392 ISIDOE GKEENWALD 



this and to note that even in the neediest families studied, the energy 

 content of the food does not fall below about 2500 calories per man per 

 day, except in the case of those of low body weight, such as the Italians 

 studied by Manfredi or the Japanese and Malays studied by others. 



Amount of Protein. The character of the food and, consequently, the 

 relative importance of protein, fat and carbohydrate in making up the total 

 energy content of the diet varies considerably with different peoples and 

 different circumstances. But there are some quite evident uniformities 

 and comparisons. Except in the most needy families, the protein content 

 of the food anywhere in the world does not fall appreciably below one gram 

 per kilo or 70 grams for the man of average weight in northern Europe and 

 in the United States and it is generally as much as 1.3 to 1.5 grams per 

 kilo, or 100 grams per man. The fraction of the total energy contributed 

 by protein varies from 8.5 per cent in some Oriental diets and in those 

 of some of the poorer classes in Europe to as much as 18 or 19 per cent 

 in some of the Swedish and Finnish diets and even to 32 per cent in the 

 case of the fishers at the mouth of the Volga who probably subsist largely 

 upon fish and to 44 per cent among the Esquimaux (Krogh). But except 

 for people under such unusual .circumstances, the protein rarely contributes 

 over 18 per cent and generally only from 12 to 15 per cent of the total 

 energy. This comparatively narrow range is worthy of note. 



Effect of Work. Men at hard work eat more protein than do those not 

 so engaged, but, apparently, this is due entirely to the greater consumption 

 of food and not to a specific demand for protein or foods rich in protein. 

 The fraction of the energy contributed by protein to the diet of men at hard 

 work is frequently less than in the case of others of similar economic status 

 and engaged at lighter work. This is most strikingly illustrated in the case 

 of the diet of the Maine lumbermen in which the protein contributed only 

 10.5 per cent of the calories, a smaller proportion than was reported for 

 any other group in the United States, except for some from the southern 

 states. Similarly, the diet of lumbermen in the north of Sweden con- 

 tained less than 10 per cent of the calories in the form of protein (only 

 8 per cent in the case of the man whose total was 9292, and 7.4 per 

 cent for the two men whose average was 8439), whereas Hultgren and 

 Landergren reported 16 per cent for Swedish working men and Sundstrom 

 15 to 16 per cent for the- Finnish agricultural population. 



Effect of Economic Status. The amount of protein consumed is gen- 

 erally lowest with those of smallest income and grows larger with increas- 

 ing income. But this increase is not indefinite and probably the total 

 rarely goes above 160 grams or 2.3 grams per kilo. The relative impor- 

 tance of protein as a contributor of energy may, however, be slightly greater 

 among the poor than among those of slightly greater income. A greater 

 share of the necessary economy in food is attained at the expense of the 

 fat. . At the other end of the range of incomes, the proportion of energy 



