Tehran University of Medical Sciences Journal of Nutritional Sciences and Dietetics 3 1 2017 03 28 178 178 EN Zahra Yari PhD student, Department of Clinical Nutrition and Dietetics, Faculty of Nutrition and Food Technology, National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran Samira Ebrahimof Nutrition and Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran 2017 08 22 2017 09 06 Objective: Vitamin D may have anti-inflammatory actions however; there is no consensus on the effects of vitamin D supplementation on C-reactive protein (CRP) level in randomized clinical trials. In a systematic review and meta-analysis, we hypothesized that vitamin D supplementation would reduce serum CRP levels. Materials and Methods: A systematic research of randomized controlled trials has been conducted on MEDLINE and EMBASE through PubMed, Scopus, and completed by a manual review of the literature up from January 2000 to May 2015. Pooled effect estimated by using random-effect model and heterogeneity was assessed by Cochran’s Q and I2 tests. Results: Of 157 potentially relevant studies we found in a systematic search, 20 clinical trials met the inclusion criteria. Mean baseline CRP levels in the intervention group and in the control group were 3.5±2.6 and 3.3±2.3 mg/L, respectively. Mean duration of the studies were 29.0±30.2.0 (SD) weeks (8 to 144 weeks). Doses of vitamin D3 supplementation varied between 200 to 57142 IU/day. Pooled analysis showed a non-significant increase of 0.04 mg/L (95% CI, −0.12 to 0.21; p < 0.61), with no evidence of heterogeneity (I2 = 17.8%, p < 0.17). Conclusion: The results of this meta-analysis showed that vitamin D supplementation may not be effective for the reduction of CRP. However, a more accurate estimate of the effect requires further large and well-designed clinical trials. https://jnsd.tums.ac.ir/index.php/jnsd/article/view/178 https://jnsd.tums.ac.ir/index.php/jnsd/article/download/178/164