2009_Book_FoodChemistry

6.3 Water-Soluble Vitamins 411
(6.4)
In the hydrogenation of oils, the double
bond in residue R (cf. Formula 6.4) is attacked.
Although hydrogenated vitamin K
(2 ′ ,3 ′ -dihydrophylloquinone) is absorbed, it is
apparently no longer as active as the natural
form.
6.3 Water-Soluble Vitamins
6.3.1 Thiamine (Vitamin B 1 )
6.3.1.1 Biological Role
(6.5)
Thiamine, in the form of its pyrophosphate, such
as pyruvate dehydrogenase, transketolase, phosphoketolase
and α-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 neurological
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-