348 FOOD AND NUTRITION 



and cereals supply both for the body. They are foods. Salt 

 and water which are taken into the body yield no energy to 

 the body. They are not to be thought of as foods in the 

 same way as we think of meats and cereals. 



383. Classes of Foods. Our foods may be broadly classed 

 as foods derived from animals and foods derived from plants. 

 The animal foods include such foods as beef, pork, mutton, 

 fish, game, poultry, milk and its products, and eggs. The 

 foods derived from plants include a greater variety. The 

 cereals, such as corn, wheat, oats, rye, rice, and barley are 

 used. Other plant materials such as the potato, pea, bean, 

 sugar cane, sugar beet, and nuts are used. Still other plant 

 materials commonly called fruits are widely used. 



384. The Food Principles. While there is a great variety 

 of substances used as food, it has been found that they are all 

 made up of a few essential substances called the FOOD PRIN- 

 CIPLES. These include: (1) FATS, (2) CARBOHYDRATES, and (3) 

 PROTEINS. It is from these food principles contained in greater 

 or less amount in our common foods that the body derives its 

 energy and nearly all of its substance. Mineral matter and 

 water are sometimes included in the food principles, but 

 they yield no energy to the body. 



385. The Fats. FATS are compounds of carbon, hydrogen, 

 and oxygen. They are found in plants and animals in both the 

 solid and the liquid states. The liquid fats are frequently 

 called oils. But the oils would become solid at a sufficiently 

 low temperature. Petroleum and its products, though com- 

 monly called oils, are not fats. They are without food value 

 to the body. 



Our common fats come from animals, from the cotton seed, 

 from corn, from the olive, and from certain nuts such as the 

 peanut and the cocoanut. 



386. Carbohydrates. Like the fats, the carbohydrates are 

 compounds of carbon, hydrogen, and oxygen but in different 

 proportions from those in fats. Carbohydrates are found 

 chiefly in plants, no considerable amount of them coming from 



