146 



BIOLOGY AND HUMAN LIFE 



it is especially desirable in the diet when energy output is 

 needed rather than building material or bulk. Accordingly we 

 may increase the proportion of fuel in the winter, eating more 

 fat, and reduce it in the summer. 



125. Food composition. How can we translate the products 

 of the food factories and the kitchen into terms of proteins and 



B-otdn 3.6°/. 

 Fat 4%-\ 

 Carbohydrate 



. . 4.7% 

 Ash 0.7% 



Protein 14.8% 

 Tax 10.5% 



Aah 1% 



■Protein 1.3'/, 

 ■MU 0.6% 



Fig. 80. Composition of food 



The proportions of water, protein, fat, carbohydrate, and mineral matter (ash) in a 

 glass of milk, an egg, two slices of bread, a pat of butter, and a banana are shown in 

 this diagram, designed after the Langworthy charts. Such diagrams enable us to tell 

 at a glance the relative amount of each nutrient present in our common articles of diet 



calories and vitamins ? The means for such translation is fur- 

 nished by tables that have been prepared by various experts 

 working for the government, for hospitals and other institu- 

 tions, and for manufacturers. We can make use of the results 

 obtained by these experts to guide us in our own selection of 

 food. From the diagrams in Fig. 80 we can see that some of the 



