Vitamin E found in vegetable oils, cereals, meat, eggs, fruits and vegetables, can help prevent cancer by inhibiting the activation of an enzyme that is essential for tumour cell survival, scientists say.
Researchers discovered the elusive anti-cancer property of vitamin E that has long been presumed to exist, but difficult to find.
Many animal studies have suggested that vitamin E could prevent cancer, but human clinical trials following up on those findings have not shown the same benefits.
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 tumour 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.
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.
"Our goal is to develop a safe pill at the right dose that people could take every day for cancer prevention. It takes time to optimise the formulation and the dose," he said.
Chen has filed an invention disclosure with the university, and Ohio State has filed a patent application for the agent.
Vitamin E occurs in numerous forms based on their chemical structure, and the most commonly known form belongs to a variety called tocopherols.
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.
The scientists manipulated the structure of that vitamin E molecule and found that the effectiveness of this new agent they created was 20-fold higher than the vitamin itself in cells. In experiments in mice, this agent reduced the size of prostate cancer tumours.
These findings suggest that an agent based on the chemical structure of one form of vitamin E could help prevent and treat numerous types of cancer - particularly those associated with a mutation in the PTEN gene, a fairly common cancer-related genetic defect that keeps Akt active.
