Soy Protein Intake Research Articles

Additive impact of soy protein dietary intake and exercise on visceral fat mass reduction and mitochondrial complex I activation in skeletal muscle.

Soy protein has shown remarkable effectiveness in reducing fat mass compared with other protein sources, and exercise has the potential to further enhance this fat loss effect. Previous studies have demonstrated that soy protein intake leads to decreased fatty acid synthesis, which contributes to its fat-loss properties. However, the exact mechanism by which these lipids are consumed remains unclear. To investigate this, we conducted a comprehensive study using C57/BL6 male mice, comparing the effects of soy and casein proteins with and without exercise (Casein-Sed, Casein-Ex, Soy-Sed, and Soy-Ex groups) under high- and low-protein conditions (14% or 40% protein). Our findings revealed that combining soy protein intake with exercise significantly reduced epididymal white adipose tissue (eWAT) weight, particularly in the high-protein diet group. Further analysis revealed that exercise increased the expression of lipid oxidation-regulatory proteins, including mitochondrial oxidative phosphorylation protein (OXPHOS) complexes, in the plantaris muscle regardless of the protein source. Although soy protein intake did not directly affect muscle mitochondrial protein expression, the activity of OXPHOS complex I was additively enhanced by exercise and soy protein under the 40% protein condition. Notably, complex I activity inversely correlated with eWAT weight in the soy protein diet group. These results highlight the potential link between improved complex I activity induced by soy protein and fat mass reduction, which emphasizes the promising benefits of combining soy protein with exercise in promoting fat loss.NEW & NOTEWORTHY The findings revealed that soy protein intake combined with exercise resulted in reduced adipose tissue weight compared with that obtained with casein protein intake. Furthermore, the joint impact of exercise and soy protein consumption resulted in enhanced activity of oxidative phosphorylation protein (OXPHOS) complex I in fast-twitch muscles, which appears to be associated with fat mass reduction. These findings elucidate the potential additive effects of soy protein and exercise on body weight management.

Abstract 6468: Association of food groups and dietary pattern with breast cancer risk: A systematic review and meta-analysis

Abstract We conducted a systematic review and meta-analysis of current evidence for the association between food groups, dietary patterns, and breast cancer risk among the Asian population. This systematic review and meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. We performed a systematic literature search up to November 2022 in English in the PubMed, Web of Science, Embase, and Cochrane databases. Risk ratios (RRs) with 95% confidence intervals (CIs) were extracted as effect sizes. Publication bias was estimated by the funnel plot method. We collected the data from 15 cohort studies and 30 case-control studies meeting the search criteria. The meta-analysis found that fruit and vegetable consumption was associated with a 27% and 35% lower risk of breast cancer, respectively [RR = 0.73 (0.56, 0.96); RR = 0.65 (0.47, 0.90)]. By contrast, no significance was found between meat, soy food, and green tea consumption and breast cancer risk (P > 0.05). However, soy protein and isoflavone intake could lower breast cancer risk by 35% and 32%, respectively [RR = 0.65 (0.51, 0.83); RR = 0.68 (0.55, 0.82)]. As for dietary pattern, higher adherence to a healthy dietary pattern and healthy eating index was associated with a 38% and 62% reduction in breast cancer risk, respectively [RR = 0.62 (0.44, 0.88; RR = 0.38 (0.22, 0.67)], while high adherence to an unhealthy dietary pattern was associated with a 44% increased risk [RR = 1.44 (1.06, 1.96)]. Considering alcohol consumption, a 75% increased risk of breast cancer was found [RR= 1.75 (1.33, 2.30)]. The present meta-analysis found that high intakes of fruit, vegetable, soy protein, and soy isoflavone significantly reduced the risk of breast cancer, while high intake of alcohol had a significantly increased risk. Meat, soy food, and green tea consumption were not significantly associated with breast cancer risk. Considering dietary patterns, higher adherence to a healthy eating index and a healthy dietary pattern may reduce breast cancer risk. Conversely, adherence to unhealthy dietary patterns may increase breast cancer risk. However, further studies are needed to confirm the associations between dietary patterns and breast cancer in the Asian population. This research was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No.2022R1F1A1074279). MSIT: Ministry of Science and ICT. Citation Format: Jialei Fu, Woo-Kyoung Shin, Dan Huang, Sukhong Min, Li-Juan Tan, Hyein Jung, Khongorzul Ganbat, Jiwon Jeong, Seok-Jae Oh, Bayarmaa Nasan Ulzii, Daehee Kang, Sangah Shin. Association of food groups and dietary pattern with breast cancer risk: A systematic review and meta-analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6468.

