Effect of Vitamin D Supplementation on Blood Pressure: A Systematic Review.

Hypertension is a major risk factor for cardiovascular disease and mortality. Emerging evidence suggests a potential role of vitamin D in blood pressure regulation through its influence on the renin-angiotensin-aldosterone system, endothelial function, and inflammation. However, findings from interventional studies remain inconsistent. This systematic review aims to evaluate the effect of vitamin D supplementation on systolic and diastolic blood pressure across various populations. A comprehensive literature search was conducted in PubMed, Cochrane Central, and ScienceDirect to identify randomized controlled trials and cohort studies investigating the impact of vitamin D on hypertension. Data extraction and risk of bias assessments were performed independently by two reviewers. The primary outcome was the change in systolic and diastolic blood pressure before and after vitamin D supplementation. In total, 12 studies met the inclusion criteria, with sample sizes ranging from 35 to 3,788 participants. The highest reduction in systolic blood pressure (-28.44 mmHg) and diastolic blood pressure (-7.38 mmHg) was observed in one study with 50,000 IU/week supplementation. Other studies reported reductions ranging from -0.5 to -4.5 mmHg for systolic blood pressure and -1 to -5 mmHg for diastolic blood pressure, with variability influenced by dosage and duration. Vitamin D supplementation demonstrates potential benefits in reducing blood pressure, particularly with higher doses over shorter durations. However, heterogeneity across studies warrants further research to establish optimal dosing strategies for hypertensive patients.