THE FOOD REQUIREMENT OP THE SICK 23 



oxidation (O2 decomposition and COj excretion) which characterizes individ- 

 ual pathologic conditions has only been fulfilled to a slight degree. On the 

 other hand, later researches have furnished proofs that the healthy and the 

 sick differ in the reaction of their organism to influences that increase metab- 

 olism (administration of food, work performed, and the amount of heat 

 given off). 



To appreciate these differences, the physiology of metabolism must be 

 briefly considered. 



The increase of the processes of oxidation and of heat production, under 

 the influence of the intake of nourishment, which may be subjectively noted 

 in a certain feeling of warmth, has been directly measured by calorimetry. 

 The factors of -the respiratory metabolism have also been indirectly con- 

 trolled. 



If a dog's food is increased upon three different days to 55 per cent, 

 above its previously determined calory requirement by administering iso- 

 dynamic amounts of albumin, fat and carbohydrates, its elimination of heat 

 upon the albumin day rises 19.7 per cent., upon the fat day 6.8 per cent., 

 and upon the carbohydrate day 10.2 per cent. (Eubner). 



This coincides exactly with the figures which Magnus-Levy ^ obtained in 

 his numerous analyses of the interchange of gases after the administration 

 of particular foods; he has referred to these in his valuable dissertation on 

 the influence of nourishment upon respiratory metabolism. He also deter- 

 mined that the three principal food products increase COj excretion and O2 

 consumption in very different degrees. The proteids again take the first 

 place ; they increase the intensity of oxidation from 50 to 60 per cent. ; then 

 follow the carbohydrates, after the administration of which the interchange 

 of gases is only increased 35 per cent, above the point reached when the stom- 

 ach is empty; finally the fats, which, if administered in amounts that do 

 not exceed the normal requirement, scarcely increase the consumption of O2 

 in man at all, and in the dog increase it only about 10 per cent. 



Investigations in man with a freely chosen diet make the increase of 

 metabolism after a meal very apparent. In the first four hours after break- 

 fast the O2 intake, in comparison to that in a condition of rest, is increased 

 21, 37, 22 and 10 per cent.; in the first five hours after the midday meal 36|, 

 30, 20, 18 and 18 per cent., and in the first three hours after the evening 

 meal 33, 31 and 18 per cent. According to this, the increase of the inter- 

 change of gases for a whole day, in consequence of the administration of 

 food, amounts to 13 per cent, of the O2 intake, and 19| per cent, of the CO2 

 excretion. 



Hosslin found similar figures which are the basis of Voit's investigations 

 in metabolism, and if the body's requirement does not decidedly exceed the 

 intake of nourishment, we are generally right in counting about 10 per cent, 

 as the increase of the oxidation processes due to this cause (Zuntz). 



That this increase of oxidation is due principally to the increased labor 



1 Magnus-Levy, " Ueber die Grosse des respiratorischen Stoffwechsels unter dem 

 Einflusse der Nahrungsaufnahme." Pfliiger's Arch., Bd. Iv, p. 1. 



