Abstract
BackgroundDietary protein restriction has long been thought to play an important role in the progression of chronic kidney disease (CKD); however, the effect of dietary protein on the rate of decline in kidney function remains controversial.ObjectiveWe undertook a systematic review and meta-analysis of randomized controlled trials (RCTs) to assess the influence of protein restriction on chronic kidney disease.MethodOvid MEDLINE (from 1946 to March 5, 2016), EMBASE (from 1966 to March 5, 2016), and the Cochrane Library (Inception to March 5, 2016) were searched to identify RCTs comparing different levels of protein intake for at least 24 weeks in adult patients with CKD. The outcomes included kidney failure events, the rate of change in estimated glomerular filtration rate (eGFR) per year, all cause death events, and changes in proteinuria, serum phosphorus concentration, serum albumin, and body mass index (BMI).ResultsNineteen trials with 2492 subjects were analyzed. A low protein diet reduced the risk of kidney failure (odds ratio (OR) = 0.59, 95% CI: 0.41 to 0.85) and end-stage renal disease (ESRD) (OR = 0.64, 95% CI: 0.43 to 0.96), but did not produce a clear beneficial effect for all cause death events (OR = 1.17, 95% CI: 0.67 to 2.06). The change in the mean difference (MD) for the rate of decline in the eGFR was significant (MD: −1.85, P = 0.001), and for proteinuria (MD: −0.44, P = 0.02). A low protein diet also reduced the serum phosphorus concentration (MD: −0.37, 95% CI: −0.5 to −0.24) and BMI (MD: −0.61, 95% CI: −1.05 to −0.17). However the change in albumin presented no significant difference between two groups (MD: 0.23, 95% CI: −0.51 to 0.97).ConclusionsBased on the findings of our meta-analysis, protein-restricted diet may reduce the rate of decline in renal function and the risk of kidney failure for CKD populations, but did not produce a clear beneficial effect for all cause death events. Besides However, the optimal level of protein intake in different participants is left unanswered, and the nutritional status should be regarded with caution.
Highlights
The high prevalence of chronic kidney disease (CKD) raises concerns worldwide,[1,2,3] and evidence-based strategies to delay progression have been proposed, while the application of protein restricted diet remains controversial.[4,5] Several meta-analyses of randomized, prospective trials for patients with CKD indicated that low protein diets (LPDs) and supplemented very low protein diets (SVLPDs) delay the composite outcome of death or the onset of renal replacement therapy (RRT).[6,7] the results of other studies did not consistently show that protein restriction is beneficial in patients with CKD
A low protein diet reduced the risk of kidney failure (odds ratio (OR) = 0.59, 95% confidence intervals (CIs): 0.41 to 0.85) and end-stage renal disease (ESRD) (OR = 0.64, 95% CI: 0.43 to 0.96), but did not produce a clear beneficial effect for all cause death events (OR = 1.17, 95% CI: 0.67 to 2.06)
A low protein diet reduced the serum phosphorus concentration (MD: −0.37, 95% CI: −0.5 to −0.24) and body mass index (BMI) (MD: −0.61, 95% CI: −1.05 to −0.17)
Summary
The high prevalence of chronic kidney disease (CKD) raises concerns worldwide,[1,2,3] and evidence-based strategies to delay progression have been proposed, while the application of protein restricted diet remains controversial.[4,5] Several meta-analyses of randomized, prospective trials for patients with CKD indicated that low protein diets (LPDs) and supplemented very low protein diets (SVLPDs) delay the composite outcome of death or the onset of renal replacement therapy (RRT).[6,7] the results of other studies did not consistently show that protein restriction is beneficial in patients with CKD. The original result of ‘Modification of Diet in Renal Disease’ (MDRD) study, which has far been the largest controlled trial of dietary protein management in CKD, failed to show the definite effectiveness of LPD in retarding CKD progression (measured with rate of decline in GFR). Clinical studies have shown that under careful monitoring, skeletal mass, skeletal function, and body composition are preserved in the majority of CKD patients on LPD.[12] In a recent 18-month randomized controlled trial (RCT) comparing ketoanalog-supplemented VLPD with LPD, participants in both groups showed average energy intakes of 30 kcal/kg IBW/day and preserved their nutritional status.[13] In the follow-up study of MDRD, there were no differences in nutritional parameters between the VLPD vs LPD group.[14] inadequate follow-up time, and the lack of measurement of dietary protein intake during the long-term follow-up period may mislead the conclusion. Editor: Wisit Cheungpasitporn, University of Mississippi Medical Center, UNITED STATES
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