TROPICAL FOODS 



CALCULATION OF DIETS. 



In the calculation of diets it appears to us that two important 

 matters must be considered — viz., the quantity of protein and the 

 number of Calories. 



With regard to protein, having obtained from the tables of analy- 

 sis the available protein in the food, it is necessary to determine its 

 biological value and the quantity of the absorbed protein, and from 

 this the Calories can be calculated. The fat and carbohydrate 

 present no difficulties, except that it is necessary to know the quan- 

 tity of the available matter which is absorbed. Having obtained 

 the quantities absorbed, the matter is simple arithmetic. 



Protein : fat : carbohydrate :: 5 : 3 : i. 



Having done this, certain facts must be considered. It is neces- 

 Lar}^ to remember that the figures given for Europe will not apply 

 to the tropics, and that as a rule they do not represent a minimum, 

 and that no diet should be based upon a minimum. 



Wilson has invited especial attention to the quantity of protein, 

 which is not a producer of energy until the carbohydrate and fats 

 are used up, but repairs wear and tear or is stored up as fat or carbo- 

 hydrate. 



The nearer the quantity of protein is to the minimum, the longer 

 will the organism require to rebuild damaged tissue and the less 

 will its powers of resistance be against disease. He states that 

 excess of protein will mean increased heat production, and therefore 

 in the tropics, where there is a cold season, two diets should be in 

 existence — viz., one with less protein for the hot weather, and one 

 with more protein for the cool weather or cool regions. 



If this is not done, then the increased heat must be got rid of by 

 radiation and conduction, and this can be obtained by natural or 

 artificial breezes or by exercise, when the extra heat of muscular 

 exertion will be dissipated by sweating. 



lie also draws attention to the low biological values of the vegetal 

 proteins, which are less well absorbed than are the animal proteins, 

 a fact which he thinks is due to the structure of the food materials 

 rather than to the nature of the proteins. 



His conclusion with regard to protein appears to us to be worth 

 quoting. 



' A minimum amount of protein is required daily, over and above 

 which a certain excess is desirable; this minimum is different for 

 different proteins, and is measured by the biological value of the 

 protein. In determining, therefore, the requisite amount of protein 

 it is essential to take into consideration the biological value of the 

 protein components of the diet, and fix the daily quantities on this 

 basis rather than on the nitrogen content. In determining the 

 amount of protein the defective absorption of vegetable proteins 

 must be allowed for.' 



