The Relation between Salt Intake and Blood Pressure among Iranians

Objectives: To determine the mean 24 hr urinary sodium (UNa) and chloride (UCl) excretion, and the association between these variables and blood pressure, since studies on the effect of habitual dietary salt intake and some electrolytes on blood pressure were reported different. Design: Experimental population-based study Setting: Urban areas, Isfahan city, Iran Subjects: Nine hundred and twelve randomly selected patients aged 20-60 years Main Outcome Measures: 24-hour urine and food records were collected three times in one month. Systolic (SBP) and diastolic (DBP) blood pressures, heart rate and sodium, potassium, calcium, chloride and creatinine levels in urine samples were measured. Results: Estimated mean daily salt intake based on UNa excretion in Iranian population is 9.9 + 2.9 g/day (men: 11.1 + 3.0 g/day and women: 9.6 + 2.9 g/day; p = 0.001). The UNa excretion value was 189.7 + 51.4 mmol for men and 164.6 + 49.8 mmol for women, with a significant difference (p = 0.001). After adjustment for confounding factors and other urinary electrolytes, no relationship was found between UNa and SBP (b = 0.001, p = 0.89) or DBP (b = 0.007, p = 0.34) in the pooled data. Significant relationship was observed between UCl excretion and SBP in hypertensives (b = 0.113, p = 0.001), UNa excretion and DBP in the entire group (r = 0.04, p = 0.004) and in normotensive men (r = 0.036, p = 0.03). Conclusion: Salt intake is one of the main factors affecting blood pressure among Iranian men but not women.