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.