Associations between salt-restriction spoons and long-term changes in urinary na+/k+ ratios and blood pressure: Findings from a population-based cohort

Abstract

BACKGROUND: There have been few studies on the relationship between long-term changes in sodium intake and blood pressure. A method of reducing sodium intake in a population that is known for high-sodium intake based on homemade cooking is also needed. METHODS AND RESULTS: Our study was based on a baseline survey of 15 350 individuals aged 18 to 69 years with multistage random sampling and a 3-year salt-restriction campaign across Shandong Province, China. We included 339 individuals from six districts/counties in this cohort study, and the 24-hour urinary sodium-potassium ratio (Na+/K+) served as an indicator of sodium intake. The average change in ratio was 2.39 (95% CI, 2.17–2.61) from 6.81 (95% CI, 6.41–7.21) at baseline to 4.41 (95% CI, 4.18–4.64) during the resurvey. Following a reduction from low to high quartiles of urinary Na+/K+ ratio, the average increases were 10.9 (95% CI, 8.9–12.9), 9.2 (95% CI, 6.9–11.5), 6.3 (95% CI, 4.0–8.6), and 5.3 (95% CI, 2.9–7.7) mm Hg for systolic blood pressure (P for trend=0.019) and 3.8 (95% CI, 2.4–5.2), 2.9 (95% CI, 1.7–4.2), 1.6 (95% CI, 0.4–2.8), and −0.3 (95% CI, −1.4–0.8) mm Hg for diastolic blood pressure (P for trend=0.002), respectively. A reduction in salt intake was evident for people using a 2-g salt-restriction spoon for cooking (−3.49 versus −2.22; P=0.027) after adjustment of confounding factors, compared with nonusers. Similar findings were obtained for other salt-restriction spoon–based indicators. CONCLUSIONS: Our study indicated that using a salt-restriction spoon for cooking was associated with reduced salt intake that led to a blunting of blood pressure deterioration. This finding further supports the salt-restriction spoon–based strategy for people whose primary salt intake is from homemade cooking.