A Systematic Review of the Effects of Plant Compared with Animal Protein Sources on Features of Metabolic Syndrome

Dietary protein may play an important role in the prevention of metabolic dysfunctions. However, the way in which the protein source affects these dysfunctions has not been clearly established. The aim of the current systematic review was to compare the impact of plant- and animal-sourced dietary proteins on several features of metabolic syndrome in humans. The PubMed database was searched for both chronic and acute interventional studies, as well as observational studies, in healthy humans or those with metabolic dysfunctions, in which the impact of animal and plant protein intake was compared while using the following variables: cholesterolemia and triglyceridemia, blood pressure, glucose homeostasis, and body composition. Based on data extraction, we observed that soy protein consumption (with isoflavones), but not soy protein alone (without isoflavones) or other plant proteins (pea and lupine proteins, wheat gluten), leads to a 3% greater decrease in both total and LDL cholesterol compared with animal-sourced protein ingestion, especially in individuals with high fasting cholesterol concentrations. This observation was made when animal proteins were provided as a whole diet rather than given supplementally. Some observational studies reported an inverse association between plant protein intake and systolic and diastolic blood pressure, but this was not confirmed by intervention studies. Moreover, plant protein (wheat gluten, soy protein) intake as part of a mixed meal resulted in a lower postprandial insulin response than did whey. This systematic review provides some evidence that the intake of soy protein associated with isoflavones may prevent the onset of risk factors associated with cardiovascular disease, i.e., hypercholesterolemia and hypertension, in humans. However, we were not able to draw any further conclusions from the present work on the positive effects of plant proteins relating to glucose homeostasis and body composition.

Association of food groups and dietary pattern with breast cancer risk: A systematic review and meta-analysis

We conducted a systematic review and meta-analysis of current evidence for the association between food groups, dietary patterns, and breast cancer risk among the Asian population. This systematic review and meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. We performed a systematic literature search up to December 2022 in English in the PubMed, Web of Science, Embase, and Cochrane databases. Risk ratios (RRs) with 95% confidence intervals (CIs) were extracted as effect sizes. Publication bias was estimated by two different funnel plot methods. We collected the data from 15 cohort studies and 34 case-control studies meeting the search criteria. The meta-analysis found that the consumption of fruits and, likewise, vegetables were associated with a 29% lower risk of breast cancer, respectively [RR=0.71 (0.55, 0.93); RR=0.71 (0.53, 0.95)]. By contrast, no significance was found between meat, soy foods, and green tea consumption and breast cancer risk (P>0.05). However, soy protein and isoflavone intake could lower breast cancer risk by 35% and 32%, respectively [RR=0.65 (0.51, 0.83); RR=0.68 (0.55, 0.82)]. As for the dietary pattern, high adherence to a healthy dietary pattern and, similarly, to a healthy eating index was associated with a 38% and 51% reduction in breast cancer risk, respectively [RR=0.62 (0.44, 0.88; RR=0.49 (0.27, 0.87)], while high adherence to an unhealthy dietary pattern was associated with a 44% increased risk [RR=1.44 (1.06, 1.96)]. Considering alcohol consumption, a 75% increased risk of breast cancer was found [RR=1.75 (1.33, 2.30)]. The present meta-analysis found that high intakes of fruits, vegetables, soy protein, and soy isoflavone significantly reduced the risk of breast cancer, while high intake of alcohol had a significantly increased risk. Meat, soy food, and green tea consumption were not significantly associated with breast cancer risk. Considering dietary patterns, high adherence to a healthy eating index and a healthy dietary pattern may reduce breast cancer risk. Conversely, adherence to unhealthy dietary patterns may increase breast cancer risk. However, further studies are needed to confirm the associations between dietary patterns and breast cancer in the Asian population.

