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Blueberries improve endothelial function, but not blood pressure, in adults with metabolic syndrome: a randomized, double-blind, placebo-controlled clinical trial.
Stull, AJ, Cash, KC, Champagne, CM, Gupta, AK, Boston, R, Beyl, RA, Johnson, WD, Cefalu, WT
Nutrients. 2015;(6):4107-23
Abstract
Blueberry consumption has been shown to have various health benefits in humans. However, little is known about the effect of blueberry consumption on blood pressure, endothelial function and insulin sensitivity in humans. The present study investigated the role of blueberry consumption on modifying blood pressure in subjects with metabolic syndrome. In addition, endothelial function and insulin sensitivity (secondary measurements) were also assessed. A double-blind and placebo-controlled study was conducted in 44 adults (blueberry, n = 23; and placebo, n = 21). They were randomized to receive a blueberry or placebo smoothie twice daily for six weeks. Twenty-four-hour ambulatory blood pressure, endothelial function and insulin sensitivity were assessed pre- and post-intervention. The blood pressure and insulin sensitivity did not differ between the blueberry and placebo groups. However, the mean change in resting endothelial function, expressed as reactive hyperemia index (RHI), was improved significantly more in the group consuming the blueberries versus the placebo group (p = 0.024). Even after adjusting for confounding factors, i.e., the percent body fat and gender, the blueberry group still had a greater improvement in endothelial function when compared to their counterpart (RHI; 0.32 ± 0.13 versus -0.33 ± 0.14; p = 0.0023). In conclusion, daily dietary consumption of blueberries did not improve blood pressure, but improved (i.e., increased) endothelial function over six weeks in subjects with metabolic syndrome.
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Wine grape pomace flour improves blood pressure, fasting glucose and protein damage in humans: a randomized controlled trial.
Urquiaga, I, D'Acuña, S, Pérez, D, Dicenta, S, Echeverría, G, Rigotti, A, Leighton, F
Biological research. 2015;(1):49
Abstract
BACKGROUND The Mediterranean diet is a healthy diet with positive scientific evidence of preventing chronic diseases. Bioactive components support the healthy properties of the Mediterranean diet. Antioxidants and fiber, two components of the Mediterranean diet, are key functional nutrients for healthy eating and nutrition. Wine grape pomace is a rich source of these dietary constituents and may be beneficial for human health. Our hypothesis was that the intake of red wine grape pomace flour (WGPF) prepared from red wine grapes (Cabernet Sauvignon variety) reduced the metabolic syndrome in humans. To evaluate the effect of WGPF on components of metabolic syndrome we design a 16-week longitudinal intervention study. Thirty-eight males, 30-65 years of age, with at least one component of metabolic syndrome, were randomly assigned to either the intervention group (n = 25) or the control group (n = 13). At lunch, the intervention group was given 20 g of WGPF per day, which contained 10 g of dietary fiber, 822 mg of polyphenols and an antioxidant capacity of 7258 ORAC units. Both groups were asked to maintain their regular eating habits and lifestyles. Clinical evaluation, anthropometric measurements and biochemical blood analyses were done at the beginning and the end of the study. RESULTS WGPF intake significantly decreased systolic and diastolic blood pressure as well as fasting glucose levels. Plasma γ-tocopherol and δ-tocopherol increased and carbonyl group in plasma protein decreased in WGPT group, significantly. No significant effect was observed for waist circumference, HDL cholesterol, triglycerides, total antioxidant capacity and vitamin C in and between groups. The group-dependent magnitude of the differences between the baseline and final postprandial insulin values and γ-tocopherol concentrations was statistically significant. CONCLUSIONS The consumption of WGPF-rich in fiber and polyphenol antioxidants, as a food supplement in a regular diet improves blood pressure, glycaemia and postprandial insulin. In addition, increased antioxidant defenses and decreased oxidative protein damage indicating attenuation of oxidative stress. WGPF might be a useful food ingredient for health promotion and chronic disease prevention.
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Normal or High Polyphenol Concentration in Orange Juice Affects Antioxidant Activity, Blood Pressure, and Body Weight in Obese or Overweight Adults.
