CHAPTER II 

 THE FOOD OF MANKIND 



THE functions of food are, first, to build up the different tissues 

 of the body, and repair the waste of ordinary wear and tear ; 

 secondly, to furnish energy for the production of muscular con- 

 traction and other work the body has to perform, and to yield 

 heat for the upkeep of the body temperature. 



Foodstuffs may, therefore, be considered from two points of 

 view viz., their power or capability of forming new tissue and 

 repairing waste this is a function of the assimilable or available 

 nitrogenous material ; its power of yielding energy and heat 

 this is a function of all the organic elements of the food, protein, 

 carbohydrate, and fat. The food as taken into the body differs 

 very much in its chemical composition from the materials that 

 are utilized in carrying out the above functions, and it is by the 

 processes of digestion that the proximate principles of a diet are 

 split up and rendered easy of absorption into the blood and lymph, 

 and are prepared for assimilation and utilization by the several 

 tissues of the body. 



A review of the different foodstuffs entering into the dietaries 

 of mankind reveals a most varied assortment, differing, under 

 the varying conditions of life on the earth, with the seasons, 

 climate, customs, races, and countries. At one extreme, as pure 

 animal feeders, may be taken as examples the Esquimaux and 

 the Indians of the Pampas ; whilst at the other extreme, as 

 almost pure vegetarians, may be cited many of the natives of the 

 tropics in the East Indies. It may be accepted, however, that 

 the food of the inhabitants of any particular place depends on 

 local circumstances, and will vary with the food materials avail- 

 able during the different seasons, with the cost, and with the 

 ease with which it can be procured. Thus the Esquimaux live 

 practically of necessity upon raw or partly cooked seal, walrus, 



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