There are eight different forms of vitamin E. The four tocopherols (alpha-, beta-, gamma- and delta-tocopherol) share a saturated phytyl side chain. The four analogous tocotrienols have a triple-unsaturated side chain.
The unsaturated bonds on the side chain give the tocotrienols greater antioxidant activity and a different biologic action. When those bonds become saturated, the molecule becomes a tocopherol. Reports from laboratory studies indicate a 40-60 times higher antioxidant activity against lipid peroxidation with d-alpha-tocotrienol than with d-alpha-tocopherol and 6.5 times more protection of cytochrome P-450 against oxidative damage. Cytochrome P-450 is present in most tissues and serves as an oxygenating catalyst in a variety of reactions.