Download A Précis on Selenium

A PRÉCIS ON SELENIUM
By: Theodore Hersh, M.D.,AGAF, MACG
Copyright
Selenium is a vital trace element required by our
body for many physiologic, enzymatic and
antioxidant functions. It is derived mainly from
our diet but because selenium sources in
foodstuffs are often low particularly in countries
with deficient selenium content in the oil, our
intakes of selenium may need to be increased
from dietary supplements. Plants, grasses and
cereal grains take up selenium from the soil as
inorganic salts (selenites and selenates) and
convert these first to selenium salts and then to
organic compounds, mainly as selenomethionine. Animals then obtain their selenium in the
form of selenomethionine provided from the plant sources that animals consume as well as
additionally from commercial animal feed supplements.
Our human body’s sources of selenium from plants and animal food sources are thus
derived from the gastro-intestinal absorption as selenomethionine which then may be
incorporated into a number of proteins. Selenomethionine also acts itself as an antioxidant.
Selenium induces the production of a number of
critical enzymes, which use selenium as a cofactor in their specific physiologic functions.
Notable examples include the ubiquitous enzyme
glutathione peroxidase, which with the
antioxidant glutathione, hydrolyzes the toxic
hydrogen peroxide and renders it non-toxic. The
selenoenzyme thioredoxin reductase also works
synergistically with glutathione to regenerate the
oxidized vitamin C molecule (dehydroascorbate)
back to ascorbic acid, the antioxidant form of
vitamin C. Selenium also spares vitamins C and
E by preventing their auto-oxidation in the cell.
When the antioxidant selenomethionine neutralizes a free radical, it too is oxidized to a
selenoxide molecule. It then requires the
body’s prime antioxidant, L-glutathione, to
reduce and thereby recycle that molecule back
to the antioxidant selenomethionine.
Thus, selenium and glutathione are intimately
involved in the antioxidant-reduction reactions
neutralizing free radical species and
regenerating spent antioxidant vitamins C and
E. The glutathione and selenium complex is the
cell’s primary defender against the ravages of
oxidant damage and thereby helps prevent free
radical diseases.
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