Mega Doses of Antioxidant Supplements May Lead to Cancer


Scientists accidentally discovered that mega doses of antioxidants such as vitamins C and E can increase the occurrence of genetic abnormalities in cells, which may lead to cancer. The researchers from the Cedars-Sinai Heart Institute were quick to point out that the risk of cancer is associated with antioxidant supplements and not the antioxidants found naturally in foods.

Research results regarding the impact of antioxidants on cancer have been mixed. Some have indicated that antioxidants may help prevent or treat cancer while others have shown no benefit. In a study published in the Journal of the National Cancer Institute, for example, scientists could not find strong support for widespread use of high-dose antioxidant supplementation to prevent prostate cancer, but did note that vitamin E supplements in male smokers and beta-carotene supplements in men who had low dietary beta-carotene were associated with a reduced risk of prostate cancer.

A meta-analysis published in 2009 consisted of 22 randomized controlled trials that included 161,045 participants. The conclusion of the investigators was that there was “no clinical evidence to support an overall primary and secondary preventive effect of antioxidant supplements on cancer.” The scientists also emphasized that the effects of antioxidant supplements “should not be overemphasized because the use of those might be harmful for some cancer.”


In the new study, Eduardo Marban, MD, PhD, director of the Cedars-Sinai Heart Institute, and his colleague were working with human cardiac stem cells and searching for a way to reduce naturally occurring genetic abnormalities. In the process, they added high doses of antioxidants to the cell cultures and discovered serendipitously that the cells developed genetic abnormalities that predispose to cancer.

Marban notes that “taking one multivitamin daily is fine, but a lot of people take way too much.” He warned that “if you are taking 10 or 100 times the amount in a daily multivitamin, you may be predisposing your cells to developing cancer,” thereby supporting the idea that more is not always better.

Antioxidant supplements have been shown to be useful in helping to prevent or treat some diseases, including asthma and macular degeneration, and to protect the lungs of smokers. Several studies have even suggested that antioxidants may help to prevent Alzheimer’s disease.

This latest study supports growing evidence that the use of antioxidant supplements, but not the antioxidants in foods, to help prevent cancer may not only be ineffective, but potentially harmful when taken in mega doses.

Kirsh VA et al. Journal of the National Cancer Institute 2006 Feb 15; 98(4): 245-54.
Li T-S, Marban E. Stem Cells 2010 May 4 online
Myung S-K et al. Annals of Oncology, published online July 21, 2009; print 2010; 21(1): 166-179



So that's why I am so lazy in taking them I take them every 2-3 days if I. Remember to take them
I have been told many times by physicians that in vitro results (i.e., those performed on cell cultures outside the body), in the overwhelming majority of cases, do *not* map to in vivo results (i.e., those performed in clinical trials with actual living people). So why has there been so much indiscriminate reportage of these petri dish results as if they meant something for actual living persons? What's more, this experiment was done with stem cells, which are a very special kind of cell that can mutate into any cell in the human body. This mutability would tend to make them very susceptible to unusual amounts of *anything* in their environments. How, then, can this have significance for individuals trying to gauge how many antioxidant supplements they should be taking? I find this reportage to be extremely irresponsible and misleading.