A Meta-analysis of Randomized Control Trials: The Impact of Vitamin C Supplementation on Serum CRP and Serum hs-CRP Concentrations.

The present meta-analysis was designed to assess the effects of vitamin C supplementation on serum C-reactive Protein (CRP) levels. We conducted a comprehensive systematic search of the literature in Scopus, PubMed and Google Scholar until May 2018. The pooled Weighted Mean Difference (WMD) and its 95% Confidence Interval (CI) in baseline and at the end of the trial were calculated to assess the net change in serum CRP by using random-effects model. The heterogeneity was assessed by I2 test. Combined and stratified analyses were used in the metaanalysis. From 306 articles found and screened in our initial search, 12 studies were included with 446 participants in supplementation groups and 447 in control groups. The pooled effect size analysis showed a significant reducing effect of vitamin C supplementation on circulating CRP level (-0.23 mg/L, 95% CI, -0.44, -0.03, p=0.02), with a significant heterogeneity effect across the studies involved. Subgroup analyses showed that vitamin C supplementation significantly lowered CRP among trials. The most significant effect was found 1) on hs- CRP as the representative inflammatory marker (-0.43 mg/L, 95% CI -0.76, -0.1) 2) in subjects with a baseline CRP≥3 (-1.48 mg/L, 95% CI -2.84, -0.11) 3) in subjects under <60 years old of age (-0.23 mg/L, 95% CI -0.44,- 0.01) 4) or using intravenous administration of vitamin C (-0.89 mg/L, 95% CI -1.49,-0.3). The present meta-analysis shows that vitamin C supplementation reduces serum CRP level, particularly in younger subjects, with higher CRP baseline level, at a lower dosage and intravenous administration.

Jafarnejad S ，Boccardi V ，Hosseini B ，Taghizadeh M ，Hamedifard Z ... -  《-》

Effect of cinnamon (Cinnamomum Zeylanicum) supplementation on serum C-reactive protein concentrations: A meta-analysis and systematic review.

The effect of cinnamon (Cinnamomum Zeylanicum) on serum C-reactive protein (CRP), an acute phase protein commonly used as a marker of inflammation, is uncertain. Therefore, the objective of the present study was to conduct a systematic review and meta-analysis of published randomised controlled trials (RCTs) of cinnamon to determine the effect on levels of serum CRP, relative to controls. Studies were identified by a search of electronic databases including PubMed, Cochrane Library, Google Scholar and Scopus before August 2018. Combined and stratified analyses were used. Weighted mean differences (WMD) and its 95% confidence interval were estimated for net change in serum CRP by using random-effects model. The heterogeneity of meta-analysis was assessed by χ2 and I2 test. Six studies were identified, and data from 285 participants were included. Pooled analysis showed significant reductions in serum CRP (WMD: -0.81 mg/L, 95% CI: -1.36 to -0.26, p = 0.004), with significant heterogeneity between selected studies. Improvements in sub-group analysis were observed when baseline CRP levels were greater than 3 mg/dL, and in trials of >12 weeks duration. Doses <1500 mg/day and ≥1500 mg/day were effective in lowering serum CRP (WMD: -0.56 mg/dL, 95% CI: -1.01 to -0.10, p = 0.02 and WMD: -2.13 mg/dL, 95% CI: -4.08 to -0.19, p = 0.03), respectively, with significantly reduced heterogeneity in trials with lower doses of cinnamon <1500 mg/day (test for heterogeneity: P = 0.22 and I2 = 33%). No changes were found in controls. Cinnamon supplementation improves levels of serum CRP, particularly in chronic conditions, where basal CRP levels are raised. Further well-designed studies are warranted to confirm or not the above-mentioned findings.

Vallianou N ，Tsang C ，Taghizadeh M ，Davoodvandi A ，Jafarnejad S ... -  《-》

Effect of garlic supplementation on serum C-reactive protein level: A systematic review and meta-analysis of randomized controlled trials.

The present study was designed to systematically review randomized controlled trials (RCTs) that report on the effects of garlic supplementation on serum C-reactive protein (CRP) levels. We conducted a literature search of Scopus, PubMed, Cochrane Library, and Google Scholar up to January 2018. Weighted mean differences (WMD) were estimated for net change in serum CRP. Subgroup analyses were also performed by duration of study, dose of supplementation, baseline CRP level, and the quality of studies. From 438 articles found and screened in our initial search, nine RCTs with the sum of total sample size of 363 were included in the meta-analysis. Compared with the controls, garlic intake significantly reduced the concentrations of serum CRP by 0.8 mg/L (95% CI [-1.5, -0.1], p = 0.02) with the evidence of heterogeneity among studies. Subgroup analyses showed that garlic significantly lowered CRP by 0.82 mg/L (95% CI [-1.02, -0.62], p < 0.001) among studies with a daily garlic dose ≥1,200 mg/day and by 2.44 mg/L (95% CI [-4.02, -0.87], p = 0.002) among studies with baseline CRP ≥2 mg/L. Current data confirmed that garlic supplementation would reduce serum CRP levels. However, the changes were related to the supplemental doses and baseline levels of serum CRP.

Taghizadeh M ，Hamedifard Z ，Jafarnejad S 《-》

Effect of Magnesium Supplementation on Plasma C-reactive Protein Concentrations: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Results of previous clinical trials evaluating the effect of magnesium supplementation on inflammatory markers are controversial. A systematic review and meta-analysis of randomized controlled trials (RCTs) were performed to evaluating the effect of oral magnesium supplementation on plasma C-reactive protein (CRP) concentrations. PubMed-Medline, SCOPUS, Web of Science and Google Scholar databases were searched (from inception to August 09, 2016) to identify RCTs, evaluating the effect of magnesium on CRP levels. A random-effects model and a generic inverse variance method were used to compensate for the heterogeneity of studies. Publication bias, sensitivity analysis, and meta-regression assessments were conducted using standard methods. Overall, the impact of magnesium supplementation on plasma concentrations of CRP was assessed in 11 studies. Magnesium treatment was not found to significantly affect plasma concentrations of CRP (WMD: -0.11 mg/L, 95% CI: -0.75, 0.52, p=0.727). When the analysis was stratified to compare subgroups of studies in populations with baseline plasma CRP values of ≤ 3 and > 3 mg/L, a significant reduction of CRP values was observed in the latter subgroup (WMD: -1.12 mg/L, 95% CI: -2.05, -0.18, p=0.019) but not in the former group (WMD: 0.61 mg/L, 95% CI: -0.10, 1.32, p=0.090). The difference between subgroups was statistically significant (p=0.004). Results of the present meta-analysis indicated that magnesium supplementation reduces CRP levels among individuals with inflammation (CRP levels > 3 mg/dL). This finding suggests that magnesium supplements may have a beneficial role as an adjuvant for the management of low-grade chronic systemic inflammation.

Simental-Mendia LE ，Sahebkar A ，Rodriguez-Moran M ，Zambrano-Galvan G ，Guerrero-Romero F ... -  《-》

Effect of vitamin E supplementation on serum C-reactive protein level: a meta-analysis of randomized controlled trials.

Saboori S ，Shab-Bidar S ，Speakman JR ，Yousefi Rad E ，Djafarian K ... -  《-》