Effect of a Low Salt Diet on the Progression of Chronic Kidney Disease: A Prospective, Open-Label, Randomized Controlled Trial

Abstract

Introduction: A causal relationship exists between salt intake and hypertension, stroke, and kidney disease. However, whether or not reduced salt intake slows progression of renal diseases has been intensely debated. Methods: In this prospective, open-label, randomized controlled trial, we examined the impact of a low salt diet on renal function, blood pressure, and other metabolic parameters. Herein, 194 patients with chronic kidney disease (CKD) stages 1 to 3 were randomized in low salt (intervention) and control groups. The intervention group was provided a low salt diet (1.5 g/day) for 3 months. The control group consumed their usual diet, and daily food intake was recorded in the control group. Renal function tests, 24-h urinary sodium excretion, urinary protein, serum calcium, phosphorus, and electrolyte levels were recorded monthly. Results: After 3 months, the mean reduction in estimated glomerular filtration rate was significantly higher in the control group (mean reduction in eGFR, −3.011 mL/min/1.73 m 2 ; 95% confidence interval (CI) = −5.367, −0.656, P = .013). Blood pressure (BP) decreased significantly in both groups; systolic and diastolic BP reduction at 3 months was significantly greater in the intervention group (systolic BP mean reduction −6.57/−4.29 mmHg; 95% CI = −10.24, −2.89) and diastolic BP mean reduction −6.95, −1.64 mmHg) compared with the control group (systolic BP mean reduction −0.58/−2.63 mmHg; 95%, CI = −4.33, 3.17 and diastolic BP mean reduction −5.34, −0.08 mmHg). The mean reduction in 24-h urine sodium excretion was greater in the intervention group, reaching a significant level at month 2 (−14.45 mmol/day; 95% CI = −27.63, −1.22). Conclusion: Overall, salt restriction can help slow the progression of renal insufficiency and results in statistically significant and clinically important reductions in BP among patients with CKD. ClinicalTrials.Gov Identifier: NCT05716386 on 28/01/2023.