Study Finds Antioxidant Supplements Harmful for Cancer Patients


Researchers at the Sahlgrenska Academy in Gothenburg found the antioxidant N-acetylcysteine (NAC)—available in some nutritional supplements—can double the growth of cancer cells.

This new study, which was led by Martin Bergö, professor at the Sahlgrenska Cancer Center at the University of Gothenburg, is the first to show antioxidants increasing the rate of malignant melanoma (the deadliest form of skin cancer) to the lymph nodes of mice two-fold. Repeating the experiment in human cells grown in lab cups, the scientists found inserting cancerous skin cells with NAC and vitamin E—another strong antioxidant—became better at overrunning adjacent tissue.

The Significance of Antioxidants

People who have cancer or are at a higher risk of cancer, such as smokers or those with family history of the disease, should avoid nutritional supplements containing antioxidants, as Bergö found them dangerous to these individuals. According to the nonprofit organization Swedish Cancer Society, any dietary supplements these individuals are taking should be approved by a physician.

“There are no conclusive studies showing antioxidant supplements would be beneficial for them and there’s growing evidence it could be harmful,” added Bergö.

The researchers only looked at nutritional supplements, and Bergö stressed that individuals who do not have the disease and are not at risk for it should continue to eat antioxidant-rich foods such as fruits and vegetables to help protect cells from damage and lower the risk of other diseases and cardiovascular problems.

“Antioxidants don’t cause cancer, but if you already have small tumors, it can speed up the process,” said Bergö. “Simply put, antioxidants help both healthy cells and cancer cells.”

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