60 



ANNUAL REPORT 1920 AND 1921 



It will be noticed that only the carbohydrates of fruits are emphasized, no 

 mention being made of any other nutritional value. In order to thoroughly 

 understand how much more complete is our knowledge of fruit and nuts today 

 than it wets in 1902 it will be necessary to briefly review the progress nutrition 

 has made since that year. 



A few years ago our evaluation of a diet was based on; 



1 . Content of protein. 



2. Content of fat. 



3. Content of carbohydrates. 



If a diet contain sufficient protein in addition to the necessary fat and 

 carbohydrates to meet the caloric requirement it was considered well balanced, 

 without regard to the sources of the respective nutrients. Today we have a 

 different yard stick and measure quite differently. We realize, as we did in the 

 past, that calories are vitally necessary, but we pay more attention to the 

 sources of the required calories. This is particularly true in the C2ise of the 

 young and growing child, and of the invalid and convalescent. 



Perhaps the only nutrient which has not been affected by later theories 

 is the starch or carbohydrates of our foods. The same opinions which were 

 held years ago with reference to the role of starch in nutrition, are vahd today. 

 Not so, however, with reference to any other nutrient. We know today that 

 proteins from different sources have different biologic values. The proteins 

 from cereals, fruits, and vegetables alone are not adequate for optimum growth 

 and development. These proteins lack sufficient amounts of certain building 

 stones or units of structure, chemically called amino acids, which are well 

 supplied by animal proteins, such as that of meat, milk and eggs. It is there- 

 fore absolutely necessary that there be a liberal amount of animal protein included 

 in the diet of the young and growing animal. 



The newer knowledge of the proteins has only been obtained as result 

 of the investigations carried on during the past, say, 1 5 years. 



Previous to such studies there was very little differentiation regarding the 

 biologic values of proteins. It was a case of quantity and not quality. Today 

 the reverse is true. It is the quality which must be given equal consideration 

 with the quantity. 



Not only have great strides been made with reference to the fuller appre- 

 ciation of the value of proteins but also in connection with the biologic values 

 of different fats. A quarter of a century ago all fats were considered of equal 

 nutritional value and their main function was to build fatty and nerve tissues 

 or yield energy, and practically no other nutritional property was credited to 

 them. Today the situation is entirely different and we know that all fats have 

 not the same biological value; that there are two good fats, that of milk and 

 egg yolk, which stand out most prominently, as far as nutrition is concerned, in 

 that they both contain the so-called fat-soluble vitamine. This is a dietary 

 essential at present not identified, but absolutely necessary in any well balanced 

 diet for old or young, and particularly the latter. There are many other edible 

 fats which are the equal of butter fat and egg yolk fat as far as caloric value 

 is concerned but they are not the rich source of this dietary essential as is noted 

 for the other two fats. 



One of the most important phases of the newer knowledge of nutrition 

 relates to the importance of mineral elements in nutrition. ' 



