MINERAL METABOLISM 317 



urinary CaO is higher on a milk diet than on a mixed diet ; and milk is 

 more effective than Ca lactate in increasing urinary CaO (Givens(6)). 

 Breast-fed infants usually show higher urinary CaO, in terms of per cent 

 of total CaO, than the artificially fed. NaCl and IIC1 increase the per 

 cent of urinary CaO but do not affect the Ca balance (Givens(6), v. 

 Wendt(a)) while bases are without effect (Givens) except in pathological 

 conditions (Eppinger and Ullmann). An increased urinary CaO is 

 usually accompanied by diuresis (Schetelig). 



Calcium in the food is usually in organic combination, as in milk, eggs, 

 vegetables and cereals, though there is a not unimportant intake of lime 

 from drinking water, in inorganic combination. The question as to the 

 relative availability of these two forms has not yet been settled (Bunge(d) ; 

 McCluggage and Mendel; Rose (6) ; Aron and Frese). Givens found 

 that 0.34 g. CaO in the form of dried skim milk when added to a 

 Ca poor basal ration would produce a positive Ca balance, while 1 g. of 

 CaO in the form of lactate was necessary to accomplish the same end. In 

 two cases of exophthalmic goiter Towles found that the addition of Ca lac- 

 tate to a Ca poor diet which was giving a negative balance, resulted in a 

 positive balance which soon reverted to negative, while the addition of the 

 same amount of CaO in the form of milk gave a higher and a lasting 

 CaO retention. That inorganic Ca salts, especially the soluble ones, are 

 absorbed is indicated by Kost who found notable increased Ca in the 

 bones of rabbits fed CaCl 2 for a long period, as compared with control 

 animals. Orgler, supplying Ca in the form of Ca phosphate, found equally 

 good retention whether the salt was given in raw milk or in sterilized milk. 



The adult normal requirement for Ca has been variously estimated 

 3.3 g. (Bunge) to 0.38 g. CaO per day. Bertram maintained equilibrium 

 on 0.38 g. CaO. Renvall required 1.19-1.26 g. CaO. Von Wendt(a) con- 

 siders 0.8 g. CaO daily sufficient and Nelson and Williams by studying the 

 total elimination of four subjects on normal unrestricted diet found 0.95- 

 1.43 g. CaO excreted daily. Sherman(c) considers 0.9-1 g. CaO per day 

 sufficient, since it is considerably above the average amount found by him 

 in a compilation of 97 experiments in which a minimum CaO for equilib- 

 rium was determined (0.63 g. CaO per 70 kg. body weight) (e). He states 

 "the case of Ca is the one which would seem to call for the most liberal mar- 

 gin in intake over the estimated average maintenance requirement if indi- 

 vidual variability is to be covered by an ample factor of safety." He holds 

 that 1 g. of Ca should accompany every 100 g. of protein intake. A suffi 

 cient Qa supply is so important that some investigators have recommended 

 the addition of Ca salts to bread and others the direct ingestion of 1 to 1.5 

 g. CaCl, or Ca lactate daily (Heinze; Bertram; Loew). Such an addi- 

 tion does not affect the arteries (Kost) and has been shown in animal 

 experimentation, to have beneficial results (Emmerich and Loew(fc) ; 

 vard ; Dox and Guernsey). Pellagra producing diets have been shown t 



