TABLE 1.
Summary of the included studies in model 1 (effect of protein source/quality on postprandial muscle protein synthesis) and model 2 (effect of protein source/quality on resistance exercise–induced postprandial muscle protein synthesis) in young and older adults1
| Study ID author, year | Study arm | Participants, n | Group, age, y | Body mass, kg | Sex, M/F | Total protein dose, g | EAA dose, g | Leucine content,2 g | Resistance exercise protocol (if applicable) | Main findings (postprandial MPS, fractional synthetic rate, %/h) |
|---|---|---|---|---|---|---|---|---|---|---|
| Bendtsen, 2019 (42) | Young | |||||||||
| Hydrolyzed whey (HIGH) | 18 | 24 ± 1 | 75 ± 2 | M | 15 | 6.2 | 1.9 | — | NSD in Myofibrillar (MyoMPS) between whey (0.058 ± 0.007%/h) compared with either hydrolyzed porcine muscle (0.063 ± 0.011%/h) or hydrolyzed porcine blood (0.048 ± 0.007%/h) in healthy men. Postprandial period: 0–150 | |
| Hydrolyzed porcine blood protein | 18 | 24 ± 1 | 75 ± 2 | M | 15 | 6.1 | 1.7 | — | ||
| Hydrolyzed porcine muscle protein | 18 | 24 ± 1 | 75 ± 2 | M | 15 | 3.1 | 0.8 | — | ||
| Burd, 2012 (43) | Old | BMI3 | ||||||||
| Whey isolate (HIGH) | 9 | 72 ± 1 | 26 ± 2 | M | 20 | 10.2 | 2.8 | — | MyoMPS was significantly elevated (P < 0.05) with whey (0.043 ± 0.009%/h) compared with micellar casein (0.024 ± 0.005%/h) in healthy elderly men. Postprandial period: 0–240 min | |
| Micellar casein | 7 | 72 ± 1 | kg/m2 | M | 20 | 8.2 | 1.6 | — | ||
| Burd, 2012 (43) | Old | BMI3 | ||||||||
| Whey isolate (HIGH) | 9 | 72 ± 1 | 26 ± 2 | M | 20 | 10.2 | 2.8 | Unilateral knee extensions; 3 sets of 10 repetitions at each participant's 10RM | MyoMPS was significantly elevated (P < 0.05) with whey (0.055 ± 0.009%/h) compared with micellar casein (0.035 ± 0.005%/h) in healthy elderly men. Postprandial period: 0–240 min | |
| Micellar casein | 7 | 72 ± 1 | kg/m2 | M | 20 | 8.2 | 1.6 | |||
| Burd, 2015 (44) | Young | |||||||||
| Skim milk (HIGH) | 12 | 22 ± 1 | 74 ± 3 | M | 30 | 13.0 | 2.7 | Leg press and knee extensions; 4 sets of 8–10 repetitions until volitional fatigue | NSD in MyoMPS between milk (0.071 ± 0.017) and minced beef (0.057 ± 0.021%/h) in healthy young men. Postprandial period: 0–300 min | |
| Minced beef | 12 | 22 ± 1 | 74 ± 3 | M | 30 | 13.0 | 2.5 | |||
| Churchward-Venne, 2019 (45) | Young | |||||||||
| Whey (HIGH) | 12 | 23 ± 1 | 76 ± 2 | M | 20 | 10.1 | 2.6 | Concurrent exercise bout including 4 sets of 8 | NSD in MyoMPS between whey (0.054 ± 0.007%/h) compared with both micellar casein (0.059 ± 0.002%/h) or milk (0.059 ± 0.001%/h, | |
| Micellar casein | 12 | 24 ± 1 | 73 ± 3 | M | 20 | 9.2 | 2.0 | |||
| Milk | 12 | 24 ± 1 | 74 ± 2 | M | 20 | 7.8 | 1.7 | |||
| repetitions (∼80% 1RM) for both supine leg press and seated leg extensions followed by a 30-min continuous cycle (∼60% of maximal workload) | P > 0.05) in healthy, young, active men. Postprandial period: 0–360 min | |||||||||
| Churchward-Venne, 2019 (46) | Young | |||||||||
