Protein requirement of young adult Nigerian females on habitual Nigerian diet at the usual level of energy intake

Abstract

A short-term N balance study was conducted in twelve healthy female adults aged 21–32 years to determine their protein requirement. Four dietary protein levels (0·3, 0·4, 0·5 and 0·6 g protein/kg per d) were used. Energy intake of the subjects was kept constant at 0·18 MJ/kg per d. All subjects maintained their normal activity throughout the study period. N excretion was determined from the measurements of N in a total collection of urine, faeces, sweat and menstrual fluid for each dietary period. N balance during the four protein levels were −15·15 (SD 5·95), −5·53 (SD 6·71), + 6·15 (SD 4·76) and +12·05 (SD 8·63) mg N/kg per d for 0·3, 0·4, 0·5 and 0·6 g protein/kg per d respectively. The calculated average N requirements from regression analysis was 76·0 (sd 3·37) mg N/kg per d (0·48 g protein/kg per d). The estimate of allowance for individual variation to cover the 97·5 % population was 95 mg N/kg per d (0·6 g protein/kg per d). The net protein utilization (NPU) of the diet was 0·55. When compared with a similar study with men, there was a significant difference in the protein requirement between sexes. Thus, the unjustifiable sex difference in the protein allowance recommended by the Food and Agriculture Organization/World Health Organization/United Nations University (1985) Expert Consultation group must be reviewed.