There are eight vitamers of vitamin E (alpha-, beta-,gamma-, and delta-tocopherols and the corresponding
tocotrienols) (Figure 1), differing in their biological activity and distribution in foods. Most often vitamin E’s role is usually associated with its antioxidant activity. For
example, α-tocopherol is a well-defined chain-breaking antioxidant that protects against lipid peroxidation in biological membranes; similarly, α-tocopherol protects biological membranes by preferentially destroying pro-oxidant reactive nitrogen species. Recent research has suggested that tocotrienols are better antioxidants
in vitro. However, whether they play an important role in antioxidant defenses in vivo is questionable as tocotrienols have lower bioavailability than tocopherols following oral ingestion.