Effects of soy supplementation on blood lipids and arterial function in hypercholesterolaemic subjects

Association between plant and animal proteins intake with lipid profile and anthropometric indices: A cross-sectional study

BACKGROUND

Results of studies on the effects of plant and animal proteins on lipid profile are controversial. So we aimed to assess the relationship between plant and animal protein intake with lipid profile and novel anthropometric indices in healthy individuals.

METHOD

In this cross-sectional study, 236 participants have selected from Shiraz medical centers (Iran) through random cluster sampling. Food intakes were assessed using a 168-items food frequency questionnaire (FFQ). Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglyceride (TG) were measured. Anthropometric indices including a body shape index (ABSI), abdominal volume index (AVI), buddy roundness index (BRI), and conicity index (CI) were calculated.

RESULTS

In the crude and fully adjusted models, more consumption of plant proteins was associated with TG levels (OR = 2.31; 95% CI: 1.08, 4.95; P = 0.03 and OR = 2.39; 95% CI: 1.03, 5.15; P = 0.04). Also, there was a significant direct association between plant proteins and BRI in the curd model (OR = 3.55; 95% CI: 1.32, 9.54; P = 0.01), and after adjusting for age and energy intake (OR = 3.32; 95% CI: 1.21, 9.14; P = 0.01). More consumption of plant proteins was related to higher CI in the crude model (OR = 3.06; 95% CI: 1.12, 8.31; P = 0.03), but not in the fully adjusted model.

CONCLUSION

We found that a higher intake of plant proteins was associated with a higher TG level, BRI, and CI index. However, more research is needed to confirm these relations and provide the evidence needed to exert these findings into clinical practice.

Isoflavones Effects on Vascular and Endothelial Outcomes: How Is the Gut Microbiota Involved?

Isoflavones are a group of (poly)phenols, also defined as phytoestrogens, with chemical structures comparable with estrogen, that exert weak estrogenic effects. These phytochemical compounds have been targeted for their proven antioxidant and protective effects. Recognizing the increasing prevalence of cardiovascular diseases (CVD), there is a growing interest in understanding the potential cardiovascular benefits associated with these phytochemical compounds. Gut microbiota may play a key role in mediating the effects of isoflavones on vascular and endothelial functions, as it is directly implicated in isoflavones metabolism. The findings from randomized clinical trials indicate that isoflavone supplementation may exert putative effects on vascular biomarkers among healthy individuals, but not among patients affected by cardiometabolic disorders. These results might be explained by the enzymatic transformation to which isoflavones are subjected by the gut microbiota, suggesting that a diverse composition of the microbiota may determine the diverse bioavailability of these compounds. Specifically, the conversion of isoflavones in equol-a microbiota-derived metabolite-seems to differ between individuals. Further studies are needed to clarify the intricate molecular mechanisms behind these contrasting results.

Effects of whey and soy protein supplementation on inflammatory cytokines in older adults: a systematic review and meta-analysis

BACKGROUND AND AIMS

Low-grade inflammation is a mediator of muscle proteostasis. This study aimed to investigate the effects of isolated whey and soy proteins on inflammatory markers.

METHODS

We conducted a systematic literature search of randomised controlled trials (RCT) through MEDLINE, Web of Science, Scopus and Cochrane Library databases from inception until September 2021. To determine the effectiveness of isolated proteins on circulating levels of C-reactive protein (CRP), IL-6 and TNF-α, a meta-analysis using a random-effects model was used to calculate the pooled effects (CRD42021252603).

RESULTS

Thirty-one RCT met the inclusion criteria and were included in the systematic review and meta-analysis. A significant reduction of circulating IL-6 levels following whey protein [Mean Difference (MD): -0·79, 95 % CI: -1·15, -0·42, I² = 96 %] and TNF-α levels following soy protein supplementation (MD: -0·16, 95 % CI: -0·26, -0·05, I² = 68 %) was observed. The addition of soy isoflavones exerted a further decline in circulating TNF-α levels (MD: -0·20, 95 % CI: -0·31, -0·08, I² = 34 %). According to subgroup analysis, whey protein led to a statistically significant decrease in circulating IL-6 levels in individuals with sarcopenia and pre-frailty (MD: -0·98, 95 % CI: -1·56, -0·39, I² = 0 %). These findings may be dependent on participant characteristics and treatment duration.

CONCLUSIONS

These data support that whey and soy protein supplementation elicit anti-inflammatory effects by reducing circulating IL-6 and TNF-α levels, respectively. This effect may be enhanced by soy isoflavones and may be more prominent in individuals with sarcopenia.

The effects of phytochemicals and herbal bio-active compounds on tumour necrosis factor-α in overweight and obese individuals: a clinical review

Obesity is abnormal fat accumulation in the body which acts as a risk factor for various cardiometabolic states. Adipose tissue in excess can release inflammatory factors, including TNF-α and IL-6, and suppress adiponectin production. TNF-α increases the levels of IL-6 and acute phase reactants such as C-reactive protein. Inflammation has a crucial role in developing and progressing various cardiometabolic diseases and a wide range of obesity-related complications. It has been shown that TNF-α has a significant role in the development of insulin resistance. Recently, a growing body of evidence has focused on herbal medicine, phytochemicals and natural bioactive compounds as inexpensive, relatively easy accessible agents with low adverse effects to reduce inflammatory markers such as TNF-α and simultaneously decrease insulin resistance, glucose intolerance, and dyslipidemia in obesity. The main focus of the current review is to summarize the results of the studies, which assessed the effects of phytochemicals and herbal bio-active compounds on serum TNF-α in subjects with overweight or obesity. This review suggests that herbal medicine have favorable effects on the reduction of TNF-α concentration; however, the results were not uniform for different products. Among the reviewed plants, ginger, ginseng, resveratrol, and flaxseed had more promising effects.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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 = 0.2 pg/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 protein supplementation in men following radical prostatectomy: a 2-year randomized, placebo-controlled clinical trial

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Effects of soy intake on circulating levels of TNF-α and interleukin-6: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

Pro-inflammatory mediators, including serum tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6), can be used as biomarkers to indicate or monitor disease. This study was designed to ascertain the effects of soy products on TNF-α and IL-6 levels.

METHODS

PubMed, EMBASE, Science Direct, Web of Science, Google Scholar and the Cochrane Central Register of Controlled Trials were searched to November 2019 for RCTs around the effects of soy-based products on TNF-α and IL-6. A random effects model was used to calculate overall effect size.

RESULTS

In total, 29 eligible publications were considered in the present systematic review, of which 25 were included in this meta-analysis. The overall effect of soy products on TNF-α and IL-6 levels failed to reach statistical significance (MD = - 0.07; 95% CI - 0.22-0.09; I² 50.9; MD = 0.03; 95% CI - 0.07-0.14; I² 42.1, respectively). According to a subgroup analysis, natural soy products led to a reduction in TNF-α concentration compared with processed soy products (MD = - 0.32; 95% CI - 0.45 to - 0.19; I² 0.0). Moreover, IL-6 reduction was stronger in participants who were affected by different diseases (MD = - 0.04; 95% CI - 0.07 to - 0.02; I² 0.0).

