428 IX. CAROTENOIDS AND VITAMINS A 



hydrophilic mucilloids, which are used as purges m place of mineral oils, 

 do not decrease the utilization of carotene. Moreover, alumina gel, which 

 is often administered over protracted periods in the treatment of peptic 

 ulcer, is also without a depressing action on carotene utilization.^^ 



The tocopherols augment the biologic activity of both carotene and 

 vitamin A.^** It is beheved that this may be the result of a positive action 

 of the tocopherols against an oxidative destruction of these compounds in 

 the gastrointestinal tract. Several investigators^ ^'^^ have reported that 

 the administration of the xanthophylls (lutein and zeaxanthin) reduces the 

 utilization of /3-carotene, but the results are disputed. For example, 

 Callison and her co-workers^* were unable to demonstrate any variation in 

 the utilization of carotene for growth in rats, irrespective of whether or not 

 lutein had been supphed in the diet. 



May and McCreary^"* reported that the absorption of carotene is decreased 

 in children suffering from celiac disease, especially during the active stage. 

 Heymann^^ also demonstrated that a reduction in carotene utilization 

 occurred in sepsis, pneumonia, and grippe which could not be attributed to 

 the accompanying fever. Guggenheim^^ observed that the absorption rate 

 of carotene is decreased after prolonged administration of the antimalarial 

 drug, atabrine. 



b. The Absorption of Carotenoids Other Than ,S-Carotene. There is 

 some indication that carotenoids other than /3-carotene may be absorbed. 

 On the basis of bioassays designed to determine vitamin A biopotency, it 

 can be stated that a- and 7-carotenes have approximately half the bio- 

 potency"-^'^ of the (8-compound; pro-7-carotene 41% of the potency of all- 

 trans-^-carotene.^^ However, this evidence is not absolute, as it is possible 

 that the provitamins A might first be split to vitamin A before absorption, 

 and that only this simpler molecule is absorbed. On the other hand, the 

 demonstration by Ganguly et al}"^ that mhiimal amounts of a-carotene as 



*^ W. S. Hoffman and H. A. Dyniewicz, Gastroenterology, 5, 512 (1945). 

 5" K. C. D. Hickman and P. L. Harris, Advances in Enzymologij, 6, 469-524 (1946). 

 " A. R. Kemmerer, G. S. Fraps, and J. DeMottier, Arch. Biochem., 12, 135-138 

 (1947). 



62 B. Kelley and H. G. Day, J. Nutrition, 40, 159-168 (1950). 



63 E. C. Callison, L. F. Hallman, W. F. Martin, and E. Orent-Keiles, Arch. Biochem. 

 Biophys., 32, 407-413 (1951). 



" C. D. May and J. F. McCreary, J. Pediat., 18, 200-209 (1941). 

 « W. Heymann, Am. J. Diseases Children, 61, 273-283 (1936). 



66 K. Guggenheim, /. Nutrition, 46, 141-149 (1952). 



67 H. J. Deuel, Jr., E. Sumner, C. Johnston, A. Polgdr, and L. Zechmeister, Arch. 

 Biochem., 6, 157-161 (1945). 



68 L. Zechmeister, J. H. Pinckard, S. M. Greenberg, E. Straub, T. Fukui, and H. J. 

 Deuel, Jr., Arch. Biochem., 23, 242-245 (1949). 



69 J. Ganguly, J. W. Mehl, and H. J. Deuel, Jr., /. Nutrition, 50, 59-72 (1953). 



