THE REQUISITES OF THE DIET 343 



At the other extreme from the Esquimaux we have 

 the vegetarians of various classes. They are not likely 

 to eat too much protein and they are sure of plenty of 

 carbohydrate. When their diets are scientifically 

 planned they often contain a goodly amount of fat 

 secured by the use of nuts and vegetable oils. If milk 

 and eggs are permitted the protein and fat can be more 

 readily brought up to the standards of mixed diet. Eggs 

 are like meat in their very low carbohydrate content. 



Alcohol enters with considerable regularity into the 

 diet of many. This is particularly true in Europe. As 

 has been indicated before, it acts much like other non- 

 nitrogenous food. According to a careful estimate, 

 about one-fifth of the calorific requirement of the day 

 may be met by alcohol without producing any sugges- 

 tion of intoxication. That is to say, if 2500 Calories 

 is the total called for, some 500 may be represented 

 by alcohol. This means about 70 grams of the pure 

 compound, an amount which might be conveyed in 

 less than half a pint of whiskey, a full pint of a fortified 

 wine like port, a quart of a light wine, or 3 quarts of 

 beer. To say that it is possible to use alcohol to such 

 an extent is by no means to advise it. 



Isodynamic Quantities. From what has been said 

 it will be gathered that carbohydrate and fat are in a 

 great degree interchangeable and that alcohol can be 

 substituted for either within certain limits. We must 

 point out that when substitutions of this kind are made 

 the proportion is not gram for gram, but determined 

 by calorific values. Thus a gram of fat has the available 

 energy of about 2> grams of sugar. On the same prin- 

 ciple it can replace 1^ grams of alcohol. Quantities of 

 different foods which have equal fuel-values are said to 

 be isodynamic. 



Water. The services of water to the system should 

 be evident by this time. It is necessary, first of all, 

 to the normal constitution of the tissues. It makes up 

 about 75 per cent, of most- of them and about 65 per 



