Meta-analysis of vitamin D supplementation in the treatment of chronic heart failure

<i>Objectives</i>. We performed a meta-analysis to determine whether vitamin D supplementation is beneficial in patients with chronic heart failure (CHF). <i>Design</i>. Meta-analysis of randomised controlled trials. <i>Results</i>. Vitamin D supplementation in patients with CHF improved health-related quality of life and C-reactive protein levels [weighted mean difference (WMD): 6.75, 95% confidence interval (CI): 2.87 to 10.64, <i>p</i> &lt; .001; standardised mean difference (SMD): −0.41, 95% CI: −0.71 to −0.11, <i>p</i> = .007]. However, this supplementation was not superior to conventional treatment in terms of mortality, changes in left ventricular ejection fraction (ΔLVEF), N-terminal pro-B-type natriuretic peptide or B-type natriuretic peptide levels, and 6-minute walk distance (risk ratio: 1.11, 95% CI: 0.79 to 1.57, <i>p</i> = .53; WMD: 2.56, 95% CI: −2.18 to 7.31, <i>p</i> = .29; SMD: −0.18, 95% CI: −0.42 to 0.06, <i>p</i> = .15; WMD: −23.30, 95% CI: −58.31 to 11.72, <i>p</i> = .19). In contrast, ΔLVEF significantly improved (WMD: 6.75, 95% CI: 4.16 to 9.34, <i>p</i> &lt; .001) in the subgroup without calcium supplementation. Additionally, some randomised controlled trials showed that adverse events were more frequent in people with high vitamin D levels. <i>Conclusions</i>. Vitamin D supplementation decreases serum levels of inflammatory markers and improves quality of life in CHF patients. Pooled analysis of vitamin D supplementation did not show reduced mortality or improved left ventricular function perhaps because of excessive increase in plasma 25-hydroxyvitamin D and calcium levels. Future studies should pay attention to vitamin D and calcium levels achieved.