45 



METABOLISM, NUTRITION, AND DIET 



STANDARD DIETARIES. 



The basis of computation for these diets is to supply the necessary protein 

 nitrogen first of all, and, second, to supply enough potential energy to balance 

 the energy expended per day. 



The amount of the excreted carbon and nitrogen is not always the same. 

 It has been proven possible, for example, to subsist on 9 or 10 grams of nitro- 

 gen and 200 grams of carbon per diem, the ordinary diet for needle-women 

 in London, and the average of the cotton operatives in Lancashire during the 

 famine of 1862. The amount of these elements excreted falls to figures cor- 

 responding to such an income. Of course, upon such a diet the metabolism 

 is low, and persistent physical weakness must be the result, probably from 

 insufficient carbon. The 9 or 10 grams of nitrogen in such a semi-starvation 

 diet would be equivalent to 58 . 5 to 65 grams of protein, whereas the amount 

 of protein in some diets may be as high as 150 and more grams per day. 

 Chittenden's nutritional experiments, so often referred to in these pages, 

 have proven that adult men can subsist in nitrogenous equilibrium, and do 

 vigorous work and maintain good health, on a protein diet below that given 

 in the above example, i.e., on 6 to 10 grams of nitrogen. In such diets a 

 plentiful supply of carbohydrates is permitted, but the calorific value of the 

 diet is less than those in the table above. 



Not only the proteins but also the fats may vary. The amount may be 

 as low as 35 grams and as high as 125 grams. The carbohydrates may vary 

 from 200 grams to 500 grams and upward. Sometimes, with a small pro- 

 portion of fats, the carbohydrates may be correspondingly increased to 

 make up the necessary carbon. A useful table, after Payen, will help to show 

 in what ways it is possible to obtain the requisite amount of nitrogen and 

 carbon from the most common food stuffs. In order to obtain the amount 

 of protein present from the proportion of nitrogen, multiply by 6. 25. 



