Gender-specific effects of soybean consumption on cardiovascular events in elderly individuals from rural Northeast China - a prospective cohort study

BACKGROUND

The impact of consuming soybean and its products on cardiovascular events (CVEs), cardiovascular mortality, and all-cause mortality remains unclear. This study aimed to examine the prospective association of soybean consumption with CVEs, cardiovascular mortality, and all-cause mortality among the elderly population in rural China.

METHODS

The Northeast China Rural Cardiovascular Health Study included 2477 elderly individuals (mean age 67 ± 6 years, 49.97% men) in the initial phase of the study from 2012 to 2013, with a follow-up period between 2015 and 2017. Soybean consumption was categorized as follows: low-frequency consumption: rare consumption; moderate-frequency consumption: two to three times/week; high-frequency consumption: ≥ four times/week. Cox proportional hazard analysis assessed the potential relationship of soybean consumption with CVEs, cardiovascular mortality, and all-cause mortality.

RESULTS

The prevalence of soybean and its product consumption was as follows: 38.3% for low-frequency consumption (43.8% for women; 32.8% for men), 49.7% for moderate-frequency consumption (45.8% for women; 53.7% for men), and 11.9% for high-frequency consumption (10.4% for women; 13.5% for men). After adjusting for possible confounders, Cox proportional hazard analysis revealed that the frequency of soybean consumption was an effective predictor of CVEs [Hazard ratio (HR) high (95% CI): 0.555 (0.348, 0.883)], stroke [HR moderate (95% CI): 0.672 (0.494, 0.913); HR high (95% CI): 0.483 (0.276, 0.842)], and all-cause mortality [HR high (95% CI): 0.540 (0.310, 0.942)] in the overall older population. High-frequency consumption of soybean [HR (95% CI): 0.467 (0.225, 0.968)] and moderate-frequency consumption [HR (95% CI): 0.458 (0.270, 0.779)] were associated with stroke events in older men and women, respectively. In addition, high-frequency consumption of soybean [HR (95% CI): 0.437 (0.197, 0.968)] decreased the risk of CVEs in older women.

CONCLUSION

Soybean consumption is closely associated with CVEs and all-cause mortality in older individuals residing in rural areas, with a significant gender discrepancy in this relationship. These findings provide new insights into the impact of soybean consumption on cardiovascular well-being in the elderly rural population, thus enhancing our understanding of this field of interest.

Legume consumption in adults and risk of cardiovascular disease and type 2 diabetes: a systematic review and meta-analysis

Objectives

This study aimed to systematically review the evidence for associations between consumption of legumes and cardiovascular disease (CVD), type 2 diabetes (T2D) and their risk factors among healthy adults.

Methods

We searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and Scopus up to 16 May 2022 for ≥4 weeks long randomized (RCT) and non-randomized controlled trials and prospective cohort studies with follow-up ≥12 months, assessing legume intake (beans/lentils/peas/soybeans, excluding peanuts and legume-products/protein/powder/flour) as the intervention or exposure. Outcomes were CVD, coronary heart disease (CHD), stroke, T2D and in intervention trials only: changes in blood lipids, glycemic markers, and blood pressure. Risk of bias (RoB) was evaluated with Cochrane's RoB2, ROBINS-I, and US Department of Agriculture (USDA)'s RoB-NObS. Effect sizes were pooled using random-effects meta-analyses and expressed as relative risk or weighed mean differences with 95% confidence intervals, heterogeneity quantified as I². The evidence was appraised according to World Cancer Research Fund's criteria.

Results

Of the 181 full-text articles assessed for eligibility, 47 were included: 31 cohort studies (2,081,432 participants with generally low legume consumption), 14 crossover RCTs (448 participants), one parallel RCT and one non-randomized trial. Meta-analyses of cohort studies were suggestive of null associations for CVD, CHD, stroke and T2D. Meta-analyses of RCTs suggested a protective effect on total cholesterol (mean difference -0.22 mmol/L), low density lipoprotein (LDL)-cholesterol (-0.19 mmol/L), fasting glucose (-0.19 mmol/L), and HOMA-IR (-0.30). Heterogeneity was high (I² = 52% for LDL-cholesterol, >75% for others). The overall evidence for associations between consumption of legumes and risk of CVD and T2D was considered limited - no conclusion.