| Whey (HIGH) | 12 | 23 ± 1 | 76 ± 2 | M | 20 | 10.1 | 2.6 | Concurrent exercise bout including 4 sets of 8 repetitions (∼80% 1RM) for both supine leg press and seated leg extensions followed by a 30-min continuous cycle (∼60% of maximal workload) | NSD in MyoMPS between whey (0.054 ± 0.007%/h), soy (0.053 ± 0.013%/h, P > 0.05) in healthy, young, active men. Postprandial period: 0–360 min | |
| Soy | 12 | 23 ± 1 | 74 ± 2 | M | 20 | 6.8 | 1.4 | |||
| Dideriksen, 2011 (47) | Old | |||||||||
| Whey (HIGH) | 6 | 64 ± 1 | 76 ± 4 | M = 4; F = 2 | 15.6–30.4 | ∼12.3 | ∼3.4 | Bilateral leg press and unilateral knee extensions; 5 sets of 8 repetitions at 80% 1RM | NSD in Myo and collagen MPS between whey (0.090 ± 0.012%/h) and caseinate (0.090 ± 0.007%/h, P > 0.05) in healthy elderly individuals. Postprandial period: 0–360 min | |
| Caseinate | 6 | 70 ± 2 | 76 ± 6 | M = 3; F = 3 | (0.45 g/kg LBM)4 | ∼11.0 | ∼2.5 | |||
| Gorissen, 2016 (48) | Old | |||||||||
| Whey (HIGH) | 12 | 72 ± 2 | 79 ± 2 | M | 35 | 16.6 | 4.4 | — | MyoMPS was significantly elevated (P < 0.05) with whey (0.041 ± 0.017%/h) compared with wheat (0.035 ± 0.017%/h) and wheat protein hydrolysate (0.032 ± 0.014%/h) in healthy older men. NSD difference was observed when whey was compared with micellar casein (0.050 ± 0.017%/h, P > 0.05). Postprandial period: 0–240 min | |
| Micellar casein | 12 | 73 ± 1 | 75 ± 3 | M | 35 | 14.9 | 3.2 | — | ||
| Wheat | 12 | 68 ± 1 | 77 ± 2 | M | 35 | 9.8 | 2.5 | — | ||
| Wheat protein hydrolysate | 12 | 72 ± 2 | 79 ± 4 | M | 35 | 9.9 | 2.5 | — | ||
| Hamarsland, 2017 (49) | Young | |||||||||
| Native whey (HIGH) | 10 | 25 ± 2 | 70 ± 12 | M = 5; F = 5 | 2 × 20 g5 | 10.6 | 2.7 | Leg press and knee extensions; 4 sets of 8 repetitions to failure (i.e., 8RM) | MyoMPS was significantly elevated (P < 0.05) with native whey (0.110 ± 0.066%/h) compared with milk (0.081 ± 0.047%/h) protein in young resistance-trained men and women. Postprandial period: 60–180 min | |
| Milk | 12 | 25 ± 5 | 73 ± 12 | M = 8; F = 4 | 2 × 20 g5 | 9.3 | 2.0 | |||
| Hamarsland, 2019 (50) | Old | |||||||||
| Native whey (HIGH) | 11 | 73 ± 3 | 70 ± 12 | M = 6; F = 5 | 2 × 20 g | 10.6 | 2.7 | Leg press and knee extensions; 4 sets of 8 repetitions to failure (i.e., 8RM) | MyoMPS was significantly elevated (P < 0.05) with native whey (0.119 ± 0.061%/h) compared with milk (0.068 ± 0.038%/h) protein in healthy elderly men and women. Postprandial period: 60–180 min | |
| Milk | 10 | 75 ± 4 | 76 ± 18 | M = 7; F = 3 | 2 × 20 g | 9.3 | 2.0 | |||
| Oikawa, 2020 (51) | Old | |||||||||
| Whey (HIGH) | 10 | 67 ± 2 | 80 ± 13 | F | 30 | 15.4 | 4.3 | — | MyoMPS was significantly elevated (P < 0.0001) with whey (0.035 ± 0.011%/h) compared with collagen (0.030 ± 0.011%/h) in healthy older women. Postprandial period: 0–240 min | |
| Collagen | 10 | 69 ± 4 | 71 ± 17 | F | 30 | 5.6 | 0.9 | — | ||
| Oikawa, 2020 (51) | Old | |||||||||
| Whey (HIGH) | 10 | 67 ± 2 | 80 ± 13 | F | 30 | 15.4 | 4.3 | Four sets of unilateral knee extension exercise (∼60% 1RM) of the dominant leg | MyoMPS was significantly elevated (P < 0.0001) with whey (0.051 ± 0.009%/h) compared with collagen (0.035 ± 0.009%/h) in healthy older women. Postprandial period: 0–240 min | |
