Figure 1.

Tocopherols and tocotrienols. The isoforms differ in the number of methyl groups on the chromanol head group. Theα-tocopherol isoform is the most abundant in tissues because of preferential transfer of α-tocopherol in the liver by α-tocopherol transfer protein (α-TTP). The γ-tocopherol isoform is abundant in the diet but, in tissues, γ-tocopherol is 10 fold less abundant than α-tocopherol. The other forms of tocopherols and tocotrienols are less abundant in the diet and in tissues than α-tocopherol and γ-tocopherol.