Protein Requirements of Elderly Chinese Adults Are Higher than Current Recommendations

Background: Due to a lack of research data on the protein requirements of the elderly in China, the estimated average requirement (EAR) and the recommended nutrient intake (RNI) of protein in the elderly remain the same as those in young and middle-aged people at 0.98 g/(kg.d). Objective: The objective of this study was to determine the protein requirements of healthy Chinese adults >65y old through use of the indicator amino acid oxidation (IAAO) method. Methods: Seven healthy adult men and 7 healthy adult women participated in the study, with protein intakes ranging from 0.3 to 1.8 g/(kg.d). The diets were isocaloric and provided energy at a 1.5 resting energy expenditure. Protein was given based on the lactalbumin. Phenylalanine and tyrosine were added to protein doses of 0.3-1.5 g/kg according to the highest dose of protein content [1.8 g/(kg.d)]. Phenylalanine and tyrosine concentrations were kept constant at each protein dose. The mean protein requirement was determined by applying a nonlinear mixed-effects model analysis to the (FCO2)-C-13, which identified a breakpoint in (FCO2)-C-13 in response to graded amounts of protein. This trial was registered with the Chinese clinical trial registry as ChiCTR-BOC-17010930. Results: Protein EAR and RNI for healthy elderly Chinese adults were determined to be 0.91 and 1.17 g/(kg.d), respectively, based on the indicator amino acid oxidation technique. Conclusions: The estimates of protein requirements for Chinese adults>65 y in the present study are 3.4% and 19.4% higher than the current estimated requirements, 0.88 g/(kg.d) for EAR and 0.98 g/(kg.d) for RNI.