Vitamin E is a generic term that includes all
entities that exhibit the biological activity of atocopherol.
The most biopotent vitamin E compound is
d-a-tocopherol (Pryor, 1996). The acetate ester of
chemically synthesized, or all-racemic, a-tocopherol is
the common supplemental form of vitamin E in
ruminant diets. Naturally occurring d-a-tocopherol,
which is found in plant oils, and all-rac a-tocopherol,
arising from de-esterification by presumably pancreatic
esterases, are absorbed from the small intestine
and distributed via chylomicrons and lipoproteins
to tissues. a-Tocopherol is located within cell membranes
and seems to function as the principal chainbreaking
antioxidant in biological systems