CONCLUSIONS

A review of RCTs published to November 2019 found that natural soy products are effective in lowering TNF-α levels. While the beneficial effects on reduction of IL-6 appeared stronger in individuals affected by different diseases, this finding cannot be generalized to all individuals affected by different diseases.

The effects of soy supplementation on inflammatory biomarkers: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Soy products contain several compounds with anti-inflammatory properties like genistein and daidzein which reported to act through different pathways. Present study conducted considering the inconsistent results and lack of any comprehensive review regarding randomized controlled trials which assess the effect of soy products on inflammatory markers.

METHODS

Following electronic databases were searched up to March 2020: PubMed, Scopus, ISI web of science, and Cochrane Library All randomized trials which assessed the effect of soy product supplementation on c-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) were included for last analysis. Treatment effects were expressed as mean difference (MD) and the standard deviation (SD) of outcomes. To estimate the overall effect the random-effects model was employed.

RESULTS

Finally, 51 randomized trial were included for present study. Last analysis showed that soy product supplementation lead to significant reduction in CRP (MD -0.27 mg/L; 95% CI: -0.51, -0.02, p = 0.028) but it did not affect IL-6 (MD 0.0 pg/ml; 95% CI: -0.06, 0.06, p = 0.970) and TNF-α (MD = -0.04 pg/ml; 95% CI: -0.11, 0.03, p = 0.252). Subgroup analysis showed that soy supplementation had a significant impact on decreasing IL-6 and TNF-α levels when studies had a long-term intervention (≥12 weeks) and used low dose isoflavone (<100 mg/day).

CONCLUSION

In conclusion, present systematic review and meta-analysis found a significant reduction in CRP levels after soy supplementation whiles IL-6 and TNF-α did not affect.

Effects of plant protein and animal protein on lipid profile, body weight and body mass index on patients with hypercholesterolemia: a systematic review and meta-analysis

OBJECTIVE

We conducted a meta-analysis on the effect of plant protein or animal protein on body weight (BW), body mass index (BMI) and blood lipid profiles in patients with hypercholesterolemia.

MATERIALS AND METHODS

We used subject and free words to search PubMed, Embase and Cochrane Library databases. The risk-of-bias evaluation tool was used to assess literature quality. Data merging and statistical analyses were carried out using Review Manager 5.3 and Stata 13.0. All indicators were expressed as the mean difference (MD) and 95% confidence interval (95% CI). The heterogeneity test was conducted according to I² and Q tests. We used Egger's test to evaluate publication bias quantitatively.

RESULTS

This was a meta-analysis of intervention trials. Thirty-two studies (1562 patients) were included. The quality of the included studies was acceptable. Compared with consumption of animal protein, plant protein reduced total cholesterol (TC) (MD = - 0.19 mmol/L, 95% CI - 0.26, - 0.12), triglyceride (MD = - 0.07 mmol/L, 95% CI - 0.13, - 0.02), low-density lipoprotein cholesterol (LDL-C) (MD = - 0.19 mmol/L, 95% CI - 0.26, - 0.13), very low-density lipoprotein cholesterol (MD = - 0.05 mmol/L, 95% CI - 0.09, - 0.01), TC/LDL-C ratio (MD = - 0.17, 95% CI - 0.32, - 0.02) and LDL-C/HDL-C ratio (MD = - 0.20, 95% CI - 0.33, - 0.06) significantly and increased high-density lipoprotein cholesterol (HDL-C) (MD = 0.03 mmol/L, 95% CI 0.01, 0.06) levels, but had no effect on BW (MD = - 0.41 kg, 95% CI - 2.14, 1.33) or BMI (MD = 0.11 kg/m², 95% CI - 0.51, 0.73).

CONCLUSION

Compared with animal protein, consumption of plant protein could improve lipid profile in patients with hypercholesterolemia.

A systematic review and meta-analysis of the effects of soy on serum hs-CRP

BACKGROUND & AIM

The results of studies about the effect of soy products on serum highly sensitive C-reactive protein (hs-CRP) are inconsistent. The aim of this systematic review and meta-analysis of randomized clinical trials (RCTs) was to investigate the effect of soy products intake on serum hs-CRP concentration.

METHODS

We searched PubMed, EMBASE, Science Direct, ISI Web of Science, Google Scholar and Cochrane Central Register of Controlled Trials up to December 2016 without language restrictions. Random-effect model was used for quantitative data synthesis.

RESULTS

Thirty-six studies were included in our analyses. A meta-analysis revealed a non-significant reduction in serum hs-CRP concentrations following soy products consumption, -0.19 (mg/L) (95% CI: -0.49 to 0.09; I2 = 95.6%). Subgroup analyses suggested that natural soya products may reduce plasma levels of CRP by -0.18 mg/L (95% CI: -0.28 to -0.08; I2: 11.6) in comparison to other source of isoflavones (soya extracts, supplements). Moreover, the effect was stronger among subjects with baseline hs-CRP concentrations of less than 2.52 mg/L, -0.15 (95% CI: -0.27 to -0.02; I2: 34.6). A meta-regression analysis revealed that dosage of isoflavones seems to be a strong predictor of the effect of soya on serum hs-CRP levels.

CONCLUSION

Present review of RCTs published up to December 2016 did not provide strong evidence regarding the beneficial effect of soya products consumption on blood hs-CRP concentrations. However, it appears that natural soya products may reduce plasma levels of hs-CRP in comparison to other source of isoflavones. Large and well-designed studies are recommended to confirm this conclusion.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018069371.

Fibre supplementation for the prevention of type 2 diabetes and improvement of glucose metabolism: the randomised controlled Optimal Fibre Trial (OptiFiT)

AIMS/HYPOTHESIS

Insoluble cereal fibres have been shown in large prospective cohort studies to be highly effective in preventing type 2 diabetes, but there is a lack of interventional data. Our 2 year randomised double-blind prospective intervention study compared the effect of an insoluble oat fibre extract with that of placebo on glucose metabolism and incidence of diabetes.

METHODS

A total of 180 participants with impaired glucose tolerance underwent a modified version of the 1 year lifestyle training programme PREvention of DIAbetes Self-management (PREDIAS) and were randomised to receive a fibre supplement (n = 89; 7.5 g of insoluble fibre per serving) or placebo (n = 91; 0.8 g of insoluble fibre per serving) twice daily for 2 years. Eligible participants were men and women, were at least 18 years old and did not report corticosteroid or other intensive anti-inflammatory treatment, fibre intolerance or any of the following disorders: overt diabetes, chronic or malignant disease, or severe cardiopulmonary, endocrine, psychiatric, gastrointestinal, autoimmune or eating disorder. Participants were recruited at two clinical wards in Berlin and Nuthetal. The allocation was blinded to participants and study caregivers (physicians, dietitians, study nurses). Randomisation was conducted by non-clinical staff, providing neutrally numbered supplement tins. Both supplements were similar in their visual, olfactory and gustatory appearance. Intention-to-treat analysis was applied to all individuals.

