498 SYMPOSIUM ON FOOD PROBLEMS 



in the average dietary and the likeHhood of deficiency in individual 

 cases as well for phosphorus and for calcium as for protein. 



The phosphorus "requirement" as indicated by the results of 

 87 experiments averages 0.88 gram per man per day,^ and the aver- 

 age amount in 250 American dietaries was 1.60 grams, a margin of 

 82 per cent. 



The calcium " requirement " indicated by 63 experiments aver- 

 ages 0.4s gram,^ and the average amount in typical American 

 dietaries was 0.74 gram, a margin of 64 per cent. 



It will be seen that the margin of average consumption above 

 the bare requirement is less for phosphorus than for protein, and 

 narrowest in the case of calcium. Actual deficiencies in the sense 

 of a rate of consumption below the average of the bare requirements 

 for normal maintenance, are exceedingly rare in the case of protein, 

 not so rare in the case of phosphorus, much more frequent in the 

 case of calcium. It appears that the American dietary is more often 

 deficient in calcium "than in any other chemical element whose 

 metabolism has been studied. 



Probably because of the ability to transfer calcium from the 

 bones to the soft tissues, the body may continue to lose this element 

 for a long time as Forbes and Beegle have shown strikingly in the 

 case of milch cows. But it does not follow that the loss of body 

 calcium is to be regarded with indifference. Mendel has written 

 regarding his recent experiments that " animals may be in excellent 

 nutritive condition in so far as protein is concerned for long periods 

 of time while they are still losing calcium from their bones. It then 

 happens that suddenly a collapse comes for which there is frequently 

 no obvious explanation." And McCollum has found in his studies 

 of laboratory animals that it is largely because of insufficient cal- 

 cium that such animals do not show normal nutrition when kept 

 continuously upon rations consisting too exclusively of seeds. Our 

 investigations based chiefly upon the chemical analysis of the entire 

 intake and output of the human organism, while quite different in 

 method, have led to the same view regarding the importance of 

 calcium as has been reached by Mendel and by McCollum. 



3 These phosphorus and calcium " requirements " are derived in the same 

 manner as the protein " requirement " of 50 grams per man per day explained 

 above. 



