Association between Oral vitamin C supplementation and serum uric acid: A meta-analysis of randomized controlled trials

Introduction: Results from recent trials assessing the effect of oral vitamin C supplementation on serum uric acid (SUA) have been inconsistent.

Objectives: The purpose of this study was to explore the association between oral vitamin C supplementation and serum uric acid.

Methods: PUBMED, EMBASE, CNKI, Web of Science, and CENTRAL of Cochrane library databases were searched to identify relevant articles published up to February 2020. Heterogeneity was evaluated using I-square (I²) statistics. Random-effects model was used to pool weighted mean differences (WMD) and 95 % confidence interval (CI) as summary effect sizes.

Results: The total sixteen eligible randomized controlled trials (RCTs) containing 1,013 participants were included in this meta-analysis. The pooled findings showed that vitamin C supplementation had a significant effect of lowering SUA. The subgroup analyses showed that the effect of vitamin C supplementation on SUA has positive association with mean age of participants <65 years old, the use of placebo or blank control, duration of trials <1 month and high-quality studies. In addition, sensitivity analysis showed that the results of this study were stable. Both Egger's test and Begg's test demonstrated that no evidence of significant publication bias.

Conclusions: The results of present meta-analysis have demonstrated that vitamin C supplementation could make a reduction of SUA. The use of placebo, duration of intervention, age of the subjects and study quality have an impact on the effect of oral vitamin C, but the baseline of SUA not.