258 VITAMIN D GROUP 



month of gestation is 0.3 g. daily. A newborn premature infant simply can- 

 not ingest enough calcium to enable him to retain this amount plus the 

 extra amount needed for his rapid growth. Such an infant will need large 

 doses of vitamin D to prevent rickets. ^'^ 



The infant fed on the usual cow's milk dilutions ingests an enormous 

 amount of calcium and inorganic phosphorus per sciuare meter of body 

 surface as compared to the adult or the breast-fed infant. However, the 

 Ca/P ratio of cow's milk is far from optimal and at times may be dangerous, 

 whereas the breast-fed infant, although receiving a much smaller amount 

 of bone-forming elements, ingests these materials in a more optimal ratio 

 and in amounts which do not tax the calcium and inorganic phosphorus 

 homeostatic mechanism of the kidney. It is perhaps this which explains 

 the lower incidence of rickets and ricketic tetany in breast-fed infants. 

 More than 95 % of ingested calcium goes to form bone. For this purpose an 

 amount of phosphorus equal to about 50 % of retained calciimi is needed. 

 Since phosphorus plays an important role in all intracellular chemical proc- 

 esses, an additional amoinit of phosphorus is needed by the cells. In addi- 

 tion to this factor, it seems also that the requirement of a breast-fed infant 

 for phosphorus is generally less than that of one fed on cow's milk. 



Infections may be associated with deficiency of blood calcium and in- 

 organic; phosphorus, even when ordinarily adecjuate amounts of vitamin D 

 are ingested. 



For a clearer understanding of the problem of vitamin D dosage in the 

 human being, it is important to differentiate between the prevention and 

 the cure of vitamin D deficiency (rickets) and also to determine whether 

 we are dealing with an organism that is initially normal or one suffering 

 from visceral or other disease or immaturity of vital organs. For practical 

 reasons, an adequate preventive dose of vitamin D is one that will prevent 

 all clinical and radiographic evidence of rickets whereas a therapeutic dose 

 is one that will re-establish normal calcification and bone growth and in due 

 time correct most of the deformities of the disease. Some telltale radio- 

 graphic evidence may persist in spite of adecjuate dosage, and occasionally 

 gross changes may recjuire surgical intervention or other forms of therapy. 

 A dose of vitamin D that Avill cure rickets is also adeciuate to prevent the 

 disease. 



For the prevention of rickets in the average normal infant 1000 units of 

 vitamin D given daily orally either as a concentrated fish oil or as vitamin 

 D dispersed in water will suffice. Vitamin D-enriched milk containing 400 

 U.S. P. units per liter is now widely used either with fresh cow's milk, evapo- 

 rated, or dried milk. The advantage of vitamin D-enriched milk is that 



1" P. C. Jeans and G. Stearns, The Vitamins, p. 493. American Medical Association, 

 Chicago, 1939. 



