Abstract
The direction and magnitude of the association between sodium and potassium excretion and blood pressure (BP) may differ depending on the characteristics of the study participant or the intake assessment method. Our objective was to assess the relationship between BP, hypertension and 24-h urinary sodium and potassium excretion among Chinese adults. A total of 1424 provincially representative Chinese residents aged 18 to 69 years participated in a cross-sectional survey in 2017 that included demographic data, physical measurements and 24-h urine collection. In this study, the average 24-h urinary sodium and potassium excretion and sodium-to-potassium ratio were 3811.4 mg/day, 1449.3 mg/day, and 4.9, respectively. After multivariable adjustment, each 1000 mg difference in 24-h urinary sodium excretion was significantly associated with systolic BP (0.64 mm Hg; 95% confidence interval [CI] 0.05–1.24) and diastolic BP (0.45 mm Hg; 95% CI 0.08–0.81), and each 1000 mg difference in 24-h urinary potassium excretion was inversely associated with systolic BP (− 3.07 mm Hg; 95% CI − 4.57 to − 1.57) and diastolic BP (− 0.94 mm Hg; 95% CI − 1.87 to − 0.02). The sodium-to-potassium ratio was significantly associated with systolic BP (0.78 mm Hg; 95% CI 0.42–1.13) and diastolic BP (0.31 mm Hg; 95% CI 0.10–0.53) per 1-unit increase. These associations were mainly driven by the hypertensive group. Those with a sodium intake above about 4900 mg/24 h or with a potassium intake below about 1000 mg/24 h had a higher risk of hypertension. At higher but not lower levels of 24-h urinary sodium excretion, potassium can better blunt the sodium-BP relationship. The adjusted odds ratios (ORs) of hypertension in the highest quartile compared with the lowest quartile of excretion were 0.54 (95% CI 0.35–0.84) for potassium and 1.71 (95% CI 1.16–2.51) for the sodium-to-potassium ratio, while the corresponding OR for sodium was not significant (OR, 1.28; 95% CI 0.83–1.98). Our results showed that the sodium intake was significantly associated with BP among hypertensive patients and the inverse association between potassium intake and BP was stronger and involved a larger fraction of the population, especially those with a potassium intake below 1000 mg/24 h should probably increase their potassium intake.
Highlights
The direction and magnitude of the association between sodium and potassium excretion and blood pressure (BP) may differ depending on the characteristics of the study participant or the intake assessment method
In fully adjusted linear regression models (Table 3), sodium excretion was directly associated with Systolic blood pressure (SBP) (0.64 mm Hg; 95% CI 0.05–1.24), diastolic blood pressure (DBP) (0.45 mm Hg; 95% CI 0.08–0.81), and MBP (0.54 mm Hg; 95% CI 0.10–0.99) for each 1000 mg increase in sodium intake
Twenty-four-hour urinary excretion is considered the gold standard for estimated sodium intake, and in comparison with self-reported dietary salt intake data, urinary sodium excretion does not depend on the accuracy of self-reporting or food composition tables, and approximately 95% of ingested sodium is excreted through u rine[21]
Summary
The direction and magnitude of the association between sodium and potassium excretion and blood pressure (BP) may differ depending on the characteristics of the study participant or the intake assessment method. The sodium-topotassium ratio was significantly associated with systolic BP (0.78 mm Hg; 95% CI 0.42–1.13) and diastolic BP (0.31 mm Hg; 95% CI 0.10–0.53) per 1-unit increase These associations were mainly driven by the hypertensive group. These accurate and in-depth relationship studies benefit from multiple complete 24-h urine collections rather than food frequency methods or questionnaire survey methods because they are not restricted by high variability of dietary intake patterns or recall bias. We used cross-sectional survey data from the Salt Reduction and Hypertension Prevention Project (SRHPP) in Zhejiang Province, China to estimate the associations of sodium or potassium and their ratio with BP or hypertension among Chinese adults, adjusting for within-person variability in 24-h urinary electrolyte excretion and potential confounding variables
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