MILK AS A FOOD. 407 



The author proposes to calculate the ratio between the various 

 constituents as follows : — 



Anabolic ratio = fat : sugar : proteins. 



,, ^ . ,. ^. fat X 2-38 + sugar + proteins x 1-26 



Metabolic ratio = ^ , . '^ . 



proteins 



Instead of the figures 2 "38 and 1"26, the round figures 2 '5 and 



1 "25 may be used without appreciable error. The author believes 



that the above ratios will give a truer idea of the proportionate 



value of different constituents than the usual nutritive ratio, 



, . , . fat X 2 '5 + sugar 



which IS ,— . . 



protein 



Pood Value. — Wo may now consider the food value of 



various milks. 



The ratios for human milk are — 



Anabolic ratio, 2-2 : 4-3 : 1 



Metabolic ratifi, 11-3 



For cow's milk — 



Anabolic ratio, . 1-l.j : 1-4 1 



Metabolic ratio, . ."]-.")4 



The marked difference of the two milks, due to the smaller 

 amount of proteins in human milk, is very apparent. 



It is assumed in calculating these ratios that the constituents 

 are all digestible ; this is approximately true with human milk. 

 The same cannot be said of cow's milk, owing to a difference in 

 the proteins ; the action of rennet, one of the enzymes of the 

 stomach, on cow's milk results in the formation of clots of ciu'd, 

 which are not readily digested. If the fat has been partially 

 churned in the milk, this also is not perfectly digested. 



Experiments have shown that children do not derive the 

 most benefit from milk unless the anabolic ratio approximates 

 to 2 ; 4 ; 1, and the constituents are in such a form that they 

 are as finely divided as possible in the stomach. 



Milk as a Food for Infants — Artificial Human Milk. — Many 

 preparations of artificial human milk, or humanised milk, are 

 made ; they correspond in composition more or less exactly 

 with human milk. The condition of the proteins necessary to 

 produce a fine state of division in the stomach is attained — 



(1) By simple dilution with «ater, and addition of fat and sugar. 



(2) By removal of casein, and addition of fat and sugar. 



(3) B\- acting on the milk with a proteolytic enzyme — i.e., peptonising 

 it, and addition of tat and sugar. 



(4) By adding u. lue pa ration containing diastase and diluting it, and 

 adding fat and sugar. 



(5) The fine division of the proteins is aided by the presence of a colloid, 

 such as the small proportion of starch in barley water. 



