Does vitamin e reduce the risk of breast cancer?

No

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by Dr Sal Levy

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Despite significant progress in breast cancer treatment, this condition is still the second most frequent cause of cancer-related death in women. In the US, more than 200,000 new cases are diagnosed every year. Therefore, looking for new means of prevention of this disease is a major and constant concern of scientists worldwide.

Vitamin E describes a group of eight compounds with similar chemical structures and biological activities, called tocopherols and tocotrienols. Tocopherols are present in significant amounts in vegetable oils used in human foods, such as soybean, corn, and cottonseed.

One interesting property possessed by certain vitamin E synthetic compounds, namely vitamin E succinate (VES) and a novel vitamin E analogue referred to as alpha-TEA is their ability to provoke cancer cells but not normal cells to undergo a form of cell death called apoptosis. They may also inhibit blood vessel formation within tumors. Studies with alpha-TEA show it to be a strong inducer of apoptosis in a wide variety of cancer cell types, including breast, prostate, lung, colon, ovarian, and uterus in laboratory cell cultures, and to be effective in significantly reducing tumor burden and metastasis in a mouse breast tumor model, as well as in animal grafts of human breast cancer cells. In contrast, with the exception of one study, the natural vitamin E does not exhibit such anti-cancer properties under laboratory conditions.

Until today, human population studies failed to prove any significant effect of vitamin E dietary supplementation upon reduction of breast cancer occurrence rate. In almost 57,000 women enrolled in the 1993 Canadian National Breast Screening Study, vitamin E intake was not associated with altered risk of breast cancer.
In 1996, Freudenheim et al. found no relation between breast cancer and consumption of vitamins C and E and folic acid in pre-menopausal women in New-York. A 2001 North Carolina survey showed little or no evidence for an association between any vitamin supplement (C, E, and multivitamins) and breast cancer. In the Iowa Women's Health Study, which examined over 34,000 postmenopausal women, unremarkable relative risk patterns were seen for the intakes of vitamins C and E and of retinol and carotenoids. In a Korean 2003 study, vitamin A and vitamin C but not vitamin E intake lowered the breast cancer risk. In Denmark, Nissen et al. found no link between breast cancer and intake of vitamin A or E in postmenopausal women, whereas for vitamin C they even found an increase in breast cancer rate with increasing intake. The only research that provided some interesting results was the 2007 Shanghai Breast Cancer Study, which showed a 20% reduction in risk with vitamin E supplement use only among women with low-dietary vitamin E intake. Finally however, a recent comprehensive analysis of the twelve most relevant studies worldwide, including 167,000 participants with various types of cancer, came to the conclusion that vitamin E was not associated with a decrease in total mortality, cancer incidence, or cancer mortality; still, tocopherol was found to reduce only the incidence of prostate cancer by 15 percent.

In conclusion, despite certain beliefs, vitamin E supplementation has not yet been proved to prevent breast cancer, although laboratory research with synthetic vitamin E derivatives does encourage further clinical trials.

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