CAROTENOIDS AND VITAMINS A IN THE BLOOD 461 



(.ja^jj.296 cited as the arbitrary standard of the Oxford Nutrition Survey a 

 value above 100 /zg. % as normal; a figure below 50 ^g- % represents ex- 

 treme abnormality. 



In the case of the cow, the blood carotene values vary with the nature of 

 the feed. Averages as high as 1520 ng. % were recorded by Braun,-^'' al- 

 though levels as low as 140 /xg. % have also been noted on low carotene in- 

 takes. Moore-^^ stated that the sera of Jersey cows and of other Channel 

 Island breeds frequently contain as much as 2000 /xg. %; 200 /zg. % may be 

 considered to be an average level for plasma carotene during the summer 

 months, when the intake of carotene is high. In contrast to this, the 

 figure for the blood carotene le\-el of the horse is given by Rasmussen 

 et al.-^^ as only 97 ± 78 fig. %. 



In a study by Ganguly and collaborators,-" the following values were 

 noted for carotenes and xanthophylls, respectively (expressed in ug. %), 

 for animals belonging to the several classes, as related to carotenoid metab- 

 ohsm: Group A (high carotene, high carotenol), frogs, and not deter- 

 mined; Group B (high carotene, low carotenol), cow, 435, 16.9; Group D 

 (low carotene, high carotenol), chicken, 4.2, 162; and Group C (low caro- 

 tene, low carotenol), rat, 0, and ewe, 0, 0. 



c. Factors Altering the Level of Blood Carotene, (a) Diet. As noted 

 earlier, the most important factor responsible for variations in blood carotene 

 is the effect of diet. Getz^"" was able' to increase the blood carotene in 

 patients to maximum values of 900 to 1100 ug. % by the simple expedient 

 of feeding large doses of carotene (120 mg.). As the dosage of /3-carotene 

 was further increased, the rise in the blood carotene level did not keep pace 

 with the increased intake. Presumably, a larger proportion was lost in the 

 feces. 



After moderate doses of carotene, the maximum level is reached in the 

 blood after seven to ten hours. ^"^ Murrill et al.-^^ reported a similar result 

 after a large dose of this provitamin A (80 mg.), although a second maxi- 

 mum level was obtained twenty -four to forty-eight hours after its adminis- 



296 H. M. Sinclair, Vitamins and Hormones, 6, 101-162 (1948). 



2" W. Braun, J. Nutrition, 29, 61-71 (1945). 



"8 T. Moore, The Fat-Soluble Vitamins, in G. H. Bourne and G. W. Kidder, Bio- 

 chemistry and Physiology of Nutrition, Vol. I, Academic Press, New York, 265-290, 195.3, 

 p. 269. 



2" R. A. Rasmussen, C. L. Cole, and M. J. Miller, J. Animal Sci., 3, 346-350 (1944). 



^^ H. R. Getz, Induction of Vitamin A Deficiency in Man, presented at Vitamin Con- 

 ference, A.A.A.S., Gibson Island, Jul}', 1944; cited by J. C. Fritz, Ann. Rev. Biochem., 

 U, 525-560 (1945). p. 533. 



«" E. P. Ralli, H. Brandaleone, and T. Mandelbaum, J. Lab. Clin. Med., 20, 1266-1275 

 (1935). 