RESULTS

After 1 year, 2 h OGTT levels decreased significantly in both groups but without a significant difference between the groups (fibre -0.78 ± 1.88 mmol/l [p ≤ 0.001] vs placebo -0.46 ± 1.80 mmol/l [p = 0.020]; total difference 0.32 ± 0.29 mmol/l; not significant). The 2 year incidence of diabetes was 9/89 (fibre group) compared with 16/91 (placebo group; difference not significant). As secondary outcomes, the change in HbA_1c level was significantly different between the two groups (-0.2 ± 4.6 mmol/mol [-0.0 ± 0.0%; not significant] vs +1.2 ± 5.2 mmol/mol [+0.1 ± 0.0%; not significant]; total difference 1.4 ± 0.7 mmol/mol [0.1 + 0.0%]); p = 0.018); insulin sensitivity and hepatic insulin clearance increased in both groups. After 2 years, improved insulin sensitivity was still present in both groups, although the effect size had diminished. Separate analysis of the sexes revealed a significantly greater reduction in 2 h glucose levels for women in the fibre group (-0.88 ± 1.59 mmol/l [p ≤ 0.001] vs -0.22 ± 1.52 mmol/l [p = 0.311]; total difference 0.67 ± 0.31 mmol/l; p = 0.015). Levels of fasting glucose, adipokines and inflammatory markers remained unchanged in the two groups. Significantly increased fibre intake was restricted to the fibre group, despite dietary counselling for both groups. No severe side effects occurred.

CONCLUSIONS/INTERPRETATION

We cannot currently provide strong evidence for a beneficial effect of insoluble cereal fibre on glycaemic metabolism, although further studies may support minor effects of fibre supplementation in reducing glucose levels, insulin resistance and the incidence of type 2 diabetes.

TRIAL REGISTRATION

clinicaltrials.gov NCT01681173 Funding: German Diabetes Foundation (grant no. 232/11/08).

The effect of dietary soy intake on weight loss, glycaemic control, lipid profiles and biomarkers of inflammation and oxidative stress in women with polycystic ovary syndrome: a randomised clinical trial

BACKGROUND

The present study aimed to evaluate the effects of dietary soy intake on weight loss and metabolic status of patients with polycystic ovary syndrome (PCOS).

METHODS

A randomised clinical trial was conducted among 60 women with PCOS. Participants were randomly assigned into two groups to receive either a test diet (n = 30) or a control diet (n = 30) for 8 weeks. Participants in the test group consumed a diet containing 0.8 g protein kg^-1 body weight (35% animal proteins, 35% soy protein and 30% vegetable proteins) and participants in the control group consumed a similar diet containing 70% animal proteins and 30% vegetable proteins.

RESULTS

Adherence to the test diet, compared with the control diet, resulted in significant decreases [mean (SD)] in body mass index (BMI) [-0.3 (0.6) versus +0.1 (0.5) kg m^-2 , P = 0.02], fasting plasma glucose [-0.2 (0.5) versus +0.1 (0.3) mmol L^-1 , P = 0.01], total testosterone [-0.3 (0.7) versus +0.3 (0.3) mmol L^-1 , P < 0.001], insulin [-15.0 (18.0) versus +4.8 (18.6) pmol L^-1 , P < 0.001] and insulin resistance [-0.6 (0.6) versus +0.2 (0.7), P < 0.001], as well as a significant increase in quantitative insulin sensitivity check index [+0.01 (0.01) versus -0.002 (0.02), P = 0.01]. In addition, significant decreases in triglycerides [-0.1 (0.4) versus +0.2 (0.3) mmol L^-1 , P = 0.01] and malondialdehyde (MDA) [-1.2 (1.0) versus +0.2 (1.2) μmol L^-1 , P < 0.001] and significant increases in nitric oxide (NO) [+13.6 (14.1) versus +0.9 (24.3) μmol L^-1 , P = 0.01] and glutathione (GSH) [+170.1 (175.5) versus +24.2 (168.7) μmol L^-1 , P = 0.002] were seen in the test group compared to the control.

CONCLUSIONS

Adherence to test diet among subjects with PCOS significantly decreased BMI, glycaemic control, total testosterone, triglycerides and MDA, and significantly increased NO and GSH compared to the control diet.

Interplay between proteins and metabolic syndrome-A review

Metabolic syndrome is characterized by hypertension; hyperglycemia; hypertriglyceridemia; reduced high-density lipoprotein cholesterol levels and abdominal obesity. Abundant data suggest that, compared with other people, patients meeting these diagnostic criteria have a greater risk of having substantial clinical consequences, the two most prominent of which are the development of diabetes mellitus and coronary heart disease. The metabolic syndrome is a health issue of epidemic proportions. Its prevalence in the world continues to increase, hand in hand with that of obesity. Protein, on the other hand, is the foundation of cell-building, especially in muscle tissue. The body needs protein to build not only muscle cells, but the cells of major organs, skin and red blood cells. For people with metabolic syndrome, one of the other functions of protein is to slow down the absorption of carbohydrates. When proteins are consumed with carbohydrates, it takes longer for the digestive system to break down that meal. This means that the sugar created from those carbohydrates is released at a slower rate, preventing spikes in both blood sugar and insulin. As the understanding of the metabolic syndrome evolves, it is likely that more comprehensive therapeutic options will become available.

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

Soy protein intakes ≥25 g d⁻¹significantly decreased SBP and DBP, which may be due to the isoflavones component.

The effect of soy or isoflavones on homocysteine levels: a meta-analysis of randomised controlled trials

BACKGROUND

The present study aimed to evaluate the effect of soy or isoflavones on blood homocysteine levels via a systematic review and meta-analysis.

METHODS

Pubmed, Embase, Web of Science and the Cochrane Library (up to 16 December 2015) were used for the literature review. Only randomised controlled trials were included. The primary outcome was the standard mean difference (SMD) of blood homocysteine levels between the experimental and control groups.

RESULTS

Nineteen randomised controlled studies were included for qualitative analysis. Eighteen studies were included in the data synthesis. Soy or isoflavones were found to have no effect on homocysteine levels, with a SMD of -0.21 (95% confidence interval = -0.43 to 0.00, I² =67.7%, random effect model). No publication bias was found among those studies (P = 0.296 for Egger's test, and P = 0.198 for Begg's test).

CONCLUSIONS

Soy or isoflavones were not found to be associated with a reduction in homocysteine levels. Further studies might still be needed in carefully selected populations.

The Effect of Soy Intake on Metabolic Profiles of Women With Gestational Diabetes Mellitus

CONTEXT

To our knowledge, no study has examined the effects of soy intake on metabolic status of women with gestational diabetes mellitus (GDM).

OBJECTIVE

This study was designed to assess the effects of soy intake on metabolic status of GDM women.

METHODS

A randomized clinical trial was performed among 68 women with GDM. Women were randomly assigned to receive either a control diet containing 0.8-g/kg protein (70% animal and 30% plant proteins) (n = 34) or a soy diet containing the same amount of protein with 35% animal protein, 35% soy protein, and 30% other plant proteins (n = 34) for 6 weeks.

