'Changes in Kidney Function Do Not Differ between Healthy Adults Consuming Higher- Compared with Lower- or Normal-Protein Diets: A Systematic Review and Meta-Analysis

Abstract

BackgroundHigher-protein (HP) diets are advocated for several reasons, including mitigation of sarcopenia, but their effects on kidney function are unclear.ObjectiveThis meta-analysis was conducted to determine the effect of HP intakes on kidney function in healthy adults.MethodsWe conducted a systematic review and meta-analysis of trials comparing HP (≥1.5 g/kg body weight or ≥20% energy intake or ≥100 g protein/d) with normal- or lower-protein (NLP; ≥5% less energy intake from protein/d compared with HP group) intakes on kidney function. Medline and EMBASE databases were searched. Randomized controlled trials comparing the effects of HP with NLP (>4 d duration) intakes on glomerular filtration rate (GFR) in adults without kidney disease were included.ResultsA total of 2144 abstracts were reviewed, with 40 articles selected for full-text review; 28 of these were analyzed and included data from 1358 participants. Data were analyzed using random-effects meta-analysis (RevMan 5; The Cochrane Collaboration), meta-regression (STATA; StataCorp), and dose-response analysis (Prism; GraphPad). Analyses were conducted using postintervention (post) GFR and the change in GFR from preintervention to post. The post-only comparison showed a trivial effect for GFR to be higher after HP intakes [standardized mean difference (SMD): 0.19; 95% CI: 0.07, 0.31; P = 0.002]. The change in GFR did not differ between interventions (SMD: 0.11; 95% CI: −0.05, 0.27; P = 0.16). There was a linear relation between protein intake and GFR in the post-only comparison (r = 0.332, P = 0.03), but not between protein intake and the change in GFR (r = 0.184, P = 0.33). The main limitation of the current analysis is the unclear risk of selection bias of the included trials.ConclusionsPostintervention GFR comparisons indicate that HP diets result in higher GFRs; however, when changes in GFR were compared, dietary protein had no effect. Our analysis indicates that HP intakes do not adversely influence kidney function on GFR in healthy adults.

Safety and tolerability of 6-month supplementation with a vitamin D, calcium and leucine-enriched whey protein medical nutrition drink in sarcopenic older adults

“…During OLE, no (further) change in eGFR was observed in any of the (sub)groups. The alteration of eGFR in response to a high protein diet is in line with observations by others and is thought to be an adaptive response to the protein feeding and not the development of CKD per se [31,33,34]. The observed plateau in eGFR after 13 weeks of treatment with 2 servings of WP-MND during the OLE period, supports this notion of adaptation.…”

“…The consistent high protein intake in line with recommendations, especially in participants receiving 2 servings of WP-MND throughout the entire 26-week study period (during RCT and OLE), enabled evaluation of the effect of a prolonged high protein intake on kidney function. Concerns regarding the adverse effect of a high protein diet on kidney function are related to glomerular hyperfiltration and hypertensive effects [31][32][33]. During the RCT, eGFR increased in the test vs. no change in the control group (p = 0.002).…”

Anti‐Inflammatory and Antioxidative Properties of Isoflavones Provide Renal Protective Effects Distinct from Those of Dietary Soy Proteins against Diabetic Nephropathy

“…Whether restricted protein intake is necessary for the patient with DN is still under debate; [ 7–9 ] soy proteins substitution has been shown to improve renal function in patients with DN. [ 16 ] Clinical trials indicated that ingestion of a soy protein decreases urinary urea nitrogen concentrations, proteinuria, blood sodium levels, and serum and urinary creatinine levels in patients with DN.…”

“…Available data debates the idea that restricted protein intake is necessary for the patient with DN. [ 7–9 ] Previous studies have that soy‐based dietary protein protects renal function in DN related to type 1 diabetes. [ 10,11 ] In the streptozotocin (STZ)‐induced diabetic rat model, soy proteins helped to maintain aquaporin and osteoponitn expression, [ 12 ] and genistein repressed renal inflammation and fibrosis that is associated with tyrosine kinase inhibition in mesangial cells.…”

Pre-Sleep Casein Protein Ingestion Does Not Impact Next-Day Appetite, Energy Intake and Metabolism in Older Individuals

“…Based on these per meal protein intakes, it has been suggested that the current recommended dietary allowance (RDA) for protein of 0.8 g·kg −1 ·day −1 is suboptimal for the maintenance of skeletal muscle mass with advancing age. However, increasing protein intakes up to 1.2-2.0 g·kg −1 ·day −1 has been shown to reduce long-term lean mass loss in the elderly [13], and has been shown to have no negative side-effects on health outcomes such as kidney function [14]. Oftentimes the overnight period is overlooked as a window of opportunity to increase protein intake.…”