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. 2014 May 22;9(5):e97656. doi: 10.1371/journal.pone.0097656

Table 1. Characteristics of the included studies in the meta-analyses.

References (References S1) Sample size Mean age (yrs), Duration (weeks) Study design Protein (g * kg body weight−1 * d−1, % of TEC) Protein sources in the HP group Calcium (mg/d) Daily energy (kcal) Microalbuminuria GFR- measurement
Mean baseline BMI (kg/m2) Female, %
% diabetics
Brinkworth et al. 2004 58 50.2 68 RCT HP: 30% 30 g skim milk powder, 60 g low-fat cheese, 200 g diet yogurt, 200 g lean meat or poultry, 250 ml low-fat milk n.d 12-week energy restricted According to [46], [47] (ml/min)
34 78% NP/LP: 15% n.d 12-week energy restricted
0%
Brinkworth et al. 2010 68 51.5 52 RCT HP: 35% 125 ml milk, 70 g cheddar cheese, 1 egg, 300 g (raw weight) beef, chicken or fish, 100 g (cooked) ham, tuna, beef, turkey, chicken, 40 g raw unsalted nuts n.d 1433–1672 Modification in renal disease study equation was used [48] (ml/min/1.73 m2)
33.5 64% NP/LP: 24% n.d 1433–1672
0%
Cao et al. 2011 16 56.9 7 Crossover HP: 1.6 g; 20% 500 ml milk, 80 g ham, 120 g roast beef, 120 g baked chicken, 50 g steamed peas 865 Isocaloric
26.8 100% NP/LP: 0.8 g; 10% 907 Isocaloric
0%
Ferrara et al. 2006 15 26.4 24 RCT HP: 1.9 g Beaf, pork, ham, poultry n.d n.d
23.5 0% NP/LP: 1.3 g n.d n.d
0%
Frank et al. 2009 24 24.1 1 crossover HP: 2.4 g; 26.6%; 21.7% (animal protein) Animal sources including milk and milk products n.d 2743 Assessed on the basis of sinistrin clearence (ml/min)
22.3 0% NP/LP: 1.2 g; 13.3%; 7.4% (animal protein) n.d 2736
0%
Friedman et al. 2012 307 45.5 104 RCT HP: LC diet Unlimited protein cosnumption n.d n.d Calculated by dividing the 24-hr urinary creatinine excretion (mg/d) by 1440 (min/d) and then dividing aigan by the serum creatinine (mg/dl) x100. (ml/min)
36.1 68% NP/LP: 15% n.d 1200–1500
0%
Gross et al. 2002 28 57.3 4 Crossover HP: 1.4 g Chicken 712 n.d x Measured using the 51 Cr-EDTA single-injection technique (ml/min/1.73 m2)
26.3 25% NP/LP: 0.66 g 732 n.d
100%
Jenkins et al. 2001 20 55.6 4 Crossover HP: 27.4%; 20.1% (vegetable protein) 80 g wheat gluten protein (bread) n.d 2764 Not described (ml/min)
26 25% NP/LP: 15.6%; 8.2% (vegetable protein) n.d 2835
0%
Jesudason et al. 2013 45 60.9 12 RCT HP: 30% 90–120 g/d n.d 1435–1674 x Calculated from serum creatinine using the Modification of diet and renal disease study formula [49](ml/min/1.73 m2)
36 22% NP/LP: 20% n.d 1435–1674
100%
Johnston et al. 2004 20 19–54 6 RCT HP: 31.5% Egg beater scramble with 28 g ham and 28 g cheese, 1 l milk, 84 open faced turkey, 28 g provolone, chicken chow mien dinner, peas and beans 1828 1700 Not described (ml/s/m2)
28.9 90% NP/LP: 15% 1187 1700
0%
Juraschek et al. 2013 164 53.5 6 Cross-over HP: 25%, 12.5% Food sources used for protein replacement primarily were vegetable-based n.d n.d eGFR was calculated using the CKD Epidemiology Collaboration cystatin C equation [43] (ml/min/1.73 m2)
30.2 45% NP/LP: 15%, 5.4% n.d n.d
0%
Krebs et al. 2012 419 57.8 104 RCT HP: 30% n.d n.d −500 x
36.6 60% NP/LP: 15% n.d −500
100%
Larsen et al. 2011 99 59.4 52 RCT HP: 30% A combination of lean meat, chicken and fish n.d 12-week energy restricted x Not described (ml/min/1.73 m2)
27–40 52% LP/NP: 15% n.d 12-week energy restricted
100%
Leidy et al. 2007 46 50 12 RCT HP: 1.4 g; 30% 180 g cooked pork, loin, ham, or Canadian bacon n.d −750 Calculated from serum creatinine using the Modification of diet and renal disease study formula [49] (ml/min/1.73 m2)
30.6 100% NP/LP: 0.8 g; 18% n.d −750
0%
Li et al. 2010 100 49.3 52 RCT HP: 2.2 g, 30% Formula 1, Herbalife Intl., Los Angeles n.d −500 Not described (ml/min)