Rangel-Huerta, OD, Aguilera, CM, Martin, MV, Soto, MJ, Rico, MC, Vallejo, F, Tomas-Barberan, F, Perez-de-la-Cruz, AJ, Gil, A, Mesa, MD
The Journal of nutrition. 2015;(8):1808-16
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Abstract
BACKGROUND The consumption of orange juice may lead to reduced oxidative stress and may enhance the antioxidant defense system. OBJECTIVE The aim was to evaluate the effects of the intake of orange juice containing either normal (NPJ) or high (HPJ) concentrations of polyphenols (299 and 745 mg/d, respectively) on the antioxidant defense system, oxidative stress biomarkers, and clinical signs of metabolic syndrome in 100 nonsmoking subjects who were either overweight or obese. METHODS A randomized, double-blind crossover study was conducted over two 12-wk periods with a 7-wk washout period. The effects on enzymatic and nonenzymatic blood antioxidant defense systems, urinary and plasma oxidative stress biomarkers, and clinical signs of metabolic syndrome were evaluated before and after an intervention with both of the orange juices. Paired t tests and linear mixed-effects models were used to evaluate the effects of juice, time, and interactions. RESULTS The intake of either NPJ or HPJ led to a decrease in urinary 8-hydroxy-2'-deoxyguanosine (NPJ: 935 ± 134 to 298 ± 19 ng/mg creatinine; HPJ: 749 ± 84 to 285 ± 17 ng/mg creatinine), 8-iso-prostaglandin F2α (NPJ: 437 ± 68 to 156 ± 14 ng/mg creatinine; HPJ: 347 ± 43 to 154 ± 13 ng/mg creatinine), erythrocyte catalase, and glutathione reductase activities. A decrease was also observed in body mass index, waist circumference, and leptin (all P < 0.05). The NPJ intervention decreased systolic and diastolic blood pressures (systolic blood pressure: 128 ± 1 to 124 ± 2 mm Hg; diastolic blood pressure: 79 ± 1 to 76 ± 1 mm Hg), whereas the HPJ intervention increased erythrocyte superoxide dismutase (SOD) activity (17.7 ± 1.5 to 23.1 ± 1.7 U/mg hemoglobin). CONCLUSIONS Our results show that the consumption of either NPJ or HPJ protected against DNA damage and lipid peroxidation, modified several antioxidant enzymes, and reduced body weight in overweight or obese nonsmoking adults. Only blood pressure and SOD activity were influenced differently by the different flavanone supplementations. This trial was registered at clinicaltrials.gov as NCT01290250.
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A randomized controlled trial of the effects of pioglitazone treatment on sympathetic nervous system activity and cardiovascular function in obese subjects with metabolic syndrome.
Straznicky, NE, Grima, MT, Sari, CI, Eikelis, N, Lambert, GW, Nestel, PJ, Karapanagiotidis, S, Wong, C, Richards, K, Marusic, P, et al
The Journal of clinical endocrinology and metabolism. 2014;(9):E1701-7
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CONTEXT Insulin resistance and sympathetic nervous system overactivity are closely associated and contribute to cardiovascular risk. OBJECTIVE The objective of the study was to test the hypotheses that pharmacological improvement in insulin sensitivity would (1) attenuate sympathetic neural drive and (2) enhance neuronal norepinephrine uptake. PARTICIPANTS AND METHODS A randomized, double-blind trial was conducted in 42 obese, unmedicated individuals with metabolic syndrome (mean age 56 ± 1 y, body mass index 34 ± 0.6 kg/m(2)) who received 12 weeks of pioglitazone (PIO; 15 mg for 6 wk, then 30 mg daily) or matched placebo. Clinical measurements included whole-body norepinephrine kinetics [spillover rate, plasma clearance, and the steady state ratio of tritiated 3,4-dihydroxyphenylglycol to tritiated norepinephrine ([(3)H]-DHPG to [(3)H]-NE) as an index of neuronal uptake-1], muscle sympathetic nerve activity, spontaneous baroreflex sensitivity, euglycemic hyperinsulinemic clamp, oral glucose tolerance test, ambulatory blood pressure, and Doppler echocardiography. RESULTS PIO treatment increased glucose uptake by 35% and was accompanied by significant reductions in diastolic blood pressure and improved left ventricular diastolic and endothelial function. Resting muscle sympathetic nerve activity burst frequency decreased by -6 ± 3 burst/min compared with baseline (P = .03), but the magnitude of change was not different from placebo (P = .89). Norepinephrine spillover and clearance rates and baroreflex sensitivity were unchanged. Post hoc subgroup analyses revealed an 83% increase in [(3)H]-DHPG to [(3)H]-NE ratio in hyperinsulinemic (P = .04) but not normoinsulinemic subjects (time × group interaction, P = .045). Change in [(3)H]-DHPG to [(3)H]-NE ratio correlated with improvements in diastolic blood pressure (r = -0.67, P = .002), the ratio of early (E) to late (A) peak transmitral diastolic inflow velocity (r = 0.62, P = .008), E wave deceleration time (r = -0.48, P = .05), and Δinsulin area under the curve0-120 during the oral glucose tolerance test (r = -0.42, P = .08). CONCLUSIONS Compared with placebo, PIO does not affect resting sympathetic drive or norepinephrine disposition in obese subjects with metabolic syndrome. Treatment induced changes in the [(3)H]-DHPG to [(3)H]-NE ratio related to reduction in hyperinsulinemia and improvements in diastolic function.
