用短期和长期的氮平衡方法测定了我国成年男子吃动植物混合膳食时蛋白质的需要量。受试者均为成年男性职工,短期组10名,长期组6名。短期组平均年龄、体重和身高分别为37.9岁、64.3kg及173cm;长期组分别为30.2岁、67.7kg及171cm。 短期组实验分5期,每期14天,第一天吃低氮膳、第2～11天吃实验膳,最后3天吃一般膳食,不加限制。各期蛋白质水平按实验顺序分别为0.60、0.73、0.42、0.90和1.05g/kg体重/日;长期组实验期为三个月,蛋白质水平为0.93(0.91～0.94)g/kg体重/日。用凯氏定氮法测定了各代谢期中主副食及粪尿中氮的合量。短期组结果表明,在0.42、0.60和0.73g水平时,机体均处于负氮平衡状态,在0.90g时多数达到正氮平衡,而至1.05g时全部达到正氮平衡。通过直线回归方程式计算,y=-47.75±0.32x(n=46,r=0.83、P<0.01),当y=0时,x=129.4～192.5mg氮,平均为147.7±18.6mg氮,相当于每日每公斤体重摄入0.92g蛋白质才能达到氮平衡。长期组的结果表明,当蛋白质水平为0.93g/kg体重/日,在为期三个月的实验中即可维持机体正氮平衡。二组结果相一致。若加上维持氮平衡平均摄入量的二个标准差作为安全系数,则蛋白质的需要量为1.16g/kg体重/日。 Short-term and long-term nitrogen balance methods were used to determine the amount of protein required for eating adult animals in our country. Subjects were male adult workers, short-term group of 10, long-term group of 6. The average age, weight and height of the short-term group were 37.9 years, 64.3 kg and 173 cm respectively. The long-term group was 30.2 years, 67.7 kg and 171 cm respectively. Short-term group experiment is divided into 5 phases, each period of 14 days, the first day to eat low-nitrogen diet, the first 2 to 11 days to eat experimental diet, the last 3 days to eat a general diet, without restrictions. The protein levels in each phase were 0.60, 0.73, 0.42, 0.90 and 1.05 g / kg body weight / day, respectively. The long-term experiment period was 3 months and the protein level was 0.93 (0.91-0.94) g / kg body weight / day. Kjeldahl method was used to determine the amount of nitrogen in the main non-staple food and excretion in each metabolic period. Short-term group results showed that at 0.42, 0.60 and 0.73g levels, the body is in a negative nitrogen balance, most of the positive nitrogen balance at 0.90g, and all to the positive nitrogen balance at 1.05g. Y = -47.75 ± 0.32x (n = 46, r = 0.83, P <0.01) calculated from the linear regression equation. When y = 0, x = 129.4 to 192.5 mg of nitrogen with an average of 147.7 ± 18.6 mg of nitrogen, In the daily intake of 0.92g per kilogram of body weight of protein in order to achieve nitrogen balance. The results of the long-term group showed that when the protein level was 0.93 g / kg body weight / day, the positive nitrogen balance of the body was maintained during the three-month experiment. The two groups are consistent. If two standard deviations are added to maintain the average nitrogen balance intake as a safety factor, the protein requirement is 1.16 g / kg body weight / day.