1 44 Physiology. 



Fats. Fats are composed of carbon, hydrogen, and 

 oxygen. The oxygen is small in amount, so these foods 

 yield a great amount of energy by the oxidation of their 

 carbon (forming carbon dioxid) and hydrogen (forming 

 water). The fats most used are animal fats, including 

 butter. But some vegetable oils, such as olive and cotton- 

 seed oils, are used. 



The Carbohydrates. Starch and sugar are the chief 

 carbohydrates. They are composed of carbon, hydrogen, 

 and oxygen, but not in the same proportions as in fats. 

 Starch is used in larger quantity than any other foodstuff 

 except water. Sugar is usually regarded as a luxury, yet 

 it is an important food. It is quickly absorbed. 



Carbohydrate-containing Foods. The principal carbo- 

 hydrate-containing foods are the grains, vegetables, and 

 fruits. The most important grains are wheat, corn, rice, 

 oats, rye, and barley. 



Wheat Wheat furnishes the principal breadstuff among 

 the more civilized nations. It is especially adapted to the 

 temperate zones. Taking into consideration its composi- 

 tion, digestibility, and other characteristics, it is the most 

 desirable of all the grains. 



Wheat Flour. In ordinary white flour nearly all the 

 gluten has been removed with the bran or "middlings." 

 While wheat or bread made from the whole grain of the 

 wheat may support life, one would starve if he tried to live 

 on common white bread alone. It is almost entirely starch. 

 In the "entire wheat flour" it is claimed that all the gluten 

 is retained, only the very thin outer husk of the grain being 

 removed. It does not make so white a flour, but it is better 

 adapted to use as a food. If we use white bread, having 

 thrown away the nitrogenous part of the wheat, we need to 



