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      A Systematic Review of Renal Health in Healthy Individuals Associated with Protein Intake above the US Recommended Daily Allowance in Randomized Controlled Trials and Observational Studies


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          A systematic review was used to identify randomized controlled trials (RCTs) and observational epidemiologic studies (OBSs) that examined protein intake consistent with either the US RDA (0.8 g/kg or 10–15% of energy) or a higher protein intake (≥20% but <35% of energy or ≥10% higher than a comparison intake) and reported measures of kidney function. Studies ( = 26) of healthy, free-living adults (>18 y old) with or without metabolic disease risk factors were included. Studies of subjects with overt disease, such as chronic kidney, end-stage renal disease, cancer, or organ transplant, were excluded. The most commonly reported variable was glomerular filtration rate (GFR), with 13 RCTs comparing GFRs obtained with normal and higher protein intakes. Most ( = 8), but not all ( = 5), RCTs reported significantly higher GFRs in response to increased protein intake, and all rates were consistent with normal kidney function in healthy adults. The evidence from the current review is limited and inconsistent with regard to the role of protein intake and the risk of kidney stones. Increased protein intake had little or no effect on blood markers of kidney function. Evidence reported here suggests that protein intake above the US RDA has no adverse effect on blood pressure. All included studies were of moderate to high risk of bias and, with the exception of 2 included cohorts, were limited in duration (i.e. <6 mo). Data in the current review are insufficient to determine if increased protein intake from a particular source, i.e., plant or animal, influences kidney health outcomes. These data further indicate that, at least in the short term, higher protein intake within the range of recommended intakes for protein is consistent with normal kidney function in healthy individuals.

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          Dietary Acid Load and Incident Chronic Kidney Disease: Results from the ARIC Study

          Background: Higher dietary acid load can result in metabolic acidosis and is associated with faster kidney disease progression in patients with chronic kidney disease (CKD). However, the relationship between dietary acid load and incident CKD has not been evaluated. Methods: We conducted prospective analyses of the Atherosclerosis Risk in Communities study participants without CKD at baseline (1987-1989, n = 15,055). Dietary acid load was estimated using the equation for potential renal acid load by Remer and Manz, incorporating dietary intake data from a food frequency questionnaire. Incident CKD was assessed from baseline through 2010 and defined as estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m2 accompanied by 25% eGFR decline, CKD-related hospitalization or death or end-stage renal disease identified by linkage to the US Renal Data System registry. Results: In the overall study population, 55% were female, 26% were African-American and mean age at baseline was 54 years. During a median follow-up of 21 years, there were 2,351 (15.6%) incident CKD cases. After adjusting for demographics (age, sex, race-center), established risk factors (diabetes status, hypertension status, overweight/obese status, smoking status, education level, physical activity), caloric intake and baseline eGFR, higher dietary acid load were associated with higher risk of incident CKD (hazard ratio [HR] for quartile 4 vs. 1: 1.13, 95% CI 1.01-1.28, p for trend = 0.02; HR per interquartile range increase: 1.06, 95% CI 1.00-1.11, p = 0.04). Conclusion: Dietary acid load is associated with incident CKD in a population-based sample. These data suggest a potential avenue for CKD risk reduction through diet.
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            Effects of high-protein diets on body weight, glycaemic control, blood lipids and blood pressure in type 2 diabetes: meta-analysis of randomised controlled trials.

            High-protein diets are popular for weight management, but the health effects of such diets in diabetic persons are inconclusive. The aim of the present meta-analysis was to examine the effects of high-protein diets on body weight and metabolic risk factors in patients with type 2 diabetes. We searched the PubMed and Cochrane Library databases for relevant randomised trials up to August 2012. Either a fixed- or a random-effects model was used to combine the net changes in each outcome from baseline to the end of the intervention. Overall, nine trials including a total of 418 diabetic patients met our inclusion criteria. The study duration ranged from 4 to 24 weeks. The actual intake of dietary protein ranged from 25 to 32% of total energy in the intervention groups and from 15 to 20% in the control groups. Compared with the control diets, high-protein diets resulted in more weight loss (pooled mean difference: 22.08, 95% CI 23.25, 20.90 kg). High-protein diets significantly decreased glycated Hb A1C (HbA1C) levels by 0.52 (95% CI 20.90, 20.14) %, but did not affect the fasting blood glucose levels. There were no differences in lipid profiles. The pooled net changes in systolic and diastolic blood pressure were 23.13 (95% CI 26.58, 0.32)mmHg and 21.86 (95% CI 24.26, 0.56) mmHg, respectively. However, two studies reported a large influence on weight loss and HbA1C levels, respectively. In summary, high-protein diets (within 6 months) may have some beneficial effects on weight loss, HbA1C levels and blood pressure in patients with type 2 diabetes. However, further investigations are still required to draw a conclusion.
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              Comparison of High vs. Normal/Low Protein Diets on Renal Function in Subjects without Chronic Kidney Disease: A Systematic Review and Meta-Analysis

              Background It was the aim of the present systematic review and meta-analysis to investigate the effects of high protein (HP) versus normal/low protein (LP/NP) diets on parameters of renal function in subjects without chronic kidney disease. Methods Queries of literature were performed using the electronic databases MEDLINE, EMBASE, and the Cochrane Trial Register until 27th February 2014. Study specific weighted mean differences (MD) were pooled using a random effect model by the Cochrane software package Review Manager 5.1. Findings 30 studies including 2160 subjects met the objectives and were included in the meta-analyses. HP regimens resulted in a significantly more pronounced increase in glomerular filtration rate [MD: 7.18 ml/min/1.73 m2, 95% CI 4.45 to 9.91, p<0.001], serum urea [MD: 1.75 mmol/l, 95% CI 1.13 to 237, p<0.001], and urinary calcium excretion [MD: 25.43 mg/24h, 95% CI 13.62 to 37.24, p<0.001] when compared to the respective LP/NP protocol. Conclusion HP diets were associated with increased GFR, serum urea, urinary calcium excretion, and serum concentrations of uric acid. In the light of the high risk of kidney disease among obese, weight reduction programs recommending HP diets especially from animal sources should be handled with caution.

                Author and article information

                Adv Nutr
                Adv Nutr
                Advances in Nutrition
                Oxford University Press
                19 July 2018
                July 2018
                19 July 2018
                : 9
                : 4
                : 404-418
                [1 ]Van Elswyk Consulting, Inc., Longmont, CO
                [2 ]Weatherford Consulting Services, La Vernia, TX
                [3 ]National Cattlemen's Beef Association, Centennial, CO
                Author notes
                Address correspondence to MEVE (e-mail: mveconsulting@ 123456q.com )
                © 2018 American Society for Nutrition.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( http://creativecommons.org/licenses/by-nc/4.0/), which permits noncommercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@ 123456oup.com

                : 27 March 2018
                : 04 October 2017
                : 10 October 2017
                Page count
                Pages: 15

                protein intake,renal,kidney,glomerular filtration rate,blood pressure


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