96 



TROPICAL FOODS 



these there are peoples who have begun to cultivate the ground, while others 

 still live upon the food which they can gather. Thus the Dra vidian Mundas 

 and Uraons eat insects, lizards, snakes, rats, jackals, and pigs — or, in other 

 words, anything which they can catch. Their daily dietary is composed of 

 protein 80 grammes, carbohydrates 500 grammes, and fats 50 grammes, which 

 provides calories 2,800. 



The Todas of the Nilghiri Hills live upon milk, the meat of buffaloes and of 

 such animals as they can kill or capture. They take no vegetal food, and 

 hence, like the carnivora, require no salt, which is an essential to vegetal 

 feeders in order to prevent acidosis. 



The Bushmen of South Africa and the Bedouin of Arabia are meat eaters. 



The necessity for food is to provide heat and energy, and to form 

 new bodily tissues, as well as to make good the wear and tear of 

 existing tissues; and to do this a community requires pure water 

 and plenty of it, and good and varied foodstuffs in quantity pro- 

 portional to the numbers of the population, a fact which the present 

 war has made clear to nearly every family in the civilized regions 

 of the earth. 



Dietetics are based upon chemical and physiological considera- 

 tions, into which we will now inquire very briefly. 



CHEMICAL COMPOSITION. 



In order to meet the requirements of the body, foods must be 

 composed of the same essential chemical substances as that body. 

 They are therefore made up of proteins, carbohydrates, fats, mineral 

 substances, and water, but these alone are insufficient to keep the 

 body in health, and they must be associated with vitamines and 

 lipoids or nitrogenous fats. 



Proteins may be obtained from the muscles, bones, and organs of 

 animals used as food, also from animal products such as milk and 

 eggs, while the many vegetal substances, but particularly legumes, 

 nuts, and cereals, also provide this valuable food constituent. Their 

 primary value is as tissue formers, and their secondary value as 

 heat-energy producers, but all proteins are not of equal value, as we 

 shall see later. 



Carbohydrates are chiefly of vegetal origin, and are principally 

 of value as heat-energy producers. 



Fats are widely distributed both in the animal and in the vegetal 

 kingdoms, and are essentially heat-energy producers, while the 

 Lipoids or nitrogenous fats are indispensable to man, though their 

 exact use is not known. 



Mineral Substances are compounds of sodium, potassium, calcium, 

 magnesium, manganese, and iron, either with carbonic, sulphuric, 

 phosphoric, and silicic acids, or with acetic, citric, malic, oxalic, and 

 tartaric acids, or with chlorine or fluorine. They produce no heat 

 or energy, but are essentials for building up the fluids and tissues 

 of the body, in which they represent some 5 or 6 per cent, of the total 

 weight. 



Water, forming some 58*5 per cent, by weight of the human body, 

 is an indispensable. 



