CH AFTER XII 



THE METABOLISM AND NUTRITIONAL 

 VALUE OF THE VITAMINS K 



1. Introduction 



The \'itainins K represent the most recently disco\^ered major group of 

 the fat-soluble \'itamms. As early as 1929, Dam' reported that certain 

 symptoms, includmg subcutaneous and intramuscular hemorrhages, could 

 be produced in chicks by an artificial diet low in lipids. The deficiency 

 failed to respond to any of the known vitamins. Dam- later found that 

 the disease was associated with prolonged blood clotting time. It was 

 first postulated in 1934, bj^ Dam and Schpnheyder,^ that the hemorrhagic 

 disease in chicks resulted from an avitaminosis. The essential vitamin con- 

 cerned was found to be present in green leaves and in certain vegetables,^ 

 and was named vitamin K,^'" inasmuch as Dam and others had most fre- 

 cfuently referred to it as koagulationsvitamin, in the German and Danish 

 literature. Others, who reported before 1935 that modifications in the diet 

 led to hemorrhagic symptoms in the chick, or to changes in blood clotting 

 time, included Hoist and Halbrook,^ Horvath,^ and McFarlane et a/.^-^ 



The first convincing chemical eiadence that vitamin K occurs in the fat- 

 soluble, non-saponifiable, non-sterol fraction of fats was reported in 1935 

 by Dam^'^ and by Almquist and Stokstad.^"''' Dam, Sch0nheyder, and 

 Tage-Hansen'- demonstrated that vitamin K is of importance in regulating 



1 H. Dam, Biochem. Z., 215, 475-492 (1929). 



2 H. Dam, Biochem. Z., 220, 158-163 (1930). 



3 H. Dam and F. Sch0nhevder, Biochem. J., 28, 1355-1359 (1934). 

 ' H. Dam, Biochem. J., 29, 1273-1285 (1935). 



* H. Dam, A'ature, 135, 652-653 (1935). 



« W. F. Hoist and E. R. Halbrook, Science, 77, 354 (1933). 



^ A. A. Horvath, Am. J. Physiol., 94, 65-68 (1930). 



« W. D. McFarlane, W. R. Graham, Jr., and G. E. Hall, J. Nidrition, 4, 331-349 

 (1931). 



' W . D. McFarlane, W. R. Graham, Jr., and F. Richardson, Biochem. J., 25, 358-366 

 (1931). 



"> H. J. Almquist and E. L. R. Stokstad, Nature, 136, 31 + (1935). 



" H. J. Almquist and E. L. R. Stokstad, J. Biol. Chem., Ill, 105-1 13 (1935). 



" H. Dam, F. Sch0nheyder and E. Tage-Hansen, Biochem. J., 30, 1075-1079 (1936). 



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