Soy Food Intake Research Articles

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.

Midlife intake of the isoflavone genistein and soy, and the risk of late-life cognitive impairment: the JPHC Saku Mental Health Study.

The number of people with cognitive impairment, including dementia, in the world is steadily increasing. Although the consumption of isoflavones and soy is associated with a reduced risk of cardiovascular disease, it might also be associated with cognitive impairment. The low number of studies investigating the association between soy/isoflavone intake and cognitive function warrant additional research. The Japan Public Health Center-based prospective (JPHC) Study is a large population-based cohort. Midlife dietary intake of soy and the isoflavone genistein was assessed on two occasions: in the years 1995 and 2000. In 2014-2015, 1299 participants from Nagano prefecture completed a mental health screening. Of these, a total of 1036 participants were included in analyses. Logistic regression was used to determine Odds Ratios (OR) and 95% Confidence Intervals (CI) for the association between midlife energy-adjusted genistein and soy food intake and cognitive impairment. There were 392 cases of cognitive impairment (346 cases of MCI and 46 cases of dementia). Compared to the lowest dietary quartile of energy-adjusted genistein intake, the highest quartile was significantly associated with cognitive impairment (OR=1.51; 95% CI, 1.02-2.24; p for trend=0.03) in the final multivariable analysis. High midlife intake of the isoflavone genistein is associated with late-life cognitive impairment.

Relationships of beans intake with chronic kidney disease in rural adults: A large-scale cross-sectional study.

Dietary factors play an important role in the development of chronic kidney disease (CKD). However, evidence on the relationship of beans consumption with CKD remains limited and inconclusive, especially in the middle-and low-income populations. The current study aimed to investigate the relationships of beans intake with indicators of kidney injury and CKD prevalence in rural adults. A total of 20,733 rural adults from the Henan Rural Cohort Study in 2018-2022 were included. The total beans intake was collected using a validated food frequency questionnaire. Indicators of kidney injury and CKD was determined by the estimated glomerular filtration rate and the urinary albumin to creatinine ratio. Generalized linear regression and logistic regression models were applied to estimate the relationship of beans intake with continuous and dichotomized indicators of renal function, respectively. Of the 20,733 participants, 2,676 (12.91%) subjects were identified as CKD patients. After adjusting for potential confounders, participants in the higher quartiles of beans intake had a lower prevalence of CKD (odds ratio and 95% confidence interval, OR (95%CI); Q2: 0.968(0.866-1.082); Q3: 0.836(0.744-0.939); Q4: 0.854(0.751-0.970)) and albuminuria (Q2: 0.982(0.875-1.102); Q3: 0.846(0.750-0.954); Q4: 0.852 (0.746-0.973)), compared with the Q1. Per 50 g/day increment in beans intake was significantly associated with a 5 and 4% decreased prevalence of albuminuria and CKD, respectively. These inverse relationships were also significant in the subgroups of men, elder, and high-income participants (p < 0.05). Dietary beans intake was inversely associated with the prevalence of albuminuria and CKD in rural adults, suggesting that promoting soy food intake might help reduce the occurrence of CKD in rural adults.

Calcium Intake and Lung Cancer Risk: A Pooled Analysis of 12 Prospective Cohort Studies

BackgroundPrevious studies on calcium intake and lung cancer risk reported inconsistent associations, possibly due to the differences in intake amounts and contributing sources of calcium and smoking prevalence. ObjectivesWe investigated the associations of lung cancer risk with intake of calcium from foods and/or supplements and major calcium-rich foods in 12 studies. MethodsData from 12 prospective cohort studies conducted in the United States, Europe, and Asia were pooled and harmonized. We applied the DRI to categorize calcium intake based on the recommendations and quintile distribution to categorize calcium-rich food intake. We ran multivariable Cox regression by each cohort and pooled risk estimates to compute overall HR (95% CI). ResultsAmong 1,624,244 adult men and women, 21,513 incident lung cancer cases were ascertained during a mean follow-up of 9.9 y. Overall, the dietary calcium intake was not significantly associated with lung cancer risk; the HRs (95% CI) were 1.08 (0.98–1.18) for higher (>1.5 RDA) and 1.01 (0.95–1.07) for lower intake (<0.5 RDA) comparing with recommended intake (EAR to RDA). Milk and soy food intake were positively or inversely associated with lung cancer risk [HR (95% CI) = 1.07 (1.02–1.12) and 0.92 (0.84–1.00)], respectively. The positive association with milk intake was significant only in European and North American studies (P-interaction for region = 0.04). No significant association was observed for calcium supplements. ConclusionsIn this largest prospective investigation, overall, calcium intake was not associated with risk of lung cancer, but milk intake was associated with a higher risk. Our findings underscore the importance of considering food sources of calcium in studies of calcium intake.

