Foods Highest In Vitamin E Prevent Cancer, Not Supplements
Vitamin E's role in cancer prevention has been ambiguous due to several conflicting studies. Research suggests that the Vitamin E found in its natural form in foods such as almonds and sunflower seeds is indeed protective, while synthetic Vitamin E (alpha tocopherol acetate) supplements do not show the same protective effect. Researchers have identified an elusive anti-cancer property of vitamin E that has long been presumed to exist, but difficult to find.
Foods highest in vitamin E such as sunflower seeds, pecans, almonds, spinach, and collard greens are known to protect the skin from ultraviolet light, prevent cell damage from free radicals, allow cells to communicate effectively and protect against cancer and Alzheimer's disease.
In this new work, researchers showed in prostate cancer cells that one form of vitamin E inhibits the activation of an enzyme that is essential for cancer cell survival. The loss of the enzyme, called Akt, led to tumor cell death. The vitamin had no negative effect on normal cells.
“This is the first demonstration of a unique mechanism of how vitamin E can have some benefit in terms of cancer prevention and treatment,” said lead author Ching-Shih Chen, professor of medicinal chemistry and pharmacognosy at The Ohio State University and an investigator in Ohio State’s Comprehensive Cancer Center.
Even though its name makes it sound like a single substance, vitamin E is actually a family of fat-soluble vitamins that are active throughout the body. Some members of the vitamin E family are called tocopherols. These members include alpha tocopherol, beta tocopherol, gamma tocopherol, and delta tocopherol.
Other members of the vitamin E family are called tocotrienols. These members include alpha, beta, gamma, and delta tocotrienol. As increasing information has become available about these forms of vitamin E, more and more of them are understood to have unique functions.
Vitamin E Foods, But Not Supplements Offer Protection Against Cancer and Alzheimer's Disease
Chen cautioned that taking a typical vitamin E supplement won’t offer this benefit for at least two reasons: The most affordable supplements are synthetic and based predominantly on a form of the vitamin that did not fight cancer as effectively in this study, and the human body can’t absorb the high doses that appear to be required to achieve the anti-cancer effect.
In this study, researchers showed that, of the tocopherols tested, the gamma form of tocopherol was the most potent anti-cancer form of the vitamin.
While the type of vitamin E usually used in supplements is alpha-tocopherol, research published in the December 2004 issue of the Proceedings of the National Academy of Sciences indicates another form of vitamin E, gamma-tocopherol, but not alpha-tocopherol, inhibits prostate cancer cell proliferation, without affecting healthy prostate cells.
Plus, the anti-cancer effect of gamma-tocopherol, when combined with other forms of vitamin E such as delta-tocopherol, appears to be additive.
Recent research has revealed that, in humans, other vitamin E fractions may be even more beneficial. Gamma-tocopherol has been found to exhibit anti-inflammatory effects, which has led researchers to think this fraction may be more cardioprotective than the alpha-tocopherol found in most supplements. Not only is gamma-tocopherol anti-inflammatory, but it is also highly attracted to the nucleus in cells--the site where mutations in the genetic code can promote the development of cancer.
Gamma-tocopherol, particularly in combination with other forms of vitamin E such as delta-tocopherol, induced apoptosis (cell death) in androgen-sensitive prostate cancer cells within 3 days of treatment. Alpha-tocopherol alone did not have this effect.
The researchers in Chen's study began the work with both alpha and gamma forms of the vitamin E molecule. Both inhibited the enzyme called Akt in very targeted ways, but the gamma structure emerged as the more powerful form of the vitamin.
In effect, the vitamin halted Akt activation by attracting Akt and another protein, called PHLPP1, to the same region of a cell where the vitamin was absorbed: the fat-rich cell membrane. PHLPP1, a tumor suppressor, then launched a chemical reaction that inactivated Akt, rendering it unable to keep cancer cells alive.
“This is a new finding. We have been taking vitamin E for years but nobody really knew about this particular anti-cancer mechanism,” Chen said.
The gamma form was most effective because its chemical shape allowed it to attach to Akt in the most precise way to shut off the enzyme.
Not Just Prostate Cancer
A high intake of vitamin E from food, but not from supplements (which usually contain just alpha-tocopherol) is also inversely associated with Alzheimer's disease. Rush University's Martha Clare Morris, Sc.D., lead nutrition researcher for CHAP, the Chicago Health and Aging Project, found a 67% lower risk of Alzheimer's in subjects with the highest intakes of vitamin E from food and concluded: "various tocopherol forms rather than alpha-tocopherol alone may be important in the vitamin E protective association with Alzheimer's disease."
A Nurses Health Study studied 83,234 women at baseline and sought to assess the incidence of breast cancer during a 14-year follow-up. The study showed that pre-menopausal women with a family history of breast cancer who consumed the highest quantity of vitamin E enjoyed a 43 percent reduction in breast cancer incidence compared to only a 16 percent risk reduction for women without a family history of breast cancer. The data indicates that some of the vitamin E compounds in food may account for the dramatic reductions in breast cancer incidence when dietary intake levels of vitamin E are measured.
In a study of 29,092 Finnish men in their 50s and 60s who were smokers, those with the highest concentrations of the vitamin E in their blood at the study's outset were the least likely to die during the follow-up period, which lasted up to 19 years, Dr. Margaret E. Wright of the National Cancer Institute in Bethesda, Maryland and colleagues report.
A combination of exercise and vitamin E may also help slow the aging process. That power of that potent combination was detailed in a University of Florida (UF) study in the current issue of Biological Research for Nursing. The study of 59 healthy men and women aged 60 to 75 found those who exercised regularly and took vitamin E supplements became healthier and greatly decreased their levels of a blood marker that signals destruction of certain cells.
A group of Italian researchers found that the more vitamin E women consumed in their diets, the less likely they were to have the beginning traces of thickening in the neck's carotid arteries, a marker of artery disease throughout the body.
High levels of hormone-like substances called prostaglandins have been implicated in dysmenorrhea, or painful menstruation. Because vitamin E can help block prostaglandin formation, Dr. S. Ziaei of Tarbiat Modarres University in Iran and colleagues tested the vitamin as a treatment for dysmenorrhea. Individuals in both the vitamin E group reported slightly less menstural pain than they did at the start of the study, according to a report in a recent issue of the British Journal of Obstetrics and Gynaecology.