Vitamin E, an important antioxidant in the human and animal diet, is not a single substance but a series of chemical compounds with related chemical structure. There are two main types of vitamin E compounds: tocopherols and tocotrienols. These are organic compounds, meaning that they are made up mainly of hydrogen and carbon atoms, and they are also soluble in fat. Differences in the structure of vitamin E compounds provide eight variations in total — four tocopherol and four tocotrienol structures, each labeled alpha, beta, gamma, and delta.
The general structure of vitamin E consists of two bonded rings of atoms, one of which includes an oxygen atom bonded to carbon atoms and the other of which is an aromatic ring. An aromatic ring is a hexagonal ring composed of six bonded carbons. Three of the bonds are double bonds, meaning that the atoms in these bonds each share four electrons rather than the usual two. In an aromatic ring, these bond types alternate among the carbon atoms.
In all forms of vitamin E, these rings are connected to a tail of carbon and hydrogen atoms. Tocopherols have a saturated tail, meaning that all carbon atoms are bonded to hydrogen atoms with single bonds — a single pair of electrons is shared in each bond. With tocotrienols, the tail is unsaturated, and some carbons are double bonded, sharing four electrons. The structure of vitamin E also includes a hydroxyl group in its carbon ring — an oxygen atom bonded to a hydrogen atom.
Tocopherols are found in plants, nuts, and oils, such as sunflower and peanut oil. Human beings tend to absorb the most common form, known as alpha-tocopherol. Alpha, beta, gamma, and delta tocopherols are distinguished from each other based on slight variations in their chemical structures. These variations occur in the groups of atoms bonded to carbons in the aromatic ring.
Tocotrienols occur naturally in coconut oil, barley, and a few other foods, though they are not as common as tocopherols. The structure of vitamin E in its tocotrienol form makes it effective in anti-aging skin products. This is due to the molecule’s unsaturated tail, which makes it better able to move into areas of saturated fat.
The hydroxyl group in the structure of vitamin E gives the vitamin its antioxidant properties. This group chemically captures free radicals, compounds that would otherwise cause a chain reaction leading to cell damage. Vitamin E’s ability to prevent oxidation makes it valuable to overall tissue health.