Could Antioxidants Speed Up Cancer Progression?
Study of mice suggests people with lung cancer or at risk for the disease should avoid these supplements
The findings suggest that people carrying small undiagnosed tumors in their lungs should avoid taking extra antioxidants, the study concludes.
"If you have lung cancer, or if you have an increased risk of developing lung cancer, then taking extra antioxidants may be harmful and it could speed up the growth of a tumor," Bergo said.
While studies involving animals can be useful, they may fail to produce similar results in humans.
However, this isn't the first study to indicate that antioxidants are bad for cancer patients, said Peter Campbell, director of the Tumor Repository at the American Cancer Society.
Human trials conducted in the 1980s and 1990s found that the antioxidants beta-carotene, vitamin A and vitamin E substantially increased the incidence of lung cancer in smokers, he said.
"This study doesn't stick out like a sore thumb," Campbell said. "We've known for some time that some of these agents tend to backfire. It's nice to have laboratory evidence to corroborate what we've seen in human populations."
The human body creates its own antioxidants, and is built to use additional antioxidants gained from the food a person eats, Campbell said. By taking antioxidant supplements, people could be defeating the body's ability to fight cancer and disease.
"There is a food supplement industry that has done a really good job marketing itself, suggesting that if we take these molecules normally found in food we will have better health and, well, a little is good so a whole lot would be better," Campbell said. "There are very intricate, complicated pathways that are supposed to sense and signal and destroy these precancerous cells. When our body doesn't turn that system on, these cancerous cells can proliferate."
However, the Swedish researchers stopped short of saying that no one should take antioxidants.
"If I had a patient with lung cancer, I would probably recommend they do not take extra antioxidants," Bergo said. "Would I make that recommendation with healthy people? Absolutely not."