Vitamin E. Polarized light micrograph of crystals of alpha-tocopherol. This is the most effective of the Vitamin E group, which contains methylated tocopherols and tocotrienols. The alpha form is properly known as 5,7,8-trimethyltocol. Vitamin E is widely distributed in vegetable lipids and the body fat in animals. It protects unsaturated fat from oxidation, and is thus thought to stabilize cell membranes. Vitamin E deficiency is rare, as the dietary supply of Vitamin E group chemicals is normally ample and it has a long residence time in the body. Magnification: x4 at 35mm size; x8 at 5x7cm size.