CHAPTER IV 



Milk as a Food 



Milk is first of all the food for the young, — until a 

 certain age the only food, and a perfect food. It con- 

 tains but little refuse or waste and is under favorable 

 conditions almost wholly digestible. 



NUTRIENTS 



All foods contain certain groups of nutrients which 

 may be classified according to various functions in nu- 

 trition and their chemical com.position. 



Protein. — The protein- group of nutrients contains 

 nitrogen and is necessary for building up the tissues 

 of the body, the muscles and the tendons which also 

 contain nitrogen. Only by this group can tissues 

 wasted by constant wear and tear be rebuilt. Proteins 

 are the flesh-forming group. To some degree the pro- 

 teins or albuminoids are also active in producing fat 

 in the body, but the other groups of nutrients, espe- 

 cially the fats, also contribute. 



Fats and Carbohydrates. — ^Another important func- 

 tion of food is to produce and maintain the animal 

 heat. The main sources of this necessity are the fats 

 and the carbohydrates, so called because they consist 

 of the element carbon combined with oxygen and 

 hydrogen, the last two in the exact proportion in which 

 they are combined in water. All of these three groups 

 furnish the fuel, so to speak, for the body, but they 



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