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

Aim 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. Methods 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. Results 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). Conclusions 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.