Intake of soy products and soy isoflavones in relation to ovarian reserve

To investigate the association between intake of soy food and isoflavone with ovarian reserve. Previous studies suggest on the relationship between soy intake and human fertility are inconsistent. Some clinical studies suggest that soy and phytoestrogens may not be deleterious to reproduction and may even be beneficial in couples undergoing infertility treatment. However, no studies have evaluated the relationship between soy or isoflavone intake with markers of ovarian reserve other than follicle-stimulating hormone (FSH). Cross-sectional study. An academic fertility center. Patients presenting to an academic fertility center between 2007 and 2019 were invited to participate in the Environment and Reproductive Health Study. Six hundred and sixty seven participants reported their soy food intake and had an antral follicle count (AFC) assessment. Intake of 15 soy-based foods during the previous 3 months was obtained at baseline and intake of isoflavone was estimated. Participants were divided into 5 groups based on soy food and isoflavone intake considering those who did not consume soy as the reference group. Ovarian reserve was assessed using AFC as the primary outcome measure, with antimüllerian hormone (AMH) and FSH as secondary outcome measures. The AFC was measured on the third day of the menstrual cycle. Moreover, FSH and AMH levels were measured in blood samples obtained on the third day and the follicular phase of the menstrual cycle. To evaluate the association between soy intake and ovarian reserve, we used Poisson regression models for AFC and quantile regression models for AMH and day 3 FSH levels by adjusting for confounders. Participants had a median age of 35.0 years. The median intake of soy was 0.09 servings/day and isoflavones was 1.78 mg/day. Moreover, AFC, AMH, and FSH were unrelated to soy intake in crude analyses. We found no association between soy food intake with AFC or day 3 FSH level in multivariable models. However, participants in the highest category of soy food intake had significantly low AMH levels (-1.16, 95% confidence interval: -1.92, -0.41). Soy intake had no association with AFC, AMH, or FSH in sensitivity analyses that included using different cutoff points of soy intake, excluding participants in the highest 2.5 percentile of intake, and additional statistical adjustment for dietary patterns. The results of this study are not consistent with a strong positive or inverse association of soy or isoflavone intakes within the observed range of intake, which substantially overlaps with that in the general population of the United States as well as the ovarian reserve among individuals presenting to fertility centers.

Isoflavone and soy food intake and risk of lung cancer in never smokers: report from prospective studies in Japan and China.

Evidence from several cohorts has suggested that a higher intake of isoflavone is associated with lower risk of lung cancer in never smokers, but the association has not been investigated by histologic type of lung cancer. Adenocarcinoma is a common histologic type found in never smokers. We hypothesized that a higher intake of isoflavone is associated with a lower risk of lung adenocarcinoma among never smokers. Here, we examined the associations of isoflavone and soy food intake with lung cancer and its histologic types in never smokers. We performed a pooled analysis using data from the Japan Public Health Center-based Prospective Study, Shanghai Women's Health Study and Shanghai Men's Study with 147,296 never smokers aged 40-74years with no history of cancer. During 1,990,040 person-years of follow-up, 1247 lung cancer cases were documented. Dietary isoflavone and soy food intake were assessed using a food-frequency questionnaire. Multivariable Cox proportional hazards models assessed the associations between isoflavone and soy intake with incidence of lung cancer by histologic type. A higher intake of dietary isoflavone and soy food were associated with reduced risk of lung adenocarcinoma. The multivariable hazard ratios (HRs) (95% CI) of risk of lung adenocarcinoma for the highest versus lowest intakes of isoflavone and soy food were 0.74 (0.60-0.92) and 0.78 (0.63-0.96), respectively. The multivariable HRs of risk of lung adenocarcinoma associated with each 10mg/day increase in isoflavone and each 50g/day increase in soy food intake were 0.81 (0.70-0.94) and 0.84 (0.73-0.96), respectively. Higher intake of isoflavone and soy food was associated with lower risk of lung adenocarcinoma in never smokers.

