Re: Why do we have names for vitamins A through E and then we skip to K?

Vitamins were originally classified according to their solubility in 
water or fats; they were also classified alphabetically as more and 
more were discovered. The fat soluble vitamins are A, D, E, and K, 
the rest being water soluble. Vitamin K was identified in 1934 by the 
Danish biochemist Henrik Dam, who won the Nobel prize, together 
with E. A. Doisy, in 1943 for their discovery of Vitamin K. This vitamin 
is essential to the clotting of blood. Published originally in the 
German literature-Koagulations-Vitamin, thus Vitamin K. This later 
discovered vitamin was not consistant with the continued alphabetic 
listing of all vitamins. There was a group of substances which 
decreased blood capillary fragility, called the vitamin P group. They 
are no longer considered to be vitamins. See Albert von Haller, The 
Vitamin Hunters (1962). All the vitamins differ in structure, there being 
no chemical grouping common to them all.  Casimir Funk merely 
coined the name "vitamines" to emphasize that they are essential to 
life.