A NOKMAL DIET 411 



that, when the diet ''is deficient in fats, particularly in those of animal 

 origin, it must contain considerable quantities of the green leafy vegetables 

 as these and the animal fats appear to be the only sources of the fat-soluble 

 vitamin or vitamins. 



But if fat is not absolutely necessary, it is certainly very useful, for our 

 whole accustomed cookery is dependent upon the use of fat. Without it. 

 the housewife of western Europe and of the United States does not know 

 how to prepare food nor does her husband relish it when it is prepared. 

 Food prepared without fat leaves the stomach rapidly it does not "stay 

 with one." For those who require a large supply of energy, the use of fat 

 is advantageous in that it supplies energy in a very concentrated form, nine 

 calories per gram and all of it food, instead of four calories per gram, as 

 with protein and carbohydrate, with each gram accompanied by from 0.5 

 to 9 grams water. 



Carbohydrate Minimum. Carbohydrates furnish more than fifty per 

 cent of the energy content of 'most diets. If greatly reduced in amount, 

 signs of defective fat metabolism may appear. However, the inhabitants 

 of the arctic regions appear to maintain good health on diets containing 

 very little carbohydrate. The possible ill effects of an excess of carbohy- 

 drate, particularly of the simple sugars, have already been mentioned 

 (page 410) and are discussed more fully in the chapter on diabetes. 



Minimum of Ash Constituents. The requirements of the body for in- 

 organic constituents have been, as yet, only scantily investigated and the 

 demands for phosphorus and calcium have received the greater part of the 

 attention that has been given to the subject. 



Sherman (d) (e) (1920) has compiled the available data for these 

 elements in a manner similar to that used in the determination of the pro- 

 tein requirement, to which reference has already been made. In 95 experi- 

 ments included in 17 investigations (12 of which were by Sherman and his 

 collaborators), the daily requirement of phosphorus varied from 0.52 to 

 1.20, with an average of 0.88 gram per 70 kilos body weight. Sherman 

 states that "in a detailed study of the food supplies of 224 families or other 

 groups of people selected as typical of the population of the United States 

 only eight showed less than 0.88 gram of phosphorus per man per day and 

 in all but two of these cases the phosphorus content would have reached this 

 figure if the food consumed (without changing its character) had been in- 

 creased in amount to a level of 3000 calories per man per day. The two 

 cases which apparently contained less than the average actual requirement 

 of phosphorus and would still have been thus deficient if the food had been 

 sufficient in amount to cover the energy requirement amply were both re- 

 ported from the southern states. . . . Outside of the southern regions where 

 the food consists too largely of patent flour and new process (degerminated) 

 cornmeal, the danger that a freely chosen American dietary will be deficient 

 in either protein or phosphorus does not appear serious, in the light of our 



