RATE OF ABSORPTION OF COMMON FATS 173 



Table 21 



Mean Percentages of Fats Absorbed by Previously Fasted Male Rats 



at Several Periods after the Feeding of 1.5 ml. of the Various Fats by 



Stomach Tube 



Absorption time* 

 Fat fed 2 hrs. 4 hrs. 6 hrs. 8 hra. 12 hrs. 



Butterfat... 36.2 ±1.6 60.3 ±1.2 77.2 ± 2.0 91.2 ±1.1 97.4 ±0.4 



Butter oil... 37.4 ± 2.3 71.0 ±1.2 86.4 ±1.7 95.6 ±1.0 



Cod-liver oil. 40.8 ±1.4 67.7 ±1.9 79.7 ±1.5 89.2 ±0.7 98.2 ±0.4 



Corn oil 28.9±0.8 58.3 ±0.9 71.4±2.1 94.4±0.7 97.9±0.3 



Halibut 



liver oil... 39.4 ±1.6 70.2 ± 2.0 78.1 ±1.3 85.4 ±0.9 



Lard 24.1 ±0.8 57.0 ±1.5 67.5 ±1.5 92.3 ± 0.9 97.8 ±0.4 



Shortening A 26.6 ±1.5 53.8 ±1.6 68.5 ±1.7 86.0 ±1.3 98.6 ±0.3 



ShorteningB 27.1 ±1.8 52.8 ±2.4 71.1 ±1.5 85.6 ±1.2 99.6 ±0.1 



° H. Steenbock, M. H. Irwin, and J. Weber, /. Nutrition, 12, 103-111 (1936). 

 6 Including Probable Error of the Mean. 



Although considerable data are found in the literature on the complete- 

 ness of the digestibility of fats, there is a paucity of information as to con- 

 ditions obtaining where the time relations have been studied. Moreover, 

 much of the information cannot be compared, since different units have 

 been employed to express absorption rates. The index of absorption rate 

 as used by Steenbock, Irwin, and Weber 812 is the percentage of ingested fat 

 which is absorbed during a four-hour period. As long as the size of the 

 animals, the time of absorption, and the dosage employed are uniform, one 

 would expect to obtain fairly consistent results by this procedure. How- 

 ever, this index is not of value when any of these conditions are varied. 



A second procedure for comparing absorption rates is to base them on 

 terms of the quantity absorbed per unit surface area of the body per hour. 614 

 In employing this method of evaluation, Deuel, Hallman, and Leonard 614 

 noted that fairly constant results are obtained with rats of widely varying 

 sizes, and with different dosages over various time intervals. The use of the 

 index proposed by Steenbock et al. S12 was shown to yield inconsistent re- 

 sults under such conditions (see pages 128 and 129). 



The absorption rates of some common fats in the case of adult male rats 

 at two-hour intervals up to twelve hours after feeding are summarized in 

 Table 21. The animals were fed 1.5 ml. of the oil or melted fat, and the 

 absorption rate is expressed in percentages of ingested fat absorbed. In 

 Table 22, the results of the four-hour tests were calculated on the basis of 

 surface area as well. 



812 H. Steenbock, M. H. Irwin, and J. Weber, /. Nutrition, 12, 103-111 (1936). 



