124 THE HYGIENE OF DIGESTION 



any reason, as in illness, a proper amount of food can- 

 not be taken at the regular times, the intervals between 

 the meals should be shortened but still kept regular. 



Composition of food. That food may fully nourish 

 the body, it must not only be taken at the proper time 

 and in the proper amount but it must also be of the 

 right composition, that is, it must combine the right pro- 

 portions of proteid, carbohydrate and hydrocarbon. The 

 amount of proteid which is needed daily by the body has 

 been shown by investigation to be fairly constant and 

 smaller than was formerly thought. The proper amount 

 of carbohydrate and hydrocarbon varies with our ac- 

 tivity. Muscular energy may come from the oxidation of 

 either the carbohydrates or the hydrocarbons, although, 

 as a matter of fact, it is usually derived more largely 

 from the carbohydrates since the fats are ordinarily 

 eaten in much smaller amounts. 1 They are both oxi- 

 dized and their waste products removed in the same 

 way. If taken in excessive amounts, they may both 

 give rise to indigestion. 



Necessity for variety. The kinds of food which con- 

 tribute the proteids, carbohydrates and hydrocarbons 

 are important, since their proportion may be right and 

 yet the monotony of the food be distinctly injurious, 

 especially if there is a tendency to overeating. Loss 

 of appetite and failure of digestion may result from an 

 unvarying diet. It is necessary therefore to plan to 

 have the kinds of food changed frequently enough to 

 avoid monotony. 



Importance of good teeth However carefully we 

 may determine the amount and kind of the food which 



1 In cold climates and in cases of poor nutrition and of tuber- 

 culosis, much larger amounts of fats may sometimes be taken with 

 benefit, provided they are not used in such a way as to make other 

 foods indigestible, as in frying. 



