Dec. 15, 2004 -- Researchers have found that vitamin E may fight prostate and lung cancer.

Form of Vitamin E Found in Food, but not Supplements, May Fight Prostate and Lung Cancer

The term vitamin E describes a family of eight antioxidants. Researchers say that one form in particular appears to fight prostate cancer without harming normal cells. But it's not the kind of vitamin E used in most supplements. Instead, it's the most common form found in the American diet. It occurs naturally in foods such as sesame seeds, walnuts, pecans, and corn and sesame oils.

The form of vitamin E is called gamma-tocopherol.

Most supplements provide a different form of the vitamin, alpha-tocopherol, which has attracted attention for more than 25 years. Some studies have shown that it has anticancer abilities. Other studies have shown that the anticancer properties of increased levels of alpha-tocopherol are found only when gamma-tocopherol levels are also high.

Recently a team of scientists tested gamma-tocopherol to see if it had any cancer-fighting potential. The researchers included Qing Jiang, formerly of Children's Hospital and Research Center in Oakland, Calif. The report is published online by the Proceedings of the National Academy of Sciences, which will also include the study in its Dec. 21 print edition.

The researchers had nothing against alpha-tocopherol. "Alpha-tocopherol has justifiably earned a good reputation as an antioxidant," says Jiang, in a news release. Instead, she wanted to see if other forms of vitamin E were promising. Jiang, now an assistant professor of foods and nutrition at Purdue University in Indiana, has studied gamma-tocopherol before. In 2000, she and her colleagues found that it inhibits inflammation, which has been linked to cancer.

This time, Jiang's team pitted gamma-tocopherol against human prostate and lung cancer cells. For comparison, they also exposed healthy human prostate cells to alpha-tocopherol.

Gamma-tocopherol aced its lab tests. It inhibited the spread of prostate and lung cancer cells without hurting the healthy cells. That indicates that gamma-tocopherol might be able to combat cancer without damaging unaffected cells.

Here's how it worked. Apparently, gamma-tocopherol interfered with the cell membranes of the cancer cells. The effect was fatal -- killing off the cancer cells. Results were even better when gamma-tocopherol got a little help from its relatives.

Mixing several forms of vitamin E -- including gamma-tocopherol -- was even better at blocking cancer's spread. "Combinations of different forms of vitamin E may be superior to each alone," write the researchers.

Next, they want to test different forms of vitamin E on animals and humans. Meanwhile, overindulging in nuts, seeds, and oils that contain gamma-tocopherol might not be a great idea.

"Foods rich in gamma-tocopherol are also rich in fats, and some products bring other hazards, as well," says Jiang, in a news release. "Corn oil, for example, is rich in linolic acid, which has been shown to promote certain types of cancer in some studies. But sesame seeds and pecans seem to be good all-around choices." Gamma-tocopherol supplements -- in appropriate amounts -- might help high-risk groups, such as older men vulnerable to prostate cancer, she says. But so far, that hasn't been proven.

Jiang and one of her fellow researchers hold a patent with Children's Hospital Oakland Research Institute on the combinations of vitamin E forms, says the journal.

SOURCES: Jiang, Q. Proceedings of the National Academy of Sciences, Dec. 21, 2004; vol 101: News release, Purdue University, Indiana.