Vitamin E has eight chemically distinct isoforms; four tocopherols and four tocotrienols (α, β, γ and δ isoforms respectively). However, α-tocopherol (α-T1) is the only isoform that is extensively studied as it is the predominant form of vitamin E in human tissues and α-T1 shows strong binding affinity to α-Tocopherol Transfer Protein (α-TTP).
The non α-tocopherol isoforms, on the other hand, are poorly studied as the research on tocotrienol contributes only 1% of the entire literature on vitamin E, leading to a major void in the research of vitamin E.
Studies on α-tocopherol alone cannot be represented as the health benefits of vitamin E as a whole because tocotrienols offer distinct health benefits that are not shared with tocopherols such as preserving the health of brain, heart, liver, skin and immune system. Only after year 2000, research on tocotrienols has been gaining substantial momentum, which marks a major swing in the direction of vitamin E research.