Vitamin E is a mixture alpha-, beta-, gamma- and delta-tocopherols that are fat-soluble antioxidants. Alpha-tocopherol is best assimilated by the human body. In its pure form, vitamin E, is a very thick oil. On the market, both a natural form of Vitamin E, that is purified from a natural vitamin E-rich source such as sunflower oil, and a synthetically produced form exist. The concentration of vitamin E is given in international units (IU), which is a unit for biological activity and varies for different substances. For vitamin E, 1 IU = 0.67 mg natural d-alpha-tocopherol. Use 0,1-1% vitamin E in skincare recipes to prolong the shelf-life of oils and butters and protect them from going rancid. Vitamin E oil from natural sources is usually not completely pure but a concentrated form of the oil that it is purified from. You may need to use a higher concentration to get the same effect as with synthetic vitamin E.