Conclusion

Legume consumption was not found to influence risk of CVD and T2D in healthy adult populations with generally low legume consumption. However, protective effects on risk factors, seen in RCTs, lend some support for recommending legume consumption as part of diverse and healthy dietary patterns for prevention of CVD and T2D.

Soy Consumption and the Risk of Type 2 Diabetes and Cardiovascular Diseases: A Systematic Review and Meta-Analysis

Soy is rich in plant protein, isoflavones, and polyunsaturated fatty acids. To clarify the associations between soy intake and type 2 diabetes (T2D) and cardiovascular diseases (CVDs) events, we performed a meta-analysis and review. A total of 1963 studies met the inclusion criteria, and 29 articles with 16,521 T2D and 54,213 CVDs events were identified by the eligibility criteria. During a follow-up of 2.5–24 years, the risk of T2D, CVDs, coronary heart disease, and stroke in participants with the highest soy consumption decreased by 17% (total relative risk (TRR) = 0.83, 95% CI: 0.74–0.93), 13% (TRR = 0.87, 95% CI: 0.81–0.94), 21% (TRR = 0.79, 95% CI: 0.71–0.88), and 12% (TRR = 0.88, 95% CI: 0.79–0.99), respectively, compared to the lowest sot consumption. A daily intake of 26.7 g of tofu reduced CVDs risk by 18% (TRR = 0.82, 95% CI: 0.74–0.92) and 11.1 g of natto lowered the risk of CVDs by 17% (TRR = 0.83, 95% CI: 0.78–0.89), especially stroke. This meta-analysis demonstrated that soy consumption was negatively associated with the risks of T2D and CVDs and a specific quantity of soy products was the most beneficial for the prevention of T2D and CVDs. This study has been registered on PROSPERO (registration number: CRD42022360504).

Dietary phytoestrogens and total and cause-specific mortality: results from 2 prospective cohort studies

BACKGROUND

Evidence regarding dietary phytoestrogens in relation to mortality remains limited.

OBJECTIVES

The objective of the study is to examine the associations of intake of isoflavones, lignans, and coumarins with total and cause-specific mortality in US males and females.

METHODS

We followed 75,981 females in the Nurses' Health Study (1984-2018) and 44,001 males in the Health Professionals Follow-up Study (1986-2018), who were free of cardiovascular disease (CVD), diabetes, or cancer at baseline. Their diet was repeatedly assessed using validated food frequency questionnaires every 2-4 y. Associations with mortality were assessed using time-dependent Cox models with adjustments for demographics, dietary and lifestyle factors, and medical history.

RESULTS

During 3,427,156 person-years of follow-up, we documented 50,734 deaths, including 12,492 CVD deaths, 13,726 cancer deaths, and 24,516 other non-CVD and noncancer deaths. After multivariable adjustment, the higher total phytoestrogen intake was associated with lower risk of total CVD and other non-CVD and noncancer mortality: comparing extreme quintiles, the pooled HRs (95% CIs) were 0.89 (0.87, 0.92), 0.90 (0.85, 0.96), and 0.86 (0.82, 0.90), respectively. We did not find a significant association with cancer mortality [0.97 (0.92, 1.03)]. For individual phytoestrogens in relation to total mortality, the pooled HRs (95% CIs) comparing extreme quintiles were 0.90 (0.87, 0.92) for isoflavones, 0.93 (0.90, 0.96) for lignans, and 0.93 (0.90, 0.95) for coumarins. Individual phytoestrogens were also significantly associated with lower risk of CVD mortality and other types of mortality. Primary food sources of phytoestrogens, including tofu, soy milk, whole grains, tea, and flaxseed, were also inversely associated with total mortality.

CONCLUSIONS

A higher intake of total phytoestrogens, including isoflavones, lignans, and coumarins, and foods rich in these compounds was associated with lower risk of total and certain cause-specific mortality in generally healthy US adults. These data suggest that these phytochemicals and their dietary sources may be integrated into an overall healthy diet to achieve a longer life span.

