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Fed State Protein Turnover in Healthy Older Persons under a Usual Protein‐Rich Diet
Author(s) -
Pfrimer Karina,
Marchini Julio Sergio,
Moriguti Julio Cesar,
Ferriolli Eduardo
Publication year - 2009
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1750-3841.2009.01136.x
Subject(s) - protein turnover , nitrogen balance , turnover , urea nitrogen , protein metabolism , chemistry , glycine , zoology , dietary protein , nitrogen cycle , urea , metabolism , protein degradation , medicine , nitrogen , endocrinology , biology , biochemistry , creatinine , protein biosynthesis , amino acid , management , organic chemistry , economics
The objective of this study was to verify the protein turnover rates of healthy older persons under a usual protein‐rich diet and to compare values to those described in the literature. This cross‐sectional study was conducted at Metabolism Unit, Univ. Hospital of the School of Medicine of Ribeirao Preto, Univ. of Sao Paulo, Brazil. In this study, 7 healthy older persons aged 65.4 ± 2.8 y, with BMI 22.7 ± 2.4 kg/m 2 and a mean daily protein intake of 1.34 g of protein/kg were studied. A 9‐h whole‐body 15 N‐glycine single‐dose study was performed after an overnight fast. During the study, each subject received 6 isoenergetic, isonitrogenous meals at 2‐h intervals based on their average intake. Ammonium, urea, and total nitrogen were quantified and analyzed by mass spectrometry, with the determination of total protein turnover rates by the 15 N‐glycine method. The results show that total nitrogen output was 3.2 ± 0.96 g/N and intake 7.7 ± 1 g/N, 15 N nitrogen flux was 30.6 ± 6.3 g/9 h. Endogenous nitrogen balance was positive (4.5 g ± 1 g/N in 9 h). In conclusion, the protein turnover of healthy older persons under a usual protein‐rich diet is positive during the fed state and has synthesis and degradation rates similar to those previously described in studies involving diet adaptation periods.