292 IV. DIGESTION OF LIPIDS OTHER THAN FATS 



On the other hand, a-tocopherol or sulfasuxidine did not affect the utiliza- 

 tion of carotene in spinach, as demonstrated by liver storage tests for 

 vitamin A. 



Kelley and Day 285 reported later that, when large amounts of lutein 

 (xanthophyll) were given to rats, the vitamin A storage in the tissues was 

 lower after the administration of 5-carotene or vitamin A than when the 

 carotenol was absent from the diet. However, the ingestion of xantho- 

 phyll did not affect the rate of disappearance of vitamin A already present 

 in the tissues. This is interpreted as meaning that the inhibitory action 

 of xanthophyll is exerted in the gastrointestinal tract. This inhibitory 

 action is not counteracted by an extra dose of vitamin E. It was like- 

 wise shown that the effect of xanthophyll is not the result of a specific 

 impairment of the enzymatic mechanism for the transformation of 0- 

 carotene to vitamin A. In a later paper from this laboratory, High and 

 Day 286 confirmed the earlier report, but also noted that the quantity 

 of vitamin A stored in the liver and kidneys was increased when small 

 amounts of xanthophyll were administered. It was also found that large 

 amounts of phytol, squalene, and a-tocopherol acetate, when fed with 

 carotene or vitamin A, likewise decreased the extent of storage of vitamin 

 A. However, squalene, phytol, geraniol, and menthol were all without 

 effect in decreasing the quantity of vitamin A already present in the liver 

 and kidneys. Vavich and Kemmerer 287 reported that xanthophylls, 

 when fed at levels of 300 or 600 /xg. daily, did not reduce the storage of 

 vitamin A in the livers of chicks fed 65 ng. of 0-carotene daily. However, 

 doses of 100, 300, or 600 fig. of xanthophylls did cause a reduction in the 

 amount of vitamin A stored in the livers of chicks fed 130 fig. of carotene 

 daily. In the case of rats, Callison, Hallman, Martin, and Orent-Keiles 288 

 could not demonstrate any change in carotene utilization for growth. 

 This would indicate that the difference, in availability of the carotenes, 

 between green and in yellow vegetables, respectively, is not explicable on 

 the basis of the xanthophylls, which are present in large amounts in the 

 green leaves, but which are almost wholly lacking in the yellow vegetables. 



The several investigators are all in agreement that any effect which 

 the xanthophylls may exert on the vitamin A storage is concerned with 

 the absorptive rather than with the metabolic phases. There appears 

 also to be some agreement in the results as indicating that the quantity 



286 B. Kelley and H. G. Dav, /. Nutrition, 40, 159-168 (1950). 



286 E. G. High and H. G. Day, J. Nutrition, 43, 245-260 (1950). 



287 M. G. Vavich and A. R. Kemmerer, Arch. Biochem., 28, 295-298 (1950). 



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

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



