Vitamin E includes the tocopherols of which d-alpha tocopherol is the most active. It is the major lipid soluble antioxidant protecting the polyunsaturated fatty acids (PUFA) in membranes against peroxidation. The usual intake is about 12 IU/day. Peroxidation of the PUFA causes membrane damage. Vitamin E has other protective properties. It destroys nitrite, which has been shown to increase the incidence of cancer. It protects the red blood cells in lungs against the toxic effect of ozone and hydroxyl radical toxicity. Thus it has been shown to have a weak protective effect against some of the cancers (1)
More recent studies have shown an inverse relationship between levels of Vitamin E in blood and the development of cancer. One study (2) compared the vitamin E levels in 289 patients with cancer of the colon and rectum against 1267 matched controls. The E levels were slightly lower in the cancer cases. Similar findings were reported by Knekt (3), Palan et al., (4), and deVries, et al (5). Knekt and colleagues (6) examined alpha-tocopherol levelsin 36,2675 adults in Finland. After eight years there were 766 cases of cancer. Persons with low levels had 1 1/2 times the chance of getting cancer compared to the highest level. The association was strongest with gastrointestinal cancers and for other cancers not related to smoking. LeGardeur et al (7) concluded from their data that vitamin E deficiency maybe associated with lung cancer and to a greater degree than vitamin A.
Thus the association between cancer and vitamin E consumption and cancer is not strong, but an increasing number of reports appear showing that there is some connection. When so many variables are involved it is very difficult to find very high correlations between the condition and the effect of only one of the nutrients. As long as we can not be sure what are the most effective cancer preventive agents and therapeutic compounds it seems only prudent to ensure that the subjects are obtaining enough vitamin E. The main question is how much is enough. Certainly the role of the RDA's is being seriously questioned by many and recommendations have been made that for each disease there may be unique RDA.
(1) Comstock, G.W. Helzlsouer, K.H. and Bush, T.L. Prediagnostic serum levels of carotenoids and vitamin E as related to subsequent cancer in Washington County, Maryland. Am. J. Clin. Nutr. 53: 260 S - 264 S, 1991.
(2) Longnecker, M.P. Martin-Morreno, J.M. Knekt, P. Nomura, A.M. Schober, S.E.St:ahelin, H.B. Wald, N.J. Gey, K.F. and Willett, W.C. Serum alpha-tocopherol concentrations in relation to subsequent colorectal cancer: pooled data from five cohorts. J. Nat Can Institute 84; 430-435, 1992.
(3) Knekt, P. Role of vitamin E in the prophylaxis of cancer. Annals of Medicine 23; 3 - 12, 1991.
(4) Palan, P.R. Mikhail, M.S. and Romney, S.L. Plasma levels of antioxidant beta-carotene and alpha-tocopherol in uterine cervix dysplasia and cancer. Nutrition and Cancer 15; 13 - 20, 1991.
(5) de Vries, N and Snow, G.B. Relationship of vitamins A and E and beta-carotene serum levels to head and neck cancer patients with and without second primary tumors. European Archives Oto-rhino-laryngology 247; 368-370,1990.
(6) Knekt, P. Aromaa, A. Maatela, J. Aaran, R.K. Nikkara, T. Hakama, M. Hakulinen, T. Peto, R. and Teppo,L. Vitamin E and cancer prevention. American Journal of Clinical Nutrition 53, 283S-286S, 1991.
(7) LeGardeur, B.Y., Lopez, A. and Johnson, W.D. A case-control study of serum vitamins A, E, and C in lung cancer patients. Nutrition and Cancer 14;133-140, 1990.
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