6 results on '"Ashor, Ammar W."'
Search Results
2. Effects of inorganic nitrate and beetroot supplementation on endothelial function: a systematic review and meta-analysis
- Author
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Lara, Jose, Ashor, Ammar W., Oggioni, C., Ahluwalia, A., Mathers, John C., and Siervo, Mario
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- 2016
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3. Mediterranean Diet Increases Endothelial Function in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
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Shannon, Oliver M, Mendes, Inês, Köchl, Christina, Mazidi, Mohsen, Ashor, Ammar W, Rubele, Sofia, Minihane, Anne-Marie, Mathers, John C, and Siervo, Mario
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MEDITERRANEAN diet ,RANDOMIZED controlled trials ,META-analysis ,ADULTS ,CARDIOVASCULAR disease prevention ,ENDOTHELIUM physiology ,RESEARCH ,CLINICAL trials ,RESEARCH methodology ,SYSTEMATIC reviews ,HEALTH status indicators ,EVALUATION research ,MEDICAL cooperation ,VASODILATION ,COMPARATIVE studies ,MEDLINE ,BODY mass index ,CARDIOVASCULAR disease diagnosis - Abstract
Background: The endothelium plays a key role in the maintenance of vascular health and represents a potential physiological target for dietary and other lifestyle interventions designed to reduce the risk of cardiovascular diseases (CVD) including stroke or coronary heart disease.Objective: To conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) investigating the effects of the Mediterranean dietary pattern (MedDiet) on endothelial function.Methods: Medline, Embase, and Scopus databases were searched from inception until January 2019 for studies that met the following criteria: 1) RCTs including adult participants, 2) interventions promoting the MedDiet, 3) inclusion of a control group, and 4) measurements of endothelial function. A random-effects meta-analysis was conducted. Metaregression and subgroup analyses were performed to identify whether effects were modified by health status (i.e., healthy participants versus participants with existing comorbidities), type of intervention (i.e., MedDiet alone or with a cointervention), study duration, study design (i.e., parallel or crossover), BMI, and age of participants.Results: Fourteen articles reporting data for 1930 participants were included in the meta-analysis. Study duration ranged from 4 wk to 2.3 y. We observed a beneficial effect of the MedDiet on endothelial function [standardized mean difference (SMD): 0.35; 95% CI: 0.17, 0.53; P <0.001; I2 = 73.68%]. MedDiet interventions improved flow-mediated dilation (FMD)-the reference method for noninvasive, clinical measurement of endothelial function-by 1.66% (absolute change; 95% CI: 1.15, 2.17; P <0.001; I2 = 0%). Effects of the MedDiet on endothelial function were not modified by health status, type of intervention, study duration, study design, BMI, or age of participants (P >0.05).Conclusions: MedDiet interventions improve endothelial function in adults, suggesting that the protective effects of the MedDiet are evident at early stages of the atherosclerotic process with important implications for the early prevention of CVD. This study has the PROSPERO registration number: CRD42018106188. [ABSTRACT FROM AUTHOR]- Published
- 2020
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4. Limited evidence for a beneficial effect of vitamin C supplementation on biomarkers of cardiovascular diseases: an umbrella review of systematic reviews and meta-analyses.
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Ashor, Ammar W., Brown, Rebecca, Keenan, Patrick D., Willis, Naomi D., Siervo, Mario, and Mathers, John C.
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ARTERIAL diseases , *BIOMARKERS , *BLOOD pressure , *BLOOD sugar , *CARDIOVASCULAR system , *CARDIOVASCULAR diseases risk factors , *DIETARY supplements , *ENDOTHELIUM , *INFORMATION storage & retrieval systems , *MEDICAL databases , *MEDICAL information storage & retrieval systems , *LIPIDS , *LOW density lipoproteins , *MEDLINE , *META-analysis , *OBESITY , *TRIGLYCERIDES , *VITAMIN C , *SYSTEMATIC reviews , *GLYCEMIC control - Abstract
Abstract Vitamin C is an essential nutrient with important antioxidant properties. Higher vitamin C intake appears to be associated with positive effects on cardiovascular risk factors in cohort studies, whereas large randomized controlled clinical trials did not confirm the benefits of supplemental vitamin C on cardiovascular disease (CVD) outcomes. In this overview of systematic reviews and meta-analyses, an "umbrella review," we investigated the effects of vitamin C supplementation on biomarkers of cardiovascular risk, that is, arterial stiffness, blood pressure, endothelial function, glycemic control, and lipid profile. In addition, we assessed the strength of the evidence and the methodological qualities of available studies. Two independent investigators searched 4 databases (Medline, Embase, Scopus, and The Cochrane Library databases) from inception until February 2018. After full text examination, 10 systematic reviews and meta-analyses were included in the umbrella review which included 6409 participants. Three systematic reviews investigated the effects of vitamin C on endothelial function with contrasting results (2 reviews reported a significant effect, and all 3 showed a high heterogeneity [ I 2> 50%]); 1 systematic review reported significant improvement for each of the following risk factors: blood pressure, and blood concentrations of glucose, low-density lipoprotein cholesterol, and triglycerides. There were no overall effects of vitamin C on arterial stiffness and blood concentration of insulin, total cholesterol, and high-density lipoprotein cholesterol, but subgroup analyses revealed some evidence for significant improvements in subpopulations with higher body mass index, higher plasma concentrations of glucose or cholesterol, and low plasma concentration of vitamin C. Results from this umbrella review emphasize the weakness of the current evidence base about effects of vitamin C supplementation on markers of CVD risk. There is limited evidence that some population subgroups (older people, the obese, those with lower vitamin C status at baseline, and those at higher CVD risk) may be more responsive to vitamin C supplementation and offer opportunities for tailored nutritional interventions to improve cardiometabolic health. Future studies should implement a selective recruitment strategy that is informed by evidence-based literature synthesis. [ABSTRACT FROM AUTHOR]
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- 2019
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5. Effect of vitamin C and vitamin E supplementation on endothelial function: a systematic review and meta-analysis of randomised controlled trials.
