Vitamin E is part of a family of eight compounds, tocopherols and tocotreinols with their variants, alpha, beta, gamma and delta. These compounds have a basic chromanol ring (chroman ring with an alcoholic hydroxyl group) and a 12-carbon aliphatic side chain containing methyl groups. These structures can be modified spatially, and this property of organic compounds to have different structures but same composition is called isomerism.

Alpha-tocopherol has two isomers, d-alpha and l-alpha, the structures like that of the two hands, hence the letters