Use of antioxidants and other supplements during chemotherapy linked to increased breast cancer recurrence and death

Use of antioxidant and other certain supplements during chemotherapy by patients with breast cancer may increase their risk for disease recurrence and death, according to results of a research study published in Journal of Clinical Oncology.

Data obtained from 1,134 patients with breast cancer (18% of which used antioxidants) who participated in the Diet, Exercise, Lifestyle, and Cancer Prognosis (DELCaP) study revealed that using any antioxidants, such as vitamin A, C, E, carotenoids, and Coenzyme Q10 before and during chemotherapy were 41% more likely to have breast cancer recurrence and 40% more likely to die. In addition, patients who used vitamin B12, iron, and omega-3 fatty acid supplements also had an increased risk of the cancer returning and death. Patients who used multivitamin, however, was not associated with increase risk of breast cancer recurrence or death. Also taking antioxidant only before treatment or only during treatment did not affect the either risk. 

The researchers concluded that antioxidants and other supplements may not be beneficial and can cause patients more harm by making the treatment less effective.  

Should people not take antioxidants and supplements during chemotherapy if they took them before they were diagnosed with breast cancer?   The results of this study are not definitive enough to answer this question, but the results are compelling, and people should be cautious about using any supplements before and during chemotherapy and always talk with their doctors about whether they should take these. Antioxidants obtained through diet are considered safe and people can achieve that with a healthy and balanced diet.   




Ambrosone CB, Zirpoli GR, Hutson AD, McCann WE, McCann SE, Barlow WE, Kelly KM, Cannioto R, Sucheston-Campbell LE, Hershman DL, Unger JM, Moore HCF, Stewart JA, Isaacs C, Hobday TJ, Salim M, Hortobagyi GN, Gralow JR, Budd GT, Albain KS.(2020). Dietary Supplement Use During Chemotherapy and Survival Outcomes of Patients With Breast Cancer Enrolled in a Cooperative Group Clinical Trial (SWOG S0221). J Clin Oncol. 2020 Mar 10;38(8):804-814. doi: 10.1200/JCO.19.01203. Epub 2019 Dec 19.