Dietary supplements (BAA) reduce the effectiveness of chemotherapy and increase the likelihood of relapse of the disease and death in women who are being treated for breast cancer, Journal of Clinical Oncology reported referring to a study.

Scientists from the Roswell Park Cancer Center in Buffalo found that chemotherapy is reduced by the use of seemingly innocuous dietary supplements with antioxidants, iron, vitamin B12 and omega-3 fatty acids.

It is believed that antioxidants can affect the ability of chemotherapy to kill cancer cells. One of the mechanisms of action of chemotherapy is the induction of strong oxidative stress. Antioxidants are thought to block oxidative stress and make chemotherapy less effective, Reuters reported referring to specialist.

Scientists analyzed data from 1134 patients who were followed up for an average of 6 years. As it turned out, patients took dietary supplements much less often than usual: 20% of participants before chemotherapy and 13% during treatment.

After taking into account other risk factors, the researchers found that in patients taking any antioxidants (including carotenoids, coenzyme Q10 and vitamins A, C and E) before and during chemotherapy, the probability of recurrence of breast cancer increased by 41%, and the probability of death was the entire observation period is 40%.