P-647 Intake of soy foods and soy isoflavones in relation to ovarian reserve among women presenting to a fertility center

Abstract Study question Are soy food and isoflavone intakes associated with ovarian reserve as measured by antral follicle count (AFC)? Summary answer Within the observed range of intake, soy food or isoflavone consumptions are not associated with AFC. What is known already Phytoestrogens are structurally similar to 17β-estradiol, and bind to ER-α and ER-β in vitro resulting in weak estrogenic activity. Previous work in ruminants, felines and rodents has shown that exposure to phytoestrogens can have major adverse impacts on reproduction. However, findings of studies in humans suggest that soy foods and soy phytoestrogens may not have major deleterious impacts on reproductive hormone levels or reproductive outcomes, and could even be beneficial in couples undergoing infertility treatment. Study design, size, duration Women presenting to a large academic fertility center between April 2007 and December 2019 were invited to participate in the Environment and Reproductive Health (EARTH) Study, a prospective cohort study. Intake of 15 soy-based foods during the previous three months was obtained at baseline and intake of soy phytoestrogens was estimated from these reports. AFC was assessed with transvaginal ultrasound performed as part of diagnostic evaluation for infertility. Participants/materials, setting, methods We included 667 women who reported their soy food intake and had an AFC assessment. Women were divided in groups of increasing soy food and soy isoflavone intake with women who reported not consuming soy-based foods serving as the reference group. We evaluated the association of soy foods and soy isoflavones intake with AFC using Poisson regression models adjusting for confounders. Analyses were also stratified by age, BMI, and smoking status. Main results and the role of chance Women had median baseline age of 35.0 years and BMI of 23.4 kg/m2. Mean (range) intake of soy foods was 0.1 (0-7.4) servings/day, and mean (range) intake of isoflavones was 6 (0-166) mg/day, which is comparable to that of women in the general population of the USA. Intakes of soy foods or isoflavones were not related to AFC. The median (IQR) AFC for women who did not consume soy foods and women in the highest category of soy intake (&amp;gt;0.45 servings/day, median 0.88 servings/day) were 12 (9, 18) and 13 (9, 19). After adjustment for potential confounders, the mean difference in AFC between women in the highest category of soy intake and women who did not consume soy was -0.5% (-6.6%, 6.1%). Soy food intake remained unrelated to AFC when intake was categorized using different cutoff values when intake was modeled as a continuous variable when departures from a linear association were considered, and when we excluded from analysis 76 women whose AFC ultrasound scan was performed before they completed the diet assessment. Soy intake was also unrelated to AFC within categories of age, BMI and smoking status. Findings for soy isoflavones mirrored those for soy-food intake. Limitations, reasons for caution Self-reported soy intake may have resulted in measurement error leading to attenuation of observed relations towards the null. Also, all participants were women presenting to a fertility center and therefore, findings may not be generalizable to women in the general population. Wider implications of the findings Our findings suggest soy food and isoflavone intakes within the ranges observed among women in the general population of the USA is unlikely to influence ovarian reserve in any meaningful way. Trial registration number Not applicable

Soy foods and nuts consumption during early pregnancy are associated with decreased risk of gestational diabetes mellitus: a prospective cohort study

