METABOLISM, NUTRITION AND DIETETICS 



547 



nitrogen, while little more than half this amount would furnish 

 the necessary 250 grammes carbon. Of course a diet consisting, 

 week in week out, entirely of potatoes or rice, would represent 

 an extreme case. A certain amount of the necessary nitrogen is 

 obtained even by the poorest populations, in the form of fish, 

 milk, eggs, or bacon. A man attempting to live on flesh alone 

 would be well fed as regards nitrogen with 500 grammes of meat, 

 but nearly four times as much would be required to yield 

 250 grammes of carbon. Oatmeal and wheat-flour contain 

 nitrogen and carbon in nearly the right proportions (i N : 15 C), 

 oatmeal being rather the better of the two in this respect ; and 

 the best-fed labouring populations of Europe still live largely 

 on wheaten bread, while, one hundred years ago, the Scotch 

 peasant still cultivated the soil, as the Scotch Reviewer the Muses, 

 ' on a little oatmeal.' But although bread may, and does, as 

 a rule, form the great staple of diet, it is not of itself sufficient. 



It is necessary to recognise that habit has much to do with 

 the quantity as well as with the quality of the food used by an 

 individual or a community. Some concession may be made to 

 custom in what is, after all, not a purely physiological question, 

 and in this country it is probable that 20 grammes of nitrogen 

 and 300 grammes of carbon, while a liberal is not an excessive 

 allowance, although it is certain that a man can maintain a 

 normal body-weight and perform a normal amount of work on 

 considerably less, in some cases even with advantage to his health. 



We may take 500 grammes of bread and 250 grammes of 

 lean meat as a fair quantity for a man fit for hard work. Add- 

 ing 500 grammes milk, 75 grammes oatmeal (as porridge), 

 30 grammes butter, 30 grammes fat (with the meat, or in other 

 ways), and 450 grammes potatoes, we get approximately 

 20 grammes nitrogen and 300 grammes carbon contained in 

 135 grammes protein, rather less than 100 grammes fat, and 

 somewhat over 400 grammes carbo-hydrates. Thus 



This would be a fair ' hard work ' diet for a well-nourished 

 labourer. But the great elasticity of dietetic formulae is shown 



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