

THE REQUISITES OF THE DIET 353 



critics have expressed surprise that the diets recom- 

 mended have furnished no more protein and no greater 

 fuel-value than the food of the very poor in London or 

 the " punishment ration" of British prisons. .We are 

 not disposed to deny the force of this comparison, but 

 we realize much more fully than we did even five years 

 ago that quality as well as quantity must be taken into 

 account in any such discussion. 



We have seen that two rations may be equal in protein, 

 as shown by ordinary analysis, and far from equal in 

 their power to nourish. If the protein in one case is 

 from meat or. rice it will determine the superiority of 

 that diet to one in which the protein is from beans or 

 corn. We now see, in addition, that one ration may 

 satisfy requirements not met by the other because of 

 its minor constituents both mineral and organic. The 

 vitamins must be supposed to arise as by-products of 

 metabolism in the living matter which, is destroyed to 

 become our food; they cannot be obtained from proteins 

 by mere digestion. Quite failing to modify the figures that 

 represent quantitative composition, they still confer the 

 most important properties upon foods which contain them. 



Recent presentations of this subject tend to be cast in 

 the following form. The valuable accessory substances of 

 the diet are of two kinds. One kind is distinguished as 

 "water soluble," and it is seldom entirely absent save from 

 a few artificially refined foods, like sugar and polished rice. 

 The second type of essential accessory is "fat soluble," 

 and is best obtained in cream. It is furnished by other 

 animal fats also, but more liberally by the fat of glands 

 (e. g., cod-liver oil) than by ordinary adipose tissue. Vege- 

 table oils do not yield it at all freely, but it is obtainable in 

 green plant tissue even though this is poor in fats. The 

 highly suggestive statement has been made by an expert in 

 nutrition that we need to eat a definite amount of tissue that 

 was recently the seat of active metabolism, particularly such 

 as is associated with growth. Green leaves and young tips 

 have this character. Milk has similar properties, for it. 

 comes from intensely active cells. 

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