Available high- quality RCTs did not support a beneficial effect of cholecalciferol on systemic IL-6 and CRP .
Vitamin D and Serum Cytokines in a Randomized Clinical Trial
Background . The role of vitamin D in the body 's ability to fight influenza and URI 's may be dependent on regulation of specific cytokines that participate in the host inflammatory response . The aim of this study was to test the hypothesis that vitamin D can influence intracellular signaling to regulate the production of cytokines . Subjects and Methods . This study was a 3-month prospect i ve placebo-controlled trial of vitamin D3 supplementation in ambulatory adults [ Li-Ng et al. , 2009 ] . 162 volunteers were r and omized to receive either 50 μg/d ( 2000 IU ) of vitamin D3 or matching placebo . 25(OH)D and the levels of 10 different cytokines ( IL-2 , 4 , 5 , 6 , 8 , 10 , 13 , GM-CSF , IFN-γ , TNF-α ) were measured in the serum of participants at baseline and the final visit . There were 6 drop-outs from the active vitamin D group and 8 from the placebo group . Results . In the active vitamin D group , we found a significant median percent decline in levels of GM-CSF ( −62.9 % , P < .0001 ) , IFN-γ ( −38.9 % , P < .0001 ) , IL-4 ( −50.8 % , P = .001 ) , IL-8 ( −48.4 % , P < .0001 ) , and IL-10 ( −70.4 % , P < .0001 ) . In the placebo group , there were significant declines for GM-CSF ( −53.2 % , P = .0007 ) and IFN-γ ( −34.4 % , P = .0011 ) . For each cytokine , there was no significant difference in the rate of decline between the two groups . 25(OH)D levels increased in the active vitamin D group from a mean of 64.3 ± 25.4 nmol/L to 88.5 ± 23.2 nmol/L. Conclusions . The present study did not show that vitamin D3 supplementation changed circulating cytokine levels among healthy adults
Available high- quality RCTs did not support a beneficial effect of cholecalciferol on systemic IL-6 and CRP .