34.5 66% NP/LP: 1.1 g, 15% n.d −500
0%
Liu et al. 2013 50 47.9 12 RCT HP: LC diet Boiled eggs 2 (ad libitum for snacks, Lactalbumin (15 g), Duck leg (220 g) n.d ad libitum
26.7 100% NP/LP: 18% n.d 1500
0%
Luger et al. 2013 44 62.4 12 RCT HP: 30% Received data sheets referring to protein-rich foods: major high-protein sources included: soy-based foods, milk products, fish and poultry n.d 1272 x Calculated from serum creatinine using the Modification of diet and renal disease study formula [49](ml/min/1.73 m2)
33.3 55% NP/LP: 15% n.d 1235
100%
Luscombe-Marsh et al. 2005 73 20–65 16 RCT HP: 40% 400 ml skim milk, 40 g skim milk powder, 40 g low-fat cheese, 300 g meat, poultry or fish, 20 g almonds, 200 g low-fat artificially sweetened yogurt n.d 12-week energy restricted (urine creatinine concentration in mmol/l x urine volume in ml/1140 min/ plasma creatinine concentration in µmol/l×1000 ml x min)×0.7. (ml/min)
27–40 65% NP/LP: 20% n.d 12-week energy restricted
0%
Noakes et al. 2005 100 49.5 12 RCT HP: 34% 250 ml milk, 200 g low-fat yogurt, 300 g lean meat, poultry or fish 777 1342 Not described (ml/min)
32.5 100% NP/LP: 17% 594 134
0%
Nuttall et al. 2003;Gannon et al. 2003 12 n.d 5 Crossover HP: 30% 1 l low-fat milk, 113 g beef, 255 g baked chicken, 113 g low-fat cheese, 227 g low-fat yogurt n.d 2235 x
n.d 17% NP/LP: 15% n.d 2266
100%
Nuttall et al. 2006 8 63 5 Crossover HP: 30% 124 g egg substitute, 56 g cheddar cheese, 226 g roasted ham, 85 g swiss cheese, 253 split pea soup, 170 g tuna, 80 g peas, 56 g dry-roasted peanuts n.d Isocaloric x
31 0% NP/LP: 15% n.d Isocaloric
100%
Pomerleau et al. 1993 20 58 3 Crossover HP: 1.9 g; 22%; Supplements (casein, gelatin, vegetable proteins, yeast, and soy) 883 2182 x 99mTechnicum-DTPA (diethylenetriamine pentaacetic acid) plasma clearance (ml/s/1.73 m2)
33 33% NP/LP: 0.8 g; 10% 930 2110
100%
Roughead et al. 2003 15 60.5 8 Crossover HP: 1.62 g; 20% Pork, turkey breast, beef round, ham, chicken breast 596 2296 Calculated from serum and urinary creatinine, which were measured using alkaline picric acid (ml/s)
26.5 100% NP/LP: 0.94 g; 12% 617 2296
0%
Sargrad et al. 2005 12 47.5 8 RCT HP: 30% Chicken, fish, eggs, low-fat milk, cheeses, nuts 567 1275 n.d
34.5 75% NP/LP: 15% 521 1371
100%
Skov et al. 1999 50 39.6 24 RCT HP: 25% Dairy products and meat, the latter represented by both beef, pork, poultry, lamb n.d ad libitum Measured using the 51Cr-EDTA single-injection technique (ml/min)
30.4 76% NP/LP: 12% n.d ad libitum
0%
Stern et al. 2004 132 53.5 12 RCT HP: LC diet Unlimited: meat, fowl, fish, shellfish, eggs, 110 g hard cheese n.d −500
42.9 17% NP/LP: 15% n.d no
41%
Velázquez Lopez et al. 2008 41 67 4 RCT HP: 1–1.2 g n.d n.d isocaloric x Assessed using creatinine-clearance estimation by the Cockroft and Gault formula [50] (ml/min)
26.82 65% NP/LP: 0.6–0.8 g n.d Isocaloric
100%
Wagner et al. 2007 22 30.8–60.2 1 Crossover HP: 2 g Meat, dairy products, and egg white powder n.d Isocaloric Calculated from serum creatinine using the Modification of diet and renal disease study formula [49] (ml/min/1.73 m2)
25.5 69% NP/LP: 0.5 g n.d Isocaloric
0%
Westman et al. 2008; Yancy et al. 2007 84 51.8 24 RCT HP: VLC diet Unlimited: meat, fowl, fish, shellfish, eggs, 120 g hard cheese; 60 g fresh cheese n.d ad libitum x
38 78% NP/LP: 15% n.d −500
100%
Wycherley et al. 2012 68 50.8 52 RCT HP: 35% 3 serves low-fat dairy, 300 g lean red meat, 100 deli-scliced meat/canned fish n.d 1680 According to [51] (ml/min/1.73 m2)
33 0% LP: 17% n.d 1680
0%

BMI, Body-Mass-Index; CKD, chronic kidney disease; HP, high protein; n.d, no data; NP/LP, normal/low protein; RCT, randomized controlled trial; VLC, very-low carbohydrate.