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

Abstract

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. 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. 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 m²; 95% confidence interval (CI) = -5.367, -0.656, <i>P</i> = .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). 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. NCT05716386 on 28/01/2023.