Japanese-Style Diet and Cardiovascular Disease Mortality: A Systematic Review and Meta-Analysis of Prospective Cohort Studies

This systematic review and meta-analysis elucidate the effects of the Japanese-style diet and characteristic Japanese foods on the mortality risk of cardiovascular disease (CVD), cerebrovascular disease (stroke), and heart disease (HD). This review article followed the PRISMA guidelines. A systematic search in PubMed, The Cochrane Library, JDreamIII, and ICHUSHI Web identified prospective cohort studies on Japanese people published till July 2020. The meta-analysis used a random-effects model, and heterogeneity and publication bias were evaluated with I² statistic and Egger’s test, respectively. Based on inclusion criteria, we extracted 58 articles, including 9 on the Japanese-style diet (n = 469,190) and 49 (n = 2,668,238) on characteristic Japanese foods. With higher adherence to the Japanese-style diet, the pooled risk ratios (RRs) for CVD, stroke, heart disease/ischemic heart disease combined (HD/IHD) mortality were 0.83 (95% CI, 0.77–0.89, I² = 58%, Egger’s test: p = 0.625, n = 9 studies), 0.80 (95% CI, 0.69–0.93, I² = 66%, Egger’s test: p = 0.602, n = 6 studies), and 0.81 (95% CI, 0.75–0.88, I² = 0%, Egger’s test: p = 0.544, n = 6 studies), respectively. Increased consumption of vegetables, fruits, fish, green tea, and milk and dairy products decreased the RR for CVD, stroke, or HD mortality. Increased salt consumption elevated the RR for CVD and stroke mortality. Increased consumption of dietary fiber and plant-derived protein decreased the RR for CVD, stroke, and HD/IHD mortality. The Japanese-style diet and characteristic Japanese foods may reduce CVD mortality. Most studies conducted diet surveys between 1980 and the 1990s. This meta-analysis used articles that evaluated the same cohort study by a different method. A new large-scale cohort study matching the current Japanese dietary habits is needed to confirm these findings.

Intake of Soy, Soy Isoflavones and Soy Protein and Risk of Cancer Incidence and Mortality

Background and Aims

Associations between soy intake and risk of cancer have been evaluated in prospective observational studies with inconsistent results. Whether the potential anticancer effects offered by soy were attributed to soy isoflavones and soy protein still needs to be elucidated. This study aimed to comprehensively quantify the association of soy, soy isoflavones and soy protein intake with risk of cancer incidence and cancer mortality by conducting a meta-analysis of all available studies.

Methods

PubMed, Embase, Web of Science, and Cochrane Library databases were searched up to 16 September 2021. Prospective cohort studies that examined the effect of soy, soy isoflavones and soy protein on cancer incidence and cancer mortality were identified. Random-effects models were used to pool the multivariable-adjusted relative risks (RRs) and corresponding 95% confidence intervals (CIs). The potential dose-response relations were explored by using generalized least-squares trend estimation.

Results

Eighty one prospective cohort studies were included in the meta-analysis. A higher intake of soy was significantly associated with a 10% reduced risk of cancer incidence (RR, 0.90; 95% CI, 0.83–0.96). Each additional 25 g/d soy intake decreased the risk of cancer incidence by 4%. Intake of soy isoflavones was inversely associated with risk of cancer incidence (RR, 0.94; 95% CI, 0.89–0.99), whereas no significant association was observed for soy protein. The risk of cancer incidence was reduced by 4% with each 10 mg/d increment of soy isoflavones intake. Similar inverse associations were also found for soy in relation to site-specific cancers, particularly lung cancer (RR, 0.67; 95%CI, 0.52–0.86) and prostate cancer (RR, 0.88; 95%CI, 0.78–0.99). However, high intake of soy, soy isoflavones and soy protein were not associated with cancer mortality.

Conclusions

Higher intake of soy and soy isoflavones were inversely associated with risk of cancer incidence, which suggested that the beneficial role of soy against cancer might be primarily attributed to soy isoflavones. These findings support recommendations to include soy as part of a healthy dietary pattern for the prevention of cancer.

Association of soy food with cardiovascular outcomes and all-cause mortality in a Chinese population: a nationwide prospective cohort study

PURPOSE

This study aimed to clarify the association of soy intake with cardiovascular disease (CVD) and all-cause mortality.

