2 BULLETIN 505, U. S. DEPAETMENT OF AGRICULTTJRE. 



ration (supplying a minimum of fat) composed of wheat biscuits, 

 oranges, sugar, and tea, or coffee if desired, was supplemented by a 

 blancmange or cornstarch pudding, in which was incorporated the 

 vegetable fat under consideration. 



The test periods were of tliree days' or nine meals' duration, to 

 agree with the experimental conditions under which the animal fats 

 were studied, and the following four days formed a rest period in 

 which the subjects furnished their own meals, which differed in no 

 special way from an ordinary mixed diet. 



Normal young men in good health and moderately active, all of 

 whom were medical or dental students, were the subjects of the diges- 

 tion experiments. The prescribed routine involved regularity, espe- 

 cially with respect .to the time for eating, but the subjects were per- 

 mitted to exercise in their customary ways and as required in the 

 performance of their daily work. In most cases the subjects had 

 had previous experience in similar experiments, and all of them proved 

 to be careful and trustworthy assistants. 



Weighings were made of the net amounts of food eaten and feces 

 excreted, and samples of both food and feces were analyzed to deter- 

 mine the percentages of protein, fat, and carbohydrate which were 

 actually digested. 



The experimental method followed has been reported in a previous 

 bulletin of this series,^ the analytical methods being those which are 

 approved by the Association of Official Agricultural Chemists .^ 



DIGESTION EXPERIMENTS. 



OLIVE OIL. 



Although olive oil has been known from earUest times as a food 

 product, exact information regarding the proportion assimilated by 

 the body is comparatively limited, its food value having been gen- 

 erally discussed with respect to its theoretical energy value, its 

 quality, and cuhnary and table uses. As regards earHer work, a 

 five-day experiment with a healthy man was conducted by Berta- 

 relli,^ who tested the digestibility of a mixture of olive and colza oils 

 in a basal ration of white bread and meat; the fat was 95.8 per cent 

 digested. Moore ^ has reported a number of animal feeding experi- 

 ments in which he found that ohve oil was assimilated to the extent 

 of from 96.7 to 98.7 per cent. In a comparative series of tests he 

 noticed that uncooked oils in the food of guinea pigs were somewhat 

 less thoroughly available than was the case when the oil was cooked 

 with the food. In general all of the vegetable fats studied were 

 digested to practically the same extent. 



1 U. S. Dept. Agr. Bui. 310 (1915). 



s V. S. Dept. Agr., Bur. Chem. Bui. 107 (1912), rev. ed. 



3 Riv. Ig. e Sanit. Pub., 9 (1S9S), Nos. 14, pp. 538-545; 15, pp. 570-579. 



* Arkansas Sta. Bui. 78 (1903), pp. 33-41. 



