Effects of a Low-Protein Diet on Kidney Function in Patients With Chronic Kidney Disease: An Umbrella Review of Systematic Reviews and Meta-analyses of Randomized Controlled Trials.

Abstract

Chronic kidney disease (CKD) stands out as one of the most widespread diseases globally. Dietary interventions, such as adopting a low-protein diet (LPD), play a crucial role as a key approach in impeding the advancement of CKD. The objective of this umbrella review was to provide understanding into the effects of an LPD on kidney function among individuals with CKD, along with evaluating the certainty of the available evidence. Searches for relevant studies were conducted without limitations through databases such as PubMed, Scopus, Web of Science, and Google Scholar, encompassing findings up to June 2023. The effect sizes for each meta-analysis were recalibrated using a random-effects model. The certainty of the evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Twenty-five meta-analyses including 47 randomized controlled trials were included in this study. Moderate certainty of the evidence suggests that LPDs may reduce glycated hemoglobin (HbA1c) and phosphorus levels, and the risk of progressing to end-stage renal disease in patients with CKD. Moreover, notable outcomes include increased glomerular filtration rate and decreased levels of serum albumin, blood urea nitrogen, and bicarbonate, although the certainty of evidence is low. In addition, LPDs can substantially decrease proteinuria, urine urea, and parathyroid hormone (PTH), although with very low certainty. The effects on serum creatinine, calcium, systolic blood pressure, and diastolic blood pressure are statistically nonsignificant, with the certainty of evidence ranging from low to moderate. LPDs demonstrated beneficial effects on renal function in patients with CKD, which is supported by moderate to very low certainty evidence. PROSPERO registration no. CRD42023473647.