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Effects of water extracts of Graptopetalum paraguayense on blood pressure, fasting glucose, and lipid profiles of subjects with metabolic syndrome.
Yen, CH, Chen, SJ, Liu, JT, Tseng, YF, Lin, PT
BioMed research international. 2013;:809234
Abstract
This study was aimed to investigate the effects of water extracts of Graptopetalum paraguayense (WGP, 4 g/d) on blood pressure, blood glucose level, and lipid profiles in subjects with metabolic syndrome (MS). Participants with MS (n = 54) were randomly assigned to the placebo (n = 28) and WGP groups (n = 26), and the intervention was administered for 12 weeks. Systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting glucose (FG), lipid profiles (total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C), and high density lipoprotein (HDL-C)), and antioxidant enzymes activities (catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx)) were measured. Forty-two subjects completed the study (placebo, n = 19; WGP, n = 23). FG, SBP, and LDL-C levels were significantly lower and HDL-C level and antioxidant enzymes activities (CAT and SOD) were significantly higher after WGP supplementation. Blood pressure, FG, and lipid profiles were significantly correlated with antioxidant enzymes activities after supplementation (P < 0.05). The present study demonstrated a significant reduction in blood pressure, blood glucose, and lipid profiles and an increase in antioxidant enzymes activities in subjects with MS after WGP supplementation. Taken together, the antioxidative capacity of WGP might exert a beneficial effect on MS. This trial is registered with ClinicalTrials.gov NCT01463748.
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Grape polyphenols reduce blood pressure and increase flow-mediated vasodilation in men with metabolic syndrome.
Barona, J, Aristizabal, JC, Blesso, CN, Volek, JS, Fernandez, ML
The Journal of nutrition. 2012;(9):1626-32
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Abstract
We evaluated the effects of grape polyphenols in individuals classified with metabolic syndrome (MetS). Men (n = 24) aged 30-70 y were randomly assigned to consume either a freeze-dried grape polyphenol powder (GRAPE) or a placebo for 30 d in a double-blind, crossover design, separated by a 3-wk washout period. Participants were asked to maintain their usual diet and physical activity during the study and abstain from consuming polyphenol-rich foods. MetS criteria including blood pressure (BP) and markers of vascular endothelial function including brachial artery flow-mediated vasodilation (FMD), plasma total nitrite + nitrate (NOx) to estimate NO production, plasma soluble intercellular adhesion molecule-1 (sICAM-1), and soluble vascular cell adhesion molecule-1 (sVCAM-1) were measured at the end of each dietary period. Systolic BP (P < 0.0025) and plasma sICAM-1 concentrations (P < 0.025) were lower, whereas the FMD response was higher (P < 0.0001), during the GRAPE compared with the placebo period. In addition, changes in sVCAM-1 concentrations between periods were positively correlated with changes in systolic BP (r = 0.45; P < 0.05). Although NOx concentrations did not differ between periods, changes in systolic BP were negatively correlated with changes in NOx concentrations (r = -0.44; P < 0.05), indicating the vasodilating properties of NO. Other MetS variables did not differ between the GRAPE and placebo periods. These results suggest that GRAPE polyphenols may potentiate vasorelaxation and reduce BP and circulating cell adhesion molecules, resulting in improvements in vascular function.