METHODS

We conducted a prospective cohort study in a Chinese population composed of 97,930 participants aged ≥ 40 years old without CVD at baseline in 2011. Habitual soy intake over a period of 12 months was evaluated using a food frequency questionnaire. All participants were classified into four groups based on their soy food consumption levels: < 15, 15-29, 30-59, and ≥ 60 g/day, with the lowest category as the reference group. Follow-up was conducted between 2014 and 2016 to assess CVD incidence and all-cause mortality since baseline, which was collected from the local mortality and disease registers of the National Disease Surveillance Point System and National Health Insurance System. The Cox proportional hazards regression models were used to analyze the relationship of soy intake with later CVD events and all-cause mortality.

RESULTS

During 350,604 person-years of follow-up (median [interquartile range]: 3.16 [2.98, 4.77] years), 2523 total CVD events and 1473 all-cause mortalities were documented. After controlling for covariates, the hazard ratios (95% confidence intervals) for total CVD events across increasing soy intake levels were 1.03 (0.93-1.14); 0.96 (0.86-1.07); and 0.86 (0.75-0.98; p for trend = 0.0434), while those for all-cause mortality were 0.88 (0.77-1.02); 0.86 (0.74-1.00); and 0.83 (0.69-0.99; p for trend = 0.0084).

CONCLUSION

High soy intake was associated with a reduced risk of total CVD events and all-cause mortality among a Chinese population.

Intake of isoflavones reduces the risk of all-cause mortality in middle-aged Japanese

BACKGROUND/OBJECTIVES

To clarify the effects of intake of legumes and isoflavones on all-cause mortality in middle-aged and older Japanese.

SUBJECT/METHODS

The subjects were 2136 randomly chosen community-dwelling Japanese men and women aged 40-79 years who participated in a first-wave survey (1997-2000; baseline). The subjects were followed from baseline to December 31, 2017 (mean period of 16.6 ± 4.2 years). Intake of legumes, soybeans, and isoflavones at baseline was assessed using a 3-day dietary record with photographs. The relationships of intake amounts of legumes and isoflavones to mortality were assessed using Cox proportional hazards regression controlling for age, sex, education, employment, body mass index, smoking habits, medical histories, drinking, and energy intake.

RESULTS

There were 491 deaths during the follow-up period. We found inverse associations of the intake of total soy products and intake of each of the isoflavones with all-cause mortality (p for trend < 0.05) in subjects aged < 60 years: the multivariate-adjusted hazard ratios (95% confidence intervals) for all-cause mortality in the highest intake group (third tertile) of total soy products and total isoflavones were 0.32 (0.13-0.78) and 0.35 (0.17-0.73), respectively, compared with the reference group (first tertile). In contrast, there were no significant associations of intake amounts of legumes, soybeans, and isoflavones with all-cause mortality in subjects aged 60 years or older.

CONCLUSIONS

The findings suggest that a higher intake of isoflavones might decrease the risk of all-cause mortality, especially in middle-aged Japanese.

The association between soy-based food and soy isoflavone intake and the risk of gastric cancer: a systematic review and meta-analysis

Soy contains many bioactive phytochemicals, such as isoflavones, which have the effect of preventing many cancers. Some studies have shown the beneficial effect of soy-based food and isoflavone intake on gastric cancer (GC), while others claimed no effect. Therefore, whether the beneficial effect of soy-based food is related to its fermentation or whether its protective effect comes from isoflavones still remains inconclusive. Our aim was to investigate the relationship between total soybean, fermented soybean, non-fermented soybean and isoflavone intake, and the risk of GC. Ten cohort studies and 21 case-control studies involving 916 354 participants were included. The association between soy-based food and isoflavone intake and the risk of GC was calculated with the pooled relative risks (RRs) for the highest versus lowest intake categories. The results showed that isoflavone intake might be a protective factor to GC, but the result was not statistically significant (RR = 0.92; 95% CI: 0.79-1.07). However, total soybean intake could significantly decrease the risk of GC by 36% (RR = 0.64; 95% CI: 0.51-0.80), which might be credited to non-fermented soybean products (RR = 0.79; 95% CI: 0.71-0.87). In contrast, high intake of fermented soybean products could increase the risk of GC (RR = 1.19; 95% CI: 1.02-1.38). High intake of total soybean and non-fermented soybean products could reduce the risk of GC, and high intake of fermented soybean products could increase the risk, which indicated that the beneficial effect of soy-based food might be related to its non-fermentation. However, high intake of isoflavones may not be associated with the incidence of GC. © 2021 Society of Chemical Industry.

