Effect of a low-salt diet on chronic kidney disease outcomes: a systematic review and meta-analysis

Abstract

ObjectiveThe benefits of a low-salt diet for patients with chronic kidney disease (CKD) are controversial. We conducted a systematic review and meta-analysis of the effect of a low-salt diet on major clinical outcomes.DesignSystematic review and meta-analysis.Data sourcesMEDLINE by Ovid, EMBASE and the Cochrane Library databases.Eligibility criteria for selecting studiesWe included randomised controlled trials (RCTs) and cohort studies that assessed the effect of a low-salt diet on the renal composite outcomes (more than 50% decline in estimated glomerular filtration rate (eGFR) during follow-up, doubling of serum creatinine or end-stage renal disease), rate of eGFR decline, change in proteinuria, all-cause mortality events, cardiovascular (CV) events, and changes in systolic blood pressure and diastolic blood pressure.Data extraction and synthesisTwo independent researchers extracted data and evaluated their quality. Relative risks (RRs) with 95% CIs were used for dichotomous data. Differences in means (MDs) or standardised mean differences (SMDs) with 95% CIs were used to pool continuous data. We used the Cochrane Collaboration risk-of-bias tool to evaluate the quality of RCTs, and Newcastle–Ottawa Scale to evaluate the quality of cohort studies.ResultsWe found 9948 potential research records. After removing duplicates, we reviewed the titles and abstracts, and screened the full text of 230 publications. Thirty-three studies with 101 077 participants were included. A low-salt diet produced a 28% reduction in renal composite outcome events (RR: 0.72; 95% CI: 0.58 to 0.89). No significant effects were found in terms of changes in proteinuria (SMD: −0.71; 95% CI: −1.66 to 0.24), rate of eGFR (decline MD: 1.16; 95% CI: −2.02 to 4.33), risk of all-cause mortality (RR: 0.92; 95% CI: 0.58 to 1.46) and CV events (RR: 1.01; 95% CI: 0.46 to 2.22).ConclusionA low-salt diet seems to reduce the risk for renal composite outcome events in patients with CKD. However, no compelling evidence indicated that such a diet would reduce the eGFR decline rate, proteinuria, incidence of all-cause mortality and CV events. Further, more definitive studies are needed.PROSPERO registration numberCRD42017072395.

Dietary salt intake and kidney function in rural Senegalese populations: A cross-sectional study

“…In addition to inducing obesity, high salt consumption could also directly or indirectly affect kidney function through an increase in blood pressure. However, some studies have shown that sodium intake is a predictor of renal outcome, even in individuals with normal renal function and blood pressure [41][42][43][44]. Therefore, our study revealed a signi cantly lower glomerular ltration rate (GFR) in subjects whose salt intake exceeded 12 g/day as well as a signi cant correlation between the glomerular ltration rate and sodium intake (Table 3).…”

Lifestyle Modifications and Nutritional and Therapeutic Interventions in Delaying the Progression of Chronic Kidney Disease: A Review

“…A low-salt diet (<2.3 g/day) lowers the doubling of serum Cr from the baseline and ESRD. However, the effect of a lowsalt diet on the rate of estimated glomerular filtration rate (eGFR) reduction, proteinuria, and all-cause mortality needs further investigation [18].…”

Tissue Sodium Accumulation Induces Organ Inflammation and Injury in Chronic Kidney Disease

“…In contrast to office and daytime systolic blood pressure, salt intake was found to be associated with only nocturnal blood pressure in non-dialysis CKD patients, which shows more predictive value in poor cardio-renal outcomes [17]. A low-salt diet tends to reduce the risk of renal events and adverse outcomes in patients with CKD [4,[18][19][20][21][22][23]. The Kidney Disease Improving Global Outcomes guideline suggests that salt intake should be reduced to <2 g of sodium per day in CKD patients with high blood pressure [24].…”