326 ASCORBIC ACID 



B vitamin supplements may have been responsible for the differences be- 

 tween these results and those of Meyer and Krehl.^^^ The highly purified 

 diet used l)y Meyer and Krehl may have been lacking in substances which 

 act as stimulators of ascorliic acid synthesis. ^^'"^ It also seems quite possible 

 that the yeast may have equalized the food intake of the two groups and 

 thus may have contributed to an equalization of ascorbic acid synthesis. 

 That the synthesis of vitamin C may be related in some measure to food 

 intake has been shown by Mapson and Walker.^'*^ They reported that in 

 male rats deficient in vitamin A the lowered urinary excretion of ascorbic 

 acid and its concentration in the liver and blood could be attributed to the 

 lowered food intake, but in the females the concentration of ascorbic acid 

 in both the liver and blood appeared to be unrelated either to food intake or 

 to vitamin A deficiency. They also observed that the rise in urinary excre- 

 tion of vitamin C in response to chloretone was less in vitamin A-deficient 

 rats of both sexes than in the control animals, but the difference was elim- 

 inated if, in the control group, food intake was restricted to that of the 

 deficient animals. 



(c) Effects of Excess Vitamhi A on Development of Scurvy. Mouri- 

 quand and MicheP''® reported that an excess of cod liver oil interferes with 

 the cure of scurvy in guinea pigs. Collet and Eriksen^"*^ confirmed this find- 

 ing and observed also that a moderate excess of vitamin A did not interfere 

 with ascorbic acid. Tul'chinskaya^^^ in a study of antagonism and syn- 

 ergism among vitamins observed that carotene lessens the capacity of 

 guinea pig tissues to retain ascorbic acid. One milligram of carotene in 0.2 

 ml. of vegetable oil partially neutralized the effect of 5 mg. of ascorbic 

 acid but appeared to have no effect against doses of 20 to 50 mg. of vitamin 

 C. Oral administration of ascorbic acid was less effective than parenteral in 

 increasing the tissue storage. Vedder and Rosenberg^"*^ reported that rats 

 given large doses of jewfish oil with a high content of vitamin A developed 

 scurvy -like symptoms and the ascorbic acid excretion was greatly reduced. 

 Supplementation with 5 mg. of ascorbic acid per day gave almost complete 

 protection. RodahP*" found that prolonged administration of excessive 

 doses of vitamin A in the form of polar bear liver resulted in a scurvy -like 

 condition in rats which could be alleviated with supplements of ascorbic 

 acid, although it appeared certain that lack of ascorbic acid is not the only 



34^b H. E. Longenecker, R. R. Musulin, R. II. TuUy, and C. G. King, ./. Biol. Chem. 



129, 445 (1939). 

 3« h. W. Mnpson and S. E. Walker, Brit. ./. Nutrition 2, 1 (1948). 

 8" G. Mouriquand and P. Michel, Compt. rend. soc. biol. Part 1, 1170 (1922). 

 3^' E. Collett and B. Eriksen, Biochem. J. 32, 2299 (1938). 



"8 K. Z. Tul'chinskaya, Proc. Sci. Inst. Vitamin Research (U.S.S.R) 3, 218 (1941). 

 "9 E. B. Vedder and C. Rosenberg, J. Nutrition 16. 57 (1938). 

 «o K. Rodahl, Nature 164, 530, 531 (1949). 