A Non-Probiotic Fermented Soy Product Reduces Total and LDL Cholesterol: A Randomized Controlled Crossover Trial

Traditional Asian fermented soy food products are associated with reduced cardiovascular disease risk in prospective studies, but few randomized controlled trials have been conducted in at-risk populations. The aim of this study was to investigate the effect of a commercial non-probiotic fermented soy product on blood lipids in adults with cardiovascular risk biomarkers. In a randomized, crossover, intervention study, 27 men and women (aged 29–75 y) exhibiting at least two risk factors, consumed two packets (12.5 g each) daily of a fermented powdered soy product, or an isoenergic control powder made from germinated brown rice for 12 weeks each. The consumption of the fermented soy product resulted in a significantly greater mean change from baseline (compared to the germinated rice, all p < 0.05) in total cholesterol of −0.23 mmol/L (CI: −0.40, −0.06) compared with 0.14 mmol/L (CI: −0.03, 0.31), respectively; and low density lipoprotein (LDL) cholesterol −0.18 mmol/L (CI: −0.32, −0.04) compared with 0.04 mmol/L (CI: −0.01, 0.018) respectively. This was accompanied by an increase in high density lipoprotein (HDL) cholesterol in the germinated rice group, a decrease in apolipoprotein B (ApoB) in the fermented soy group, and a between-treatment effect in apolipoprotein A1 (ApoA1); however, the ratio of the LDL:HDL and of Apo B:ApoA1 did not differ between the groups. The ratio of total cholesterol:LDL decreased in men in the fermented soy group (p < 0.001). Twenty-four-hour urine collection at the end of each treatment period resulted in an increased excretion expressed as a ratio in μmol/d between treatments of 10.93 (CI: 5.07, 23.54) for daidzein; 1.24 (CI: 1.14, 4.43) for genistein; and, 8.48 (CI: 4.28, 16.80) for glycitein, all p < 0.05. The fermented soy powder consumed by participants in this study without implementing other changes in their typical diets, decreased the total and LDL cholesterol, and may serve as a dietary strategy to manage blood lipids. The trial was registered at ClinicalTrials.gov as NCT03429920.

What is the scientific definition of the Japanese diet from the viewpoint of nutrition and health?

The Japanese people have enjoyed longevity for several decades, and Japanese dietary habits are considered to contribute to this longevity. The scientific definition of the Japanese diet, however, is not yet fully established. The Working Group 1 of the Healthy Diet Research Committee of the International Life Sciences Institute Japan reviewed the literature to collect definitions of the Japanese diet appearing in articles in the fields of diet, nutrition, foods, and human health. This report addresses the definitions and the questions raised by these definitions. Among 283 relevant articles identified, 116 were carefully screened and included in the analysis. In most of the articles, the authors self-defined the Japanese diet; some studies used a government-proposed definition. This review revealed no systematic approach to define the Japanese diet from the viewpoints of nutrition and health. Before conducting studies to determine whether the Japanese diet is healthy, it is important to address the question of what the Japanese diet is from the viewpoint of human nutrition rather than culinary culture.

Soy intake and chronic disease risk: findings from prospective cohort studies in Japan

There has been much interest in the potential role of soy in reducing the risk of chronic diseases. Soy foods are uniquely rich in isoflavones, a fact that has triggered much research including intervention studies. However, there have been few long-term prospective observational studies that include disease itself as an outcome. High intake of soy foods is intrinsic to the Japanese diet, which can be advantageous for conducting such studies in Japan. The present report reviews the findings from Japanese prospective cohort studies on soy intake and the risk of cardiovascular diseases, cancer, type 2 diabetes, osteoporosis, menopausal symptoms, and dementia. The results suggest a beneficial role of soy in several chronic diseases, but they are not without controversy. Discrepancies have been observed in the findings of studies of Japanese or other Asians as compared to those of non Asians. This review discusses the issues to be explored in future studies.

