DIGESTION, ETC. OF CAROTENOIDS IN THE G.I. TRACT 301 



47% in rats receiving 20 /xg. daily to 33% for those receiving 60 ng. Kem- 

 merer and Fraps 230 found that the digestibility of /3-carotene in rats 

 varied with the amount fed and with the vehicle. When it was fed to 

 rats in dehydrated alfalfa at levels of 1, 10.5, or 20 parts per million, the 

 digestibility coefficients were 43, 22, and 18 to 23, respectively. When 

 chickens were the test animals, values of 69 and 29 were obtained for the 

 1 part/million and 20 part/million dosage levels, respectively. 



(b) The Effect of the Food Given Simultaneously with Carotene. Di- 

 gestibility coefficients are much higher for carotene when the provitamin 

 is given in oil. Thus, Kemmerer and Fraps 230 reported a coefficient of 

 digestibility of 51 when carotene was given in oil to rats, and one of 22 

 when it was fed as dehydrated alfalfa without added fat. Kreula 352 

 reported that, whereas the absorption of carotene from finely grated car- 

 rots by three human subjects on a fat-free diet was only 10%, it was in- 

 creased to 50% when carotene dissolved in olive oil was taken in a* single 

 dose. When the oil solution was taken in two portions, as much as 70% 

 was utilized. 



The carotene digestibility varies considerably according to the vegetable 

 source. Thus, Wilson and co-workers 228 observed a digestibility of 90% 

 for carotene when it was given in raw or cooked carrots or cooked spinach 

 with fat, but the coefficient of digestibility was only 50 when it was given 

 without fat. On the other hand, van Eekelen and Pannevis 229 found that 

 99% of the carotene from carrots and 95% of the carotene from spinach 

 was present in the feces. Kreula and Virtanen 235 likewise observed that 

 the digestibility for carotene varied between 1 and 36%, and generally 

 amounted to 10%. Very finely grated carrots appeared to be more favor- 

 able for utilization than were those which had been merely masticated. 

 With 353 reported that carotene was absorbed to the extent of 30 to 60% 

 from purees of tomatoes, carrots, spinach, and carrot meal. The Vitamin 

 A Sub-Committee of the Accessory Food Factors Committee 354 reported 

 a 25% utilization of carotene from carrots and a utilization of about 40% 

 from spinach. Hume and Krebs 355 also studied the efficiency of absorp- 



362 M. S. Kreula, Biochem. J ., 41, 269-273 (1947). 



353 T. K. With, Absorption, Metabolism and Storage of Vitamin A and Carotene, Munks- 

 gaard, Copenhagen, 1940, and Milford, London, 1940; cited by M. S. Kreula, Biochem. 

 J., 41, 269-273 (1947), p. 269. 



354 Report of the Vitamin A Subcommittee of the Accessory Food Factors Committee, Lister 

 Inst., Rep. Med. Research Council (Brit.), 1939-1945, pp. 107-109. H. M. Stationery 

 Office, London, 1945. 



386 E. M. Hume and H. A. Krebs, Vitamin A Requirements of Human Adults, Report 

 of the Vitamin A Subcommittee of the Accessory Food Factors Committee, Med. Re- 

 search Council (Brit.), Spec. Rep. Ser., No. 264, H. M. Stationery Office, London, 1949. 



