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. 2014 Feb 11;58:10.3402/fnr.v58.23364. doi: 10.3402/fnr.v58.23364

Table 1.

Summary table N-balance studies

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.