DIGESTION, ETC. OF CAROTENOIDS IN THE G.I. TRACT 287 



to be unable to absorb carotene on a fat-low diet, although an almost 

 complete utilization of the provitamin obtained when 10% of fat was in- 

 corporated in the diet. These conclusions have been confirmed, for both 

 animal and human subjects, by a number of investigators 227-231 ; Shaw 

 and Deuel 219 observed a correlation between the quantities of fat and of 

 carotene absorbed by rats. The same dietary requirement for the utiliza- 

 tion of carotene also obtains for hens as for other animals, according to 

 Russell and co-workers. 232 Fraps and Meinke 233 found that carotene fed 

 in the form of vegetables was less effective than when given as a com- 

 ponent of butterfat or of beef liver. Between 25 and 45% of carotene 

 from raw spinach or grated carrots can be absorbed by man, 234 while the 

 absorption from the cooked material was found to be considerably less, 

 i.e., 2 to 12%. It has also been reported, in the case of man, that caro- 

 tene is biologically more effective when given in butter than when ad- 

 ministered as a component of carrots. 235 On the other hand, Random 

 et a/. 236 reported that rats can utilize /^-carotene and vitamin A as well on 

 a fat-free diet as on one containing 10% of peanut oil. These workers 237 

 likewise reported a greater efficiency in the utilization of carotene when 

 it was mixed in the diet than when it was given as a supplement in an oily 

 solution. This result is interpreted to mean that some dietary compo- 

 nent may have a protective action on carotene in the gastrointestinal tract. 

 Thus, Molander 238 noted that carotene dissolved in corn oil or in mineral 

 oil could be demonstrated by examination of human serum when the 

 particle size was 0.5 \i. On the other hand, it was reported that the corn 

 oil fatty acids do not carry carotene efficiently from the gastrointestinal 

 tract to the tissues, but rather carry the chromogen to the liver. These 

 experiments would seem to indicate that carotene may gain entrance to 



227 N. K. Basu, Z. Vitaminforsch., 6, 106-110 (1937). 



228 H. E. C. Wilson, S. M. Das-Gupta, and B. Ahmad, Indian J. Med. Research, 2/,, 

 807-811 (1937). 



229 M. van Eekelen and W. Pannevis, Nature, 141, 203-204 (1938). 



230 A. R. Kemmerer and G. S. Fraps, ./. Nutrition, 16, 309-315 (1938). 



231 S. Y. Thompson, R. Braude, A. T. Cowie, J. Gangulv. and S. K. Kon, Biochem. J., 

 44, ix-x (1949). 



232 W. C. Russell, M. W. Taylor, H. A. Walker, and L. J. Polskin, J. Nutrition, 24, 

 199-211 (1942). 



233 G. S. Fraps and W. W. Meinke, Food Research, 10, 187-196 (1945). 



234 W. van Zeben, Z. Vitaminforsch., Sonderabdruck, 17, 74-84 (1946). 



235 M. Kreula and A. I. Virtanen, Upsala, Ldkareforen. Forh., 45, 355-362 (1939); 

 Chem. Abst., 34, 5897 (1940). 



236 L. Random, D. Hugot, and J. Causeret, Compt. rend. soc. bioL, 145, 65-68 (1951). 



237 L. Randoin, D. Hugot, and J. Causeret, Compt. rend. soc. biol, 145, 68-70 (1951 ). 



238 D. W. Molander, Yale J. Biol. Med., 21, 201-210 (1949). 



