Antioxidants and Chemotherapy

A listserv friend recently wrote a post about a study titled Impact of antioxidant supplementation on chemotherapeutic efficacy: A systematic review of the evidence from randomized controlled trials, published in Cancer Treatment Reviews in January 2007. With the help of an Italian friend (grazie mille!), I managed to gain access to the full study, not just the abstract (which is available at: It is estimated that between 13 and 87 % of all cancer patients take antioxidant supplements. Significant numbers. Yet many MM patients have told me that their doctors warned them, sometimes quite strongly!, against taking any supplements while doing chemotherapy, based on the myth that supplements could interfere with and even diminish treatment efficacy. Well, perhaps this 2007 study will debunk the myth once and for all.

This group of researchers went through electronic databases and looked at the randomized, controlled clinical trials that reported survival and/or tumor response 19 trials met the inclusion criteria. Antioxidants evaluated were: glutathione (7), melatonin (4), vitamin A (2), an antioxidant mixture (2), vitamin C (1), N-acetylcysteine (1), vitamin E (1) and ellagic acid (1). Subjects of most studies had advanced or relapsed disease. A total of 1554 patients were evaluated. Most of the 845 trials were excluded for a variety of reasons–because they were not controlled trials, because antioxidants were not given together with chemotherapy, etc.

An aside: since ellagic acid is on my June list, I was interested to read that prostate cancer patients taking ellagic acid had significantly decreased neutropenia over patients taking a placebo (33 versus 75 %). Those patients also lived longer and had a better response to treatment. Another interesting bit of news is that all studies reported similar or less neurotoxicity in the antioxidant group than the control group.

The study concludes that patients taking antioxidants during chemotherapy had increased survival, increased tumour responses and fewer toxic side effects. The researchers hope that their data will pave the way to larger studies on the concurrent use of antioxidants with chemotherapy. However, even though this study examined only a small sample of clinical trials, I believe its findings are significant enough to make dubious doctors change their minds on supplements. About time.


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