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 allracemic, 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 allrac a-tocopherol, arising from deesterification 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