A new study has cast doubt on the cancer-fighting power of antioxidants- found in many vegetables and whole grains - by showing that they can also help cancer cells to survive and thrive in some situations.
Antioxidants have previously been found to prevent the formation of tumours by preventing free radicals, or highly reactive molecules, from causing DNA damage.
Now, scientists have shown that antioxidants may have the opposite effect in human breast cells.
In the new study, antioxidants behaved like cancer-causing agents, protecting cells that should otherwise have died-which allowed them to multiply and become cancerous.
"The survival of these cells could be contributing to [tumour creation], rather than the opposite," National Geographic News quoted study leader Zachary Schafer of the University of Notre Dame in Indiana as saying.
Schafer and a team at Harvard Medical School cultured breast-tissue cells using simulated scaffolding that mimics how cells grow in the body.
The cells formed a spherical structure that became hollowed out as the cells in the center detached from the cells on the scaffolding and died.
However, when the researchers introduced a cancer gene into the mix, the detached cells did not die-just as happens in the body.
"This happens in early breast cancer lesions," said Schafer.
Meanwhile, the researchers noticed that the normal, detached cells without the cancer gene were being damaged by naturally occurring free radicals.
Also, the detached cells were not producing enough ATP, a critical energy molecule.
The researchers added high concentrations of antioxidants to the cell culture in an effort to suppress the harmful free radicals and boost ATP production.
They found that antioxidants have exactly the same effect as the cancer gene: The detached cells did not die.
This is because the antioxidants are helping the cells recover their ability to produce ATP, Schafer said. The cancer gene also restored ATP production in the cells.
The researchers, however, insist that the findings should not alarm cancer patients as the research is laboratory based and the results may not replicate in people.
The study has been reported online in the journal Nature.