Antioxidants & Chemotherapy

Impact of Antioxidant Supplementation on Chemotherapeutic Efficacy

In a review of randomized controlled trials evaluating the effects of concurrent use of antioxidants and chemotherapy, antioxidant use during chemotherapy was not found to decrease the effectiveness of chemotherapy and in fact, was associated with increased survival time, increased tumor responses, and fewer toxicities. The authors searched various medical databases and identified 845 articles, out of which 19 randomized, controlled clinical trials met their inclusion criteria. Antioxidants used in the studies included: glutathione (7 studies), melatonin (4), vitamin A (2), antioxidant mixture (2), vitamin C (1), N-acetylcysteine (1), vitamin E (1), and ellagic acid (1). Analysis of the results of these studies found no sign of decreased efficacy of chemotherapy as a result of antioxidant supplementation, as has been argued by some. On the contrary, increased survival times, increased tumor responses, and fewer toxicities were found among persons taking antioxidants along with chemotherapy as compared to those on chemotherapy alone. The reviewers point out that lack of adequate statistical power was a consistent limitation. The authors conclude, “Large, well-designed studies of antioxidant supplementation concurrent with chemotherapy are warranted.”

Reference: “Impact of antioxidant supplementation on chemotherapeutic efficacy: A systematic review of the evidence from randomized controlled trials,”

Block KI, Koch AC, et al, Cancer Treat Rev, 2007 Mar 14; [Epub ahead of print]. (Address: Institute for Integrative Cancer Research and Education, 1800 Sherman Avenue, Suite 350,Evanston, IL 60201, United States. E-mail: Keith I. Block,, or Amanda C. Koch,