Vitamin D supplementation effects on the clinical outcomes of patients with coronary artery disease: a systematic review and meta-analysis

Abstract

In this systematic review and meta-analysis our aim was to assess the effect of vitamin D supplementation on cardiac outcomes in patients with coronary artery disease (CAD). The search terms were performed from January 2000 to January 2018, only randomized clinical trials (RCT) in human subjects were considered, with no language restrictions. The electronic databases used in this study were: PubMed; Cochran library; Embase; and Scopus. Two independent expert reviewers carried out data extraction according to Cochrane recommendations. Only four RCTs were found in relation to the effects of vitamin D supplementation on the coronary artery disease. In these 299 patients, vitamin D supplementation had significant favorable effects on Diastolic Blood Pressure (DBP) (- 2.96, p = 0.02) and Parathyroid hormone (PTH) (- 4.05, p < 0.001). However, it had no significant effects on hs-CRP mean difference (- 0.04, p = 0.25), total cholesterol (TC) (- 0.46, p = 0.83), triglyceride (TG) (0.68, p = 0.89), low-density lipoproteins (LDL) (2.08, p = 0.56), and high-density lipoproteins (HDL) (- 2.59, p = 0.16). In conclusion, the use of vitamin D was associated with improvements in some cardiac outcomes of CAD patients with vitamin D deficiency. Also, further research is needed to clarify these results.

Figure 1

PRISMA flow-diagram of the study selection process.

Figure 2

Forest plot of randomized controlled trials showing weighted mean difference in hs-CRP concentrations between the vitamin D-supplemented and placebo groups for all eligible studies. For all the inclusion studies pooled, the non-significant effect of vitamin D supplement on reducing hs-CRP concentrations was observed (P value for heterogeneity = 0.75, and χ² = 0.58).

Figure 3

Forest plot of randomized controlled trials showing weighted mean difference in total Cholesterol levels between the vitamin D-supplemented and placebo groups for all eligible studies. For all the inclusion studies pooled, the non-significant effect of vitamin D supplement on reducing total Cholesterol levels was observed (P value for heterogeneity = 0.89, and χ² = 0.23).

Figure 4

Forest plot of randomized controlled trials showing weighted mean difference in triglyceride levels between the vitamin D-supplemented and placebo groups for all eligible studies. For all the inclusion studies pooled, the non-significant effect of vitamin D supplement on reducing triglyceride levels was observed (P value for heterogeneity = 0.68, and χ² = 0.78).

Figure 5

Forest plot of randomized controlled trials showing weighted mean difference in LDL levels between the vitamin D-supplemented and placebo groups for all eligible studies. For all the inclusion studies pooled, the non-significant effect of vitamin D supplement on reducing LDL levels was observed (P value for heterogeneity = 0.77, and χ²= 0.52).

Figure 6

Forest plot of randomized controlled trials showing weighted mean difference in HDL levels between the vitamin D-supplemented and placebo groups for all eligible studies. For all the inclusion studies pooled, the non-significant effect of vitamin D supplement on HDL levels was observed (P value for heterogeneity = 0.22, and χ² = 1.51).

Figure 7

Forest plot of randomized controlled trials showing weighted mean difference in SBP levels between the vitamin D-supplemented and placebo groups for all eligible studies. For all the inclusion studies pooled, the non-significant effect of vitamin D supplement on systolic blood pressure levels was observed (P value for heterogeneity = 0.11, and χ² = 2.50).

Figure 8

Forest plot of randomized controlled trials showing weighted mean difference in DBP levels between the vitamin D-supplemented and placebo groups for all eligible studies. For all the inclusion studies pooled, the significant effect of vitamin D supplement on reducing diastolic blood pressure levels was observed (P value for heterogeneity = 0.69, and χ² = 0.16).

Figure 9

Forest plot of randomized controlled trials showing weighted mean difference in PTH concentrations between the vitamin D-supplemented and placebo groups for all eligible studies. For all the inclusion studies pooled, the significant effect of vitamin D supplement on reducing PTH concentrations was observed (P value for heterogeneity = 0.42, and χ² = 0.66).