Compositions comprising a synthetic, non-plant based, substantially pure stereoisomer or stereoisomers of an alpha, beta, gamma, or delta tocopherol or alpha, beta, gamma, or delta tocotrienol, or the quinone or hydroquinone form thereof, or a metabolite thereof, are disclosed. The compositions of the present disclosure can, for example, have improved activity in cells as compared to compositions comprising equimolar mixtures of all stereoisomers.