RESULTS

Compared with soy protein consumption, the control group significantly increased fasting plasma glucose (+1.4 ± 11.6 vs -12.7 ± 13.2 mg/dL, P < .001), serum insulin levels (+5.0 ± 11.6 vs -0.9 ± 10.0 μIU/mL, P = .02), homeostasis model of assessment-insulin resistance (+1.2 ± 2.7 vs -0.8 ± 2.2, P = .002), and decreased quantitative insulin sensitivity check index (-0.007 ± 0.02 vs +0.01 ± 0.03, P = .004). Administration of the control diet resulted in a significant difference in serum triglycerides changes (+31.3 ± 38.0 vs +8.9 ± 46.1 mg/dL, P = .03) compared with soy protein. There were a significant decrease in total antioxidant capacity (-35.0 ± 136.2 vs +81.8 ± 188.8 mmol/L, P = .005) and glutathione (-41.3 ± 145.7 vs +53.3 ± 117.3 μmol/L, P = .004) by the control diet intake compared with soy protein. The control diet group had a higher incidence of newborn hyperbilirubinemia (32.4% vs 8.8%, P = .01) and newborn hospitalization (20.6% vs 2.9%, P = .02) compared with soy protein.

CONCLUSION

Soy protein consumption in women with GDM significantly improved the glucose homeostasis parameters, triglycerides, and biomarkers of oxidative stress, as well as reductions in the incidence of newborn hyperbilirubinemia and hospitalizations.

A select review reporting the quality of studies measuring endothelial dysfunction in randomised diet intervention trials

A quality assessment of the primary studies reported in the literature carried out using select dietary ingredients (DI) purported to affect vascular endothelial function was conducted through a systematic PubMed search from January 2000 to August 2012. A total of seventy randomised controlled trials with defined DI (folic acid (fifteen), n-3 fatty acids (twenty), cocoa (fifteen) and isoflavones (twenty)) and standardised measures of vascular endothelial function were evaluated. Jadad scores, quality scoring parameters for DI and flow-mediated dilation (FMD) methodology used were ascertained. A total of 3959 randomised subjects, mean age 51 (se 0·21) years (range 9-79 years), were represented in the dataset. The mean Jadad scores did not differ statistically among the DI studies, with the majority of the studies being of good quality. Higher DI quality scores were achieved by studies using the botanical ingredients cocoa and isoflavones than by those using the nutrient ingredients folic acid and n-3 fatty acids. The mean DI quality scores were 4·13 (se 0·34), 5·20 (se 0·47), 6·13 (se 0·41) and 6·00 (se 0·59) for the folic acid, n-3 fatty acid, cocoa and isoflavone intervention studies, respectively (and significantly different). The mean Corretti FMD scores were 7·27 (se 0·56), 7·46 (se 0·79), 6·29 (se 0·61) and 7·11 (se 0·56) for the folic acid, n-3 fatty acid, cocoa and isoflavone intervention studies, respectively (NS). FMD studies failed to adequately describe the equipment used and more than half failed to provide an adequate description of the procedures used for vascular image acquisition and measurement. DI can be utilised for dietary intervention studies; however, the methodology should be clearly reported using the guidelines for assessment for both DI and FMD.

Vitamin D receptor BsmI polymorphism modulates soy intake and 25-hydroxyvitamin D supplementation benefits in cardiovascular disease risk factors profile

Vitamin D receptor polymorphisms may predispose that not all individuals could have benefits from the nutritional supplementation of 25-hydroxyvitamin D. Furthermore, vitamin D-related cardiovascular effects may also be influenced by soy isoflavones considered endocrine regulators of cardiovascular homeostasis. To find possible gene-diet interactions by evaluating individualized lipid metabolism benefits from an increase in soy and 25-hydroxyvitamin D intake, 106 healthy individuals, genotyped for vitamin D receptor (VDR) gene polymorphism rs1544410 (BsmI) were randomly assigned to either no intake, to daily 250 mL or 500 mL of a 25-hydroxyvitamin D supplemented SB for 2 months. The soybean beverage induced differences in cardiovascular risk factors (lipid profile, blood pressure, TNFα and MCP-1), as well as vitamin D metabolites in a dose-gene-dependent relation. Thus, VDR BsmI polymorphism affected individual response being the GG genotype the ones that showed dose-dependent manner responsiveness in the reduction in total cholesterol, LDL and triglycerides in comparison with the AA/AG genotype. These differences were associated with increased plasma levels of 1α,25-dyhydroxyvitamin D3 in the carriers of the GG genotype. It was concluded that metabolic response to 25-hydroxyvitamin D and soybean supplementation is dependent on VDR BsmI GG genotype due to a higher conversion rate from vitamin D precursors.

Effect of dairy proteins on appetite, energy expenditure, body weight, and composition: a review of the evidence from controlled clinical trials

Evidence supports that a high proportion of calories from protein increases weight loss and prevents weight (re)gain. Proteins are known to induce satiety, increase secretion of gastrointestinal hormones, and increase diet-induced thermogenesis, but less is known about whether various types of proteins exert different metabolic effects. In the Western world, dairy protein, which consists of 80% casein and 20% whey, is a large contributor to our daily protein intake. Casein and whey differ in absorption and digestion rates, with casein being a "slow" protein and whey being a "fast" protein. In addition, they differ in amino acid composition. This review examines whether casein, whey, and other protein sources exert different metabolic effects and targets to clarify the underlying mechanisms. Data indicate that whey is more satiating in the short term, whereas casein is more satiating in the long term. In addition, some studies indicate that whey stimulates the secretion of the incretin hormones glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide more than other proteins. However, for the satiety (cholecystokinin and peptide YY) and hunger-stimulating (ghrelin) hormones, no clear evidence exists that 1 protein source has a greater stimulating effect compared with others. Likewise, no clear evidence exists that 1 protein source results in higher diet-induced thermogenesis and promotes more beneficial changes in body weight and composition compared with other protein sources. However, data indicate that amino acid composition, rate of absorption, and protein/food texture may be important factors for protein-stimulated metabolic effects.

Effect of flavonoids on circulating levels of TNF-α and IL-6 in humans: a systematic review and meta-analysis

Epidemiological or in vitro evidence suggests a potential role for flavonoids as anti-inflammatory agents; we investigated the effect of flavonoids-rich foods or supplements on tumor necrosis factor- alpha (TNF-α) and interleukin-6 (IL-6) in long-term placebo-controlled human intervention trials. From 110 human intervention studies selected (MEDLINE, EMBASE, CHORANE, and FSTA databases), 32 long-term placebo-controlled trials were suitable for meta-analysis. After sensitivity analysis, seven studies imputed of bias were excluded and 25 studies were analyzed (TNF-α, n = 2404; IL-6, n = 2174). Levels of TNF-α decreased after flavonoid consumption in the fixed model only (mean difference (MD) (95% CI): -0.098 (-0.188, -0.009), p = 0.032), but metaregression results showed that neither higher dose, nor a longer duration of intervention were associated with a greater effect size. Subgroup analysis did not reveal any significant effect for quercetin and soy, but other sources (red wine, pomegranate, and tea extracts) showed a significant effect size both in fixed (MD (95% CI): TNF-α -0.449 (-0.619, -0.280), p < 0.001; IL-6 -0.346 (-0.612, -0.079), p = 0.011) and random (MD (95% CI): TNF-α -0.783 (-1.476, -0.090), p = 0.027; IL-6, -0.556 (-1.062, -0.050), p = 0.031) effect models. High-quality placebo-controlled trials are needed in order to identify flavonoids as the active ingredients.

