Effect of vitamin D supplementation on serum lipid profiles: a systematic review and meta-analysis.

Context Vitamin D deficiency is highly prevalent across the world. The existing evidence suggests vitamin D may have beneficial effects on serum lipid profiles and thus cardiovascular health. Objective The objective of this systematic review and meta-analysis was to examine the effect of vitamin D supplementation on serum lipid profiles. Data Source Original randomized controlled trials (RCTs) examining the effect of vitamin D supplementation on serum lipid profiles and published before July 2018 were identified by searching online databases, including PubMed, Google Scholar, and ScienceDirect, using a combination of relevant keywords. Data Extraction Data on study characteristics, effect size, measure of variation, type of vitamin D supplementation, and duration of follow-up were extracted by the author. Data Analysis PRISMA guidelines for systematic reviews were followed. Random effects (DerSimonian and Laird [D-V)] models were used to pool standardized mean differences in total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides between the active and the placebo arms of RCT studies. Between-study heterogeneities were assessed using Cochrane Q and I2, and publication bias was assessed using Begg's test, Egger's test, and funnel plot. Results A total of 41 RCTs comprising 3434 participants (n = 1699 in the vitamin D supplementation arm and n = 1735 in the placebo arm) were identified and included in the meta-analysis. Approximately 63.4% of study participants were women, with 14 studies conducted entirely among women. Approximately 24% of the trials had follow-up duration >6 months, whereas the remaining 76% had follow-up duration of < 6 months. The standardized mean differences (SMDs) and 95% confidence intervals (CIs) for comparing the change from baseline to follow-up between the vitamin D supplementation arm and the placebo (control) arm were as follows: total cholesterol = –0.17 (–0.28 to –0.06); LDL cholesterol = –0.12 (–0.23 to –0.01); triglycerides = –0.12 (–0.25 to 0.01); and HDL cholesterol = –0.19 (–0.44 to 0.06). After removing a trial that was an outlier based on the magnitude of the effect size, the SMD for triglycerides was –0.15 (–0.24 to –0.06) and that for HDL cholesterol was –0.10 (–0.28 to 0.09). The improvements in total cholesterol and triglycerides were more pronounced in participants with baseline vitamin D deficiency. Conclusions Vitamin D supplementation appeared to have a beneficial effect on reducing serum total cholesterol, LDL cholesterol, and triglyceride levels but not HDL cholesterol levels. Vitamin D supplementation may be useful in hypercholesterolemia patients with vitamin D insufficiency who are at high risk of cardiovascular diseases. [ABSTRACT FROM AUTHOR]