METABOLISM 199 



and cream diet containing only about 6 grams of nitrogen a 

 day for several days. Chittenden drew the conclusion that 

 the most desirable amount of protein for an average sized 

 adult is 40 grams per day or somewhat over 6 grams of 

 nitrogen. This is much less than the standards previously 

 recommended. Voit, for example, basing his conclusions on the 

 amount of protein consumed per capita in several European 

 cities, recommended 118 grams of protein (19 grams nitrogen) 

 as the proper amount, and most other standards were of this gen- 

 eral magnitude. 



It has been shown that nitrogen equilibrium may be estab- 

 lished on a level even lower than that of Chittenden. Thus 

 Thomas reduced his nitrogen to 2.2 grams a day (about 15-20 

 grams protein). In fact on a low protein intake the protein evi- 

 dently is used more economically by the body. But the problem 

 remains, is so low a level of protein intake desirable or safe? 

 Some evidence has accumulated on this point. Certain tribes in 

 India who live on low protein diet have been observed to be less 

 efficient and to possess less endurance than neighboring tribes 

 of meat eaters. Races living in cold climates usually live on 

 a high protein diet, and such races display great endurance. 

 The whole experience of the human race seems to have tended 

 toward a fairly high protein diet. If low protein intake resulted 

 in greater efficiency, it is only reasonable to suppose that races 

 or nations living on low protein rations would have dominated 

 over others. From the experiments of Chittenden and others it 

 appears possible to maintain a group of individuals for several 

 months on a low protein diet, apparently with good results and 

 increased efficiency and health. It might be suggested, however, 

 that such favorable results may be due in part to the carefully 

 regulated living, wisely directed exercise and wholesome food 

 of the subjects, for it is an unfortunate but incontrovertible 

 fact that many of us are sadly lax in the ordering of such im- 

 portant factors in our existence as exercise, proper food, and 

 general healthful living. From experiments of but a few 

 months' duration it is dangerous to draw conclusions of so im- 