Favourable effects of the Dietary Approaches to Stop Hypertension diet on glucose tolerance and lipid profiles in gestational diabetes: a randomised clinical trial

Although gestational diabetes mellitus (GDM) is associated with an increased risk of maternal and neonatal morbidity, there is no consensus as to the optimal approach of nutritional management in these patients. The present study was designed to assess the effect of the Dietary Approaches to Stop Hypertension (DASH) eating plan on glucose tolerance and lipid profiles of pregnant women with GDM. The present randomised controlled clinical trial was performed among thirty-four women diagnosed with GDM at 24–28 weeks of gestation. Subjects were randomly assigned to consume either the control diet (n 17) or the DASH eating pattern (n 17) for 4 weeks. The control diet was designed to contain 45–55 % carbohydrates, 15–20 % protein and 25–30 % total fat. The macronutrient composition of the DASH diet was similar to the control diet; however, the DASH diet was rich in fruits, vegetables, whole grains and low-fat dairy products, and contained lower amounts of saturated fats, cholesterol and refined grains with a total of 2400 mg Na/d. Fasting blood samples were taken at baseline and after 4 weeks of intervention to measure fasting plasma glucose, glycated Hb (HbA1c) and lipid profiles. Participants underwent a 3 h oral glucose tolerance tests and blood samples were collected at 60, 120 and 180 min to measure plasma glucose levels. Adherence to the DASH eating pattern, compared with the control diet, resulted in improved glucose tolerance such that plasma glucose levels reduced at 60 ( − 1·86 v. − 0·45 mmol/l, Pgroup= 0·02), 120 ( − 2·3 v. 0·2 mmol/l, Pgroup= 0·001) and 180 min ( − 1·7 v. 0·22 mmol/l, Pgroup= 0·002) after the glucose load. Decreased HbA1c levels ( − 0·2 v. 0·05 %, Pgroup= 0·001) was also seen in the DASH group compared with the control group. Mean changes for serum total ( − 0·42 v. 0·31 mmol/l, Pgroup= 0·01) and LDL-cholesterol ( − 0·47 v. 0·22 mmol/l, Pgroup= 0·005), TAG ( − 0·17 v. 0·34 mmol/l, Pgroup= 0·01) and total:HDL-cholesterol ratio ( − 0·6 (sd 0·9) v. 0·3 (sd 0·8), Pgroup= 0·008) were significantly different between the two diets. Additionally, consumption of the DASH diet favourably influenced systolic blood pressure ( − 2·6 v. 1·7 mmHg, Pgroup= 0·001). Mean changes of fasting plasma glucose ( − 0·29 v. 0·15 mmol/l, Pgroup= 0·09) were non-significant comparing the DASH diet with the control diet. In conclusion, consumption of the DASH eating pattern for 4 weeks among pregnant women with GDM resulted in beneficial effects on glucose tolerance and lipid profiles compared with the control diet.

Impact of postprandial glycaemia on health and prevention of disease

Postprandial glucose, together with related hyperinsulinemia and lipidaemia, has been implicated in the development of chronic metabolic diseases like obesity, type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). In this review, available evidence is discussed on postprandial glucose in relation to body weight control, the development of oxidative stress, T2DM, and CVD and in maintaining optimal exercise and cognitive performance. There is mechanistic evidence linking postprandial glycaemia or glycaemic variability to the development of these conditions or in the impairment in cognitive and exercise performance. Nevertheless, postprandial glycaemia is interrelated with many other (risk) factors as well as to fasting glucose. In many studies, meal-related glycaemic response is not sufficiently characterized, or the methodology with respect to the description of food or meal composition, or the duration of the measurement of postprandial glycaemia is limited. It is evident that more randomized controlled dietary intervention trials using effective low vs. high glucose response diets are necessary in order to draw more definite conclusions on the role of postprandial glycaemia in relation to health and disease. Also of importance is the evaluation of the potential role of the time course of postprandial glycaemia.

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

BACKGROUND AND AIM

The effect of soy isoflavones on blood pressure is controversial. The objective of this study was to evaluate the effect of dietary soy isoflavones on blood pressure.

METHODS AND RESULTS

Trials were searched in PubMed, the Cochrane Library, Embase and references cited in related reviews and studies. A total of eleven trials were reviewed. Meta-analysis results showed a mean decrease of 2.5 mm Hg (95% CIs, - 5.35 to 0.34 mm Hg; P = 0.08) for systolic blood pressure and 1.5 mm Hg (95% CIs, - 3.09 to 0.17 mm Hg; P = 0.08) for diastolic blood pressure in the soy isoflavones-treated group compared to placebo. Meta-regression and subgroup analyses indicated that blood pressure status was a significant predictor of heterogeneity for the effect of soy isoflavones on blood pressure. Subgroup analysis of hypertensive subjects revealed that a greater blood pressure reduction was identified in the soy isoflavone-treated group compared to placebo (5 trials; SBP: - 5.94, 95% CIs [- 10.55, - 1.34] mm Hg, P = 0.01; DBP: - 3.35, 95% CIs [- 6.52, - 0.19] mm Hg, P = 0.04). In contrast, treatment with soy isoflavones did not lead to a significant reduction in blood pressure in normotensive subjects (6 trials; SBP: 0.29, 95% CIs [- 2.39, 2.97] mm Hg, P = 0.83; DBP: - 0.43, 95% CIs [- 1.66, 0.81] mm Hg, P = 0.50).

CONCLUSION

Soy isoflavones had an effect of lowering blood pressure in hypertensive subjects, but not in normotensive subjects. Larger trials need to be carried out to confirm the present findings.

Exposure to isoflavone-containing soy products and endothelial function: a Bayesian meta-analysis of randomized controlled trials

BACKGROUND AND AIMS

To determine whether and to what degree exposure to isoflavone-containing soy products affects EF. Endothelial dysfunction has been identified as an independent coronary heart disease risk factor and a strong predictor of long-term cardiovascular morbidity and mortality. Data on the effects of exposure to isoflavone-containing soy products on EF are conflicting.

