592 IX. CAROTENOIDS AND VITAMINS A 



(6) Vitamin Bn- When rats were fed a diet low in vitamin B12, the effect 

 of supplementary vitamin A upon growth was found by High and Wilson^^* 

 to be less than when larger amounts of vitamin B12 were given; however, 

 an increased vitamin B12 intake did not raise the level of storage of vitamin 

 A in the liver. In contradistinction to these results, the administration of 

 vitamin B12 to rats on a diet containing /^-carotene augmented both growth 

 and vitamin A storage in the liver. 



(c) Proteins. According to Mayer and Krehl,^^'^ high levels of dietary 

 protein increased the severity of vitamin A deficiency symptoms in rats; 

 at least part of these effects are believed to be mediated through the con- 

 comitant decrease in vitamin C reserve. The type of protein in the food ap- 

 pears to influence the fate of ingested ;5-carotene. Thus, James and El 

 Gindi^''^^ reported that rats receiving lactalbumin or gluten in their diets 

 excreted more carotene in the feces than they did when casein or zein was 

 the dietary protein. These workers beheve that vitamin A is consumed 

 during an hepatic process concerned with the change of moieties from in- 

 gested proteins to other proteins or to amino acids. The vitamin A levels 

 in the plasma of rats receiving casein or lactalbumin were higher than was 

 the case in rats on regimens containing zein or gluten. 



{d) Choline. Bentley and Morgan^ ^^ reported that hepatic storage of 

 vitamin A by depleted rats was not affected by choHne when a high-fat, 

 low-protein diet was employed. On the other hand, when the diet was a 

 low-fat, low-protein regimen, the addition of choline increased the vitamin 

 A content of the livers. Vitamin A deposition after the ingestion of caro- 

 tene was best in the group of rats recei\ang the low -fat regimen, but choline 

 had little influence upon the extent of deposition of vitamin A. 



(e) Antibiotics. Although Burgess et al.^^^ did note an increase in the 

 \dtamin A storage in chicks when penicilhn was added to the diet, Coates 

 and co-workers'"^' stated that the effect was non-specific, since it occurred 

 only when the growth of the chicks was also stimulated by the penicillin, 

 Aureomycin had no effect upon liver storage of vitamin A.'°^* 



(/) Mineral Oil. It is well known that the consumption of mineral oil 

 reduces the absorption of /3-carotene to an appreciable extent.^^-^* Mineral 

 oil exerts less effect upon the absorption of vitamin A than on that of caro- 

 tene,'''^"''' although some workers^'^^'^^"^^'"^""^ recorded a decrease in the 

 absorption of the vitamin when mineral oil was consumed. Steigmann and 



10" W. H. James and I. M. El Gindi, /. muriiion, 51, 97-108 (1953). 



1023 M. E. Coates, G. F. Harrison, S. K. Kon, J. W. G. Porter, and S. Y. Thomi)son, 

 Chemistry & Industry, 1952, 149. 



1024 E \v Hartsook, E. Batchelor, and B. C. Johnson, Proc. Soc. Exptl. Biol. Med., 

 83, 43-45 (1953). 



