NDLI: Effects of vitamin C supplementation on blood pressure: a meta-analysis of randomized controlled trials.

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Juraschek, Stephen P. Guallar, Eliseo Appel, Lawrence J. Miller, Edgar R.
Description	Country affiliation: United States Author Affiliation: Juraschek SP ( Johns Hopkins School of Medicine, Johns Hopkins Bloomberg School of Public Health, and Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins Medical Institutions, Baltimore, MD 21205, USA.)
Abstract	BACKGROUND: In observational studies, increased vitamin C intake, vitamin C supplementation, and higher blood concentrations of vitamin C are associated with lower blood pressure (BP). However, evidence for blood pressure-lowering effects of vitamin C in clinical trials is inconsistent. OBJECTIVE: The objective was to conduct a systematic review and meta-analysis of clinical trials that examined the effects of vitamin C supplementation on BP. DESIGN: We searched Medline, EMBASE, and Central databases from 1966 to 2011. Prespecified inclusion criteria were as follows: 1) use of a randomized controlled trial design; 2) trial reported effects on systolic BP (SBP) or diastolic BP (DBP) or both; 3) trial used oral vitamin C and concurrent control groups; and 4) trial had a minimum duration of 2 wk. BP effects were pooled by random-effects models, with trials weighted by inverse variance. RESULTS: Twenty-nine trials met eligibility criteria for the primary analysis. The median dose was 500 mg/d, the median duration was 8 wk, and trial sizes ranged from 10 to 120 participants. The pooled changes in SBP and DBP were -3.84 mm Hg (95% CI: -5.29, -2.38 mm Hg; P < 0.01) and -1.48 mm Hg (95% CI: -2.86, -0.10 mm Hg; P = 0.04), respectively. In trials in hypertensive participants, corresponding reductions in SBP and DBP were -4.85 mm Hg (P < 0.01) and -1.67 mm Hg (P = 0.17). After the inclusion of 9 trials with imputed BP effects, BP effects were attenuated but remained significant. CONCLUSIONS: In short-term trials, vitamin C supplementation reduced SBP and DBP. Long-term trials on the effects of vitamin C supplementation on BP and clinical events are needed.
File Format	HTM / HTML
ISSN	00029165
e-ISSN	19383207
DOI	10.3945/ajcn.111.027995
Journal	American Journal of Clinical Nutrition
Issue Number	5
Volume Number	95
Language	English
Publisher	American Society for Nutrition
Publisher Date	2012-05-01
Publisher Place	United States
Access Restriction	Open
Subject Keyword	Discipline Nutritional Sciences Ascorbic Acid Pharmacology Blood Pressure Drug Effects Dietary Supplements Vitamins Hypertension Randomized Controlled Trials As Topic Meta-analysis Research Support, N.i.h., Extramural
Content Type	Text
Resource Type	Article
Subject	Nutrition and Dietetics Medicine

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