| Collagen | 10 | 69 ± 4 | 71 ± 17 | F | 30 | 5.6 | 0.9 | |||
| Pennings, 2011 (52) | Old | |||||||||
| Whey (HIGH) | 16 | 73 ± 1 | 76 ± 2 | M | 20 | 9.3 | 2.4 | — | Mixed MPS was significantly elevated (P < 0.05) with whey (0.15 ± 0.08%/h) compared with both casein (0.08 ± 0.04%/h) and casein hydrolysate (0.10 ± 0.04%/h) in healthy older men. Postprandial period: 0–360 | |
| Casein | 16 | 74 ± 1 | 75 ± 3 | M | 20 | 7.9 | 1.4 | — | ||
| Casein hydrolysate | 16 | 74 ± 1 | 76 ± 2 | M | 20 | 7.9 | 1.4 | — | ||
| Reitelseder, 2011 (53) | Young | |||||||||
| Whey isolate (HIGH) | 9 | 28 ± 2 | 79 ± 3 | M | 17.5 | 8.8 | 2.1 | Unilateral seated leg extension; 10 sets of 8 repetitions at 80% 1RM | NSD in MyoMPS between whey (0.123 ± 0.016%/h) and casein (0.098 ± 0.011%/h, P > 0.05) in healthy male adults. Postprandial period: 60–360 min | |
| Casein caseinate | 9 | 28 ± 2 | 79 ± 3 | M | 17.5 | 8.1 | 1.5 | |||
| Reitelseder, 2019 (54) | Old | |||||||||
| Caseinate MIPRODAN40 (HIGH) | 9 | 68 ± 2 | 80 ± 3 | M | ∼38 | 17.9 | 3.6 | — | NSD in MyoMPS between caseinate MIPRODAN40 (0.045 ± 0.009%/h) and whey PEPTIGEN IF-3090 (0.043 ± 0.013%/h, P > 0.05) in healthy older males. Postprandial period: 60–360 min | |
| Whey PEPTIGEN IF-3090 | 10 | 69 ± 2 | 85 ± 3 | M | (0.45 g/kg LBM)4 | 17.8 | 3.3 | — | ||
| Reitelseder, 2019 (54) | Old | |||||||||
| Caseinate MIPRODAN40 (HIGH) | 9 | 68 ± 2 | 80 ± 3 | M | ∼38 | 17.9 | 3.6 | Unilateral leg extensions; 10 sets of 8 repetitions at 70% 1RM | NSD in MyoMPS between caseinate MIPRODAN40 (0.043 ± 0.012%/h) and whey PEPTIGEN IF-3090 (0.041 ± 0.013%/h, P > 0.05) in healthy older males. Postprandial period: 60–360 min | |
| Whey PEPTIGEN IF-3090 | 10 | 69 ± 2 | 85 ± 3 | M | (0.45 g/kg LBM)4 | 17.8 | 3.3 | |||
| Tang, 2009 (55) | Young | |||||||||
| Whey hydrolysate (HIGH) | 6 | 23 ± 4 | 87 ± 14 | M | 21.4 | 10.0 | 2.3 | — | Mixed MPS was significantly elevated (P < 0.01) with whey hydrolysate (0.091 ± 0.006%/h) compared with micellar casein (0.047 ± 0.004%/h) in healthy young men. NSD was observed when comparing whey hydrolysate with soy (0.077 ± 0.014%/h, P > 0.05). Postprandial period: 0–180 | |
| Micellar casein | 6 | 23 ± 4 | 87 ± 14 | M | 21.9 | 10.1 | 1.8 | — | ||
| Soy | 6 | 23 ± 4 | 87 ± 14 | M | 22.2 | 10.1 | 1.8 | — | ||
| Tang, 2009 (55) | Young | |||||||||
| Whey hydrolysate (HIGH) | 6 | 23 ± 4 | 87 ± 14 | M | 21.4 | 10.0 | 2.3 | Unilateral leg press and knee extensions; 4 sets at 10–12 RM | Mixed MPS was significantly elevated in whey hydrolysate (0.150 ± 0.13%/h) compared with micellar casein (0.069 ± 0.005%/h, P < 0.01) and soy (0.116 ± 0.010%/h, P < 0.05) in healthy young men. Postprandial period: 0–180 | |
| Micellar casein | 6 | 23 ± 4 | 87 ± 14 | M | 21.9 | 10.1 | 1.8 | |||
| Soy | 6 | 23 ± 4 | 87 ± 14 | M | 22.2 | 10.1 | 1.8 | |||
| Walrand, 2016 (56) | Old | |||||||||
