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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.

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.

SUBMITTER: Stull AJ

PROVIDER: S-EPMC4488775 | biostudies-literature | 2015 May

REPOSITORIES: biostudies-literature

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Project description:BackgroundAnthocyanin-rich blueberry intake is associated with reduced type 2 diabetes and cardiovascular disease (CVD) risk in prospective studies, although long-term randomized controlled trials (RCTs) have not been conducted in at-risk populations.ObjectiveIn the longest-duration RCT to date, we examined the effect of 6-mo blueberry intake on insulin resistance and cardiometabolic function in metabolic syndrome.MethodsA double-blind, parallel RCT (n = 115; age 63 ± 7 y; 68% male; body mass index 31.2 ± 3.0 kg/m2) was conducted, which fed 2 dietarily achievable blueberry intakes [equivalent to 1/2 and 1 cup/d (75/150 g)] compared with matched placebo. Insulin resistance was assessed via the homeostasis model assessment of insulin resistance (primary endpoint) and confirmed by [6-6-2H2]-glucose-labeled, 2-step hyperinsulinemic clamp (n = 20). Clinically relevant cardiometabolic endpoints [including flow-mediated dilatation, augmentation index, lipoprotein status (by nuclear magnetic resonance spectroscopy), and nitric oxide (NO)-related metabolite assay] and anthocyanin metabolism were assessed.ResultsA daily intake of 1 cup of blueberries improved endothelial function (flow-mediated dilatation: +1.45%; 95% CI: 0.83%, 2.1%; P = 0.003), systemic arterial stiffness (augmentation index: -2.24%; 95% CI: -3.97%, -0.61%; P = 0.04) and attenuated cyclic guanosine monophosphate concentrations. In statin nonusers (n = 71), elevated high-density lipoprotein cholesterol (+0.08 mmol/L; P = 0.03), high-density lipoprotein particle density (+0.48n, ×10-6; P = 0.002) and apolipoprotein A-I (+0.05 g/L; P = 0.01) concentrations were observed following the 1-cup/d intervention. Treatment compliance was 94.1% (wrapper returns) and total concentrations of anthocyanin-derived phenolic acid metabolites significantly increased, dose-dependently, in serum and 24-h urine (P < 0.01 and P < 0.001, respectively). Insulin resistance, pulse wave velocity, blood pressure, NO, and overall plasma thiol status were unaffected. Likewise, a half cup per day had no effect on any biomarkers.ConclusionsDespite insulin resistance remaining unchanged we show, to our knowledge, the first sustained improvements in vascular function, lipid status, and underlying NO bioactivity following 1 cup blueberries/d. With effect sizes predictive of 12-15% reductions in CVD risk, blueberries should be included in dietary strategies to reduce individual and population CVD risk. This study was registered at clinicaltrials.gov as NCT02035592.

Project description:BACKGROUND:Treatment for epistaxis includes application of intranasal vasoconstrictors. These medications have a precaution against use in patients with hypertension. Given that many patients who present with epistaxis are hypertensive, these warnings are commonly overridden by clinical necessity. OBJECTIVE:Our aim was to determine the effects of intranasal vasoconstrictors on blood pressure. METHODS:We conducted a single-center, randomized, double-blind, placebo-controlled trial from November 2014 through July 2016. Adult patients being discharged from the emergency department (ED) at Mayo Clinic (Rochester, Minnesota) were recruited. Patients were ineligible if they had a contraindication to study medications, had a history of hypertension, were currently taking antihypertensive or antidysrhythmic medications, or had nasal abnormalities, such as epistaxis. Subjects were randomized to one of four study arms (phenylephrine 0.25%; oxymetazoline 0.05%; lidocaine 1% with epinephrine 1:100,000; or bacteriostatic 0.9% sodium chloride [saline]). Blood pressure and heart rate were measured every 5 min for 30 min. RESULTS:Sixty-eight patients were enrolled in the study; of these, 63 patients completed the study (oxymetazoline, n = 15; phenylephrine, n = 20; lidocaine with epinephrine, n = 11; saline, n = 17). We did not observe any significant differences in mean arterial pressure over time between phenylephrine and saline, oxymetazoline and saline, or lidocaine with epinephrine and saline. The mean greatest increases from baseline in mean arterial pressure, systolic and diastolic blood pressure, and heart rate for each treatment group were also not significantly different from the saline group. CONCLUSIONS:Intranasal vasoconstrictors did not significantly increase blood pressure in patients without a history of hypertension. Our findings reinforce the practice of administering these medications to patients who present to the ED with epistaxis, regardless of high blood pressure.

