Antioxidant Supplements Worsen Lung Tumors, Study Finds

You see them advertised everywhere, blasted from vitamin-pill packaging and wrinkle cream jars. In theory, antioxidants are supposed to prevent aging and cancer. Yet large studies of people taking antioxidant supplements, have mostly found that supplement-takers aren’t less likely to die from cancer.
In some specific cases, antioxidant vitamins even seem to raise people’s risk for lung and prostate cancers.
Now, a new study in mice offers an explanation for at least some of these puzzling findings. A team of researchers from the University of Gothenburg in Sweden found mice that already had small lung tumors grew more numerous and more aggressive tumors after eating antioxidant supplements mixed into their food.
The researchers also examined what’s happening at a molecular level, when the immune system fights off cancerous cells, and how antioxidants may tilt that battle in lung cancer’s favor. 
"This article is beautiful because it takes something that was certainly found in humans and looked at what happens in an animal model," says Paul Offit, a pediatrician at the Children’s Hospital of Philadelphia.
Although he specializes in infectious disease, not cancer, Offit has written extensively about vitamin supplements. He thinks they should be much better regulated, based on those studies linking supplements with higher cancer risk in some.