Aims To study the relationship of soy foods and nuts consumption during early pregnancy with the risk of gestational diabetes mellitus (GDM). Methods This was a prospective observational study conducted in Southwest China. Dietary information was assessed through 3-day 24-h dietary recalls at 6–14 gestational weeks. For soy foods and nuts, non-consumers were used as the reference category and the consumers were categorized into tertiles. GDM was assessed with the 75-g, 2-h oral glucose tolerance test at 24–28 gestational weeks. Log-binomial models were used to assess the effects of soy foods and nuts on GDM. Results Of the 1495 pregnant women, 529 were diagnosed with GDM. Median (IQRs) intakes of soy foods and nuts were 2.9 (0.0, 10.3) and 5.0 (0.0, 15.0) g/d, respectively. Our study found that, compared with the non-consumers, the highest tertile of soy foods intake was associated with a decrease in risk of GDM (RR = 0.73, 95%CI: 0.54–0.99, p = .049). Similarly, compared with the non-consumers, a negative relationship between the highest tertile of nuts intake and GDM risk was identified (RR = 0.65, 95%CI: 0.48–0.89, p = .007). Conclusions Consumption of soy foods and nuts are independently inversely associated with the risk of GDM during early pregnancy.

Longer-term soy nut consumption improves vascular function and cardiometabolic risk markers in older adults: Results of a randomized, controlled cross-over trial

Soy foods may contribute to the beneficial health effects of healthy plant-based diets on the risk to develop cardiovascular disease (CVD). However, their effects on vascular function have hardly been studied. To investigate longer-term effects of soy nut consumption on vascular function and cardiometabolic risk markers in healthy older men and women. Twenty-three healthy participants (age: 60-70 years; BMI: 20-30kg/m2) participated in a randomized, controlled, single-blinded cross-over trial with an intervention (67g/day of soy nuts providing 25.5g protein and 174mg isoflavones) and control period (no nuts) of 16 weeks, separated by eight weeks wash-out. Adults followed the Dutch food-based dietary guidelines. No serious adverse events were reported and the soy nut regime was well tolerated. Body weights remained stable during the whole study. A higher protein (3.1 energy percent [En%]) and a lower carbohydrate intake (2.0 En%) was observed during the intervention period. Total fat intake was comparable, but that of saturated (-1.3 En%), cis-monounsaturated (-1.5 En%) and cis-polyunsaturated fatty acids (+1.9 En%) differed. Serum isoflavone concentrations were higher after the intervention as compared with the control period (daidzein: 127.8ng/mL; 95% CI: 74.3-181.3ng/mL; p<0.001 and genistein: 454.2ng/mL; 95% CI: 266.6-641.8ng/mL; p<0.001). Brachial artery flow-mediated vasodilation was 1.48 percent points (pp; 95% CI: 0.08-2.89 pp; p=0.040) higher following soy nut intake. The carotid artery reactivity response and arterial stiffness did not differ. Serum LDL-cholesterol was lower (0.17mmol/L; 95% CI: 0.02-0.32mmol/L; p=0.027), while HDL-cholesterol and triacylglycerol concentrations were comparable. Mean arterial pressure (MAP) was lower (3mmHg; 95% CI: 0-6mmHg; p=0.035). Longer-term soy nut intake as part of a healthy diet improved endothelial function, LDL-cholesterol concentrations and MAP levels, suggesting mechanisms by which an increased soy food intake beneficially affects CVD risk in older adults. Registered under ClinicalTrials.gov Identifier no. NCT03627637.

Soy Food Intake Associated with Obesity and Hypertension in Children and Adolescents in Guangzhou, Southern China.

