REQUISITES OF A NORMAL DIET 



STANDARD DIETARIES. 



423 



The basis of these diets is to supply the necessary prdteid 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 proved 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, 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 proteid, whereas the amount 

 of proteid 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 proteid diet below that given 

 in the above example, i.e., on 4 to 10 grams of nitrogen. In such diets a 

 plentiful supply of carbohydrates is permitted. 



Not only the proteids 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 fat, the carbohydrate may be correspondingly increased to make 

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



TABLE OF PERCENTAGES OF N AND C IN THE FOLLOWING SUBSTANCES. 



N. C. 



Beef (without bone) . . 3 . 1 1 . 



Roast beef 3.528 17.76 



Eggs 1-9 13-5 



Cow's milk 0.66 8. 



Cheese 2 to 7 35 . to 



Beans 4.5 42. 



Lentils 4.1 48- 



