Estimation of salt intake by 24-hour urinary sodium excretion: a cross-sectional study in Yantai, China

Background: High levels of dietary sodium are associated with raised blood pressure and adverse cardiovascular health. To determine baseline salt intake, we investigated the average dietary salt intake from 24-hour urinary sodium excretion with a small sample of Yantai adults in the Shandong province of China. Methods: One hundred ninety one adults aged 18-69 years were randomly selected from the Yantai adult population. Blood pressure, anthropometric indices and sodium excretion in a 24-hour urine collection were measured. Consumption of condiments was derived from 3-day weighted records. Completeness of urine collections was verified using creatinine excretion in relation to weight. Results: The mean Na and K outputs over 24 hours were 201.5 +/- 77.7 mmol/day and 46.8 +/- 23.2 mmol/day, respectively (corresponding to 11.8 g NaCl and 1.8 g K). Overall, 92.1% of the subjects (96.9% of men and 87.1% of women) had intakes of over 6 g salt (NaCl)/d. The main sources of salt intake from weighed condiments records were from home cooking salt (74.7%) followed by soy sauce (15.0%). Salt intake from condiments and salt excretion were weakly correlated((r = 0.20, p = 0.005). A positive linear correlation between salt intake was associated with systolic blood pressure in all adjusted and unadjusted model (r = 0.16, p = 0.01). Each 100 mmol/day increase in sodium intake was associated with a 4.0 mmHg increase in systolic blood pressure. Conclusion: Dietary salt intake in Yantai adults was high. Reducing the intake of table salt and soy sauce used in cooking will be an important strategy to reduce sodium intake among Yantai adults.