616 IX. CAROTENOIDS AND VITAMINS A 



liver, hyperthyroxinemia, reduced secretion of thyrotropic hormone, and 

 loss m weight of the thyroid gland, accompanied by a reduction in the con- 

 tent of protein-linked iodine in the gland. 



b. Interaction with Calcium and Phosphorus. Since hone fracture is a 

 prominent symptom of hj^pervitaminosis A, it appears possible that the 

 excess vitamin A might have the capacity to react with phosphorus and 

 calcium in the animal organism. An increased excretion of calcium and 

 phosphorus in the urine was shown to occur after the subcutaneous injection 

 of biosterol ("fat-soluble A"),'^^^ possibly due to the destruction of diges- 

 tive organs and muscles consequent to the hyper\dtaminosis. The action 

 of the vitamin D, which is also present in biosterol, cannot be entirely dis- 

 counted. The decrease in these minerals in the bones following the ad- 

 ministration of Vogan has been cited as the cause for the tendency to bone 

 fractures in hypervitaminosis A.^^^^ However, the calcium and phosphate 

 levels of the blood of rats with hypervitaminosis A have been reported to 

 be normal, ^^^^'^^^^ and no reduction of these substances in bone ash could 

 be demonstrated in rats treated with large doses of vitamin A.^'^^'^'^^ 

 Hypervitaminosis A results in a marked increase in the content of alkaline 

 phosphatase in the epiphyseal j unction, '^^® although the phosphatase con- 

 tent in other bones is decreased. 



c. Interaction with the Vitamin B Complex. Hojer,^^^^ in 1927, and Bell 

 et al.'^^^'^ several years later, reported that certain B \itamins exert a favor- 

 able effect upon symptoms of hj^Dervitaminosis A produced by cod-liver 

 oil. It is now beheved that the beneficial effect in these cases can be at- 

 tributed to the antagonism of the B complex toward the toxicity of the 

 saponifiable fraction of the fat. Moore and Wang"^^ are of the opinion 

 that 3''east does not influence the course of gestation in hypervitaminosis 

 A in rats. Scheunert and Wagner' ^^^ did not observe any synergism or 

 antagonism between thiamine and toxic doses of \dtamin A. This con- 

 clusion is concurred in by Rodahl.^^^' Vedder and Rosenberg^^^' had 

 earlier reported that 500 I.U. of thiamine increased the toxicity of high dos- 

 ages of vitamin A given in jewfish liver oil. 



d. Interaction with Ascorbic Acid. A number of the earlier investiga- 

 tions indicated that an antagonism existed between vitamin A and ascorbic 



ii8« T. Munehisa, Sei-i-kwai Med. J. (Tokyo), 48, No. 5, 57-81, Ahst. Seel., 2-3; No. 

 10, 77-107, English Sect., 4 (1929). 



1'" K. Rodahl, /. Nutntion, 41, 399-421 (1950). 



"88 K. S. Ludwig, Int. Z. Vitaminforsch., 25, 98-103 (1953). 



i>83 A. Hojer, Acta Paediat., 6, 180-190 (1927). 



i>s» A. Scheunert and K. H. Wagner, Z. phy.siol. Chem., 256, 111-121 (1938). 



11" E. B. Vedder and C. Rosenberg, /. Nutrition, 16, 57-68 (1938). 



