6.3 Water-Soluble Vitamins 411( 6. 4 )In the hydrogenation of oils, the double
bond in residue R (cf. Formula 6.4) is at-
tacked. Although hydrogenated vitamin K
(2′,3′-dihydrophylloquinone) is absorbed, it is
apparently no longer as active as the natural
form.
6.3 Water-SolubleVitamins
6.3.1 Thiamine (Vitamin B 1 )...................................
6.3.1.1 BiologicalRole.........................................
(6.5)Thiamine, in the form of its pyrophosphate, such
as pyruvate dehydrogenase, transketolase, phos-
phoketolase andα-ketoglutarate dehydrogenase,
in reactions involving the transfer of an activated
aldehyde unit (D: donor; A: acceptor):
(6.6)Vitamin B 1 deficiency is shown by a decrease
in activity of the enzymes mentioned above. The
disease known as beri-beri, which has neurolog-
ical and cardiac symptoms, results from a severe
dietary deficiency of thiamine.6.3.1.2 Requirement,Occurrence.................................
The daily requirement is shown in Table 6.3.
Since thiamine is a key substance in carbohy-