Association of Serum Levels of Vitamin D with Blood Pressure Status in Northern Iranian Population: The PERSIAN Guilan Cohort Study (PGCS)

BACKGROUND: Evidence in the last decades has indicated an association between vitamin D and cardiovascular risk factors including blood pressure. The present study aimed to determine whether serum 25-hydroxyvitamin D is independently associated with blood pressure in a large population-based study. METHODS: The study was based on subjects from PERSIAN Guilan Cohort Study (PGCS), a prospective, population-based cohort study in Guilan, Iran. In 9520 men and women, aged 35–70 years, serum 25-hydroxyvitamin D, systolic and diastolic blood pressure were measured. Multiple logistic and linear regression analyses were conducted with adjustments for demographic factors (age and gender), anthropometric characteristics (waist circumference and body mass index), lifestyle variables (physical activity, alcohol, and smoking consumption), and renal function (serum creatinine). RESULTS: Fully adjusted linear regression analyses revealed a weak but statistically significant negative association between serum 25-hydroxyvitamin D levels and systolic blood pressure (β = –0.02, 95% CI= −0.052 to −0.0001, P-value=0.04), whereas vitamin D status was not significantly associated with diastolic blood pressure (β = –0.01, 95% CI= −0.026 to 0.009, P-value=0.3). Serum 25-hydroxyvitamin D status showed no significant association with the presence of hypertension (OR 1.09, 95% CI=0.94 to 1.25 for the lowest (25OHD <12 ng/mL) versus the highest (25OHD ≥20 ng/mL) category). CONCLUSION: Lower serum vitamin 25 (OH) D levels were associated with higher systolic blood pressure; however, it was not associated with diastolic blood pressure and presence of hypertension.