METHODS AND RESULTS

A comprehensive literature search was conducted using the PUBMED database (National Library of Medicine, Bethesda, MD) inclusively through August 21, 2009 on RCTs using the keywords: soy, isoflavone, phytoestrogen, EF, flow mediated vasodilation, and FMD. A Bayesian meta-analysis was conducted to provide a comprehensive account of the effect of isoflavone-containing soy products on EF, as measured by FMD. A total of 17 RCTs were selected as having sufficient data for study inclusion. The overall mean absolute change in FMD (95% Bayesian CI) for isoflavone-containing soy product interventions was 1.15% (-0.52, 2.75). When the effects of separate interventions were considered, the treatment effect for isolated isoflavones was 1.98% (0.07, 3.97) compared to 0.72% (-1.39, 2.90) for isoflavone-containing soy protein. The models were not improved when considering study-specific effects such as cuff measurement location, prescribed dietary modification, and impaired baseline FMD.

CONCLUSIONS

Cumulative evidence from the RCTs included in this meta-analysis indicates that exposure to soy isoflavones can modestly, but significantly, improve EF as measured by FMD. Therefore, exposure to isoflavone supplements may beneficially influence vascular health.

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

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

Effects of soy intake on glycemic control: a meta-analysis of randomized controlled trials

BACKGROUND

Evidence from animal and observational studies has supported the beneficial effects of soy intake on glycemic control, but intervention studies in humans have generated mixed results and have not been systematically examined.

OBJECTIVE

We aimed to quantitatively evaluate the effects of soy intake on measures of glycemic control.

DESIGN

We conducted a structured electronic search of PubMed, EMBASE, the Cochrane Library, and the China National Knowledge Infrastructure (updated to March 2010) databases for randomized controlled trials that described the effectiveness of different soy regimes on measures of glycemic control [homeostatic model assessment of insulin resistance (HOMA-IR) and fasting glucose and insulin, glycated hemoglobin (Hb A(1c)), and 2-h glucose and insulin concentrations]. Data on participants, interventions, outcomes, and potential effect modifiers were extracted independently. Weighted mean effect sizes were calculated for net changes by using fixed-effects or random-effects models. We performed prespecified subgroup analyses to explore the influence of covariates on net changes of fasting glucose and insulin concentrations.

RESULTS

Twenty-four trials with a total of 1518 subjects were included in the meta-analysis. Soy consumption did not significantly affect measures of glycemic control. The mean (95% CI) difference was -0.69 mg/dL (-1.65, 0.27 mg/dL) for fasting glucose concentrations in the fixed-effects model (P = 0.16) and -0.18 mg/dL (-0.70, 0.34 mg/dL) for fasting insulin concentrations in the random-effects model (P = 0.50). Significant heterogeneity was noted in the results of fasting insulin concentrations and HOMA-IR.

CONCLUSIONS

There was not a significant overall effect of soy intake on improvements of fasting glucose and insulin concentrations; however, a favorable change in fasting glucose concentrations was observed in studies that used whole soy foods or a soy diet in the subgroup analysis. Evidence for other glycemic variables such as Hb A(1c) and 2-h postchallenge glucose and insulin concentrations was limited because of the small number of trials.

Equol: pharmacokinetics and biological actions

Equol [7-hydroxy-3-(4'-hydroxyphenyl)-chroman], an isoflavan produced by intestinal bacteria in response to soy isoflavone intake in some but not all humans, exhibits a wide range of biological properties. It exists as the diastereoisomers S-(-)equol and R-(+)equol. Intestinal bacteria produce exclusively S-(-)equol, which has selective affinity for estrogen receptor (ER)-beta. The evidence is conflicting on whether there is an advantage to producing S-(-)equol in response to soy isoflavone intakes, but the ability to now synthesize these diastereoisomers opens the way for future clinical trials to directly examine their potential in a number of hormone-dependent conditions. In this review, the plasma and urinary pharmacokinetics of S-(-)equol and R-(+)equol are reviewed and summarized, and some of the more recent evidence supporting potential biological effects of S-(-)equol is considered.

Soy and the exercise-induced inflammatory response in postmenopausal women

Aging is associated with increasing inflammation and oxidative stress in the body, both of which can have negative health effects. Successful attenuation of such processes with dietary countermeasures has major public health implications. Soy foods, as a source of high-quality protein and isoflavones, may improve such indices, although the effects in healthy postmenopausal women are not well delineated. A single-blind, randomized controlled trial was conducted in 31 postmenopausal women who were assigned to consume 3 servings of soy (n = 16) or dairy (n = 15) milk per day for 4 weeks. Parameters of systemic inflammation (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6)) and the oxidative defense system (superoxide dismutase (SOD), glutathione peroxidase, cyclooxygenase-2) were measured post supplementation, before and after an eccentric exercise bout performed to elicit an inflammatory response. A significant group-by-time effect for plasma TNF-α was observed (p = 0.02), with values in the dairy group increased post supplementation and then decreasing into the postexercise period. Additionally, significant time effects were observed for plasma SOD (p < 0.0001) and IL-6 (p < 0.0001) in the postexercise period. Overall results from our study do not support the notion that 4 weeks of daily soy milk ingestion can attenuate systemic elevations in markers of inflammation or oxidative defense. However, data do suggest that the downhill-running protocol utilized in this study can be effective in altering systemic markers of inflammation and oxidative defense enzyme activity, and that the ingestion of soy may help prevent fluctuations in plasma TNF-α.

Effects of soy protein and isoflavones on glycemic control and insulin sensitivity: a 6-mo double-blind, randomized, placebo-controlled trial in postmenopausal Chinese women with prediabetes or untreated early diabetes

BACKGROUND

In vitro and animal studies have suggested that soy protein and isoflavones have favorable effects on glucose and insulin regulation, but intervention studies in humans are limited, and the results are controversial.

OBJECTIVE

We investigated whether soy protein with isoflavones and soy isoflavone extracts could improve glycemic control and insulin sensitivity in postmenopausal women with early hyperglycemia.

DESIGN

This was a randomized, double-blind, placebo-controlled trial that included 180 postmenopausal Hong Kong Chinese women with prediabetes or early untreated diabetes. After a 2-wk adaptation period, participants were randomly assigned to 1 of 3 arms to receive 15 g soy protein and 100 mg isoflavones, 15 g milk protein and 100 mg isoflavones, or 15 g milk protein on a daily basis for 6 mo.

RESULTS

Three- or 6-mo treatments with soy protein with or without isoflavone supplementation did not result in favorable changes in the descriptors for glycemic control and insulin resistance, namely fasting and 2-h postload glucose, fasting and postload insulin, glycated serum protein, and homeostasis model assessment for insulin resistance and beta-cell function.

CONCLUSIONS

This 6-mo randomized controlled trial did not support the hypothesis that soy protein with or without isoflavone supplementation had favorable effects on glycemic control and insulin sensitivity among postmenopausal Chinese women. The favorable change in postload glucose needs to be further confirmed.

Effect of oral isoflavone supplementation on vascular endothelial function in postmenopausal women: a meta-analysis of randomized placebo-controlled trials

BACKGROUND

The effect of isoflavone on endothelial function in postmenopausal women is controversial.

OBJECTIVE

The objective of this study was to evaluate the effect of oral isoflavone supplementation on endothelial function, as measured by flow-mediated dilation (FMD), in postmenopausal women.