Soy protein intake increased bone mineral density under nonenergy-deficiency conditions but decreased it under energy-deficiency conditions in young female rats

Many young individuals attempt to lose too much weight because of a false body image, which induces low bone mineral density (BMD) resulting from energy restriction. In addition, a decrease in estrogen has been observed along with the decrease in BMD. Estrogen is responsible for maintaining bone mass, and soybeans contain high levels of isoflavones, which have estrogen-like effects. Thus, we hypothesized that soy protein prevents low BMD caused by energy deficiency in young female rats. The purpose of this study was to examine the effect of soy protein intake on bone loss by energy deficiency in young female rats. Female Sprague-Dawley rats (6 weeks old) were randomly divided into the following 4 experimental groups: ad libitum feeding and casein diet (AL-Cas); ad libitum feeding and soy diet (AL-Soy); 40% energy restriction and casein diet (ER-Cas); and 40% energy restriction and soy diet (ER-Soy). The experimental period was 10.5 weeks. The AL-soy group had significantly higher BMD of the femur than the AL-Cas group (AL-Cas = 156 ± 5 mg/cm2, AL-Soy = 165 ± 7 mg/cm2; P < .05). Meanwhile, the ER-Soy group had significantly lower BMD of the tibia, femur, and lumbar spine than the ER-Cas group (ER-Cas = 147 ± 7 mg/cm2, ER-Soy = 133 ± 10 mg/cm2; P < .01). These results show that compared with ad libitum control groups, soy protein resulted in higher BMD under nonenergy deficiency, but under energy-deficiency conditions, it resulted in lower BMD.

Effects of Soy Protein Intake on Low Bone Mass Caused by Energy Restriction in Young Female Rats

Abstract Objectives Eating disorders, such as anorexia nervosa, in young adulthood have been shown to lower bone mineral density (BMD), possibly due to the dysfunction of growth and gonadal hormones caused by reduced energy intake, which leads to bone loss. Isoflavones in soy protein have estrogen-like effects and are used as an alternative treatment for a wide range of hormonal disorders such as osteoporosis. The purpose of this study was to determine the effect of soy protein intake on bone fragility caused by energy restriction in young female rats. Methods Six-week-old Sprague–Dawley female rats were acclimated for 1 week and then divided into four groups: (1) ad libitum intake and casein diet group (Cas: n = 8), (2) ad libitum intake and soy diet group (Soy: n = 8), (3) energy-restricted and casein diet group (ER-Cas: n = 8), and (4) energy-restricted and soy diet group (ER-Soy: n = 8). The animals were maintained under these feeding conditions for 10.5 weeks. In the energy-restricted groups, the calorific intake was reduced by 40%. After rearing, viscera, blood, muscle, and bone samples were collected. Bone samples were evaluated for BMD by the dual-energy x-ray absorptiometry method. Two-way analysis of variance and multiple comparison tests were used to evaluate the differences among the four groups. Results The bodyweight and uterine weight results revealed a significant main effect of energy restriction on bone mineral content (BMC), bone area, and BMD. BMC and BMD results revealed a significant interaction of soy protein and energy restriction. BMD was highest in the Soy group, followed by the Cas group, ER-Cas group, and ER-Soy group. There was no difference in estradiol among the four groups. Energy restriction had a significant main effect on insulin-like growth factor I (IGF-I), which was significantly reduced in the ER-Soy group compared with the two ad libitum groups. Conclusions Soy protein showed a tendency of having a positive effect on BMD and IGF-I under ad libitum conditions, whereas under energy restriction, it had a negative effect and did not suppress the effect of energy restriction. Funding Sources This work was supported by the Research Grant of Fuji Foundation for Protein Research and the Cooperative Research Grant of Advanced Research Initiative for Human High Performance, University of Tsukuba.