Project description:BackgroundIn Sub-Saharan Africa, current strategies are struggling to control the burgeoning hypertension epidemic. Dietary interventions such as inorganic nitrate or folic acid supplementation could represent promising strategies for reducing blood pressure (BP) in this setting.ObjectivesThis feasibility study explores the effects of dietary inorganic nitrate supplementation, alone or in combination with folic acid, on BP in Tanzanian adults with elevated BP in Tanzania.MethodsA placebo-controlled, double-blind, randomized controlled feasibility trial was conducted. Forty-seven middle-aged and older participants (age: 50-70 y, BMI: 26.3-29.1 kg/m2) were randomly assigned to 3 conditions for a period of 60 d: 1) high-nitrate beetroot juice (∼400 mg nitrate) and folic acid (∼5 mg folic acid) (N + F), 2) high-nitrate beetroot juice and placebo (N + P), or 3) nitrate-depleted beetroot juice and placebo (P + P). Clinic and 24-h ambulatory BP and measurements of compliance in plasma (nitrate and folate concentrations) and saliva (nitrate and nitrite) were obtained at baseline, 30 d, and 60 d.ResultsBaseline resting systolic and diastolic BP (mean ± SD) was 151.0 ± 19.4 mm Hg and 91.8 ± 11.7 mm Hg, respectively. Compliance to the interventions was high (>90%) in all groups which was confirmed by the significant increase in nitrate and folic acid concentrations in plasma and saliva samples in the treatment arms. After 60 d, 24-h systolic BP dropped by -10.8 ± 9.8 mm Hg (P < 0.001), -6.1 ± 13.2 mm Hg (P = 0.03), and -0.3 ± 9.7 mm Hg (P = 0.83) in the N + P, N + F, and P + P groups, respectively. There was a significant decrease in 24-h diastolic BP in the N + P group (-5.4 ± 5.0 mm Hg, P = 0.004), whereas changes were not significant in the N + F (-1.8 ± 8.1 mm Hg, P = 0.32) and P + P (1.6 ± 8.3 mm Hg, P = 0.43) groups.ConclusionsDietary inorganic nitrate represents a potential nutritional strategy to lessen the hypertension epidemic in Sub-Saharan Africa. These findings support the rationale for future long-term investigations exploring the efficacy of dietary nitrate for lowering BP and attenuating cardiovascular disease risk in this setting.This trial was registered at isrctn.com as ISRCTN67978523.

Project description:BackgroundA fixed-dose combination of phentermine and extended-release topiramate (PHEN/TPM - approved for weight management) has demonstrated in-clinic reduction of blood pressure (BP). Ambulatory BP monitoring (ABPM) may be a better predictor of cardiovascular disease risk than in-clinic BP.MethodsThis randomized, multicenter, double-blind study enrolled 565 adults with overweight/obesity. Inclusion criteria included participants willing to wear ABPM device for 24 h. Exclusion criteria included screening blood pressure >140/90 mmHg and antihypertensive medications not stable for 3 months prior to randomization. Participants received placebo (n = 184), phentermine 30 mg; (n = 191), or PHEN 15 mg/TPM 92 mg; (n = 190). 24-hour ABPM was performed at baseline and at week 8. The primary endpoint was mean 24-h systolic BP (SBP) as measured by ABPM, in the per protocol population.ResultsParticipants were mostly female (73.5 %) and White (81.6 %), with a mean age of 53.4 years; 32.4 % had no hypertension diagnosis or treatment, 62.5 % had hypertension using 0 to 2 antihypertensive medications, and 5.1 % had hypertension using ≥ 3 antihypertensive medications. Baseline mean SBP/diastolic BP (DBP) was 123.9/77.6 mmHg. At week 8, mean SBP change was -0.1 mmHg (placebo), +1.4 mmHg (phentermine 30 mg), and -3.3 mmHg (PHEN/TPM). Between-group difference for PHEN/TPM versus placebo was -3.2 mmHg (95 % CI: -5.48, -0.93 mmHg; p = 0.0059). The between-group difference for PHEN/TPM versus phentermine 30 mg was -4.7 mmHg (95 % CI: -6.96, -2.45 mmHg; p < 0.0001). Common (>2 % in any treatment group) adverse events (i.e., dry mouth, constipation, nausea, dizziness, paresthesia, dysgeusia, headache, COVID-19, urinary tract infection, insomnia, and anxiety) were mostly mild or moderate.ConclusionsIn this randomized, multicenter, double-blind ABPM study, PHEN/ TPM reduced SBP compared to either placebo or phentermine 30 mg (Funding: Vivus LLC; ClinicalTrials.gov: NCT05215418).

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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.

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