DESIGN

A meta-analysis of randomized placebo-controlled trials was conducted to evaluate the effect of oral isoflavone supplementation on endothelial function in postmenopausal women. Trials were searched in PubMed, Embase, the Cochrane Library database, and reviews and reference lists of relevant articles. Summary estimates of weighted mean differences (WMDs) and 95% CIs were obtained by using random-effects models. Meta-regression and subgroup analyses were performed to identify the source of heterogeneity.

RESULTS

A total of 9 trials were reviewed in the present meta-analysis. Overall, the results of the 9 trials showed that isoflavone significantly increased FMD (WMD: 1.75%; 95% CI: 0.83%, 2.67%; P = 0.0002). Meta-regression analysis indicated that the age-adjusted baseline FMD was inversely related to effect size. Subgroup analysis showed that oral supplementation of isoflavone had no influence on FMD if the age-adjusted baseline FMD was > or = 5.2% (4 trials; WMD: 0.24%; 95% CI: -0.94%, 1.42%; P = 0.69). This improvement seemed to be significant when the age-adjusted baseline FMD levels were <5.2% (5 trials; WMD: 2.22%; 95% CI: 1.15%, 3.30%; P < 0.0001), although significant heterogeneity was still detected in this low-baseline-FMD subgroup.

CONCLUSIONS

Oral isoflavone supplementation does not improve endothelial function in postmenopausal women with high baseline FMD levels but leads to significant improvement in women with low baseline FMD levels.

Soy consumption, adhesion molecules, and pro-inflammatory cytokines: a brief review of the literature

Given the interest in the vascular effects of both soyfoods and soy isoflavones, the purpose of this short review is to evaluate clinical trials that have examined the effects of isoflavone-rich soy products on the novel cardiovascular risk factors, cellular adhesion molecules, and pro-inflammatory cytokines. A total of 14 randomized clinical studies were assessed. From the data evaluated, evidence suggests that neither soyfoods nor soy isoflavones affect IL-6 or TNF-alpha expression. In contrast, the effects of soy on cellular adhesion molecules are mixed. Study design characteristics possibly contributing to the inconsistent data are discussed and recommendations for future research in this area are presented.

Novel black soy peptides with antiobesity effects: activation of leptin-like signaling and AMP-activated protein kinase

OBJECTIVE

To investigate the mechanisms underlying the antiobesity effects of a novel isoflavone-free peptide mixture (BSP) derived from black soybean.

DESIGN

Long-term effects of BSP were evaluated in diet-induced obese (DIO) mice fed a high-fat (HF) diet without or with BSP (2, 5 or 10% of energy) for 13 weeks, or for 8 weeks in combination with exercise. Acute effects of BSP on food intake and body weight in rats and leptin-deficient ob/ob mice were evaluated. Cell culture models or tissue extracts were used to investigate the mechanisms underlying the antiobesity effect.

MEASUREMENT

Total food intake, body weight gain, white adipose tissue (WAT) mass, plasma concentrations of leptin, adiponectin, cholesterol and triglyceride were measured. Janus kinase 2 (JAK2)-dependent signal transducers and activators of the transcription 3 (STAT3) phosphorylation and AMP-activated protein kinase (AMPK) activity were determined using Western-blot in cultured cells or tissue extracts.

RESULTS

DIO mice fed an HF diet with BSP (2, 5 or 10%) for 13 weeks gained less body weight (21.4, 19.8 or 17.1 g, respectively) than the mice fed an HF diet without BSP (22.6 g) concurrent with inhibition of total food intake in a dose-dependent manner. BSP also significantly decreased food intake in rats and leptin-deficient ob/ob mice. The highest dose of BSP (10%) significantly elevated the plasma adiponectin and decreased plasma triglyceride. BSP activated JAK2-dependent STAT3 in a cell model, and elevated the level of hypothalamic phospho-STAT3 in ob/ob mice. BSP also phosphorylated AMPK and acetyl-CoA carboxylase of C2C12 myocytes in a dose-dependent manner. The antiobesity effect was augmented by low-intensity wheel-based exercise. In exercised mice, BSP significantly decreased periepididymal WAT mass and body weight gain.

CONCLUSION

These results provided evidences that BSP decreased appetite and HF diet-induced body weight gain particularly in combination with exercise, through leptin-like STAT3 phosphorylation and AMPK activation.

The evidence for dietary prevention and treatment of cardiovascular disease

During the past few decades numerous studies have reported the atherogenic potential of saturated fatty acids, trans-fatty acids, and cholesterol, and beneficial effects of fiber, phytostanols/phytosterols, n-3 fatty acids, a Mediterranean diet, and other plant-based approaches. The purpose of this article is to provide a comprehensive and systematic review of the evidence associated with key dietary factors and risk of cardiovascular disease-an umbrella term encompassing diseases that affect the heart and blood vessels, including coronary heart disease, coronary artery disease, dyslipidemia, and hypertension-in conjunction with the work of the American Dietetic Association Evidence Analysis Library review on diet and lipids, updated with new evidence from the past 2 years. The criteria used and results cited provide scientific rationale for food and nutrition professionals and other health professionals for counseling patients. Details of these searches are available within the American Dietetic Association Evidence Analysis Library online (http://adaevidencelibrary.com). Potential mechanisms and needs for future research are summarized for each relevant nutrient, food, or food component.

Pasta naturally enriched with isoflavone aglycons from soy germ reduces serum lipids and improves markers of cardiovascular risk

Most studies of soy and cholesterol have tested foods made from purified soy proteins containing mainly isoflavone glycosides. Fermented soy foods have mainly isoflavone aglycons and account for a high proportion of the soy protein source in Asia, where there is an inverse relationship between soy intake and serum cholesterol. The aim of this study was to compare a novel soy germ pasta, naturally enriched in isoflavone aglycons as a result of the manufacturing process, with conventional pasta for effects on serum lipids and other cardiovascular risk markers. In this randomized, controlled, parallel study design of 62 adults with hypercholesterolemia who consumed a Step II diet that included one 80-g serving/d of pasta, we measured serum lipids, high sensitivity C-reactive protein (hsCRP), urinary isoprostanes, and brachial artery flow-mediated vasodilatation at baseline and after 4 and 8 wk. The pasta delivered 33 mg of isoflavones and negligible soy protein and led to a serum isoflavone concentration of 222 +/- 21 nmol/L; 69% of subjects were equol producers. Soy germ pasta reduced serum total and LDL cholesterol by 0.47 +/- 0.13 mmol/L (P = 0.001) and 0.36 +/- 0.10 mmol/L (P = 0.002) more than conventional pasta, representing reductions from baseline of 7.3% (P = 0.001) and 8.6% (P = 0.002), respectively. Arterial stiffness (P = 0.003) and hsCRP (P = 0.03) decreased and improvements in all the above risk markers were greatest in equol producers. All measures returned to baseline when patients were switched to conventional pasta. In conclusion, pasta naturally enriched with isoflavone aglycons and lacking soy protein had a significant hypocholesterolemic effect beyond a Step II diet and improved other cardiovascular risk markers.