The associations between soy food intake and cardio-metabolic risk factors in children remain unclear due to limited evidence. We aim to explore soy food intake and its association with the risks of obesity and hypertension in Chinese children and adolescents. A total of 10,536 children and adolescents aged 7–18 years (5125 boys and 5411 girls) were enrolled in a cross-sectional study in Guangzhou City, southern China. Data on demographic characteristics and dietary consumption were collected using self-reported questionnaires, and anthropometric characteristics were measured. Obesity, abdominal obesity, and hypertension were defined using Chinese criteria for children and adolescents. A multiple logistic regression model was applied to estimate the association between soy food intake and obesity and hypertension. Roughly 39.5% of the participants consumed soy food more than three times per week. The mean amounts of liquid and solid soy food intake were 0.35 ± 0.54 cups/day and 0.46 ± 0.63 servings/day, respectively. The adjusted odds ratios (OR) of hypertension among those with high liquid soy food intake and a high frequency of all soy food intake (more than three times/week) were 0.79 (95% confidence interval (CI), 0.67–0.94), and 0.83 (95% CI, 0.70–0.97) compared to those with no intake. Additionally, the adjusted OR of obesity among those with high solid soy food intake and a high frequency of all soy food intake were 1.34 (95% CI, 1.09–1.63) and 1.30 (95% CI, 1.07–1.58), respectively. In conclusion, 39.5% of southern Chinese children and adolescents had high soy food intake (more than three times/week), which was significantly associated with a lower prevalence of hypertension and a greater prevalence of obesity.

Soy Intake and Risk of Type 2 Diabetes Among Japanese Men and Women: JACC Study.

The evidence on the protective effects of soy foods against type 2 diabetes has been inconsistent. We thought to examine the association between the dietary intakes of soy and the risk of diabetes in a prospective study encompassing 21,925 healthy Japanese men and women aged 40–79 years. A validated self-administered food frequency questionnaire determined the intakes of soy, and their associations with risk of type 2 diabetes were evaluated by the logistic regression analysis. During the 5-year follow-up period, we observed 593 new cases of type 2 diabetes (302 in men and 291 in women). There was no association between dietary intakes of soy foods and the risk of type 2 diabetes among men. Whereas among women, higher tofu intake was inversely associated with risk of type 2 diabetes; the multivariable odds ratios (ORs) of type 2 diabetes were 0.92 (95% CI: 0.69–1.21) for 3–4 times per week and 0.67 (95% CI: 0.49–0.94) for almost daily (p-trend = 0.03) in reference to those consuming tofu less than 3 times per week. Intakes of boiled beans and miso soup were not associated with the risk in both genders. The inverse association tended to be more evident among overweight women and postmenopaused women. In conclusion, the frequency of tofu intake was inversely associated with the risk of type 2 diabetes among women.

Longer-Term Soy Nut Consumption Improves Vascular Function and Cardiometabolic Risk Markers in Older Adults: Results of a Randomized, Controlled Cross-Over Trial

Abstract Objectives Soy foods may contribute to the beneficial effects of plant-based diets on cardiovascular disease (CVD) risk. However, their effects on vascular function have hardly been investigated. The objective was to investigate if longer-term soy nut consumption improves vascular function and cardiometabolic health in older adults. Methods Twenty-three apparently healthy participants (60–70 years; BMI between 20–30 kg/m2) participated in a randomized, controlled, single-blinded cross-over trial with an intervention (67 g of soy nuts daily providing 25.5 g soy protein) and control period (no nuts) of 16 weeks, separated by eight weeks wash-out. Volunteers followed the Dutch food-based dietary guidelines. At baseline and at 8 and 16 weeks anthropometric measurements and fasting blood samples were collected. Markers of vascular function (i.e., endothelial function, arterial stiffness, and microvascular structure) were assessed at week 16. Results No serious adverse events were reported and the soy nut regime was well tolerated. Body weight remained stable. Serum isoflavone concentrations, a marker of compliance, increased after the intervention period (daidzein: 128.3 ng/mL; 95% CI: 72.6–183.9 ng/mL; P &amp;lt; 0.001 and genistein: 439.8 ng/mL 95% CI: 246.7–632.9 ng/mL; P &amp;lt; 0.001). The brachial artery flow-mediated vasodilation (FMD) response increased by 1.49 pp (95% CI: 0.03–2.95 pp; P = 0.046) following the soy intervention, but no effect was found on the carotid artery reactivity (CAR) response. Arterial stiffness, assessed by carotid-to-femoral pulse wave velocity (PWVc-f), was unchanged. Retinal arteriolar calibers (CRAE), a measure for microvascular structure, tended to improve by 1.42 mm (95% CI: −0.05–2.90 mm; P = 0.059). Soy consumption also lowered serum LDL-cholesterol concentrations by 0.17 mmol/L (95% CI: 0.02–0.32 mmol/L; P = 0.027). HDL-cholesterol and triacylglycerol (TAG) did not change. Finally, office SBP and DBP decreased by 4 mmHg (95% CI: 0–8 mmHg; P = 0.034) and 2 mmHg (95% CI: 1–4 mmHg; P = 0.005), respectively. Conclusions A longer-term daily intake of soy nuts improved endothelial function, office blood pressure, and serum LDL-cholesterol concentrations, suggesting mechanisms by which an increased soy food intake beneficially affects CVD risk in older adults. Funding Sources This study was supported by a grant from the Alpro Foundation.