A Greater Flavonoid Intake Is Associated with Lower Total and Cause-Specific Mortality: A Meta-Analysis of Cohort Studies

Introduction: The links between flavonoid intake and mortality were previously evaluated in epidemiological studies. The aim of the present study was to perform a systematic review and meta-analysis of cohort studies evaluating the link of flavonoid consumption with total and cause-specific mortality. Methods: Prospective cohort studies reporting flavonoid intake and mortality data published up to 30th April 2019 (without language restriction) were searched using PubMed, Scopus and EMBASE database. Generic inverse variance methods and random effects models were used to synthesize pooled and quantitative data. Sensitivity analysis was also performed by a leave-one-out method. Results: Overall, 16 articles met the inclusion criteria (nine studies were performed in Europe, five in the USA, one in Asia and one in Oceania); a total of 462,194 participants (all adults aged >19 years) with 23,473 mortality cases were included in the final analysis. The duration of follow-up ranged from 4.8 to 28 years. Most of the studies assessed flavonoid intake using food frequency questionnaires, whereas four studies used interviews and 1 study used 4-day food records. The meta-analysis showed that flavonoid consumption was inversely and significantly associated with total (relative risk (RR): 0.87, 95% confidence interval (CI) = 0.77–0.99) and cardiovascular disease mortality risk (RR: 0.85, 95%CI = 0.75–0.97), but not cancer (0.86, 95%CI = 0.65–1.14) mortality risk. These findings remained robust in sensitivity analyses. Conclusions: The present findings highlight the potential protective role of flavonoids against total and cause-specific mortality. These results support the recommendations for flavonoid-rich foods intake to prevent chronic diseases.

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.

Soy, Soy Isoflavones, and Protein Intake in Relation to Mortality from All Causes, Cancers, and Cardiovascular Diseases: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies

OBJECTIVE

We conducted a systematic review and dose-response meta-analysis of prospective studies to summarize findings on the associations between intakes of soy, soy isoflavones, and soy protein and risk of mortality from all causes, cancers, and cardiovascular diseases.

METHODS

Online databases were systematically searched to identify relevant articles published earlier than May 2018. We applied restricted cubic splines using random-effects analysis to assess dose-response associations. Between-study heterogeneity was assessed by I2 value and Cochrane Q test. Potential publication bias was assessed by visual inspection of funnel plots and Begg regression test.

RESULTS

In total, 23 prospective studies with an overall sample size of 330,826 participants were included in the current systematic review and the meta-analysis. Soy/soy products consumption was inversely associated with deaths from cancers (pooled relative risk 0.88, 95% CI 0.79 to 0.99; P=0.03; I2=47.1%, 95% CI 0.0% to 75.4%) and cardiovascular diseases (pooled effect size: 0.85, 95% CI 0.72 to 0.99; P=0.04; I2=50.0%, 95% CI 0.0% to 77.6%). Such significant associations were also observed for all-cause mortality in some subgroups of the included studies, particularly those with higher quality. In addition, higher intake of soy was associated with decreased risk of mortality from gastric, colorectal, and lung cancers as well as ischemic cardiovascular diseases. Participants in the highest category of dietary soy isoflavones intake had a 10% lower risk of all-cause mortality compared with those in the lowest category. We also found that a 10-mg/day increase in intake of soy isoflavones was associated with 7% and 9% decreased risk of mortality from all cancers and also breast cancer respectively. Furthermore, a 12% reduction in breast cancer death was indicated for each 5-g/day increase in consumption of soy protein. However, intake of soy protein was not significantly associated with all-cause and cardiovascular diseases mortality.

CONCLUSIONS

Soy and its isoflavones may favorably influence risk of mortality. In addition, soy protein intake was associated with a decreased risk in the mortality of breast cancer. Our findings may support the current recommendations to increase intake of soy for greater longevity.

