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Effects of walnuts on endothelial function in overweight adults with visceral obesity: a randomized, controlled, crossover trial.

ABSTRACT: OBJECTIVES:Metabolic syndrome is a precursor of diabetes and cardiovascular disease (CVD). Walnut ingestion has been shown to reduce CVD risk indices in diabetes. This randomized controlled crossover trial was performed to investigate the effects of daily walnut consumption on endothelial function and other biomarkers of cardiac risk in a population of overweight individuals with visceral adiposity. METHODS:Forty-six overweight adults (average age, 57.4 years; 28 women, 18 men) with elevated waist circumference and 1 or more additional signs of metabolic syndrome were randomly assigned to two 8-week sequences of walnut-enriched ad libitum diet and ad libitum diet without walnuts, which were separated by a 4-week washout period. The primary outcome measure was the change in flow-mediated vasodilation (FMD) of the brachial artery. Secondary measures included serum lipid panel, fasting glucose and insulin, Homeostasis Model Assessment-Insulin Resistance values, blood pressure, and anthropometric measures. RESULTS:FMD improved significantly from baseline when subjects consumed a walnut-enriched diet as compared with the control diet (1.4% ± 2.4% versus 0.3% ± 1.5%; p = 0.019). Beneficial trends in systolic blood pressure reduction were seen, and maintenance of the baseline anthropometric values was also observed. Other measures were unaltered. CONCLUSION:Daily ingestion of 56 g of walnuts improves endothelial function in overweight adults with visceral adiposity. The addition of walnuts to the diet does not lead to weight gain. Further study of the potential role of walnut intake in diabetes and CVD prevention is warranted.

SUBMITTER: Katz DL

PROVIDER: S-EPMC3756625 | biostudies-literature | 2012 Dec

REPOSITORIES: biostudies-literature

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Effects of walnuts on endothelial function in overweight adults with visceral obesity: a randomized, controlled, crossover trial.

Katz David L DL Davidhi Anna A Ma Yingying Y Kavak Yasemin Y Bifulco Lauren L Njike Valentine Yanchou VY

Journal of the American College of Nutrition 20121201 6

<h4>Objectives</h4>Metabolic syndrome is a precursor of diabetes and cardiovascular disease (CVD). Walnut ingestion has been shown to reduce CVD risk indices in diabetes. This randomized controlled crossover trial was performed to investigate the effects of daily walnut consumption on endothelial function and other biomarkers of cardiac risk in a population of overweight individuals with visceral adiposity.<h4>Methods</h4>Forty-six overweight adults (average age, 57.4 years; 28 women, 18 men) wi ...[more]

PMID: 23756586

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Project description:BackgroundHigh-fat meal (HFM) consumption may induce transient postprandial atherogenic responses, including impairment of vascular endothelial function, in individuals with overweight/obesity. Red beetroot juice (RBJ) may modulate endothelial function and other measures of cardiometabolic health.ObjectiveThis study investigated the impact of acute and chronic RBJ consumption, including nitrate-dependent and -independent effects, on postprandial endothelial function and other cardiometabolic responses to a HFM.MethodsFifteen men and postmenopausal women with overweight/obesity were enrolled in this randomized, double-blind, placebo-controlled, 4-period, crossover clinical trial. Following an overnight fast, participants underwent baseline assessment of endothelial function (reactive hyperemia index; RHI) and hemodynamics, and biological sample collection. In random order, participants consumed 70 mL (acute visit) of: 1) RBJ, 2) nitrate-free RBJ (NF-RBJ), 3) placebo + nitrate (PBO + NIT), or 4) placebo (PBO), followed by a HFM. RHI was remeasured 4 h post-HFM, and hemodynamic assessment and biological sample collection were performed 1, 2, and 4 h post-HFM consumption. Participants consumed treatments daily for 4 wk (chronic visit), and assessments were repeated before/after the HFM (without consuming treatments).ResultsHFM consumption did not induce significant impairment of postprandial RHI. No significant differences in RHI were detected across treatment groups following acute or chronic exposure, despite increases in circulating nitrate/nitrite (NOx) concentrations in the RBJ and PBO + NIT groups compared with PBO and NF-RBJ (P < 0.0001 for all time points at the acute visit; P < 0.05 for all time points at the chronic visit). Although the HFM led to significant alterations in several secondary outcomes, there were no consistent treatment effects on postprandial cardiometabolic responses.ConclusionsHFM consumption did not impair postprandial endothelial function in this population, and RBJ exposure did not alter postprandial endothelial function or other outcomes despite increasing NOx concentrations. This trial is registered at clinicaltrials.gov as NCT02949115.