Association between Soy Food and Dietary Soy Isoflavone Intake and the Risk of Cardiovascular Disease in Women: A Prospective Cohort Study in Korea.

The association between soy food and soy isoflavone intake and cardiovascular disease (CVD) risk is uncertain, especially in women. We aimed to investigate this association in Korean women. We analyzed data from the Korean Genome and Epidemiology Study, including 4713 Korean women aged 40–69 years with no CVD or cancer at baseline. Dietary information was obtained using a validated semi-quantitative food frequency questionnaire, and the incidence of CVD was assessed using biennial self-reported questionnaires on medical history. The mean follow-up time was 7.4 years, during which 82 premenopausal and 200 postmenopausal women reported CVD incidence. The highest tofu, total soy foods, and dietary soy isoflavone intake groups were significantly associated with a decreased CVD risk in premenopausal women (tofu: hazard ratio (HR) 0.39; 95% confidence interval (CI), 0.19–0.80; total soy food: HR 0.36; 95% CI, 0.18–0.70; dietary soy isoflavones: HR 0.44; 95% CI, 0.22–0.89), whereas no association was observed in postmenopausal women. Other soy foods showed no association with CVD incidence. Dietary soy isoflavones and total soy foods are associated with a decreased CVD risk in premenopausal women. Among soy foods, only tofu showed significant health benefits.

Pre-diagnosis and early post-diagnosis dietary soy isoflavone intake and survival outcomes: A prospective cohort study of early stage breast cancer survivors

BackgroundThere is concern that the estrogen-like effects of soy isoflavones may stimulate mammary tumor growth and interfere with the efficacy of breast cancer treatment. This study aimed to examine prospectively the associations of dietary soy isoflavone intake with all-cause mortality and breast cancer (BC) specific mortality and recurrence among BC survivors. DesignThe study included 1460 Chinese women with early-stage incident BC. Pre-diagnosis and early post-diagnosis soy food intakes were assessed at study entry, and at 18-month follow-up using validated soy food frequency questionnaire. Associations of soy isoflavone intake with prognostic outcomes within 48 months were examined using multivariable adjusted Cox proportional hazards models. ResultsWe observed increasing pre-diagnosis and early post-diagnosis soy isoflavone intakes up to the third quartile (Q3) were associated with reductions for adverse prognostic outcomes. Relative to the lowest quartile (Q1), the hazard ratios (HRs) for all-cause mortality for pre-diagnosis and post-diagnosis Q3 intake were respectively 0.34 (95% CI, 0.16–0.74), and 0.44 (95% CI, 0.22–0.89). A similar risk reduction was observed for pre- and post-diagnosis intakes and BC-specific mortality when comparing Q3 versus Q1 with the respective HRs 0.36 (95% CI, 0.16–0.82), and 0.49 (95% CI, 0.23–1.01). Subgroup analyses showed more favourable prognostic outcomes in association with moderate soy intake among premenopausal women, those with triple negative cancer and recipients of tamoxifen treatment. ConclusionModerate soy isoflavone intake was associated with favourable prognostic outcomes in Chinese early stage BC survivors.

