EFFECT ON VARIOUS PHYSIOLOGIC PROCESSES 669 



of calcium by forming insoluble salts with it. He considers it to be an 

 "anti^-itamin D." 



c. Phytase and the Action of Vitamin D. It is of considerable interest 

 to determine whether or not the beneficial effect of vitamin D when admin- 

 istered to rats on a phytin-containing diet is attributable to its stimulating 

 effect upon the phytin-hydrolyzing enzyme, phytase. Partwardhan^"^ 

 noted that an extract of the mucous membrane of rat intestine possessed 

 some ph>i:ase activity. Mellanb}^^"^ also observed phytase actix-it}' in an 

 extract from rat intestine, but very Httle from the intestines of puppies, 

 and only in the duodenal and rectal contents. 



When vitamin D is administered to animals which have been fed phytic 

 acid, less phytic acid is excreted than occurs in vitamin D-deficient ani- 

 mals. -^^ In later work^"^"^^^ it was found that vitamin D exerted a con- 

 stant beneficial effect upon phytin-treated rats, as indicated by bone ash 

 studies. It was beheved that vitamin D resulted in an increased utihza- 

 tion of phytin. However, since there was no increased acti\'ity in the 

 phytase of the intestine of \dtamin D-treated rats, Spitzer and co-workers^^^ 

 concluded that the action of the \dtamin was of a secondary nature. One 

 is led to conclude that the improA'ed utihzation of phytic acid following the 

 administration of vitamin D is probably not to be ascribed to any action of 

 phytase. 



A second possibility to explain the increased utihzation of phytin follow- 

 ing \dtamin D therapy, as suggested by Mellanbj^,^"^ is that the vitamin D 

 counteracts the calcium-depriving action of phytate. A number of facts 

 support this second hypothesis. The fact that extra calcium in the diet 

 reduced the digestibility of phytate-phosphorus in man,^^^ in rats,^°* 

 and in puppies-^^-^"^ suggests that, in rickets, the greater amount of cal- 

 cium in the gut would bring about the same depression in the digestion of 

 phytin, both by combining vnth it and by inhibiting ph3'tase. The action 

 of Adtamin D in \dtamin D-deficient rats would increase phytin utilization 

 by causing the absorption of calcium, and would thus lessen its phytin- 



3»« V. N. Patwardhan, Biochem. J ,31, 560-564 (1937). 



**^E. Mellanby, A Story of Nutritional Research, Williams & Wilkins, Baltimore, 

 1950. 



308 R. K. Boutwell, R. P. Geyer, A. W. Halverson, and E. B. Hart, /. Nutrition, 31, 

 193-202(1946). 



^^ C. H. Krieger, R. Bunkfeldt, and H. Steenbock, /. Nutrition, 20, 7-14 (1940). 



3'" C. H. Krieger and H. Steenbock, /. Nutrition, 20, 125-132 (1940). 



311 R. R. Spitzer, G. Maruyama, L. Michaud, and P. H. Phillips, J. Nutrition, 35, 185- 

 193(1948). 



312 E. W. H. Cruickshank, J. Duckworth, H. W. Kosterlitz, and G. M. Wamock, J. 

 P/i;/s«oL/04, 41-46(1945). 