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Ashor, Ammar W., Siervo, Mario, Lara, Jose, Oggioni, Clio, Afshar, Sorena, and Mathers, John C.
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THERAPEUTIC use of vitamin C ,THERAPEUTIC use of vitamin E ,VASODILATION ,CONFIDENCE intervals ,ENDOTHELIUM ,FOREARM ,INFORMATION storage & retrieval systems ,MEDICAL databases ,MEDICAL information storage & retrieval systems ,RESEARCH methodology ,MEDLINE ,META-analysis ,SYSTEMATIC reviews ,EVIDENCE-based medicine ,EFFECT sizes (Statistics) ,RANDOMIZED controlled trials ,DATA analysis software - Abstract
Randomised controlled trials (RCT) testing the effects of antioxidant supplements on endothelial function (EF) have reported conflicting results. We aimed to investigate the effects of supplementation with antioxidant vitamins C and E on EF and to explore factors that may provide explanations for the inconsistent results. We searched four databases (MEDLINE, Embase, Cochrane Library and Scopus) from inception until May 2014 for RCT involving adult participants aged ≥ 18 years who were supplemented with vitamins C and E alone or in combination for more than 2 weeks and reporting changes in EF measured using flow mediated dilation or forearm blood flow. Data were pooled as standardised mean difference (SMD) and analysed using a random-effects model. Significant improvements in EF were observed in trials supplementing with vitamin C alone (500–2000 mg/d) (SMD: 0·25, 95 % CI 0·02, 0·49, P= 0·043) and vitamin E alone (300–1800 IU/d; 1 IU vitamin E = 0·67 mg natural vitamin E) (SMD: 0·48, 95 % CI 0·23, 0·72, P= 0·0001), whereas co-administration of both vitamins was ineffective (vitamin C: 500–2000 mg/d; vitamin E: 400–1200 IU/d) (SMD: 0·12, 95 % CI − 0·18, 0·42, P= 0·428). The effect of vitamin C supplementation on EF increased significantly with age (β 0·023, 95 % CI 0·001, 0·05, P= 0·042). There was a significant negative correlation between baseline plasma vitamin E concentration and the effect of vitamin E supplementation on EF (β − 0·03, 95 % CI − 0·06, − 0·001, P= 0·029). Supplementation with either vitamin C or vitamin E alone improves EF. However, subgroup analysis emphasises the importance of careful characterisation and selection of a population group which may benefit from such supplementation. [ABSTRACT FROM PUBLISHER]
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- 2015
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6. Effect of vitamin C on endothelial function in health and disease: A systematic review and meta-analysis of randomised controlled trials.
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Ashor, Ammar W., Lara, Jose, Mathers, John C., and Siervo, Mario
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PHYSIOLOGICAL effects of vitamin C , *ENDOTHELIUM , *PLETHYSMOGRAPHY , *SYSTEMATIC reviews , *META-analysis - Abstract
Abstract: Background: Observational studies indicate that higher vitamin C intake is associated with reduced risk for cardiovascular diseases. However, randomised controlled trials (RCT) examining the effect of vitamin C on endothelial function (EF) have reported inconsistent results. The aims of this systematic review and meta-analysis were to determine the effect of vitamin C supplementation on EF and to investigate whether the effect was influenced by health status, study duration, dose and route of vitamin C administration. Methods: We searched the Medline, Embase, Cochrane Library, and Scopus databases from inception to May 2013 for studies that met the following criteria: 1) RCT with adult participants, 2) vitamin C administered alone, 3) studies that quantified EF using commonly applied methods including ultrasound, plethysmography and pulse wave analysis. Results: Pooling the data from 44 clinical trials showed a significant positive effect of vitamin C on EF (SMD: 0.50, 95% CI: 0.34, 0.66, P < 0.001). Stratification of the analysis by health outcome revealed improved EF in atherosclerotic (SMD: 0.84, 95% CI: 0.41, 1.26, P < 0.001), diabetic (SMD: 0.52, 95% CI: 0.21, 0.82, P < 0.001) and heart failure patients (SMD: 0.48, 95% CI: 0.08, 0.88, P < 0.02) after vitamin C supplementation. The effect size appeared to be unaffected by study design, duration, baseline plasma vitamin C concentration or route of administration of vitamin C. The meta-regression showed a significant positive association between vitamin C dose and improvement in EF (β: 0.00011, 95% CI: 0.00001, 0.00021, P = 0.03). Conclusions: Vitamin C supplementation improved EF. The effect of vitamin C supplementation appeared to be dependent on health status, with stronger effects in those at higher cardiovascular disease risk. PROSPERO Database registration: CRD42013004567, http://www.crd.york.ac.uk/prospero/ [Copyright &y& Elsevier]
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- 2014
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