| Soluble milk protein (HIGH) | 8 | 72 ± 1 | 70 ± 2 | M | 15 | 7.1 | 1.8 | — | MyoMPS was significantly elevated with soluble milk protein (0.062 ± 0.025%/h) and casein (0.027 ± 0.032%/h, P < 0.05) in healthy elderly men. Given fractionally every 20 min. postprandial period: 0–240 min | |
| Casein | 7 | 72 ± 1 | 76 ± 3 | M | 15 | 6.6 | 1.4 | — | ||
| Walrand, 2016 (56) | Old | |||||||||
| Soluble milk protein (HIGH) | 8 | 73 ± 1 | 70 ± 2 | M | 30 | 14.3 | 3.6 | — | NSD in MyoMPS between soluble milk protein (0.053 ± 0.031%/h) and casein (0.050 ± 0.014%/h, P > 0.05) in healthy elderly men. Given fractionally every 20 min. postprandial period: 0–480 min | |
| Casein | 8 | 72 ± 1 | 76 ± 3 | M | 30 | 13.2 | 2.8 | — | ||
| Wilkinson, 2007 (57) | Young | |||||||||
| Skim milk (HIGH) | 8 | 22 ± 0 | 82 ± 6 | M | 18.2 | ∼7.8 | ∼1.6 | Unilateral leg press, hamstring curl, and knee extension. For each exercise, 4 sets at 80% 1RM (10 repetitions for first 3 sets and the last set to exhaustion) | Mixed MPS was significantly elevated (P < 0.05) with milk (0.10 ± 0.01%/h) compared with soy (0.07 ± 0.01%/h) protein. Postprandial period: 0–180 min | |
| Soy | 8 | 22 ± 0 | 82 ± 6 | M | 18.2 | ∼7.5 | ∼1.3 | |||
| Yang, 2012 (58) | Old | |||||||||
| Whey (HIGH) | 10 | 72 ± 5 | 81 ± 9 | M | 20 | 9.2 | 2.0 | — | MyoMPS was significantly elevated (P < 0.005) with whey (0.043 ± 0.009%/h) compared with soy protein (0.029 ± 0.007%/h) in older healthy men. Postprandial period: 0–240 min | |
| Soy | 10 | 72 ± 6 | 78 ± 11 | M | 20 | 7.1 | 1.6 | — | ||
| Yang, 2012 (58) | Old | |||||||||
| Whey (HIGH) | 10 | 70 ± 4 | 81 ± 12 | M | 40 | 18.4 | 4.0 | — | MyoMPS was significantly elevated (P < 0.005) with whey (0.055 ± 0.009%/h) compared with soy (0.035 ± 0.008%/h) protein in older healthy men. Postprandial period: 0–240 min | |
| Soy | 10 | 70 ± 5 | 77 ± 9 | M | 40 | 14.2 | 3.2 | — | ||
| Yang, 2012 (58) | Old | |||||||||
| Whey (HIGH) | 10 | 72 ± 5 | 81 ± 9 | M | 20 | 9.2 | 2.0 | Unilateral knee extensions involving 3 sets at 10RM | MyoMPS was significantly elevated (P < 0.001) with whey (0.055 ± 0.009%/h) compared with soy (0.041 ± 0.010%/h) protein in older healthy men. Postprandial period: 0–240 min | |
| Soy | 10 | 72 ± 6 | 78 ± 11 | M | 20 | 7.1 | 1.6 | |||
| Yang, 2012 (58) | Old | |||||||||
| Whey (HIGH) | 10 | 70 ± 4 | 81 ± 12 | M | 40 | 18.4 | 4.0 | Unilateral knee extensions involving 3 sets at 10RM | MyoMPS was significantly elevated (P < 0.001) with whey (0.082 ± 0.038%/h) compared with soy (0.056 ± 0.009%/h) protein in older healthy men. Postprandial period: 0–240 min | |
| Soy | 10 | 70 ± 5 | 77 ± 9 | M | 40 | 14.2 | 3.2 |
1
Values are means ± SDs. EAA, essential amino acid; MPS, muscle protein synthesis; Myo, myofibrillar; NR, not reported; NSD, no significant difference; RM, repetition maximum.
2
Where EAA and/or leucine content was not provided, total content is provided as estimates based on information provided within each study, where possible.
3
BMI reported in the absence of body mass.
4
Estimates based on range of doses provided relative to body mass.
5
Two separate doses of a 20-g dose of protein provided.