Variability of Metabolic Response of Different Children to a Given Intake of Calcium

As the metabolic balance studies on the “so-called normal” adults 1 , 2 and 22 children 3 , 4 as well as the growth observations on 530 infants 5 have progressed in this laboratory over several years we have grown more and more impressed with the wide physiological variations found. These fluctuations are evident not only among individuals of the same age, body size and living under the same environmental conditions but of the same individual when kept under constant conditions and observed continuously over, not days, but weeks. Obviously, it becomes necessary to build up some knowledge as to how much variation one may expect to find in a healthy individual living under highly standardized conditions before it is possible to interpret the degree of differences of results found under specific experimental conditions or in disease. Moreover, in the case of children, it is exceedingly important to build up some concept of the changes that occur incident to growth and development alone, before one is able to interpret satisfactorily the significant effect of specific food or other amenable factors on the metabolism of the child.

To illustrate not only the degree of variability that may occur among healthy individuals of like age and body size but also the increments and decrements that occur in metabolism from time to time as the observations progress the present report records the calcium balances for only 25 to 65 consecutive days of 6 of the 22∗ typically healthy children who were maintained on simple diets of 70 to 100 calories per kilo of body weight per day appropriate for the age and size of the child and approximately uniform in mineral and nitrogen content. The dietary furnished one gram of calcium per day for each child.