Effects of Vitamin D2 (Ergocalciferol) on Parathyroid Hormone, Calcium, and Phosphorus in Humans: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

CONTEXT: There is a clear link between ergocalciferol, parathyroid hormone (PTH), phosphorus, and calcium. Various randomized trials have examined the effectiveness of ergocalciferol on vitamins and minerals. However, conflicting results have been reported, and the optimal dose and duration of ergocalciferol remain unclear. OBJECTIVE: This systematic review and meta-analysis of RCTs aim to evaluate the effect of vitamin D2 on PTH, calcium, and phosphorus in humans. DATA SOURCES: A comprehensive literature search was conducted with the assistance of a librarian. Independent reviewers performed searches across multiple databases, including Web of Science, Scopus, PubMed/Medline, and Embase, from their inception until September 20, 2024. DATA EXTRACTION: The random-effects model, based on the DerSimonian and Laird method, was applied to compute pooled estimates of the intervention's impact on the outcomes. DATA ANALYSES: A total of 26 articles were included in the meta-analysis. The pooled analysis, using a random-effects model, demonstrated a significant reduction in serum PTH concentrations (WMD, -12.77 pg/mL, 95% CI, -20.03 to -5.51, P = .001, I2 = 96%, P < .001) and a significant increase in calcium levels (WMD, 0.15 mg/dL, 95% CI, 0.03 to 0.27, P = .011) following vitamin D2 intervention. However, a nonsignificant effect of vitamin D2 on phosphorus concentrations was observed (WMD, 0.166 mg/dL, 95% CI, -0.08 to 0.41, P = .197). CONCLUSION: Vitamin D2 supplementation appears to improve serum calcium levels while decreasing PTH levels. Given the low cost and wide availability of ergocalciferol, it can be recommended, especially for older adults, to help maintain bone strength.