Research Bytes – Using Supplements During Chemotherapy

The science of breast cancer diagnosis, treatment, and research is continuously moving to improve the lives of cancer patients. With such a vast amount of growing and changing information, it can be overwhelming to get a grasp on it.

In the recent study, “Dietary Supplement Use During Chemotherapy and Survival Outcomes of Patients with Breast Cancer Enrolled in a Cooperative Group Clinical Trial1 the purpose was to determine if the use of over-the-counter vitamins and supplements have an effect on recurrence rates and survival seen with breast cancer patients.

“Be sure that your cancer care team is aware of your use of any vitamins and supplements while you are undergoing treatment.”

In this case, over 1,000 patients were included in the data, and their use of supplements was followed throughout their breast cancer treatment cycles with IV chemotherapy. Particular interest has surrounded the use of antioxidants (such as vitamins C and E) and their potential to “protect” all cells (including cancer cells) from the intended cell-killing effects of chemotherapy.

The outcome of the research showed that use of any antioxidants before and during chemotherapy was associated with an increased hazard of recurrence and, to a lesser extent, death. These antioxidants include vitamin A, vitamin C, vitamin E, carotenoids (phytonutrients), and coenzyme Q10. Vitamin B12 and iron use also showed similar results.

However, when a multivitamin was specifically studied, it was determined that there was no potential increased risk of recurrence and death. Based on this information, there is no obvious increased risk with the use of multivitamins during chemotherapy treatment.

During breast cancer treatment and after, nutrition plays a big role in helping you feel healthy, strong, and in control of your body.
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The most important point to note from this study is that the research on this topic is incomplete.

The topic needs to be studied via more rigorous research methods before clear recommendations can be given. Hopefully, more research will move forward in this direction in the future.

In the meantime, an ongoing discussion with your cancer care team is vital. Be sure that your team (medical oncologist, primary care provider, dietitian) is aware of your use of any vitamins and supplements while you are undergoing treatment. Your team can give recommendations on which are acceptable to continue and can walk through any questions that you may have in relation to your nutritional goals and supplement plan.

Marisa LMarisa is a physician, mom of three, and breast cancer fighter. She was diagnosed with early stage, triple positive breast cancer at the age of 35, which has given her a new passion for research and advocacy. She enjoys using her medical and research knowledge along with her personal experiences with cancer to make a positive impact in the oncology world.


1 Ambrosone, C., Zirpoli, G., Hutson, A., McCann, W., McCann, S., Barlow, W., Kelly, K., Cannioto, R., Sucheston-Campbell, L., Hershman, D., Unger, J., Moore, H., Stewart, J., Isaacs, C., Hobday, T., Salim, M., Hortobagyi, G., Gralow, J., Budd, G., Albain, K.  Dietary Supplement Use During Chemotherapy and Survival Outcomes of Patients With Breast Cancer Enrolled in a Cooperative Group Clinical Trial (SWOG S0221).” Journal of Clinical Oncology, DOI: 10.1200/JCO.19.01203. Published online December 19, 2019.

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