The effect of soy isoflavones and soy isoflavones plus soy protein on serum concentration of tumor necrosis factor-α? A systematic review and meta-analysis of randomized controlled trials.

In this study, we summarized the effect of soy isoflavones and soy isoflavones plus soy protein on serum concentration of tumor necrosis factor-alpha (TNF-α) among adult participants. We systematically searched Scopus, ISI Web of Science, Cochrane Library, PubMed, and clinicaltrials.gov for articles published up to May 2020. Effect size was calculated by mean change from baseline of TNF-α concentrations and its standard deviation (SD) for intervention and comparison groups. If the heterogeneity test was statistically significant, DerSimonian and Laird random effects model was used to estimate the summary of the overall effects and its heterogeneity. Nineteen and fourteen randomized clinical trials were included in our systematic review and meta-analysis, respectively. The result of overall effect size indicated a non-significant effect in serum concentration of TNF-α following soy isoflavones intake (WMD=0.2pg/ml, 95% CI: -0.13, 0.53; p=.226) and the combination of soy isoflavones and soy protein intake (WMD=0.02 pg/ml, 95% CI: -0.02, 0.06; p=.286). Subgroup analyses revealed no significant change in circulatory levels of TNF-α following soy isoflavones plus soy protein intake. In conclusion, the present systematic review and meta-analysis found insufficient evidence that soy isoflavones or the combination of soy isoflavones and soy protein significantly reduce serum concentration of TNF-α.

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.

Sex-specific associations of habitual intake of soy protein and isoflavones with risk of type 2 diabetes.

A possible mechanism by which intake of soy isoflavones leads to an improvement in glucose metabolism has been suggested. However, epidemiological evidence of a link between dietary soy isoflavone and type 2 diabetes is not convincing. This study aimed to evaluate the prospective associations between intake of dietary soy protein and isoflavones (total isoflavones, daidzein and genistein) and risk of type 2 diabetes in a community-based cohort of Korean adults aged≥40 years, the Korean Multi-Rural Communities Cohort (MRCohort). A total of 8269 participants who did not have type 2 diabetes were enrolled. Dietary intake was calculated using a food frequency questionnaire. Over 50,063 person-years of follow-up, 531 participants developed type 2 diabetes. Significant dose-response inverse associations were observed between dietary soy protein and isoflavones (quartiles) and type 2 diabetes in women (incidence rate ratio, IRR=0.63, 95% CI=0.45-0.87, P for trend=0.0078 for soy protein; IRR=0.62, 95% CI=0.45-0.86, P for trend=0.0031 for total isoflavones for the highest quartile compared with the lowest quartile). Similar significant linear trends were found for both daidzein and genistein. However, there were no significant associations with soy protein and isoflavones in men. The sex-specific differences in associations between soy protein and isoflavones intakes and type 2 diabetes risk were statistically significant (all P for interaction<0.05). Habitual intake of soy protein and isoflavones may be inversely associated with type 2 diabetes in women, but not in men. Dietary soy components may play different roles in the development of type 2 diabetes in men and women.

Legume and soy intake and risk of type 2 diabetes: a systematic review and meta-analysis of prospective cohort studies

Previous findings on the associations of legume and soy intake with the risk of type 2 diabetes are conflicting. We aimed to summarize the longitudinal associations between legume and soy intake and risk of type 2 diabetes. We searched for relevant prospective cohort studies in PubMed, EMBASE, and Ovid up to August 2019. Study-specific, multivariable-adjusted RRs and 95% CIs were pooled by random-effects models. We identified 15 unique cohorts including 565,810 individuals and 32,093 incident cases. The summary RRs (95% CIs) of incident type 2 diabetes were 0.95 (0.79, 1.14; NS) for total legumes, 0.83 (0.68, 1.01; NS) for total soy, 0.89 (0.71, 1.11; NS) for soy milk, 0.92 (0.84, 0.99) for tofu, 0.84 (0.75, 0.95) for soy protein, and 0.88 (0.81, 0.96) for soy isoflavones, respectively. High heterogeneity was found for total legumes (I2=84.8%), total soy (I2=90.8%), and soy milk (I2=91.7%). Potential sources of heterogeneity were not evident for total legumes or soy milk, whereas for total soy, geographic location (Asia, United States; P=0.04) and study quality (high, moderate, or low; P = 0.02) significantly predicted heterogeneity. In dose-response analysis, significant linear inverse associations were observed for tofu, soy protein, and soy isoflavones (all P < 0.05). Overall quality of evidence was rated as moderate for total legumes and low for total soy and soy subtypes. Dietary intakes of tofu, soy protein, and soy isoflavones, but not total legumes or total soy, are inversely associated with incident type 2 diabetes. Our findings support recommendations to increase intakes of certain soy products for the prevention of type 2 diabetes. However, the overall quality of evidence was low and more high-quality evidence from prospective studies is needed. This trial was registered as PROSPERO CRD42019126403 (https://www.crd.york.ac.uk/PROSPERO).