Soy product consumption and the risk of all-cause, cardiovascular and cancer mortality: a systematic review and meta-analysis of cohort studies

Currently, the association of soy intake with total- and cause-specific mortality is inconsistent. The aim of this study was to systematically review cohort studies on the association between the consumption of soy products and mortality from all-causes, cardiovascular disease (CVD), and cancer. We conducted a systematic search of the PubMed/Medline, ISI Web of Knowledge and Embase electronic databases up to October 2016. Prospective cohort studies that examined the association of soy products with the risk of all-cause, CVD and cancer mortality using the relative risk (RR) or Hazard Ratio (HR) with 95% CIs were considered. Random-effect models were used to pool the study results and heterogeneity was examined using the I2 index and Q test. Finally, 7 studies were included for the meta-analysis; three studies reported the risk of all-cause mortality. Four studies assessed the risk of mortality from CVD and cancer. In total, 39 250 deaths were reported among 627 209 participants in a 7 to 18-year follow-up. A high consumption of soy products was not significantly associated with a lower risk of mortality from all-causes (HR: 0.96, 95% CI: 0.90, 1.02, I2: 38.5%, and Pheterogeneity = 0.14), CVD (HR: 0.95, 95% CI: 0.82, 1.10, I2: 49.9%, and Pheterogeneity = 0.07), and cancer (HR: 0.98, 95% CI: 0.92, 1.05, I2: 0%, and Pheterogeneity = 0.75). These findings indicated no significant association between a high intake of soy products and all-cause, CVD, and cancer mortality. Further studies are needed to clarify the association between the types of soy products and the risk of mortality.

Dietary Flavonoid and Lignan Intake and Mortality in Prospective Cohort Studies: Systematic Review and Dose-Response Meta-Analysis

Recent evidence has suggested that flavonoid and lignan intake may be associated with decreased risk of chronic and degenerative diseases. The aim of this meta-analysis was to assess the association between dietary flavonoid and lignan intake and all-cause and cardiovascular disease (CVD) mortality in prospective cohort studies. A systematic search was conducted in electronic databases to identify studies published from January 1996 to December 2015 that satisfied inclusion/exclusion criteria. Risk ratios and 95% confidence intervals were extracted and analyzed using a random-effects model. Nonlinear dose-response analysis was modeled by using restricted cubic splines. The inclusion criteria were met by 22 prospective studies exploring various flavonoid and lignan classes. Compared with lower intake, high consumption of total flavonoids was associated with decreased risk of all-cause mortality (risk ratio = 0.74, 95% confidence intervals: 0.55, 0.99), while a 100-mg/day increment in intake led to a (linear) decreased risk of 6% and 4% of all-cause and CVD mortality, respectively. Among flavonoid classes, significant results were obtained for intakes of flavonols, flavones, flavanones, anthocyanidins, and proanthocyanidins. Only limited evidence was available on flavonoid classes and lignans and all-cause mortality. Findings from this meta-analysis indicated that dietary flavonoids are associated with decreased risk of all-cause and CVD mortality.

Food groups and risk of all-cause mortality: a systematic review and meta-analysis of prospective studies

Background: Suboptimal diet is one of the most important factors in preventing early death and disability worldwide.Objective: The aim of this meta-analysis was to synthesize the knowledge about the relation between intake of 12 major food groups, including whole grains, refined grains, vegetables, fruits, nuts, legumes, eggs, dairy, fish, red meat, processed meat, and sugar-sweetened beverages, with risk of all-cause mortality.Design: We conducted a systematic search in PubMed, Embase, and Google Scholar for prospective studies investigating the association between these 12 food groups and risk of all-cause mortality. Summary RRs and 95% CIs were estimated with the use of a random effects model for high-intake compared with low-intake categories, as well as for linear and nonlinear relations. Moreover, the risk reduction potential of foods was calculated by multiplying the RR by optimal intake values (serving category with the strongest association) for risk-reducing foods or risk-increasing foods, respectively.Results: With increasing intake (for each daily serving) of whole grains (RR: 0.92; 95% CI: 0.89, 0.95), vegetables (RR: 0.96; 95% CI: 0.95, 0.98), fruits (RR: 0.94; 95% CI: 0.92, 0.97), nuts (RR: 0.76; 95% CI: 0.69, 0.84), and fish (RR: 0.93; 95% CI: 0.88, 0.98), the risk of all-cause mortality decreased; higher intake of red meat (RR: 1.10; 95% CI: 1.04, 1.18) and processed meat (RR: 1.23; 95% CI: 1.12, 1.36) was associated with an increased risk of all-cause mortality in a linear dose-response meta-analysis. A clear indication of nonlinearity was seen for the relations between vegetables, fruits, nuts, and dairy and all-cause mortality. Optimal consumption of risk-decreasing foods results in a 56% reduction of all-cause mortality, whereas consumption of risk-increasing foods is associated with a 2-fold increased risk of all-cause mortality.Conclusion: Selecting specific optimal intakes of the investigated food groups can lead to a considerable change in the risk of premature death.

