Antioxidants and Radiation Therapy

My mother is going to receive 5 weeks of radiation for breast cancer post lumpectomy.. I have been encouraging antioxidant use but have read that there is a possible conflict with the effectiveness of radiation therapy. The main antioxidant we have had her  on is Microhydrin, averred to be the most potent free radical fighter produced.
Does anyone know if such antioxidants should be stopped during the course of radiation therapy?

[CCF-RN,MSN-JS]

Dear irisheye: The American Cancer Society Workgroup on Nutrition and Physical Activity for Cancer Survivors this month published guidelines for nutrition during and after cancer treatment in "CA - A Cancer Journal for Clinicians".  The following information is adapted from these guidelines.  

During radiation therapy part of the effect is due to the oxidative damage produced by the radiation.  Taking antioxidant vitamins and supplements during radiation therapy might reduce the effectiveness of the therapy according to some experts.  Others have pointed out that the possible harm of supplements is only a theory, and that there might be a benefit from supplements that could help protect normal cells from the collateral damage associated with such therapies.  Unfortunately, this is one of the critical questions without a good answer at this time.  The current recommendation, based on available data to date, is to avoid nutritional supplements that contain antioxidant compounds during radiation therapy.