FACTORS AFFECTING RATE OF ABSORPTION 179 



noted when very young rats are compared with adult animals. 614 Thus, it 

 was shown by Deuel and collaborators 614 that, when approximately 1100 

 mg. of fat were fed to male rats weighing 270 g., 43.2% was absorbed in 

 three hours, while in young rats with an average weight of 65 g. the per- 

 centage absorbed was only 23.1% after the feeding of a similar dose. 

 However, when the absorption rate was calculated on body surface, the 

 relative rates were much closer, namely, 43.3 and 56.1 mg. per 100 sq. cm. 

 per hour for the adult and young rats, respectively. Moreover, when a 

 standard dosage of 300 mg. per 100 sq. cm. was employed, the comparative 

 values for males (expressed in mg./lOO sq. cm./hr.) were 43.3 ±1.8 (270 g.) 

 and 53.8 ± 2.6 (74 g.); the results obtained with females were 38.1 ± 3.2 

 (150 g.) and 43.7 ±2.1 (64 g.). One can conclude that the rate of absorp- 

 tion of fats is not influenced by the size of the rat (and hence the age) 

 over a fairly wide range if the results are expressed in terms of body surface; 

 the size of the dosage of fat would appear to be of less consequence, although 

 a dosage having a constant proportion to surface area is probably the best. 



In the case of man, recent work has indicated that extreme variations in 

 age do influence the rate of absorption. Sobel and co-workers, 819 as well 

 as Tidwell, Holt et al., s ' 20 demonstrated that newborn infants and babies 

 under one year of age absorb fats quite inefficiently, as compared with older 

 children. On the other hand, the data of Becker et al. S21 indicate that fat 

 may be absorbed or metabolized much more slowly in the aged than in 

 younger subjects. This is indicated by the chylomicron count, which 

 remains at an elevated level for a prolonged period after the feeding of fats 

 to aged subjects. 



Sex does not appear to be a factor in determining the rate of fat absorp- 

 tion. This conclusion was postulated by Irwin and co-workers, 611 while the 

 results of the Deuel group recorded in Tables 23 and 24 support this state- 

 ment. Pregnancy was likewise reported to be without effect on the rate of 

 absorption of fats in the case of rats. 611 Cordier and Piery 822 reported ex- 

 tremely wide variations in the speed of absorption of peanut oil in different 

 rats; figures varying from 8 to 97% were cited for ninety-minute tests. 

 These authors suggest that the amount of absorption may be affected by the 

 amount of oil which passes into the intestine, and may be related to the 

 amount of enterogastrone set free. Extreme variations in absorption be- 



819 A. E. Sobel, L. Besman, and B. Kramer, Am. J. Diseases Children, 77, 576-591 

 (1949). 



820 H. C. Tidwell, L. E. Holt, Jr., H. L. Farrow, and S. Neale, J. Pediat., 6, 481-489 

 (1935). 



821 G. H. Becker, J. Meyer, and H. Necheles, Gastroenterology, 14, 80-90 (1950). 



822 D. Cordier and Y. Piery, Compt. rend. soc. biol, 145, 730-731 (1951). 



