has grown in the role of dietary protein in human BP. We performed a systematic review of all published scientific literature on dietary protein, including protein from various sources, in relation to human BP.

METHODOLOGY/PRINCIPAL FINDINGS

We performed a MEDLINE search and a manual search to identify English language studies on the association between protein and blood pressure, published before June 2010. A total of 46 papers met the inclusion criteria. Most observational studies showed no association or an inverse association between total dietary protein and BP or incident hypertension. Results of biomarker studies and randomized controlled trials indicated a beneficial effect of protein on BP. This beneficial effect may be mainly driven by plant protein, according to results in observational studies. Data on protein from specific sources (e.g. from fish, dairy, grain, soy, and nut) were scarce. There was some evidence that BP in people with elevated BP and/or older age could be more sensitive to dietary protein.

CONCLUSIONS/SIGNIFICANCE

In conclusion, evidence suggests a small beneficial effect of protein on BP, especially for plant protein. A blood pressure lowering effect of protein may have important public health implications. However, this warrants further investigation in randomized controlled trials. Furthermore, more data are needed on protein from specific sources in relation to BP, and on the protein-BP relation in population subgroups.

Nitric oxide enhancement and blood pressure decrease in patients with metabolic syndrome using soy protein or fish oil

OBJECTIVE: To verify the effects of fish oil and soy on nitric oxide (NO) and blood pressure in patients with metabolic syndrome (MS). SUBJECTS AND METHODS: Sixty women with MS were investigated in a parallel randomized design study. The first group maintained their usual diet; the second group received 25 g/day of soy; the third group received 3 g/day of n-3 fatty acids, and the fourth group the same amount previously cited of n-3 fatty acids and soy. RESULTS: Serum nitric oxide metabolites showed significant increase after 90 days in the fish oil and soy groups. Systolic pressure reduced after 45 days of treatment with fish oil, whereas diastolic pressure decreased significantly throughout the study in the soy group. CONCLUSIONS: NO increase and blood pressure reduction with fish oil or soy protein reinforce the importance of the influence of NO on blood pressure in patients with MS.

The role of soy in vegetarian diets

Soyfoods have long been prized among vegetarians for both their high protein content and versatility. Soybeans differ markedly in macronutrient content from other legumes, being much higher in fat and protein, and lower in carbohydrate. In recent years however, soyfoods and specific soybean constituents, especially isoflavones, have been the subject of an impressive amount of research. Nearly 2,000 soy-related papers are published annually. This research has focused primarily on the benefits that soyfoods may provide independent of their nutrient content. There is particular interest in the role that soyfoods have in reducing risk of heart disease, osteoporosis and certain forms of cancer. However, the estrogen-like effects of isoflavones observed in animal studies have also raised concerns about potential harmful effects of soyfood consumption. This review addresses questions related to soy and chronic disease risk, provides recommendations for optimal intakes, and discusses potential contraindications. As reviewed, the evidence indicates that, with the exception of those individuals allergic to soy protein, soyfoods can play a beneficial role in the diets of vegetarians. Concerns about adverse effects are not supported by the clinical or epidemiologic literature. Based on the soy intake associated with health benefits in the epidemiologic studies and the benefits noted in clinical trials, optimal adult soy intake would appear to be between two and four servings per day.