394 GENERAL NUTRITION 



GENERAL NUTRITION 



A comparison of the outgo and income of the organism and estimates 

 of the quantity of food necessary for the proper nutrition of a man of ordi- 

 nary weight and under ordinary conditions have already been given in 

 the chapter treating of alimentation. It may be stated here in general 

 terms that ten to twelve ounces (283. 5 to 340.2 grams) of carbon, and 

 four to five ounces (113. 4 to 141.75 grams) of proteids are discharged 

 from the organism daily. To meet these expenditures exactly and 

 maintain the body in a condition of physiological equilibrium would 

 require the introduction of four to five ounces (113.4 to 141.75 grams) 

 of proteids, one and one-half ounces (28.35 to 42.52 grams) of fat and 

 sixteen to nineteen ounces (453.6 to 483.6 grams) of carbohydrates. 

 Practically, however, provision should be made for unusual require- 

 ments, and the diet should be in excess of what would exactly meet the 

 outgo of material. 



Luxus-Consumption. An illustration of the necessity of a diet more 

 than sufficient exactly to meet the outgo under ordinary conditions is to 

 be found in what is called luxus-consumption. By this term it is in- 

 tended to indicate change in a certain quantity of nutritive matter, 

 especially proteids, which does not involve repair of tissue. Voit, who 

 first described this process, divided the proteids of the blood into tissue- 

 proteids and circulating proteids, the latter representing the excess of 

 proteids over and above actual nutritive requirements. Voit's theory, 

 however, failed to meet with general acceptance, and the expression 

 luxus-consumption is regarded as misleading and unscientific ; but the 

 fact remains that food taken in excess of actual nutritive requirements 

 is readily disposed of when it does not remain in the body in the form 

 of fat. 



Isodynamic Values of Foods. The theory of the isodynamic values 

 of foods is that proteids, fats and carbohydrates are theoretically inter- 

 changeable on the basis of equal heat-values in oxidation. This has been 

 formulated by Rubner into a law, of which the following is an illustration : 

 It has been found that one gram of fat is equal in heat-value to about 

 two and one-quarter grams of proteid or carbohydrate. As regards the 

 production of heat and power, therefore, fats, proteids and carbohy- 

 drates are interchangeable in the proportion of one part of fat to two 

 and one-quarter parts of either proteid or carbohydrate. In this theory 

 it is assumed that the proteids are oxidized into urea and carbon dioxide, 

 and that their heat-value is the same as when they are burned out of the 

 body. It is probable, also, that isodynamic substitution may include 

 alcohol (Rosemann). 



