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Atherosclerosis. 2014 Jul;235(1):9-20. doi: 10.1016/j.atherosclerosis.2014.04.004. Epub 2014 Apr 18.

Effect of vitamin C on endothelial function in health and disease: a systematic review and meta-analysis of randomised controlled trials.

Author information

  • 1Human Nutrition Research Centre, Institute for Ageing and Health, Newcastle University, Campus for Ageing and Vitality, Newcastle on Tyne NE4 5PL, UK; College of Medicine, University of Al-Mustansiriyah, Baghdad, Iraq. Electronic address: a.w.ashor@newcastle.ac.uk.
  • 2Human Nutrition Research Centre, Institute for Ageing and Health, Newcastle University, Campus for Ageing and Vitality, Newcastle on Tyne NE4 5PL, UK.

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 © 2014 Elsevier Ireland Ltd. All rights reserved.

KEYWORDS:

Ascorbic acid; Cardiovascular risk; Flow-mediated dilation; Forearm blood flow; Nutritional supplements

PMID:
24792921
[PubMed - indexed for MEDLINE]
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