Project description:BackgroundThe 2015-2020 Dietary Guidelines for Americans recommend a Mediterranean-type diet as one of three healthful eating patterns. However, only one previous trial has evaluated the effects of a Mediterranean diet intervention in a US sample population.MethodsTo address this gap, we conducted a pilot, non-blinded, 8-week randomized controlled trial on the comparative efficacy of consumption of a Mediterranean diet or a diet supplemented with fish oil, walnuts, and grape juice versus controls. Participants (overweight or obese US adults; 73% female and mean age 51 years) were randomly assigned to one of three groups: (1) Mediterranean diet; (2) habitual high-fat American-type diet supplemented with fish oil, walnuts, and grape juice; or (3) habitual high-fat American-type diet (controls). Intent-to-treat analysis of within-subject differences (Student's paired t-test or Wilcoxon sign ranks test) and between-subject differences (mixed-effects models with a group-by-time interaction term, adjusted for baseline health outcome) was conducted.ResultsParticipants in the Mediterranean diet arm (n = 11) had significantly greater weight loss despite no significant change in total caloric intake, and lower plasma cystine, indicative of decreased oxidative stress, compared to controls (n = 9) at both 4 and 8 weeks. Compared to controls, they also had significantly lower total cholesterol and low-density lipoprotein cholesterol levels at 4 weeks. Participants in the supplement arm (n = 10) had significantly lower adiponectin levels compared to controls at 4 weeks. No significant improvements in endothelial function or inflammatory biomarkers were observed in either intervention group compared to controls.ConclusionThese results suggest that adopting a dietary pattern reflecting a Mediterranean diet improves weight and cardio-metabolic health among overweight or obese US adults, and may be more beneficial than supplementing habitual American diets with fish oil, walnuts, and grape juice.

Project description:Obesity is now considered a state of chronic low-grade inflammation. We investigated the relationship between several inflammatory markers and body composition for identifying patients with an increased risk of visceral obesity and compared the predictive values of inflammatory indices in visceral obesity.Six hundred individuals who received health checkups for obesity-related risk factors in Severance Hospital between January 2008 and March 2017 were included in our study. Serum inflammatory markers, such as white blood cell (WBC), high-sensitivity C-reactive protein (hsCRP), neutrophil-lymphocyte ratio (NLR), and platelet-lymphocyte ratio (PLR) levels were assessed. Intra-abdominal visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) areas were measured with computed tomography. We performed analysis of covariance, trend analysis, Steiger's Z tests, and multiple linear regression analysis to investigate associations between abdominal adiposity indices and inflammatory markers.Pearson's correlation analysis revealed a stronger association of VAT with WBC counts (r = 0.157, P < .001) than with levels of NLR (r = 0.108, P = .11; Steiger's Z test, P = .04) and PLR (r = 0.036, P = .39; Steiger's Z test, P = .003). WBC and hsCRP levels linearly increased with VAT area (overall P < .001 and trend P < .001) and VAT/SAT ratio (overall P = .001 and trend P = .002; overall P < .001 and trend P < .001, respectively) but linearly decreased with SAT (overall P = .02 and trend P = .17; overall P = .03 and trend P = .01, respectively). Visceral adipose tissue area was more highly associated with WBC and hsCRP levels than with NLR and PLR. Only VAT area was significantly associated with WBC, hsCRP, and NLR levels after adjusting for confounding variables.We found that VAT, but not SAT area is independently associated with several inflammatory markers. WBC and hsCRP are more strongly correlated with VAT compared with NLR and PLR. Thus, WBC and hsCRP could be useful parameters for identifying individuals at risk for visceral obesity and cardiometabolic diseases.

Dataset Information

Effects of walnuts on endothelial function in overweight adults with visceral obesity: a randomized, controlled, crossover trial.

Publications

Effects of walnuts on endothelial function in overweight adults with visceral obesity: a randomized, controlled, crossover trial.

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