Abstract
BACKGROUND: Although protein supplementation may be desirable in the management of sarcopenia, the appropriate protein requirements for older adults with sarcopenia are presently unclear. OBJECTIVE: The aim of this study was to determine the protein requirements of older adults (65-81 year) with sarcopenia by using the indicator amino acid oxidation (IAAO) technology. METHODS: Nine older adults with sarcopenia (four male participants and five female participants) participated in the study, with protein intakes ranging from 0.1 to 1.8 g/(kg·d). Each participant consumed an adapted diet with a protein level of 1.0 g/(kg·d) and 1.7 resting energy expenditure (REE) for 2 day. Day 3 was the oxidation day of the study. Diets that delivered energy at a 1.5 × REE were isocaloric. The amounts of phenylalanine and tyrosine maintained at a constant across intakes. Therefore, phenylalanine and tyrosine were added to the protein doses of 0.1-1.5 g/kg, which was based on the highest dose of lactalbumin content [1.8 g/(kg·d)]. Applying a non-linear mixed-effects model analysis of F(13)CO(2), the protein requirement was determined by identifying the breakpoint in the F(13)CO(2) data with graded amounts of dietary protein. RESULTS: The mean estimated average requirement (EAR) and recommended nutrient intake (RNI) of protein for older adults with sarcopenia were 1.21 (95% CI: 0.95, 1.46) and 1.54 (95% CI: 1.13, 1.95) g/(kg·d), respectively. CONCLUSIONS: To our knowledge, this is the first study of protein intake in older adults with sarcopenia and indicates that older adults with sarcopenia may require a higher intake of dietary protein. CLINICAL TRIAL REGISTRATION: http://www.chictr.org.cn, ChiCTR2200061383.