Impact of vitamin D supplementation on endothelial and inflammatory markers in adults: A systematic review

This systematic review aims to evaluate randomised controlled trials (RCTs) investigating the effect of vitamin D supplementation on endothelial function and inflammation in adults. An electronic search of published randomised controlled trials, using Cochrane, Pubmed and Medline databases was conducted, with the search terms related to vitamin D and endothelial function. Inclusion criteria were RCTs in adult humans with a measure of vitamin D status using serum/plasma 25(OH)D and studies which administered the intervention through the oral route. Among the 1107 studies retrieved, 29 studies met the full inclusion criteria for this systematic review. Overall, 8 studies reported significant improvements in the endothelial/inflammatory biomarkers/parameters measured. However, in 2 out of the 8 studies, improvements were reported at interim time points, but improvements were absent post-intervention. The remaining 21 trial studies did not show significant improvements in the markers of interest measured. Evidence from the studies included in this systematic review did not demonstrate that vitamin D supplementation in adults, results in an improvement in circulating inflammatory and endothelial function biomarkers/parameters. This systematic review does not therefore support the use of vitamin D supplementation as a therapeutic or preventative measure for CVD in this respect.