Calcium, Phosphorus and Nitrogen Metabolism of Young College Women

Abstract

Calcium, phosphorus and nitrogen intakes and retentions were studied for (a) 124 college women from four states, on their customary self-chosen diets; (b) an individual for forty-four 5-day periods at intervals during her nineteenth through her twenty-second year; and (c) a group of nine young women eating basal diets supplemented with 1, 2, and 3 cups of milk, respectively. Results showed that place, age and weight differences were not significant for the 124 subjects, and that intake was significantly related to retention. Figures of regression of balance upon intake showed that mean daily intakes of 0.8 gm. calcium, 1 gm. phosphorus and 9 gm. nitrogen, respectively, were required for equilibrium. Corresponding figures for the one subject were 1.1, 1, and 8 gm. That the type of diet was one of the factors influencing calcium retention was shown by the larger percentage of calcium retentions of subjects on controlled diets as compared with those on their customary self-chosen diets, when the calcium intakes were similar. In view of the fact that diets probably vary among the general population to a greater extent than did those used by the group of college women studied, the desirability of a generous calcium allowance for young women of college age (17 to 24) seems indicated, and the calcium allowance of 1 gm. recommended by the Committee on Food and Nutrition of the National Research Council for girls of 16 to 20 might well be recommended for the group 17 to 24 years old. For the large group of 124, calcium, phosphorus and nitrogen retention relationship was similar to the relationship commonly accepted. This was not the case for the individual whose balances were studied intensively. For the purposes of estimating population needs, it would seem that a short-time study of a large group is more desirable than the intensive study of one individual.