Table 1.
Exposure/Intervention | Outcome variable | Study | No. of participants (age)
Men (M), Women (W |
Effect of protein |
Rating
A B C |
Strength of evidence: Convincing, probable, Suggestive, no conclusion |
---|---|---|---|---|---|---|
N-balance | Meta-analysis (3) | 235 M & W in 19 separate studies | EAR: 0.65 g/kg BW RDA: 0.83 g/kg BW |
B | PROBABLE no difference between young and old based on N-balance studies | |
0.8 g/kg BW | N-balance (and body composition) | 14 week controlled metabolic study (8) | 10 M & W (55–77 y) | Steady state at 2 weeks, but decreased N-excretion between week 2 and 14 | B | |
Low protein: 0.5 g/kg BW Medium protein: 0.75 g/kg BW High protein: 1.0 g/kg BW |
N-balance | 3 x 18 days controlled metabolic study (9) | 23 young and 19 old M & W | Estimated RDA: 0.85 g /kg BW |
A | |
Low protein: 0.5 g/kg BW Medium protein: 0.75 g/kg BW High protein: 1.0 g/kg BW |
N-balance (and body composition) | 3 x 18 days controlled metabolic study (10) | 11 W (70–81 y) | Mean adequate protein allowance was estimated to be 0.90 g/kg BW at week 2 and 0.76 g/kg BW at week 3, decreased N-excretion between week 2 and week 3 | B | |
Usual Protein: 1.5 g/kg FFM (11–12 E%) High protein: 3.0 g/kg FFM (22–24 E%) |
N-balance (and glomerular filtration rate) | Controlled cross-over study (11) | 10 young and nine old M & W | N-balance not different between young and old and between men and women | B | |
Usual Protein: 1.5 g/kg FFM (11–12 E%) High protein: 3.0 g/kg FFM (22–24 E%) |
Glomerular filtration rate (GFR) (and N-balance) | Controlled cross-over study (11) | 10 young and nine old M & W | GFR was lower in older participants and they had a lesser adaption response to the High protein diet | B | NO CONCLUSION |
General remark for Summary tables:
POS: positive association/effect.
INVERSE: negative association/effect.
NS: statistically non-significant association/effect.
NA: non-available.