Vitamin E: the primary fat-soluble anti-oxidant: After you have read this page, you may want to view a 20-minute video that reviews the science behind vitamin E.
 | Nutri-E 400 from Douglas Laboratories 40% gamma tocopherol 1-2 softgels per day for adults |
When we talk about "vitamin E" we are talking about a family of different-yet-related chemicals that are found in foods and supplements. Vitamin E comes in different forms, each with its own activity and importance.
Simply taking a generic vitamin E supplement does not ensure that you will receive health-promoting benefits. You have to ensure that your vitamin E supplement contains a subfraction of vitamin E called "gamma tocopherol." Most supplements only contain alpha tocopherol. Taking alpha tocopherol without gamma tocopherol causes depletion of gamma tocopherol. When people have lower levels of gamma tocopherol, they have increased risk for cancer and heart disease. Absolutely never use DL-tocopherol; it is synthetic and toxic.
This explains the paradox that is seen in conspicuously well-published articles showing that vitamin E increases the risk for certain diseases. The answer is simple: the researchers and doctors who designed the studies simply gave the wrong kind of vitamin E.
Since most supplements contain primarily alpha tocopherol, which depletes levels of the more important gamma tocopherol, they can actually increase the risk for health problems. This is why I always recommend that my patients take a separate vitamin E supplement, rich with gamma tocopherol.
Nutritional needs in environmental intoxication: vitamin E and air pollution, an example.
Menzel DB.
Environ Health Perspect. 1979 Apr;29:105-14
Dietary vitamin E affects the susceptibility of mice and rats to ozone and nitrogen dioxide, suggesting a free radical mechanism of toxicity. Conventional peroxidation does not completely explain the effects of alterations of lung fatty acid composition on both nitrogen dioxide and ozone toxicity. A new scheme is proposed based on the cyclization of beta, gamma-allylic peroxyl free radicals to monocyclic and bicyclic peroxides to explain the relationship between diet and toxicity. Similar results are likely with other toxicants producing peroxidation as a mechanism of toxicity. Such cyclic peroxides may mimic or interfere with the prostaglandin system. Several chronic diseases may be exacerbated through such a subtle toxic mechanism. The level of vitamin E needed for protection against peroxidation toxicity may be much greater than the present U. S. dietary intake.
gamma-tocopherol, the major form of vitamin E in the US diet, deserves more attention.
Jiang Q, Christen S, Shigenaga MK, Ames BN.
University of California, the Department of Molecular and Cell Biology, Berkeley , USA .
Am J Clin Nutr 2001 Dec;74(6):714-22
gamma-tocopherol is the major form of vitamin E in many plant seeds and in the US diet, but has drawn little attention compared with alpha-tocopherol, the predominant form of vitamin E in tissues and the primary form in supplements. However, recent studies indicate that gamma-tocopherol may be important to human health and that it possesses unique features that distinguish it from alpha-tocopherol. gamma-Tocopherol appears to be a more effective trap for lipophilic electrophiles than is alpha-tocopherol. gamma-Tocopherol is well absorbed and accumulates to a significant degree in some human tissues; it is metabolized, however, largely to 2,7,8-trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman (gamma-CEHC), which is mainly excreted in the urine. gamma-CEHC, but not the corresponding metabolite derived from alpha-tocopherol, has natriuretic activity that may be of physiologic importance. Both gamma-tocopherol and gamma-CEHC, but not alpha-tocopherol, inhibit cyclooxygenase activity and, thus, possess antiinflammatory properties. Some human and animal studies indicate that plasma concentrations of gamma-tocopherol are inversely associated with the incidence of cardiovascular disease and prostate cancer. These distinguishing features of gamma-tocopherol and its metabolite suggest that gamma-tocopherol may contribute significantly to human health in ways not recognized previously. This possibility should be further evaluated, especially considering that high doses of alpha-tocopherol deplete plasma and tissue gamma-tocopherol, in contrast with supplementation with gamma-tocopherol, which increases both. We review current information on the bioavailability, metabolism, chemistry, and nonantioxidant activities of gamma-tocopherol and epidemiologic data concerning the relation between gamma-tocopherol and cardiovascular disease and cancer.
Gamma-tocopherol inhibits human cancer cell cycle progression and cell proliferation by down-regulation of cyclins.
Gysin R, Azzi A, Visarius T.
Institute of Biochemistry and Molecular Biology, University of Bern , Switzerland .
Effects of gamma-tocopherol on the cell cycle and proliferation were examined in human prostate carcinoma, colorectal adenocarcinoma, and osteosarcoma cells. Many epidemiological studies have suggested an anticancer activity of vitamin E, yet mechanistic studies are sparse to date. Vitamin E consists of four tocopherols (alpha-, beta-, gamma-, delta-) and the corresponding tocotrienols. Because gamma-tocopherol is the predominant form of tocopherol found in the U.S. diet, while alpha-tocopherol is the form of vitamin E most readily found in dietary supplements, we compared physiologically relevant concentrations of these tocopherols and found a more significant growth inhibition effect for gamma- than for alpha-tocopherol. Flow cytometry analysis of gamma-tocopherol treated prostate carcinoma DU-145 cells showed decreased progression into the S-phase. This effect was associated with reduced DNA synthesis as measured by 5-bromo-2'-deoxy-uridine incorporation. Furthermore, Western-blot analysis of gamma-tocopherol treated cells showed decreased levels of cyclin D1 and cyclin E. Taken together, the results indicate that gamma-tocopherol inhibits cell cycle progression via reduction of cyclin D1 and cyclin E levels. Because gamma-tocopherol has a weaker antioxidant capacity than a-tocopherol and gamma-tocopherol more significantly inhibited cell proliferation as well as DNA synthesis than alpha-tocopherol, we suggest a non-antioxidant mechanism to be at the basis of this effect.