Fermented and nonfermented soy foods and the risk of breast cancer in a Japanese population-based cohort study.

BackgroundAlthough preclinical studies suggest that fermented soy foods may have a protective effect against breast cancer, no prospective cohort studies have examined this association.ObjectiveOur study examined the association between fermented and nonfermented soy food intake and breast cancer risk using a population‐based prospective cohort study in Japan.MethodsWe included a total of 47,614 women aged 45–74 years in an analysis of the Japan Public Health Center‐based Prospective Study (JPHC Study). A validated food frequency questionnaire (FFQ) was used for the assessment of dietary intake. Breast cancer incidence was analyzed by multivariate Cox proportional hazards regression models.ResultsDuring an average of 15.5 years of follow‐up, 825 breast cancer cases were newly identified. We found no association of intake of soy foods with breast cancer risk, regardless of fermentation, with multivariate hazard ratios (HRs) and 95% confidence intervals (CIs) for the highest quartiles of fermented and nonfermented soy food intake of 0.94 (0.67, 1.32) and 1.15 (0.85, 1.57) compared with the lowest quartile (p for trend = 0.305 and 0.393). Unlike nonfermented soy, higher intake of fermented soy foods was associated with a significant decrease in the risk of nonlocalized breast cancer. The HR and 95% CI in the highest compared to lowest intake category of fermented soy foods was 0.53 (0.28, 0.99) versus nonfermented soy foods 0.85 (0.51, 1.42) (p for trend = 0.026 and 0.797).ConclusionsOur analyses showed that fermented soy foods had no association with overall breast cancer but may be associated with decreased risk of nonlocalized breast cancer.

Soy Food Intake Is Inversely Associated with Newly Diagnosed Nonalcoholic Fatty Liver Disease in the TCLSIH Cohort Study

Animal studies have shown that soy protein and isoflavones can increase antioxidant capacity and improve insulin resistance, and thus ameliorate nonalcoholic fatty liver disease (NAFLD). However, only limited epidemiological studies have examined the association of soy food intake with NAFLD. We investigated the association between soy food intake and NAFLD in a Chinese cohort. A total of 24,622 participants aged 20-90 y were included in the study. Diet information was collected using a validated 100-item FFQ. NAFLD was defined as having fatty liver diagnosed by ultrasonography and excluding men and women who consumed>210g alcohol/wk and>140g/wk, respectively. Logistic regression analysis was used to assess the association of soy food intake with NAFLD. After adjustment for potential confounders, and taking those with<1time/wk soy food intake as the reference group, the ORs for NAFLD across soy food intake frequency were 0.94 (95% CI: 0.83, 1.07) for 1 time/wk, 0.88 (95% CI: 0.78, 0.99) for 2-3 times/wk, and 0.75 (95% CI: 0.65, 0.87) for≥4 times/wk (P-trend<0.0001). The results were similar when participants were categorized by the energy-adjusted soy food intake (grams per 1000kilocalories) quartiles (OR=0.80; 95% CI: 0.71, 0.91; comparing extreme quartiles). Higher soy food intake was associated with a lower prevalence of NAFLD in Chinese adults. Further prospective studies and randomized clinical trials are necessary to confirm if soy food intake is inversely related to the risk of NAFLD.

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.

Soy Intake and Colorectal Cancer Risk: Results from a Pooled Analysis of Prospective Cohort Studies Conducted in China and Japan

