Dietary flavonoid intake, especially berry flavonoids, has been associated with reduced risks of cardiovascular disease (CVD) in large prospective cohorts. Few clinical studies have examined the effects of dietary berries on CVD risk factors. We examined the hypothesis that freeze-dried strawberries (FDS) improve lipid and lipoprotein profiles and lower biomarkers of inflammation and lipid oxidation in adults with abdominal adiposity and elevated serum lipids. In a randomized dose-response controlled trial, 60 volunteers [5 men and 55 women; aged 49 ± 10 y; BMI: 36 ± 5 kg/m(2) (means ± SDs)] were assigned to consume 1 of the following 4 beverages for 12 wk: 1) low-dose FDS (LD-FDS; 25 g/d); 2) low-dose control (LD-C); 3) high-dose FDS (HD-FDS; 50 g/d); and 4) high-dose control (HD-C). Control beverages were matched for calories and total fiber. Blood draws, anthropometrics, blood pressure, and dietary data were collected at screening (0 wk) and after 12-wk intervention. Dose-response analyses revealed significantly greater decreases in serum total and LDL cholesterol and nuclear magnetic resonance (NMR)-derived small LDL particle concentration in HD-FDS [33 ± 6 mg/dL, 28 ± 7 mg/dL, and 301 ± 78 nmol/L, respectively (means ± SEMs)] vs. LD-FDS (-3 ± 11 mg/dL, -3 ± 9 mg/dL, and -28 ± 124 nmol/L, respectively) over 12 wk (0-12 wk; all P < 0.05). Compared with controls, only the decreases in total and LDL cholesterol in HD-FDS remained significant vs. HD-C (0.7 ± 12 and 1.4 ± 9 mg/dL, respectively) over 12 wk (0-12 wk; all P < 0.05). Both doses of strawberries showed a similar decrease in serum malondialdehyde at 12 wk (LD-FDS: 1.3 ± 0.2 μmol/L; HD-FDS: 1.2 ± 0.1 μmol/L) vs. controls (LD-C: 2.1 ± 0.2 μmol/L; HD-C: 2.3 ± 0.2 μmol/L) (P < 0.05). In general, strawberry intervention did not affect any measures of adiposity, blood pressure, glycemia, and serum concentrations of HDL cholesterol and triglycerides, C-reactive protein, and adhesion molecules. Thus, HD-FDS exerted greater effects in lowering serum total and LDL cholesterol and NMR-derived small LDL particles vs. LD-FDS in the 12-wk study. These findings warrant additional investigation in larger trials. This trial was registered at clinicaltrials.gov as NCT01883401.
Green tea, a popular polyphenol-containing beverage, has been shown to alleviate clinical features of the metabolic syndrome. However, its effects in endogenous antioxidant biomarkers are not clearly understood. Thus, we tested the hypothesis that green tea supplementation will up-regulate antioxidant parameters (enzymatic and non-enzymatic) in adults with the metabolic syndrome. Thirty-five obese participants with the metabolic syndrome were randomly assigned to receive one of the following for 8 weeks: green tea (4 cups/day), control (4 cups water/day), or green tea extract (2 capsules and 4 cups water/day). Blood samples and dietary information were collected at baseline (0 week) and 8 weeks of the study. Circulating carotenoids (alpha-, beta-carotene, lycopene) and tocopherols (alpha-, gamma-tocopherols), and trace elements were measured using high performance liquid chromatography (HPLC) and inductively-coupled plasma mass spectroscopy (ICP-MS), respectively. Serum antioxidant enzymes (glutathione peroxidase, glutathione, catalase) and plasma antioxidant capacity were measured spectrophotometrically. Green tea beverage and green tea extract significantly increased plasma antioxidant capacity (1.5μmol/L to 2.3μmol/L and 1.2μmol/L to 2.5μmol/L respectively, p<0.05) and whole blood glutathione [1783 μg/g hemoglobin (Hb) to 2395 μg/g Hb and 1905 μg/g Hb to 2751 μg/g Hb, respectively, p<0.05] versus controls at 8 weeks. No effects were noted in serum levels of carotenoids and tocopherols and glutathione peroxidase and catalase activities. Green tea extract significantly reduced plasma iron versus baseline (128μg/dL to 92μg/dL, p<0.02), while copper, zinc, and selenium were not affected. These results support the hypothesis that green tea may provide antioxidant protection in the metabolic syndrome.
