Increased confusion on the role of antioxidants in cancer prevention.
On the January 29th an animal study from University of Gothenburg showing increased cancer growth in mice supplemented with Vitamin E and N-acetylcystein, was published in Science Translational Medicine1. The study shows that tumour progression is markedly increased and survival time decreased in mice which were given the antioxidants after initiation of tumour development. These results are in accordance with earlier human studies, showing that smokers taking -carotene supplements had higher lung cancer incidence than smokers not taking any supplementation2. Data from the recent study indicate that the anti-oxidants protects the cancer-cells from the normal, reactive-oxygen species based defence system, that are used by the body to kill cancer cells. It does however not say anything on whether anti-oxidant supplements can increase protection of cancer formation, only that already established cancer-cells have increased survival and drive increased tumour progression.
1. Sayin, V. I. et al. Sci. Transl. Med. 6, 221ra15 (2014).4
2. The Alpha-Tocopherol Beta Carotene Cancer Prevention Study Group N. Engl. J. Med. 330, 1029–1035 (1994).