Calcium Metaboijsm in Old Age 111 



The physiology of calcium metabolism was recently 

 reviewed by Nicolaysen, Eeg-Larsen aiul Malm (1953), and 

 the biochemistry and physiology of vitamin D by Nicolaysen 

 and Eeg-Larsen (1953). Reference is made in these 

 publications to a number of aspects of the field. 



In Oslo we have for several years studied the calcium 

 metabolism of rats, and we have also conducted a long term 

 study in man. The studies are in part finished, in part they 

 are continuing. The main purpose here is to report briefly 

 on these experiments, which will be published in full at a 

 later date. 



Experiments in Rats 



The object has been to study the adaptation of the aVjsorp- 

 tion of calcium in adult and old rats. Some of the characteristic 

 results are reported below. 



Experimental. Adult rats of known age taken from our 

 stock colony and given a vitamin D free diet (842 g. whole 

 wheat, 100 g. casein [Ca "free" and fat free], 30 g. dried 

 brewers yeast, 10 g. NaCl, 50 g. B12 "mixture", 8 g. KH2PO4, 

 50 g. CaCOg), with a Ca content of • 25 per cent. At intervals 

 the CaCOg is removed and the diet then contains 0-03-0 -04 

 per cent Ca. With the aid of • 5 per cent Na oxalate added to 

 this Ca poor diet the animals are at given intervals deprived of 

 body calcium. 



The Ca absorption or the Ca balance is studied continu- 

 ously. In Figs. 1 and 2 two experiments are reported, one on 

 a D free diet to which vitamin D was added when the animals 

 had suffered a measured loss of Ca, the second in very old 

 rats who received 0*5 i.u. vitamin D daily throughout. 



Results 



The contrast between the group of rats given a vitamin 

 D free diet (Fig. 1) in the periods following Ca deprivation 

 (but before vitamin D was given), and the rats given vitamin 

 D throughout (Fig. 2) is striking. Thus rats without vitamin D 

 can lose 15-20 per cent of their Ca and the net absorption 

 still remains very low. When vitamin D is given to such rats 



