Since the term “antioxidants” made the leap from the realm of biochemistry labs and into the public consciousness in the 1990s, Americans have come to believe that more is better when it comes to consuming the substance that comes in things like acai berries, green tea and leafy veggies.
A provocative new study published Wednesday in the journal Nature raises important questions about that assumption.
Antioxidants — which include vitamins C and E and beta-carotene, and are contained in thousands of foods — are thought to protect cells from damage by acting as defenders against something called “free radicals” which the body produces as a part of metabolism or that can enter through the environment.
That’s all great for normal cells. But what researchers at the University of Texas Southwestern Medical Center found is that antioxidants can work their magic on cancerous cells, too — turbo-charging the process by which they grow and spread.
Researcher Sean Morrison and his colleagues conducted experiments on mice that had been transplanted with skin cancer cells (melanoma) from human patients. They gave nothing to one group. To the other they gave doses of N-acetylcysteine, which is a common antioxidant that’s used in nutritional and bodybuilding supplements and has been used as a treatment for patients with HIV/AIDS and in some children with certain genetic disorders.
The results were alarming: Those in the second group had markedly higher levels of cancer cells in their blood, grew more tumors and the tumors were larger and more widespread than in the second.
“What we’re starting to learn is that there can be bad cells from cancer that appear to benefit more from antioxidants than normal cells,” Morrison said in an interview.
Morrison, director of the Children’s Medical Center Research Institute at UT Southwestern, explained that it has to do with something called oxidative stress.
Scientists have known for a while now that cancer metastasis is a very inefficient process and that many cells die along the way. This is likely due to oxidative stress, which is an inability by the body to counteract the harmful effect of free radicals. When antioxidants supplements are given, the paper hypothesizes, they may give new life to those cancerous cells that are on the edge of dying.
Morrison said that previous studies have shown that the progression of metastasis of human melanoma cells in mice is predictive of their metastasis in humans, which raises concerns about the use of dietary antioxidants by patients with cancer.
