344 FOOD AND NUTRITION 



problem of getting food in these days is, not only a question of 

 getting enough to eat, but it is also a problem of selecting the 

 best and the cheapest foods from the great varieties offered for 

 sale in the markets. The purpose of this chapter is to study 

 the use of food to the body, the composition and value of food, 

 its cost, and some of the methods of preparing it for our use. 

 376. What Foods Do for the Body. We eat that the body 

 may be kept in health. Health demands that the foods shall 

 keep the body strong and vigorous. The foods must supply 

 the body with the materials of which it is made. They must 

 also supply the body with energy (Art. 85) so that its work may 

 be carried on. In some respects, foods are to the body what 

 coal or gasoline is to the steam or gasoline engine. The fuel 

 must be burned in the engine in order to make the engine go. 

 In a similar way, the foods eaten supply the body with the 



FIG. 243. The composition of the human body 



energy to do its work. But the foods do more for the body 

 than the fuel does for the engine. The foods provide for the 

 growth and the repair of the body. The fuel does no such 

 thing for the engine. The engine is not self-repairing by the 

 fuel supplied to it. If one part wears out it must be replaced 

 by a new part from the machine shop. It is evident then that 

 the foods must furnish the body with the materials out of which it 

 is made as well as to furnish it with energy. 



377. What Substances Must the Foods Furnish to the 

 Body? While the body is known to be composed of many 

 complex chemical compounds, it is also known that these 

 compounds are composed of but few chemical elements 

 (Fig. 243). The following table from Sherman's Chemistry of 

 Food and Nutrition gives the names and the amounts of the 

 chemical elements composing the human body. 



