Vitamin E: Information
Vitamin E refers to a family of related antioxidant compounds known as tocopherols (toe-COFF-er-ols) and tocotrienols (toe-coe-TREE-en-ols). Both tocopherols and tocotrienols occur in 4 forms; alpha, beta, delta, and gamma. Each form is important and has distinct functions but one, alpha-tocopherol, appears to be the most-important since tissues contain far higher levels of it than other forms. Most vitamin E research has been performed on this form, and this has traditionally been the form used in supplements. Newer vitamin E supplements feature all 8 forms or formulas that include high amounts of both alpha and gamma tocopherol.
Vitamin E compounds are lipid antioxidants which means they protect fat-based structures – such as cell membranes and cholesterol – from oxidative damage. That may not seem terribly exciting or important until one takes into account that every cell in the body is encased in a fatty cell membrane through which it must communicate and interact with the rest of the body. Cell membranes are easily damaged by molecules known as free radicals which chemically react with the membrane, changing its structure and impairing vital functions, often to the point of killing a cell. Free radicals are generated by natural metabolism but the most damaging types arise as a result of environmental factors like smoke, alcohol, pollution and sun exposure.
Lipid (fat) antioxidants like vitamin E are therefore taken to help minimize free radical damage within the body, promoting normal cell function and good health. Vitamin E has been the subject of extensive clinical research and benefits health by acting as an antioxidant and in other ways as well.
Vitamin E's Health Benefits
Most of the attention given to vitamin E has focused on cardiovascular health. Vitamin E can inhibit the oxidation of LDL (bad) cholesterol; oxidation of LDL has been implicated as a risk factor for cardiovascular disease.1 Additionally, gamma-tocopherol has been shown to inhibit platelet aggregation2 and to enhance vasodilation3 both of which are crucial to circulatory health. Vitamin E may also reduce levels of the pro-inflammatory C-reactive protein,4 which is gaining increased significance as a risk factor for cardiovascular disease.5
Alpha-tocopherol can also enhance specific aspects of the immune function such as the formation of antibodies needed to fight specific diseases such as hepatitis and tetanus.6 Vitamin E supplementation for diabetics may be particularly important7 since diabetes increases oxidative processes and because cardiovascular problems like heart attack and stroke are among the leading causes of death in diabetics.8
Using Vitamin E Supplements
The exact role and relationship of each form of vitamin E, the four tocopherols and tocotrienols, is unclear. Most of the vitamin E research has been performed using alpha-tocopherol and that's the form found in most supplements. Alpha-tocopherol is also the only form for which there is an RDI. There is some evidence to suggest a particular benefit of gamma tocopherol in some situations9 and also to suggest that taking a complete vitamin E supplement (with all 8 forms) is best.10 More research is needed to clarify these issues. Most people use alpha-tocopherol supplements, many of which now include at least some of the other forms. We recommend 200-400 IU per day of alpha-tocopherol for adults, in any preparation or combination of tocopherols and tocotrienols, which must be taken with fats or foods containing fat for absorption.11
Side-effects and Cautions
Side-effects of vitamin E supplementation are very rare.12 Doctors may advise temporarily discontinuing vitamin E supplements when patients use certain medications or undergo medical procedures, so check with your doctor before using vitamin in either case.