Table 4. Associations of protein intake with sarcopenia in elderly.
| Author, country | Year | Study design | Age (range) | Subject No. | Background nutrient intake | Comparison groups | Duration | Outcomes |
|---|---|---|---|---|---|---|---|---|
| Kerstetter et al. [40], USA | 2015 | RCT | > 60 yrs women | 208 | Dietary protein: 1.07 g/kg (protein group), 1.06 g/kg (carbohydrate group) | Carbohydrate group1) vs. protein group1) | 18 mon | Total and truncal lean mass was higher in the protein group |
| >70 yrs men | ||||||||
| Kim et al. [41], USA | 2015 | RCT | 52–75 yrs | 20 | No information | 1RDA2) vs. 2RDA2) | 4 days | Rates of protein synthesis of whole body and muscle were higher in the 2RDA group than 1RDA group, regardless of protein intake pattern |
| Mitchell et al. [42], Australia, New Zealand | 2017 | RCT | > 70 yrs | 29 | RDA group: 3,132 kcal, protein 101, carbohydrate 288, fat 161 g/day | Complete diet containing current RDA3) vs. 2RDA3) for protein | 10 wks | Whole body lean mass, trunk lean mass, and knee-extension peak power increased in 2RDA group |
| 2RDA group: 2,224 kcal, protein 88, carbohydrate 264, fat 75 g/day | ||||||||
| Park et al. [43], Korea | 2018 | RCT | 70–85 yrs | 120 | Protein intake at baseline: 0.84 g/kg, 0.77 g/kg, and 0.8 g/kg for 0.8 g, 1.2 g, and 1.5 g protein/kg/day groups, respectively | 0.8 g vs. 1.2 g vs. 1.5 g protein/kg/day fulfilled with placebo and protein powder supplements | 12 wks | Appendicular skeletal muscle mass, skeletal muscle mass index, and gait speed were higher in the 1.5 g protein/kg/day group |
| Houston et al. [36], USA | 2017 | Prospective cohort | 70–79 yrs | 1,998 | Baseline intake: 13.4%, 14.4%, and 15.6% energy intake from protein for < 0.7 g, 0.7–< 1.0 g, and ≥ 1.0 g protein/kg/day groups, respectively | < 0.7 g vs. 0.7–< 1.0 g vs. ≥ 1.0 g protein/kg/day | 6 yrs | Risk of mobility limitation in < 0.7 g and 0.7–< 1.0 g protein/kg/day group was higher than ≥ 1.0 g protein/kg/day group |
| Mendonça et al. [47], UK | 2019 | Cohort | ≥ 85 yrs | 722 | Not available | Protein (g/kg/day) | 5 yrs | Better disability trajectories were associated with ≥ 1.0 g protein/kg/day |
| Mustafa et al. [48], USA | 2018 | Prospective cohort | ≥ 50 yrs | 1,779 | Baseline intake: 15.9%, 17.1%, and 18.1% energy intake from protein for < 0.8 g, 0.8–1.1 g, and ≥ 1.2 g protein/kg/day groups, respectively | < 0.8 g vs. 0.8–1.1 g vs. ≥ 1.2 g protein/kg/day | 12 yrs | Functional decline was slower in ≥ 0.8 g protein/kg/day group |
| Granic et al. [49], UK | 2018 | Cohort | ≥ 85 yrs | 722 | No information | < 1 g vs. ≥ 1 g protein/kg/day | 5 yrs | Grip strength and physical performance were higher in ≥ 1 g protein/kg/day group |
| McLean et al. [50], USA | 2015 | Prospective cohort | ≥ 60 yrs | 646 | No information | Total, animal, and plant protein intake group | 6 yrs | Higher grip strength was associated with greater total and animal protein intake |
| Bradlee et al. [44], USA | 2017 | Prospective cohort | ≥ 40 yrs | 685 | Baseline intake: 1.04 and 1.01 g/day for 6 to < 8 total animal protein food servings per day in men, and women, respectively | Protein source foods (servings/day, varies depends on foods) | 16 yrs | Skeletal muscle mass was higher and functional decline was lower in higher protein (animal source) food intake group |
| Gray-Donald et al. [51], Canada | 2014 | Nested case control | 68–82 yrs | 422 | Not available | < 0.8 g vs. 0.8–< 1.0 g vs. 1.0–< 1.2 g vs. ≥ 1.2 g protein/kg/day | 1 yr | Protection against weight loss was better in ≥ 1 g protein/kg/day groups |
| Huang et al. [45], Taiwan | 2016 | Cross sectional | 65–85 yrs | 327 | Not available | Q1 of total and vegetable protein density4) vs. Q4 of total and vegetable protein density4) | Not available | Risk for low muscle mass was higher in the Q1 of total and vegetable protein density |
| Kobayashi et al. [52], Japan | 2013 | Cross sectional | 65–94 yrs | 2,108 | Not available | Q1 of total protein intake5) vs. Q5 of total protein intake5) (women) | Not available | Frailty was negatively related to total protein intake |
| Nilsson et al. [46], Sweden | 2018 | Cross sectional | 65–70 yrs | 106 | Not available | 0.8 g vs. 1.1 g protein/kg/day | Not available | Muscle mass and physical function were higher in 1.1 g protein/kg/day group |
| Oh et al. [24], Korea | 2017 | Cross sectional | ≥ 60 yrs | 4,452 | Not available | < 0.8 g vs. 0.8–1.2 g vs. > 1.2 g protein/kg/day | Not available | Risk of sarcopenia was higher in < 0.8 g and 0.8–1.2 g protein/kg/day group |
RCT, randomized controlled trial; RDA, recommended dietary allowance.
1)Carbohydrate group: carbohydrate (isocaloric maltodextrin) supplement group; Protein group: 45 g whey protein (40 g protein, 1.3 g protein/kg) group.
2)1RDA (0.8 g/kg/day), 2RDA (1.5 g/kg/day) with uneven (15/20/65% total protein amount at breakfast/lunch/dinner) or even (33/33/33% total protein amount at breakfast/lunch/dinner) intake of protein in the context of mixed meals.
3)RDA: 0.8 g/kg/day; 2RDA: 1.6 g/kg/day.
4)Q1: lowest quartile group, < 13.2% and < 5.8% for total and vegetable protein density, respectively; Q4: highest quartile group, ≥ 17.2% and ≥ 9.4% for total and vegetable protein density, respectively.
5)Q1: lowest quintile group, total protein intake ≤ 62.9 g/day; Q5: highest quintile group, total protein intake ≥ 84.3 g/day.