Although it is generally accepted that selenium (Se) is important for life, it is not well
known which forms of organic and/or inorganic Se compound are the most biologically active. In nature
Se exists mostly in two forms, namely as selenite with fourvalent and selenate with sixvalent
cations, from which all other inorganic and organic species are derived. Despite a small difference in
their electronic structure, these two inorganic parent compounds differ significantly in their redox
properties. Hence, only selenite can act as an oxidant, particularly in the reaction with free and/or protein-
bound sulhydryl (SH) groups. For example, selenite was shown to inhibit the hydroxyl radicalinduced
reduction and scrambled reoxidation of disulfides in human fibrinogen thus preventing the
formation of highly hydrophobic polymer, termed parafibrin. Such a polymer, when deposited within
peripheral and/or cerebral circulation, may cause irreversible damage resulting in the development of
cardiovascular, neurological and other degenerative diseases. In addition, parafibrin deposited around
tumor cells produces a protease-resistant coat protecting them against immune recognition and elimination.
On the other hand, parafibrin generated by Ebola’s protein disulfide isomerase can form a hydrophobic
‘spike’ that facilitates virus attachment and entry to the host cell. In view of these specific properties
of selenite this compound is a potential candidate as an inexpensive and readily available food
supplement in the prevention and/or treatment of cardiovascular, neoplastic, neurological and infectious
diseases.
