There is currently no reference for intake of
lysine for Chinese people; therefore, the present study was conducted to determine the
lysine requirement of Chinese young male adults on a habitual Chinese mixed diet based on the modified
indicator amino acid oxidation method. Seven young men with a mean age of 23.7 ± 2.2 years that were healthy based on questionnaire, physical examinations and screening tests were evaluated. Subjects were evaluated over five consecutive 7 day periods, during which time they were administered decreasing amounts of
lysine via the diet (65, 55, 45, 35, 25 mg·kg(-1)·d(-1)). Subjects were allowed to adapt from day 1 to 6 and the
isotopes were measured on day 7 in each period. The subjects'
body weights, body compositions and
plasma proteins were also examined during the study.
Amino acid kinetics were measured based on the
indicator amino acid oxidation technique using the (13)CO2 release rate and
phenylalanine oxidation rate to estimate
lysine requirements.
Body weights, body compositions, and
plasma proteins of subjects did not change significantly relative to those at baseline. The mean and the upper 95% CI of
lysine requirements of Chinese habitual diets were determined to be 58.41 and 70.09 mg·kg(-1)·d(-1), respectively, based on the (13)CO2 release rate and 54.28 and 65.14 mg·kg(-1)·d(-1), respectively, based on the
phenylalanine oxidation rate.