By Dr Liji Thomas, MD
Natural vitamin E contains 8 isoforms, of which four are alpha, beta, gamma and delta-tocotrienols. They differ because of the presence or absence of a methyl (-CH3) group at the 2, 4’ and 8’ positions on the chromanol ring. Natural tocotrienols have this group in the R configuration at the 2 position, which is responsible for its biological activity.
Sources of tocotrienols
Tocotrienols are far less common in plants than tocopherols. However, vitamin E in monocot seeds and a few dicot seeds is mostly in the form of tocotrienols. The richest source of alpha-tocotrienol is the oil of the oil palm tree Elaeis guineensis, containing up to 800 mg/kg of this vitamin in the alpha and gamma isoforms. 70% of vitamin E in palm oil is in the form of tocotrienols, quite unlike other plant oils which contain exclusively tocopherols.