Hepatic Fat Content Is Associated with Fasting-Induced Fibroblast Growth Factor 21 Secretion in Mice Fed Soy Proteins.

Previous studies suggest that circulating fibroblast growth factor 21 (FGF21) levels are elevated in patients with fatty liver, while fasting-induced secretion of FGF21 is lower in obese patients. It has been reported that soy protein prevents hepatic fat accumulation and induces FGF21 secretion. The present study was designed to evaluate the response of circulating FGF21 levels to feeding and fasting in mice fed soy protein-rich diets. For this, C57BL/6J mice were distributed into control, high-fat high-sucrose (HFHS)-casein protein, HFHS-soy protein, and HFHS-β-conglycinin diet groups. Plasma samples were collected after 10 and 11 wk either in dark periods with feeding conditions or light periods under fasting conditions using a crossover design. After a 12-wk period of feeding, HFHS-induced hepatic fat accumulation was significantly reduced in the groups fed HFHS-soy protein and HFHS-β-conglycinin as compared to that in the HFHS-casein-fed group (p<0.05). Plasma FGF21 concentration was significantly higher in the dark/feeding periods in the HFHS-casein group (p<0.05), while in the HFHS-β-conglycinin group it was higher in the light/fasting periods (p<0.05). The amount of mesenteric fat was significantly lower in the HFHS-β-conglycinin group than in the HFHS-casein and HFHS-soy protein groups (p<0.01). The fasting-induced FGF21 secretion was significantly and negatively correlated with hepatic fat content (p<0.05). The present study revealed that hepatic fat accumulation was associated with lower fasting-induced FGF21 secretion, which was regulated better by dietary intake of soy protein. These results support the preventive effects of soy protein on central obesity.

The Timing Effects of Soy Protein Intake on Mice Gut Microbiota.

Soy protein intake is known to cause microbiota changes. While there are some reports about the effect of soy protein intake on gut microbiota and lipid metabolism, effective timing of soy protein intake has not been investigated. In this study, we examined the effect of soy protein intake timing on microbiota. Mice were fed twice a day, in the morning and evening, to compare the effect of soy protein intake in the morning with that in the evening. Mice were divided into three groups: mice fed only casein protein, mice fed soy protein in the morning, and mice fed soy protein in the evening under high-fat diet conditions. They were kept under the experimental condition for two weeks and were sacrificed afterward. We measured cecal pH and collected cecal contents and feces. Short-chain fatty acids (SCFAs) from cecal contents were measured by gas chromatography. The microbiota was analyzed by sequencing 16S rRNA genes from feces. Soy protein intake whether in the morning or evening led to a greater microbiota diversity and a decrease in cecal pH resulting from SCFA production compared to casein intake. In addition, these effects were relatively stronger by morning soy protein intake. Therefore, soy protein intake in the morning may have relatively stronger effects on microbiota than that in the evening.

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

ObjectiveWe 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. MethodsOnline 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. ResultsIn 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. ConclusionsSoy 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.

