Is it Safe to Use Antioxidant Supplements with Chemotherapy?
This new study involved 52 people being treated for advanced colon cancer with a chemotherapy drug called oxaliplatin. Half of these individuals also received intravenous treatment with an antioxidant called glutathione (at an average dose of approximately 2,500 mg each time they received chemotherapy), while the other half received a placebo.
The participants receiving intravenous glutathione had a significantly lower incidence of chemotherapy-induced nerve damage than did the control group, allowing more of the chemotherapy drug to be safely administered. Perhaps more important, the addition of glutathione to the treatment regimen did not reduce the ability of the chemotherapy to shrink the size of the colon tumors. In fact, the people who received the glutathione treatment were slightly (but not significantly) more likely to have tumor shrinkage.
Antioxidants During Chemotherapy: A Hot Topic
Antioxidants, including glutathione, are agents that protect the body from damage by unstable molecules called free radicals. There are many dietary antioxidants, including vitamins C and E, beta-carotene, and coenzyme Q10. Many commonly used herbs also contain antioxidants. Glutathione is present in small amounts in the diet, but it appears to be poorly absorbed; however, glutathione is also synthesized in the body from certain amino acids, and it appears to be one of the most important antioxidants in various tissues in the body.
Because several of the common cancer treatments (including radiation and many types of chemotherapy) work in part by producing free radicals, many doctors and researchers have voiced concern that antioxidants may reduce the beneficial effect of these therapies. However, there is very little evidence from scientific research that this interference actually occurs.
In fact, the overwhelming majority of test tube, animal, and preliminary human studies have concluded either that there was no effect of the antioxidant on the tumor-fighting ability of the cancer treatment, or that the antioxidant enhanced the anticancer effect of the therapy. In addition, antioxidants often protected against some of the most common side effects of cancer treatment, such as organ damage, low blood counts, and diarrhea.
Critics of the concurrent use of antioxidants and chemotherapy often point to the lack of clinical trials in humans. Previous preliminary clinical trials, however, have concluded that the antioxidants ginkgo (Ginkgo biloba), melatonin, coenzyme Q10, and N-acetylcysteine did not appreciably reduce the effect of cancer therapies. Pharmaceutical antioxidants such as amifostine and mesna have also been extensively studied in conjunction with chemotherapy and radiation, and have not appeared to cause a negative interaction. Many prominent cancer scientists believe that the dietary and pharmaceutical antioxidants prevent some of the worst side effects of cancer treatments.
Should People Undergoing Chemotherapy Take Glutathione?
Glutathione is available as an oral supplement, although only a small amount of orally administered glutathione is absorbed intact into the blood stream. At present there is no evidence that taking glutathione orally would have the same effect as that reported for intravenous glutathione in the new study.
Unfortunately, this clinical trial doesn’t answer the question of whether it is safe or desirable to use glutathione with other types of chemotherapy. It also doesn’t address the issue of using other antioxidants with chemotherapy. However, the results of the new study, when combined with those of previous research, provide a strong rationale for intensive research on the risks and benefits of combining antioxidants with conventional cancer therapy. People interested in using antioxidants along with conventional cancer treatment should talk this issue over with their doctors.
Matt Brignall, ND is a graduate of the University of Michigan and Bastyr University. He works at the Seattle Cancer Treatment and Wellness Center, where he specializes in complementary medicine approaches to cancer. He has been published in several journals, including Alternative Medicine Review, Coping With Cancer, and the Journal of the National Cancer Institute. Dr. Brignall also teaches clinical nutrition at Bastyr University in Kenmore, WA. He is a regular contributor to Healthnotes, Healthnotes Newswire, and the Healthnotes Quick!Reference series.
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