CHAPTER VIII 

 NUTRITION 



1. FOODSTUFFS (ALIMENTARY PRINCIPLES) 



FOODSTUFFS are substances which the body must take up 

 in order to maintain its material existence, i.e. substances 

 by which the body can rebuild, restore, and replace the 

 parts which have been changed and used up by the vital 

 processes. 



We may divide foodstuffs into the following classes : 



1. Those not furnishing energy, i.e. foodstuffs which can- 

 not impart energy to the body (water and salts). 



2. Tko$e furnishing energy i i.e. substances rich in poten- 

 tial energy, which by their physiological combustion furnish 

 the body with the energy it needs for its functions. This 

 class includes: 



(a) Nitrogenous substances protcids. 



(b} Non-nitrogenous substances carbohydrates and fats. 



The energy-yielding substances are sometimes called 

 " foodstuffs " in a narrower sense. 



Strictly speaking the inhaled oxygen also belongs to the 

 class of energy-yielding foodstuffs, for it is only by its union 

 with the above-named energy-yielding foodstuffs that their 

 chemical potential energy can be set free and can be used 

 by the body. 



The water serves to replace the water lost in the secre- 

 tions, faeces, and expired air. The water formed in the body 

 by the combustion of organic substances containing hydrogen 

 can replace only a small amount of the loss, for the amount 

 so formed is only about 350 cc in 24 hours, while an adult 



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