Oral isoflavone supplementation on endometrial thickness: a meta-analysis of randomized placebo-controlled trials

Background

Isoflavone from soy and other plants modulate hormonal effects in women, and the hormone disorder might result in different caners including endometrial cancer. However, it's effect on the risk of endometrial cancer is still inconclusive. We aimed to assess the effects of isoflavone on endometrial thickness, a risk factor of endometrial cancer in peri- and post-menopausal women.

Methods

A meta-analysis of randomized controlled trials was conducted to evaluate the effect of oral isoflavone supplementation on endometrial thickness in peri- and post-menopausal women. Electronic searches were performed on the PubMed, Embase, the Cochrane Library, web of science, CINAHL, and WHO ICTRP to August 1^st, 2015. Reviews and reference lists of relevant articles were also searched to identify more studies. Summary estimates of standard mean differences (SMD's) and 95%CIs were obtained with random-effects models. Heterogeneity was evaluated with meta-regression and stratified analyses.

Results

A total of 23 trials were included in the current analysis. The overall results did not show significant change of endometrial thickness after oral isoflavone supplementation (23 studies, 2167subjects; SMD:-0.05; 95%CI:-0.23, 0.13; P=0.60). Stratified analysis suggested that a daily dose of more than 54mg could decrease the endometrial thickness for 0.26mm (10 trials, 984subjects; SMD:-0.26; 95%CI:-0.45, −0.07; P=0.007). Furthermore, isoflavone supplementation significantly decrease the endometrial thickness for 0.23mm in North American studies (7 trials, 726 subjects; SMD:-0.23; 95%CI:-0.44, −0.01; P=0.04), but it suggested an increase for 0.23mm in Asian studies (3 trials, 224 subjects; SMD: 0.23; 95%CI:-0.04, 0.50; P=0.10).

Conclusion

Oral isoflavone supplementation might have different effects in different populations and at different daily doses. Multiple-centre, larger, and long-term trials are deserved to further evaluate its effect.

Dietary soy and natto intake and cardiovascular disease mortality in Japanese adults: the Takayama study

BACKGROUND

Whether soy intake is associated with a decreased risk of cardiovascular disease (CVD) remains unclear. A traditional Japanese soy food, natto, contains a potent fibrinolytic enzyme. However, its relation to CVD has not been studied.

OBJECTIVE

We aimed to examine the association of CVD mortality with the intake of natto, soy protein, and soy isoflavones in a population-based cohort study in Japan.

DESIGN

The study included 13,355 male and 15,724 female Takayama Study participants aged ≥35 y. At recruitment in 1992, each subject was administered a validated semiquantitative food-frequency questionnaire. Deaths from CVD were ascertained over 16 y.

RESULTS

A total of 1678 deaths from CVD including 677 stroke and 308 ischemic heart disease occurred during follow-up. The highest quartile of natto intake compared with the lowest intake was significantly associated with a decreased risk of mortality from total CVD after control for covariates: the HR was 0.75 (95% CI: 0.64, 0.88, P-trend = 0.0004). There were no significant associations between the risk of mortality from total CVD and intakes of total soy protein, total soy isoflavone, and soy protein or soy isoflavone from soy foods other than natto. The highest quartiles of total soy protein and natto intakes were significantly associated with a decreased risk of mortality from total stroke (HR = 0.75, 95% CI: 0.57, 0.99, P-trend = 0.03 and HR = 0.68, 95% CI: 0.52, 0.88, P-trend = 0.0004, respectively). The highest quartile of natto intake was also significantly associated with a decreased risk of mortality from ischemic stroke (HR = 0.67, 95% CI:0.47, 0.95, P-trend = 0.03).

CONCLUSION

Data suggest that natto intake may contribute to the reduction of CVD mortality.