Calcium Metabolism in Old Age 121 



The approximations used cannot lead to serious errors 

 affecting the main results. 



In the main most of the figures for Ca requirement support 

 the view of Hegsted et al. (1952) that Ca requirement for 

 maintenance is low in men. On the other hand the higher 

 figures reached are at variance with such a view and some 

 comments on these figures are needed. The experiment in 

 No. 551 over twenty-six months leads to a comparatively 

 well established figure of 12-8 mg. Is he an exception in the 

 material presented? In view of the results in No. 242, the 

 figure reached in No. 288 can be quite off the mark, and the 

 figure reached for No. 408c is not well founded due to the 

 "abnormal" figure for faecal Ca in the third period. In the 

 course of time this high faecal output would have been followed 

 by an inverse wave, with a much lower figure for Ca require- 

 ment as the result. On the other hand the figure of 9 mg. for 

 No. 200 would seem to be not too poorly founded. Elementary 

 statistics on the requirement figures for the first 24 persons 

 results in a mean of 6 -3 mg./kg. with s.d. of 2 • 1. This would 

 imply that No. 551 is one in a thousand but it does not solve 

 the problem. 



The men above fifty years of age seem not to behave 

 differently as regards adaptation, and it appears from Fig. 3 

 that a number of them retained Ca remarkably well. The 

 development of osteoporosis implies loss of calcium from the 

 skeleton, either by a real increase of urinary Ca, or by a non- 

 reduction of urinary Ca combined with faulty absorption. 



The results in No. 790 on the highest intake level are 

 instructive as to how the absorption may seem to be low 

 when only high levels of Ca in the diets are used, and this may 

 throw some additional light on the apparent faulty absorption 

 in the old persons of Ackermann and Toro (1953). The results 

 of Bogonoff et al. (1953) on very low levels of Ca in the diet 

 are in line with the results here presented. 



As regards urinary Ca the variability between individuals 

 makes it impossible to judge if the urinary Ca in a given 

 person has been increased. Observations over many years 