Are soy foods protective against ischemic stroke?

Ischemic stroke is one of the leading causes of mortality and morbidity in the world. A large number of studies have observed the beneficial effects of soy protein and soy polyunsaturated fat in lowering blood cholesterol, reducing blood pressure and improving cardiovascular health. This study aims to investigate the potential of a soy food diet in the prevention of ischemic stroke through evaluation of evidence from clinical trials, meta-analyses, experimental and epidemiological studies.

Modificaciones en el perfil lipídico tras el consumo regular de conservas de pescado. Influencia de la adición de isoflavonas, ácidos grasos omega-3 y fitoesteroles

BACKGROUND AND OBJECTIVE

Changes in dietary habits are associated with an improvement of lipid profile. We decided to assess changes in lipid profile reached with a dietary enrichment with canned tuna in olive oil and compared them with those reached with canned tuna with additional supplementation.

SUBJECTS AND METHOD

In a prospective, randomized, single blind study, 400 participants were assigned to a daily intake of canned tuna in olive oil alone (control group) or enriched with: isoflavones, omega-3 fatty acids of phytosterols, during three months. Plasmatic lipid levels were measured before and after intervention. Changes of lipid levels between basal and final visits and differences between the 4 types of supplementations were evaluated.

RESULTS

The mean age of the study population was 53 years, 45% of them being males. In all 4 groups a significant reduction of total cholesterol, low-density lipoprotein (LDL)-cholesterol levels and total cholesterol/high-density lipoprotein (HDL)-cholesterol ratio was observed after 3 months of follow-up; there were no significant changes of triglycerides nor HDL-cholesterol levels. The comparison between different types of supplementation revealed that only phytosterols addition reached a greater reduction of total cholesterol and LDL-cholesterol levels than canned tuna in olive oil alone (p < 0.05), and the differences between the remaining 2 supplementations and the control group were not significant.

CONCLUSIONS

Regular intake of enrichment with canned tuna supplementation is associated with improvement of lipid profile. The addition of isoflavones, omega-3 fatty acids or phytosterols supplementations increases fish consume effect, although only the enrichment with phytosterols reaches significantly better results.

Hypocholesterolaemic effects of soya proteins: results of recent studies are predictable from the Anderson meta-analysis data

In 1995, Andersonet al.published a meta-analysis, derived from most of the clinical studies on soya proteins given to individuals with varying levels of cholesterolaemia that had been reported up to that time. The meta-analysis clearly indicated that cholesterolaemias were generally reduced by diets with soya given as a partial or total substitution of animal proteins, with final mean total and LDL-cholesterol reductions of 23·2 mg/dl and 21·7 mg/dl, respectively. These findings were recently strongly criticised, based on the evaluation of later studies, frequently involving individuals with normal or moderately elevated cholesterolaemias. In the present paper, these more recent studies were re-evaluated using a ‘nomogram’ prepared on the basis of the quartiles of initial cholesterol concentrations in the Anderson meta-analysis and their corresponding CI for net cholesterol change. The five studies belonging to the first quartile and thirteen out of the fourteen belonging to the second quartile gave results perfectly in line with the nomogram. Out of the fourteen studies belonging to the third quartile, ten agreed with the nomogram and two gave lower cholesterol reductions, whereas two gave higher reductions. Unfortunately, none of the recent studies belonged to the fourth quartile as treatment with statins or other lipid-lowering drugs is now mandatory in the presence of very high cholesterol levels. The re-evaluation thus shows that the thirty-three studies published in the past 10 years are in agreement with the Anderson meta-analysis and confirm its validity.

Effects of a supplement containing isoflavones and Actaea racemosa L. on asymmetric dimethylarginine, lipids, and C-reactive protein in menopausal women

OBJECTIVE

To investigate the effects of a supplement containing soy isoflavones and Actaea racemosa L. on several coronary heart disease (CHD) risk markers in menopausal women.

DESIGN

Randomized, placebo-controlled, double-blind study.

SETTING

Nine hospitals in The Netherlands.

PATIENT(S)

One hundred twenty-four menopausal women.

INTERVENTION(S)

Daily placebo (n = 64) or supplement containing soy isoflavones and Actaea racemosa L. (n = 60) for 12 weeks.

MAIN OUTCOME MEASURE(S)

Fasting blood concentrations of asymmetric dimethylarginine (ADMA), lipids, and C-reactive protein (CRP) at baseline and week 12.

RESULT(S)

In the supplement group, total cholesterol and low-density lipoprotein cholesterol showed a small absolute reduction at week 12 (-0.2, 95% confidence interval [CI] -0.3 to -0.0; and -0.2, 95% CI -0.3 to -0.0; respectively). Concentrations of ADMA, triglycerides, lipoprotein(a), and CRP did not change significantly. Analysis of covariance over the 12-week study period revealed no significant between-group differences for all parameters. No significant correlations were found between the concentrations of isoflavones and the CHD risk markers investigated.

CONCLUSION(S)

Twelve-week administration of a supplement containing soy isoflavones and Actaea racemosa L. had little or no influence on the CHD risk markers studied. This supplement probably has neither protective nor adverse effects on the cardiovascular system; however, large long-term studies are needed to test this.

Soy inclusion in the diet improves features of the metabolic syndrome: a randomized crossover study in postmenopausal women

BACKGROUND

Little evidence exists regarding the effects of soy consumption on the metabolic syndrome in humans.

OBJECTIVE

We aimed to determine the effects of soy consumption on components of the metabolic syndrome, plasma lipids, lipoproteins, insulin resistance, and glycemic control in postmenopausal women with the metabolic syndrome.

DESIGN

This randomized crossover clinical trial was undertaken in 42 postmenopausal women with the metabolic syndrome. Participants were randomly assigned to consume a control diet (Dietary Approaches to Stop Hypertension, DASH), a soy-protein diet, or a soy-nut diet, each for 8 wk. Red meat in the DASH period was replaced by soy-protein in the soy-protein period and by soy-nut in the soy-nut period.

RESULTS

The soy-nut regimen decreased the homeostasis model of assessment-insulin resistance score significantly compared with the soy-protein (difference in percentage change: -7.4 +/- 0.8; P < 0.01) or control (-12.9 +/- 0.9; P < 0.01) diets. Consumption of soy-nut also reduced fasting plasma glucose more significantly than did the soy-protein (-5.3 +/- 0.5%; P < 0.01) or control (-5.1 +/- 0.6%; P < 0.01) diet. The soy-nut regimen decreased LDL cholesterol more than did the soy-protein period (-5.0 +/- 0.6%; P < 0.01) and the control (-9.5 +/- 0.6%; P < 0.01) diet. Soy-nut consumption significantly reduced serum C-peptide concentrations compared with control diet (-8.0 +/- 2.1; P < 0.01), but consumption of soy-protein did not.

CONCLUSION

Short-term soy-nut consumption improved glycemic control and lipid profiles in postmenopausal women with the metabolic syndrome.