The Role of Vitamin D Supplementation in the Treatment of Primary Hypertension: A Double-Blinded Randomized Placebo-Controlled Clinical Trial

Background: Hypertension is one of the most serious global concerns since it has affected over 1.2 billion people. Objectives: The present study aimed to determine the effect of vitamin D supplementation on blood pressure, fasting blood sugar, and lipid profile in hypertensive patients with vitamin D deficiency. Methods: In this double-blinded randomized placebo-controlled clinical trial study, 116 hypertensive patients (intervention and placebo groups, 58 each) with vitamin D deficiency (< 30 ng/mL with ECL) for 14 weeks, started from the beginning of autumn 2019 in Seyed-al-Shohada Educational Hospital in Urmia City. Fifty-five patients (49%) were male with the mean vitamin D 15.89 ± 5.09 ng/mL and 57 females with 17.29 ± 6.31 ng/mL. In a stratified blocked randomization scheme, the patients were randomly allocated into similar sized intervention and control groups based on body mass index (BMI), then the randomization with four block size was performed in each of strata by random allocation software. The intervention group received six doses of 50,000 IU vitamin D supplements for 6 weeks, then two supplements for two following months (one capsule per month). Blood pressure (24/h blood pressure measured by an ambulatory blood pressure monitoring device), vitamin D, FBS, and lipid profile (HDL, LDL, CL, and TG) were all measured at baseline and end of the study. Physical activity (measured by short IPAQ questionnaire), sun exposure using a questionnaire, dietary intake of vitamin D using three 24-hour recalls during the intervention, and anthropometric indices were measured at baseline, middle, and end of the study. Fifty-six patients in each group completed the study. The study was approved by the Ethics Committee of the Urmia University of Medical Sciences (ethics code: IR.UMSU.REC.1398.192). Results: The office blood pressure, 24-h systolic blood pressure (SBP) and diastolic blood pressure (DBP), nighttime SBP and DBP were significantly reduced in the intervention group compared to the control group, whereas the reduction of daytime SBP and DBP was not statistically significant. Vitamin D supplementation significantly decreased serum triglyceride, cholesterol, and LDL levels. Conclusions: Vitamin D supplementation had positive effects on blood pressure, triglyceride, cholesterol, and LDL levels in patients with low serum vitamin D.