110 O. J. Malm, R. Nicolaysen and L. Skjelkvale 



•and representative experimental work. Tlie problem of Ca 

 balance and Ca requirement of elderly organisms has been 

 subjected to a number of studies in recent years. According 

 to McCay (1952) various species tend to get into negative Ca 

 balance when about two thirds through the span of life. Liu 

 and McCay (1953) found that they had trouble in maintaining 

 metabolic equilibrium in old dogs unless the diet was relatively 

 rich in calcium. 



Owen (1939) and Owen et at. (1940), in studies in old osteo- 

 porotic men, observed a marked tendency for Ca retention. 

 Bogonoff et al. (1953) studied the Ca balance in seven elderly 

 men (sixty-six to eighty-three years of age) of whom three 

 had osteoporosis. High, intermediate, and very low levels 

 of Ca intake were used in periods of three to four weeks. The 

 tendency to retention on high levels was small; but the loss 

 on the low level (100-130 mg. daily) was also small (100-200 

 mg. daily). In contrast Ackermann and Toro (1953a), in a 

 study of the Ca balance over fifty to seventy days in eight old 

 men given only a high Ca diet, concluded that seven of the 

 men needed 18-5 mg. Ca/kg. body weight to maintain 

 equilibrium. The eighth subject lost 0- 5-1-0 g. Ca daily in 

 spite of a very high level of Ca in the diet. 



In these experiments, as well as in earlier animal experi- 

 ments, a high faecal Ca loss was observed; in other words 

 absorption seemed to be deficient, whereas the urinary Ca in 

 these old men was in the lower range of "normal". 



Schilling and Laszlo (1951) studied various bone diseases, 

 among them seven senile osteoporotic cases. The urinary Ca 

 was low, but they retained somewhat less of an intravenously 

 injected amount of Ca salt than the normal controls (personal 

 communication). 



In view of the fact (see below) that vitamin D is a dominant 

 factor in Ca absorption in both adult and in old age, it is of 

 interest to note that Ackermann and Toro (19536) observed a 

 substantially increased Ca absorption in their subjects 

 following vitamin D administration. Balance was achieved, 

 but no retention, in the person who lost 0-5-1 -0 g. Ca daily. 



