Abstract
Background and objective:  The most common adjustable risk factor for cardiovascular disease is hypertension. Vitamin D deficiency in worldwide has become a pandemic. Yet, the relationship between hypertension and the lack of micronutrients such as vitamin D has not been determined. Therefore, this study was to determine the possible relationship between serum vitamin D concentration and blood pressure in Ilam, Iran.
Materials and methods: In this cross-sectional study, 166 participants randomly were selected from the cardiac and internal clinics of Shahid Mostafa Khomeini Hospital in Ilam. Exclusion criteria including diabetes, pregnancy, history of pancreatitis, alcohol consumption greater than 400 cc per week, hypo/hyperthyroidism, hypo/hyperparathyroidism, cushing's syndrome, addison disease, acromegaly , Kidney disease (creatinine higher than 1.5mg/dl), liver and bile duct disease, vitamin D supplementation, history of gastric or duodenal ulcer, gastric and intestinal surgery, and drug use including  diuretics, corticosteroids, Antiepileptic, androgen. Hypertension was defined as ≥ 140 mmHg for systolic blood pressure and ≥ 90 mmHg for diastolic blood pressure. The concentration of vitamin D was measured using ELISA method. The cut-off point for vitamin D deficiency was defined as 20 ng / dL. Blood sample was taken for measuring vitamin D concentration. T-test, chi-square and Pearson correlation coefficient were used to measure the association between study variables.
Findings:  The age range was between 40 to 75 years with the mean [standard deviation] of 52.3 [± 8.3] years. Participants were divided into two groups 44.6% cases (vitamin D deficiency) and 55.4% controls (sufficient level of vitamin D). There was significant association between diastolic blood pressure between two groups (P= 0.048). No significant association between diastolic blood pressure, mean age, BMI, systolic and sex, marital, occupation, education, income, and smoking between two groups (P>0.05). The correlation test showed that decreasing in serum vitamin D concentrations was increasing systolic and diastolic blood pressure. However, this correlation was not statistically significant among study participants.
Conclusion: The results showed no statistically significant relationship between blood pressure and serum 25-hydroxyvitamin D concentration in individuals aged 40 years and over.

Keywords: Vitamin D, blood pressure