Antioxidants Could Actually Promote Cancer Progression

James Watson, PhD, has launched a scathing critique on antioxidant supplements, claiming they may have caused more cancers than they have prevented.

In a paper titled “Oxidants, antioxidants and the current incurability of metastatic cancers” Professor Watson, one of the discoverers of the DNA double-helix and former director and president of Cold Spring Harbor Laboratory (New York, NY, USA) points out that the vast majority of all agents used to directly kill cancer cells, including ionizing radiation, most chemotherapeutic agents, and some targeted therapies, work either directly or indirectly by generating reactive oxygen species (ROS) that block key steps in the cell cycle, allowing dysfunctional cells which pose a threat to the survival or organisms to kill themselves.

ROS, however, are also able to irreversibly damage key proteins and nucleic acid molecules (such as DNA and RNA) in normal cells. Thus, under circumstances in which they are actually not needed to curb dysfunctional cells, ROS are constantly being neutralized by antioxidative proteins. In order to aid this neutralization, we are often urged to eat foods rich in antioxidants, such as blueberries or carrots. Prof. Watson claims that in late-stage cancer, as ROS are needed for apoptosis, suppressing them may promote the progression of threatening cells and hence cancer.

Prof. Watson also claims that this action of antioxidant supplements could also explain why cancers that develop resistance to chemotherapeutic control become equally resistant to ionizing radiotherapy, since the common feature would be their common dependence upon a ROS-mediated cell-killing mechanism. Watson also applies his theory to suggest that cancer cells largely driven by mutant proteins such as the RAS and MYC oncogenes are often hardest to respond to treatments, due to their high levels of ROS-destroying antioxidants. The thesis was published on January 8, 2012, in Open Biology.

“For as long as I have been focused on the understanding and curing cancer, well-intentioned individuals have been consuming antioxidative nutritional supplements as cancer preventatives if not actual therapies,” concluded Prof. Watson. “In light of the recent data strongly hinting that much of late-stage cancer's untreatability may arise from its possession of too many antioxidants, the time has come to seriously ask whether antioxidant use much more likely causes, than prevents, cancer; ‘had best be eaten because they taste good, not because their consumption will lead to less cancer’.”

Recent studies have shown that antioxidant supplements have negligible positive effect on healthy people, at least in terms of important things such as preventing cancer or premature death. Some supplements--notably vitamins A, E, and beta-carotene—even seem to slightly raise the risk of disease and early death.

Related Links:
Cold Spring Harbor Laboratory