The effect of vitamin-mineral supplementation on CRP and IL-6: a systemic review and meta-analysis of randomised controlled trials.
OBJECTIVE
Inflammation is regarded as a risk predictor for metabolic syndrome and atherogenesis. The objective of this study was to conduct a systematic review and a meta-analysis to confirm the effect of vitamin-mineral supplementation on cytokine levels.


RESULTS
We searched the PubMed, EMBASE and Cochrane databases up to May 2009 for randomised controlled trials regarding the effect of vitamin-mineral supplementation on C-reactive protein (CRP) and interleukin-6 (IL-6). Eighteen trials with 1747 participants for CRP and nine trials with 1037 participants for IL-6 were included, respectively. Pooled estimates and 95% confidence intervals (CIs) were calculated by fixed- or random-effects model. No significant differences were observed for CRP and IL-6 reduction between the subjects with vitamin-mineral supplementation and placebo control. A dose-dependent manner for different body mass index (BMI) subgroups in CRP analysis was observed (weighted mean difference (WMD), -0.057; 95%CI: -0.753 to 0.639 for BMI<25; WMD, -0.426; 95%CI: -0.930 to 0.079 for 25 ≤ BMI < 30; WMD, -0.491; 95%CI: -1.407 to 0.424 for BMI ≥ 30). However, no significance was detected in meta-regression (-0.046, 95%CI: -0.135 to 0.044). Moreover, the best effect for reduction in CRP levels in a supplementation duration of 4 weeks-6 months (WMD, -0.449; 95%CI: -1.004 to 0.106) was observed compared with supplementation duration less than 4 weeks (WMD, -0.137; 95%CI, -0.816 to 0.541) and more than 6 months (WMD, -0.389; 95%CI, -1.034 to 0.257) without statistical significance (P = 0.059).


CONCLUSIONS
No statistically significant evidences for the potential dose-dependent manner of BMI and best supplement duration were detected in this study. Large and well-designed studies are recommended to confirm this conclusion.
Sun
C-H
CH
Department of Nutrition and Food Hygiene, Public Health College, Harbin Medical University, Harbin, Heilongjiang Province, China. sun2002changhao@yahoo.com
Li
Y
Y
Zhang
Y-B
YB
Wang
F
F
Zhou
X-L
XL
Wang
F
F
D015992:Body Mass Index; D002097:C-Reactive Protein / Q000187:drug effects*; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D016032:Randomized Controlled Trials as Topic; D014131:Trace Elements / Q000008:administration & dosage*; D014815:Vitamins / Q000008:administration & dosage*
D015850:Interleukin-6; D014131:Trace Elements; D014815:Vitamins; D002097:C-Reactive Protein