28 May 2008

Antioxidants weaken cancer therapy

Cancer patients should avoid taking antioxidant supplements, a review of clinical trial data suggests, as they may reduce the effectiveness of chemotherapy and radiation treatment.

Cancer patients should perhaps avoid taking antioxidant supplements, a review of clinical trial data suggests, because they may diminish the effectiveness of chemotherapy and radiation treatment.

Still, findings from different studies are conflicting, so further research is warranted to determine whether antioxidants can be safely taken during cancer therapy and whether they have any benefit.

Although research looking at antioxidant use during cancer treatment has been on-going on for nearly two decades, it remains a controversial topic, note Dr Brian D. Lawenda, from the Navel Medical Centre in San Diego, California, and colleagues in their article in the Journal of the National Cancer Institute.

In researching the impact of antioxidant use on radiation therapy, the team identified three clinical studies that specifically addressed the topic.

Overall results 'seriously concerning'
Results from the largest of the three trials suggested that antioxidant therapy reduced overall survival. However, there was evidence indicating that one antioxidant, amifostine, can protect certain healthy tissues from radiation damage without increasing resistance in cancerous tissue.

Sixteen trials were identified that looked at the effects of antioxidant supplements on chemotherapy. There was no evidence that antioxidants reduced treatment response rates, although the authors warn that none of the studies were really large enough to address this properly.

"Despite some intriguing studies that have suggested the benefit of adjunctive antioxidant treatments in cancer patients, the totality of the available evidence is equivocal at best and leaves us with serious concerns about the potential for harm," Lawenda's team concludes. – (Reuters Health, May 2008)

Read more:
Antioxidants may kill
Antioxidants may up cancer risk


Read Health24’s Comments Policy

Comment on this story
Comments have been closed for this article.

Ask the Expert

Cancer expert

CANSA’s purpose is to lead the fight against cancer in South Africa. Its mission is to be the preferred non-profit organisation that enables research, educates the public and provides support to all people affected by cancer. Questions are answered by CANSA’s Head of Health Professor Michael Herbst. For more information, visit

Still have a question?

Get free advice from our panel of experts

The information provided does not constitute a diagnosis of your condition. You should consult a medical practitioner or other appropriate health care professional for a physical exmanication, diagnosis and formal advice. Health24 and the expert accept no responsibility or liability for any damage or personal harm you may suffer resulting from making use of this content.

* You must accept our condition

Forum Rules