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/
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Authors | Ammar W Ashor, Jose Lara, John C Mathers, Mario Siervo |
Journal | Atherosclerosis
(Atherosclerosis)
Vol. 235
Issue 1
Pg. 9-20
(Jul 2014)
ISSN: 1879-1484 [Electronic] Ireland |
PMID | 24792921
(Publication Type: Journal Article, Meta-Analysis, Research Support, Non-U.S. Gov't, Review, Systematic Review)
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Copyright | Copyright © 2014 Elsevier Ireland Ltd. All rights reserved. |
Chemical References |
- Antioxidants
- Ascorbic Acid
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Topics |
- Adult
- Aged
- Antioxidants
(administration & dosage)
- Ascorbic Acid
(administration & dosage, therapeutic use)
- Atherosclerosis
- Cardiovascular Diseases
(prevention & control, therapy)
- Dietary Supplements
- Endothelium
(drug effects)
- Female
- Healthy Volunteers
- Humans
- Inflammation
- Male
- Middle Aged
- Randomized Controlled Trials as Topic
- Regression Analysis
- Young Adult
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