Dietary sodium and potassium intake and their association with blood pressure in a non-hypertensive Iranian adult population: Isfahan salt study.

Abstract

The association of sodium (Na) and potassium (K) intake with blood pressure (BP) is an ongoing debate, especially in central Iran. We aimed to examine the mean Na and K intake, major sources of Na and the relationship between BP and dietary and urinary Na and K. This cross-sectional study was performed in central Iran in 2013-2014. A total of 796 non-hypertensive adults aged >18 years were randomly recruited. The semi-quantitative food frequency questionnaire was used to assess dietary Na and K intake. Moreover, 24-hour urine samples were collected to measure 24-hour urinary Na (UNa) and K (UK) as biomarkers. BP was measured twice on each arm using a standard protocol. The mean Na and K intake were 4309.6 ± 1344.4 and 2732.7 ± 1050.5 mg/day, respectively. Table and cooking salt were the main sources of Na. Odds ratio (OR) (95% confidence interval (CI)) of the crude model in the highest quartile of UNa indicated a significant association with the higher risk of prehypertension (OR (95% CI): 2.09 (1.09-4.05); P for trend = 0.007). After adjustment for potential confounders, prehypertension was significantly associated with increasing dietary Na/K ratio (OR (95% CI): 1.28 (1.01-1.57); P for trend = 0.046) and UNa/UK ratio (OR (95% CI): 2.15(1.08-4.55); P for trend = 0.029). Increasing dietary and urinary Na/K ratios and UNa were associated with elevated BP and prehypertension occurrence. These findings support the necessity of developing a salt reduction programme in our country.