Dietary Soy Intake Is Inversely Associated with Risk of Type 2 Diabetes in Japanese Women but Not in Men

Whole soy foods, as well as their components, including protein and isoflavones, have garnered attention because they may have beneficial effects against diabetes. We examined associations between the intake of soy foods, soy protein, and soy isoflavones and the risk of diabetes in the Japanese population. This prospective cohort study included 13,521 residents (5883 men and 7638 women; 35-69 y old) of Takayama City, Japan. The subjects responded to a self-administered baseline questionnaire in 1992 and to a follow-up questionnaire seeking information about diabetes in 2002. Their mean ± SD body mass index was 22.6 ± 2.6 kg/m2 (men) and 22.1 ± 2.7 (women). The intakes of total soy foods, fried soy foods, nonfried soy foods, soy protein, and soy isoflavones were estimated through the use of a validated food-frequency questionnaire administered in 1992. Associations between soy intake and the risk of diabetes were evaluated through the use of Cox proportional hazards models incorporating age, education level, physical activity, smoking status, alcohol consumption, history of hypertension, use of vitamin supplements, menopausal status, and dietary factors including glycemic load, total energy, total fat, meat, fruit, vegetables, and coffee. During a 10-y follow-up, 438 participants reported physician-diagnosed diabetes. Women in the highest tertile of intakes of total soy foods, fried soy foods, nonfried soy foods, soy protein, and soy isoflavone had significantly lower HRs, after controlling for covariates, than those with the lowest intakes. For example, HRs were 0.45 (95% CI: 0.30, 0.68; P-trend <0.001) for total soy food intake. In men, there were no significant associations between soy intake and the risk of diabetes. These results suggest that a high soy intake may be associated with a lower risk of diabetes in Japanese women.

Clinical and metabolic response to soy administration in older women with metabolic syndrome: a randomized controlled trial

BackgroundThere are many studies on the health effects of soy, only a few describe the effects of the simultaneous use of two types of soy on multiple components of metabolic syndrome (MetS). The present study was designed to determine the effects of roasted soy-nut and textured soy protein (TSP) intake on clinical and metabolic status of older women with MetS borderline parameters.MethodThis randomized, single-blind, controlled clinical trial included 75 women ≥ 60 years old with a diagnosis of MetS based on ATP III criteria. The participants were randomly allocated into three groups of 25 people; soy-nut, TSP and control groups for 12 week. Fasting blood samples were taken at the beginning and end of the trial to compare the metabolic responses. All participants provided three dietary records and physical activity records during the intervention. We used the Kolmogorov–Smirnov, ANOVA, ANCOVA, paired-t test, and the Generalized Linear Model (GLM) repeated measures analysis.ResultsDietary intake and physical activity of the participants in two groups were not significantly different. After 12 weeks of intervention the participants who received soy-nut had a significant decrease in total cholesterol (TC) (p < 0.001), low density lipoprotein, very low density lipoprotein, apolipoprotein B100, fasting blood glucose, insulin (p < 0.05), HOMA-IR, malondialdehyde (MDA) (p < 0.01) level. Morever, a significant increase in total antioxidant capacity (TAC) (p < 0.01) level compared with the control group. At the same time, the TSP brought significant decrease only in TC, insulin, MDA (p < 0.05) level and a significant increase in total TAC (p < 0.05) level. We did not find any significant effect in intervention groups, on apolipoprotein AI, triglyceride (TG), high density lipoprotein (HDL-C), TG/HDL, C-reactive protein and fibrinogen levels after intervention.ConclusionShort-term intakes of roasted soy-nut and TSP have shown to improve the lipid profiles, markers of glucose intolerance and oxidative stress; although the roasted soy-nut was more effective than TSP. Therefore, a moderate daily intake of roasted soy-nut as snacks or TSP as a meal complement by individuals with borderline parameters of MetS can be a safe and a practical modality to avoid the progression of the disease as well as to limit the side effects of drug intake.Trial registration MUBABOL.REC.1388.1

