A new study has helped shed light on why antioxidants such as vitamin E seem to accelerate the growth of early lung tumours.
Until now, scientists did not understand why some antioxidants, which should in theory protect people from cancer, had the negative effect of promoting lung cancer in high-risk people, such as smokers.
The research, published in Science Translational Medicine, used mice. The scientists gave vitamin E and a generic drug called N-acetylcysteine, both antioxidants, to mice with early lung cancer.
The antioxidants caused a 2.8-fold increase in lung tumours, made the tumours more invasive and aggressive, and caused the mice to die twice as quickly – all compared to mice not given antioxidants.
The findings suggest that some antioxidants allow cancer cells to get around the healthy cells’ usual defence system against tumours. This enables existing tumours, even those too small to be detected, to multiply uncontrollably.
Martin Bergo, an author of the study from Sweden, said: “The findings imply that taking some extra antioxidants might be harmful and could speed up the growth of (any) tumours. If I had a patient with lung cancer, I would not recommend they take an antioxidant.”
The study did not examine whether antioxidants can also initiate lung cancer. Nor did it look at whole foods naturally high in antioxidants.
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