30 THE WORLD WE LIVE IN 



PROBLEM m. WHAT ARE FOODS AND HOW ARE THEY 



USED? 



Foods. What is a food? We know that if we eat a suitable 

 amount of proper foods at regular times, we shall be able to go on 

 doing a certain amount of work, both physical and mental. We 

 know, too, that day by day, if our general health is good, we may 

 be adding weight to our bodies, and that added weight comes as 

 the result of eating food. A similar statement may be made with 

 reference to plants and foods. If food is supplied in proper quan- 

 tity and proportion, plants will live and grow ; if their food sup- 

 ply is cut off, or even greatly reduced, they will suffer and may die. 



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Compare this turkey leg with other materials used as food, by making similar analysis of them. 



However, only a small part of a food, as potatoes, can be used 

 by the body. For a food is made up of a combination of wastes — 

 as water in vegetables, skins of fruits, and tendons in meat — 

 and nutrients which repair or build up the body or, when oxidized in 

 the body, furnish it with energy. The organic nutrients found in 

 foods are carbohydrates, fats or oils, and proteins. 



Carbohydrates. Starch and sugar are common examples of 

 this group of substances. The former we find in our cereals and 

 most of our vegetables. Several kinds of sugar, such as cane 

 sugar, beet sugar, and glucose or grape sugar, are commonly used 

 as food. Glucose, the natural sugar of grapes, honey, and fruits, 

 is manufactured commercially from starch by the action of dilute 

 acids. It is used as an adulterant in sirups, honey, and candy. 



