HATE OF ABSORPTION OF COMMON FATS 175 



In the case of the hydrogenated fats other than margarine fat, Crisco, 

 a hydrogenated cottonseed oil melting at 46 °C, and a hydrogenated lard 

 melting at 48 °C, are absorbed at a slightly slower rate. On the other 

 hand, the absorption rates of the hydrogenated lard melting at 55°C. 

 and of the hydrogenated cottonseed oil having a melting point of 54° C. 

 are markedly lower than those of other fats. 



In spite of the wide discrepancies in absorption rate, most of the fats are 

 ultimately equally well digested, and only small amounts are lost in the 

 feces. An exception to this is the low digestibility of rapeseed oil in the 

 rat 813 but not in man, 814,815 of hydrogenated cottonseed oil with a higher 

 melting point (54°C.), 816 and of the higher melting hydrogenated lard 

 (55°C.). 817 



In a number of instances, the rate of absorption appears to be highest in 

 the shorter periods, while in other instances it apparently remains fairly 

 constant throughout the entire absorption period. The most marked 

 differences obtaining between the absorption rate at three and at six hours 

 are in the case of butterfat and rapeseed oil, while the other fats exhibit a 

 fairly consistent absorption rate. In the case of cottonseed oil also, 

 where tests were made at two hours, the rate was considerably higher than 

 that noted for the later periods. 



There are at least two possible explanations for these discrepancies in 

 absorption rate at different periods after administration. In the first 

 place, it is known that the rate of absorption of different triglycerides 

 varies. Where a considerable portion of the fat contains triglycerides with 

 short-chain fatty acids like butyric acid, the rapid rate of absorption of this 

 fraction will be reflected in the early hours. As the digestion and absorp- 

 tion proceed, the longer-chain fatty acid triglycerides will tend to disappear 

 at a slower but constant rate. In the case of rapeseed oil, the triglycerides 

 containing Ci 8 acids will be absorbed first. As these gradually are removed, 

 the slower absorption noted in the later periods must reflect the retardation 

 occasioned by the presence of large amounts of erucic acid, which repre- 

 sents approximately 50% of the total fat. 818 



The second explanation for the slowing up in absorption rate might be 



813 H. J. Deuel, Jr., A. L. S. Cheng, and M. G. Morehouse, /. Nutrition, 85, 295-300 

 (1948). 



814 H. J. Deuel, Jr., R. M. Johnson, C. E. Calbert, J. Gardner, and B. Thomas, J. 

 Nutrition, 38, 369-379 (1949). 



816 A. D. Holmes, U. S. Dept. Agric. Bull. No. 687, 1-20 (1918). 



816 V. Augur, H. S. Rollman, and H. J. Deuel, Jr., J. Nutrition, 83, 177-186 (1947). 



817 M. Crockett and H. J. Deuel, Jr., J. Nutrition, 38, 187-194 (1947). 



818 T. P. Hilditch, T. Riley, and N. L. Vidyarthi, J. Soc. Chem. Ind., tf, 457-462; 

 462-464T (1927). 