Effects of Intake of Soy and Non-Soy Legume on Serum HDL-Cholesterol Levels

High-density lipoprotein (HDL) has been shown to have a variety of functions that contribute to anti-atherogenesis. Here we review meta-analyses on the effects of intake of soy protein and isoflavones on serum HDL-cholesterol (HDL-C) levels, and we would also review meta-analysis on the effects of intake of non-soy legume on serum HDL-C, to make “Dietary Reference Intake for Japanese 2020”. We searched meta-analyses of randomized, placebo-controlled trials. A search was conducted by using PubMed, Embase and Google Scholar, with the following keywords: soy and HDL and meta-analysis. The search period was comprised from 2007 up to July 2018. We found three meta-analyses about effects of intake of soy protein and isoflavones on HDL-C after 2007. All meta-analyses reported that intake of soy protein and isoflavones was associated with a significant increase of HDL-C. We found the meta-analysis which evaluated effects of intake of non-soy legume on HDL-C, in which a significant association of intake of non-soy legume with HDL-C was not obtained due to a significant heterogeneity of collected data. In conclusion, intake of soy was significantly associated with elevation of HDL-C; however, non-soy consumption was not associated with a significant increase of HDL. J Endocrinol Metab. 2018;8(5):83-86 doi: https://doi.org/10.14740/jem524w

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

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 ≥ 40years old who did not have MetS at baseline (n = 5509; 2204 men and 3305 women). Dietary intake of soy protein/isoflavones at baseline and average consumption during follow-up were used. 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. 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.

Inverse association between soy food consumption, especially fermented soy products intake and soy isoflavone, and arterial stiffness in Japanese men

Studies on the associations between soy food consumption and arterial stiffness are rare. The aim of the present study was to evaluate their associations in Japanese men. A total of 652 eligible men, aged 35–69 years, who underwent the measurement of brachial-ankle pulse wave velocity (baPWV) as an index of arterial stiffness were evaluated in this cross-sectional study. Information on their lifestyle characteristics, including dietary behavior, was obtained from a structured self-administered questionnaire. The frequency of total soy products as well as fermented and non-fermented soy products intakes was calculated, and the amounts of soy protein and soy isoflavone intakes were also estimated; these were then divided into tertiles and their associations with baPWV values were evaluated using general linear models. Higher frequency of fermented soy products intake was associated with decreased baPWV after adjusting for the multivariable covariates (P value for trend was 0.002, in Model 3). This association did not alter after further adjustment with a biomarker of systemic inflammation (serum high-sensitivity C-reactive protein (hs-CRP)) (P value for trend was 0.001, in Model 4). Total soy isoflavone consumption was also inversely associated with baPWV even after adjusting for multivariable covariates including serum hs-CRP (P value for trend was 0.043, in Model 4); however total soy protein consumption was not. These results demonstrated that greater consumption of soy food, especially fermented soy products and soy isoflavone was associated with reduced arterial stiffness, independent of systemic inflammation, in Japanese men.

Short-Term Soy Protein Isolate Feeding Prevents Liver Steatosis and Reduces Serum ALT and AST Levels in Obese Female Zucker Rats.

Non-alcoholic fatty liver disease is a common liver disorder worldwide and is associated with obesity. We investigated effects of obesity and short-term intake of soy protein with isoflavones (SPI) on body weight change, energy intake, liver steatosis, and serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and leptin levels. Seventeen lean and seventeen obese (fa/fa) female Zucker rats were randomly assigned to either casein or SPI diet for 8 weeks. Body weight was recorded twice weekly; feed intake was measured weekly. Livers were examined histologically, and serum AST, ALT, and leptin levels were measured. Obese soy-fed (OS) rats gained more weight but had lower liver steatosis than obese casein-fed (OC) rats. Energy intake for OS versus OC rats were only different at weeks 2 and 3. Serum AST and ALT levels were lower in OS versus OC rats. Obesity increased serum leptin levels for both diets. In summary, short-term SPI intake reduced liver steatosis, and the only time points at which the mean energy intakes of OS and OC rats differed were at weeks 2 and 3, where OS rats had a higher mean energy intake, which may have accounted for the increased body weight in OS rats.

Nutritional Considerations for Dialysis Vegetarian Patients, Part One

Nutritional Considerations for Dialysis Vegetarian Patients, Part One