Am.  Jour.  Pharm.  "I 
November,  19 19. 
Fat-Soluble  Vitamin. 
743 
As  might  be  expected,  these  pioneer  studies  of  distribution  are 
being  followed  by  investigations  of  the  properties  of  the  unique 
something  known  as  fat-soluble  vitamin.  It  has  not  been  identified 
with  any  of  the  recognized  components  of  fats,  such  as  glycerol, 
fatty  acids,  cholesterol,  phosphatids  or  lipochromes.  Several  inves- 
tigators, of  whom  the  latest  is  Drummond3  of  the  Cancer  Hospital 
in  London,  have  called  attention  to  the  ready  destruction  of  the  fat- 
soluble  accessory  food  factor  {A)  after  relatively  short  exposure 
to  a  temperature  of  ioo°  C.  (2120  F.).  Longer  exposures  at  lower 
temperatures,  for  example,  370  C.  (98.60  F.)  may  be  equally  detri- 
mental. This  destruction  is  apparently  not  a  result  of  oxidation  or 
hydrolysis.  The  facts  just  cited  render  it  impossible  at  the  present 
state  of  knowledge  to  "  harden  "  liquid  oils,  as  is  now  so  commonly 
done  in  the  industries,  without  effecting  a  loss  of  the  fat-soluble 
vitamin  which  the  original  fats  may  contain.  This  explains,  further, 
why  it  is  that  the  popular  commercial  hardened  oils  are  devoid  of 
the  vitamin,  whatever  their  origin  may  have  been. 
The  specific  role  of  the  fat-soluble  vitamin  within  the  organism 
still  remains  unknown.  The  fact  that  it  is  found  in  certain  fat 
depots  of  the  body  has  suggested  that  it  may  play  a  part  in  the  util- 
ization of  fats.  Recent  observations  by  Drummond4  indicate  that 
this  is  not  the  case,  however.  A  deficiency  of  fat-soluble  A  in  the 
diet  does  not  exert  any  direct  influence  on  the  absorption  of  fat; 
and  animals  are  able  to  absorb  large  amounts  of  fatty  acids  and 
presumably  synthesize  these  into  fats,  in  the  absence  of  the  fat- 
soluble  vitamin.5  Drummond3  ventures  to  suggest  that  the  latter  is 
not  a  clearly  defined  chemical  substance,  but  rather  a  "labile  sub- 
stance perhaps  possessing  characteristics  resembling  those  of  an 
enzyme."  We  shall  await  further  investigations  without  the  bias  of 
a  fixed  hypothesis. 
3  Drummond,  J.  C. :  "  Researches  on  the  Fat-Soluble  Accessory  Sub- 
stance, I,  Observations  on  Its  Nature  and  Properties,"  Biochem.  J.,  13:  8 
(May),  1919. 
4  Drummond,  J.  C. :  "  Researches  on  the  Fat-Soluble  Accessory  Sub- 
stance, II,  Observations  on  Its  Role  in  Nutrition  and  Influence  on  Fat 
Metabolism,"  Biochem.  J.,  13:  95  (May),  1919. 
5  "Fatty  Acids  as  Foods,"  editorial  /.  A.  M.  A.,  73:  608  (Aug.  23),  1919. 
