Vargas E, Bressani R, Navarrete D A, Braham J E, Elías L G
Arch Latinoam Nutr. 1985 Sep;35(3):394-405.
This paper proposes a new approach to estimate the protein needs of a population; recommendations are also made on the protein intake of adults fed diets based on rice and beans. For this purpose, the nitrogen balance data previously reported for 40 adult human subjects who had participated in 160 nitrogen balance periods fed diets based on rice and beans, with and without animal protein and/or energy supplementation were used. The proposed method is based on the curvilinear response between nitrogen intake and its nitrogen balance. The second degree equation describing the relationship between nitrogen balance and intake is calculated. Using the mathematical concept of the first and second derivatives, the point of inflexion is obtained, and interpreted as that condition wherein the individual utilizes with maximum efficacy the ingested nitrogen; nitrogen ingestion, which corresponds to that point, is therefore taken as the dietary nitrogen recommendation for the individual. When the values obtained by means of the quadratic equation are compared to those obtained by the traditional linear equation, values were found to be statistically equal (p less than 0.05) for both calculation methods. The recommended protein intake of an adult population fed a diet based on rice and beans was 0.80 and 0.77 g/kg/day for the quadratic approach, and for the conventional method, respectively. When this diet was supplemented with 10% milk protein and with the same energy level, the calculated values were 0.64 and 0.71 g protein/kg/day for both methods, in this same order. The essential amino acid intake and absorption values were also calculated from the protein levels recommended by both methods to be in nitrogen balance, from a diet based on rice and beans. Findings revealed, in all cases, that the intakes of each and all essential amino acids met those levels indicated by FAO/WHO, with the exception of isoleucine and the sulphur-containing amino acids, which apparently limit the quality of the diet.
本文提出了一种估算人群蛋白质需求的新方法；同时还针对以大米和豆类为基础饮食的成年人的蛋白质摄入量给出了建议。为此，使用了先前报道的40名成年人类受试者的氮平衡数据，这些受试者参与了160个氮平衡期，食用了以大米和豆类为基础的饮食，有或没有动物蛋白和/或能量补充。所提出的方法基于氮摄入量与其氮平衡之间的曲线反应。计算描述氮平衡与摄入量之间关系的二次方程。利用一阶和二阶导数的数学概念，得到拐点，并将其解释为个体以最大效率利用摄入氮的状态；因此，与该点对应的氮摄入量被视为个体的膳食氮推荐量。当将通过二次方程获得的值与通过传统线性方程获得的值进行比较时，发现两种计算方法的值在统计学上相等（p小于0.05）。对于以大米和豆类为基础饮食的成年人群，二次方法和传统方法推荐的蛋白质摄入量分别为0.80和0.77克/千克/天。当这种饮食补充10%的乳蛋白且能量水平相同时，两种方法计算的值依次为0.64和0.71克蛋白质/千克/天。还根据两种方法推荐的处于氮平衡状态的蛋白质水平，从以大米和豆类为基础的饮食中计算了必需氨基酸的摄入量和吸收值。结果表明，在所有情况下，每种和所有必需氨基酸的摄入量均达到了粮农组织/世卫组织规定的水平，但异亮氨酸和含硫氨基酸除外，这两种氨基酸显然限制了饮食质量。
