Effect of the Time Factor and Calorie Level on Nitrogen Utilization of Young Women

Abstract

For 54 days two groups of 8 young women each were subjects for a study of the effect of the time factor and calorie level on nitrogen utilization. One group had a daily intake of approximately 43 gm of protein and the other of approximately 63 gm. The effect on nitrogen excretion of the absence or presence of animal protein in the form of 240 gm milk in the noon meal, and the effect of a calorie level of 1,800 as compared with one of 2,400, were determined. The group on the lower protein intake had a significantly lower urinary nitrogen excretion when animal protein in the form of milk was present in the noon meal than when it was absent. The group on the higher protein intake showed no difference in nitrogen excretion related to the presence or absence of animal protein in the noon meal. There was a highly significant reduction in nitrogen excretion by both groups when the calories were increased from 1,800 to 2,400 and yet animal protein was absent from the noon meal. The nitrogen sparing action of the extra calories was greatest at the lower protein intake. Thus the implications are that the lower the intake of protein and calories, the greater is the need for including high quality protein in each meal if nitrogen is to be well utilized.