Aims. To examine the antioxidant and anti-inflammatory effects of pomegranate polyphenols in obese patients with type 2 diabetes (T2DM) (n = 8) and in healthy nondiabetic controls (n = 9). Methods. Participants received 2 capsules of pomegranate polyphenols (POMx, 1 capsule = 753 mg polyphenols) daily for 4 weeks. Blood draws and anthropometrics were performed at baseline and at 4 weeks of the study. Results. Pomegranate polyphenols in healthy controls and in T2DM patients did not significantly affect body weight and blood pressure, glucose and lipids. Among clinical safety profiles, serum electrolytes, renal function tests, and hematological profiles were not significantly affected by POMx supplementation. However, aspartate aminotransferase (AST) showed a significant increase in healthy controls, while alanine aminotransferase (ALT) was significantly decreased in T2DM patients at 4 weeks (P < 0.05), though values remained within the normal ranges. Among the biomarkers of lipid oxidation and inflammation, oxidized LDL and serum C-reactive protein (CRP) did not differ at 4 weeks in either group, while pomegranate polyphenols significantly decreased malondialdehyde (MDA) and hydroxynonenal (HNE) only in the diabetic group versus baseline (P < 0.05). Conclusions. POMx reduces lipid peroxidation in patients with T2DM, but with no effects in healthy controls, and specifically modulates liver enzymes in diabetic and nondiabetic subjects. Larger clinical trials are merited.
Endothelin (ET) effected a dose-dependent increment in atrial natriuretic peptide (ANP) secretion and ANP mRNA accumulation in neonatal rat atrial and ventricular cardiocytes but had no effect on the processing of the ANP prohormone to the mature ANP product. The secretagogue effect was not limited by cell density. Both basal and ET-dependent secretory activity were abrogated by the calmodulin antagonist calmidazolium but were unaffected by meclophenamate or pertussis toxin. The magnitude of the ET-dependent increment in ANP secretion was amplified by culturing the cells in a dynamically pulsating (vs. static) environment, implying an interaction between mechanical and agonist-mediated secretory stimuli in this system. ET also promoted immunoreactive ANP release from primary cultures of fetal rat hypothalamic cultures, suggesting that this regulatory function may be generally employed in ANP gene-expressing cells. These findings demonstrate that ET has parallel effects on ANP synthesis and secretion and support a role for this peptide in the regulation of local and circulating levels of the natriuretic hormone.
Blueberries are a good source of polyphenolic flavonoids and are known to be antioxidants and anti‐inflammatory agents. We tested the hypothesis that freeze‐dried blueberry supplementation may lower lipid peroxidation, inflammation, and other features of the metabolic syndrome (MeS). Thirty‐seven subjects with MeS (NCEP, ATP III) were randomized to receive either two cups of blueberry beverage daily or an equal amount of water, as control, for 8 weeks. Each cup of blueberry beverage contained 25g freeze‐dried blueberries blended with 1.5 cups water, 0.5 cup ice and 1 teaspoon vanilla essence. Blood draws, blood pressure and anthropometrics were performed at baseline and after 4 and 8 weeks. After 8 weeks, blueberry supplementation significantly decreased systolic blood pressure (blueberry: 130.1±3.3 to 122.3±2.6 mm Hg, p<0.05) and diastolic blood pressure (blueberry: 84.0±1.8 to 81.2±1.6 mm Hg, p<0.05). Blueberry supplementation was also associated with significant decreases in plasma oxidized‐LDL (blueberry: 106.3±3.3 U/l at baseline, 76.6±4.4 U/l at 8 weeks, p<0.05; control: 103.8±10.6 U/l at baseline, 96.4±7.6 U/l at 8 weeks, NS) and the lipid peroxidation product malondialdehyde (blueberry: 1.17±0.02 μM at baseline, 1.02±0.03 μM at 8 weeks, p<0.05; control: 1.14±0.02 μM at baseline, 1.1±0.01 μM at 8 weeks, NS). No effects were noted on body weight, waist circumference, glucose, lipid profiles and biomarkers of inflammation. Thus, blueberries may be included as part of a healthy diet in lowering selected CVD risk factors. Supported by US Highbush Blueberry Council
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