Antioxidants Can Make Melanoma, Lung Cancer Worse

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Antioxidants, Melanoma, Lung CancerAntioxidants are regularly recommended to cut down on free radicals in the body and reduce your chance of developing cancer. By extension, it stands to reason that consuming antioxidants when one already has a tumor could help keep the disease in check. According to a group of Swedish researchers, this line of thinking is a mistake that could have fatal consequences. Their research, just the latest in a growing body that questions the effectiveness of antioxidants, shows that melanomas may have their metastasis accelerated in the presence of antioxidants.

In the study, lab mice bred to have a heightened melanoma risk were administered antioxidants in doses equivalent to the ones the average human would take. Although the primary melanoma tumor in the subjects did not appear to do better or worse when antioxidants were taken, their presence appeared to boost the ability of the tumor to metastasize. Metastasis is when tumor cells spread to other parts of the body and is one of the more serious complications of cancer. In melanoma in particular, metastasis is often the cause of death.

A similar round of experiments were performed on cell cultures taken from human melanoma patients. These showed the same results. As in vitro (“test tube”) findings do not always translate to full human bodies, it is not yet clear to what extent antioxidants may promote melanoma in live cancer patients. The findings are still a potential cause for concern, especially since they are similar to the same group’s 2014 results that linked antioxidants to lung cancer.

The 2014 study was carried out in much the same way to this most recent one: mice were given an increased risk of developing lung cancer and then fed antioxidants in equivalent levels to humans. The findings were that antioxidants caused the precancerous lesions to develop more quickly and that the mice developed more numerous and more advanced tumors. The current explanation for the observations of the two studies is that antioxidants may have broader-reaching effects than most people believe.

Antioxidants are most known for their ability to dispose of free radicals, a type of highly-reactive molecule that is the byproduct of numerous biological functions as well as found in certain foods. Free radicals, when in excess of what the body can normally handle, are capable of damaging the DNA of cells by oxidizing (reacting) with them. In the mice, antioxidants did their expected duty and there was the expected decrease in DNA damage. However, it was found that antioxidants also dulled the expression of p53, a tumor suppressor protein.

What this behavior means in people who do not currently have cancer or precancerous conditions is not yet explored. The findings do suggest that antioxidants are a potentially poor idea for those who already have tumors.

The Swedish researchers plan to explore how antioxidants in lotions affect melanoma progression as well as explore how they affect other types of cancers.

Sources for Today’s Article:
“Antioxidants and Cancer Prevention,” National Cancer Institute web site;, last accessed October 9, 2015.
“Antioxidants Cause Malignant Melanoma to Metastasize Faster,” EurekAlert! web site, October 9, 2015;
Le Gal, K., et al., “Antioxidants Can Increase Melanoma Metastasis in Mice,” Science Translational Medicine 2015; 7.308, doi: 10.1126/scitranslmed.aad3740.
Moyer, M.W., “Antioxidants May Make Cancer Worse,” Scientific American web site, October 7, 2015;
Sayin, V.I., et al., “Antioxidants Accelerate Lung Cancer Progression in Mice,” Science Translational Medicine 2014; 6: 221.