PUBLICDOMAINIMAGES, DEBORA CARTAGENA UCSDCPFor the second time this month, scientists have reported that antioxidant supplementation sped up cancer growth in mice with melanoma. By neutralizing free radicals, antioxidants can prevent or delay a few types of cell damage. This may be why there’s little solid evidence that antioxidants actually reduce the risk of cancer or help to treat the disease.
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Understanding how free radicals behave in cancer cells – and how antioxidants affect them – could ultimately lead to improvements in the way cancer is treated – but the picture at the moment is far from clear. They help to counterbalance the effects of free radicals. Oxidative stress in turn is the inability of the human organism to fight the free radicals on its own.
The researchers conducted the experiment on lab mice by giving doses of common antioxidant, N-acetylcysteine (NAC), which is used in nutritional and bodybuilding supplements and it has also been used in the treatment of HIV/AIDS and certain genetic disorders too in a few children.
Researchers said that the relationship between antioxidants and free radicals should not be surprising.
A similar study conducted at Vanderbilt University and published in PLoS One in 2012 involving mice with prostate cancer also showed that antioxidants appeared to increase the proliferation of cells in the pre-cancerous lesions. In this process, many cancer cells also die before they reach various parts of the body. The spread of cancer from the initial body part to others, called metastasis, is an inefficient process in which the vast majority of cancer cells fail to survive. “One potential approach is to target the folate pathway that melanoma cells use to survive oxidative stress, which would increase the level of oxidative stress in the cancer cells”. These tumours grew more slowly and cancer cells didn’t spread as much.
And previous year, Sanz-Moreno’s team – now based at King’s College London – discovered that it’s these rounded, mobile cells that pose the biggest danger of skin cancer spreading. But the same drugs are being tested in clinical trials for other diseases, such as glaucoma, high blood pressure and heart disease, so we know they are safe to use in patients. Free radicals are unpaired molecules, meaning the molecules in need of an electron to get stable.
“Some of those trials had to be stopped because the patients getting the antioxidants were dying faster”, he said.
Antioxidants in fruits and vegetables could still be critical in reducing cancer rates. Our data suggest the reason for this: “cancer cells benefit more from antioxidants than normal cells do”.
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Other studies have linked high doses of beta-carotene – a naturally occurring antioxidant – and retinol – another form of vitamin A – to a 28-percent increased risk of lung cancer in smokers.