Soy is commonly consumed in east Asian countries and is suggested to reduce colorectal cancer (CRC) risk. However, results from epidemiologic studies are inconsistent, despite the anti-inflammatory and antiproliferative properties of soy isoflavones and soy protein. We evaluated the association between soy isoflavones and soy protein and CRC risk using 4 prospective cohort studies from China and Japan. Data were pooled from the Shanghai Women's Health Study (SWHS), Shanghai Men's Health Study (SMHS), Japan Public Health Center-based Prospective Study Cohort 1 (JPHC1), and Cohort 2 (JPHC2). Cox proportional hazards models estimated HRs and corresponding 95% CIs for the association of soy protein and isoflavone intake with CRC risk. The study included 205,060 individuals, among whom 2971 were diagnosed with incident CRC over an average follow-up of 12.7 y. No statistically significant associations with CRC risk were observed for soy protein or isoflavone intake. No association was observed among ever smokers consuming higher isoflavones (HRisoflavones: 0.83; 95% CI: 0.68, 1.00) and soy protein (HRsoy protein: 0.81; 95% CI: 0.39, 1.10). However, risk reductions were observed among premenopausal women with a body mass index [BMI (kg/m2)] <23.0 at baseline for higher isoflavone (HRisoflavones: 0.58, 95% CI: 0.34, 0.98). No evidence for an overall reduction in CRC risk by increasing soy food intake (i.e., protein or isoflavones) was observed. However, the association between soy and CRC risk may vary by BMI, smoking, and menopausal status among women. Future investigations are needed to further understand the biologic mechanisms observed.

Associations of Japanese food intake with survival of stomach and colorectal cancer: A prospective patient cohort study.

Dietary factors may affect the prognosis of digestive tract cancer, but evidence has been sparse. We investigated the association between pretreatment intake of 6 Japanese foods (including soy food, miso [soybean paste] soup and seaweed) and the risk of death among patients with histologically confirmed major digestive tract cancers (stomach, 1931; colon, 793; rectum, 510) diagnosed during 1997‐2013 at a single institution in Japan. Pretreatment dietary intake was assessed using a food frequency questionnaire, and the patients were followed until December 2016. The Cox proportional hazards model was used to estimate hazard ratios (HR) and 95% confidence intervals (CI). Among the patients with stomach cancer, frequent intake of soy food was inversely associated with the risk of all‐cause (P trend for four frequency groups = 0.01; HR = 0.72, 95% CI: 0.50‐1.04 for highest vs lowest group) and stomach cancer (P trend = 0.03; HR = 0.63, 95% CI: 0.40‐0.99) death. A similar inverse association was also found for intake of miso soup. In contrast, frequent seaweed intake was inversely associated with the risk of all‐cause death among the patients with colon cancer (P trend = 0.03). Rectal cancer patients who had frequently consumed seaweed tended to have a lower risk of rectal cancer death (P trend = 0.02). These findings indicate that pretreatment intake of Japanese foods such as soybean products and seaweed may have favorable effects on patient survival of stomach and colorectal cancer, although this needs to be confirmed by further research.

Higher dietary soy intake appears inversely related to breast cancer risk independent of estrogen receptor breast cancer phenotypes

The relationship between soy intake (SI) and breast cancer (BC) has been widely investigated with limited information on the significance of hormone receptor status of BC on the association. This study assessed the relationship between SI and BC risk in the context of oestrogen receptor (ER) status of BC. We meta-analyzed data from published studies on SI and BC after a methodical search of EMBASE, PubMed and Cochrane Library through December 2019. Summary estimates with 95% confidence intervals (CI) were presented using a random-effects model. Eighteen (5 cohorts and 13 case-control) studies, were included in this meta-analysis and SI was inversely associated with BC risk [OR (95%) for highest vs. lowest soy food intake = 0.88 (0.84–0.92), P < 0.001, I2 = 76.1%, Egger's p-value = 0.425] among all women. The inverse relationship was stronger among premenopausal women [OR (95%) = 0.79 (0.71–0.87), P < 0.001, I2 = 77.3%, Egger's p-value = 0.644]. In addition, SI was inversely associated with BC risk among ER-negative (–) BC women [OR (95%) = 0.71 (0.57–0.90), P = 0.013, I2 = 72.0%, Egger's p-value = 0.355] and among ER-positive (+) BC women [OR (95%) = 0.87 (0.79–0.96), P = 0.008 I2 = 74.6%, Egger's p-value = 0.061]. SI appears inversely associated with BC risk, with a stronger inverse association among pre-menopausal and ER-negative BC women.