Month: June 2026

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Selenium and Drug-Resistant Breast Cancer

What continues to be a problem in breast cancer therapy?

Over time, many breast tumors become resistant to chemotherapy. Thus, drug-resistant tumors limit the success of anti-cancer therapies. Numerous mechanisms decrease the intracellular accumulation of anti-cancer drugs. In this way, breast cancer tumors become less responsive to the chemotherapy [Bajer 2026].

Does supplementary selenium have anti-cancer properties?
Breast cancer survivors
In breast cancer treatment, selenium compounds may help to reverse resistance to chemotherapy. The selenium may help to sensitize aggressive breast cancer cells to standard chemotherapies. We need clinical trials to establish selenium form and dosage.

Selenium is an essential trace element. Through the activity of selenoproteins, selenium is involved in the following potentially anti-cancer activities [Bajer 2026]:

  • Antioxidant defense
  • Immune modulation
  • Redox regulation

Note: Cancer cells often rely on altered redox balance. Accordingly, selenium compounds may disrupt tumor survival mechanisms. At the same time, they can spare normal cells and tissues.

How do selenium compounds attack drug-resistant cancer?

In a 2026 review, Bajer et al make the point that multi-drug resistance in breast cancer often stems from several resistance pathways acting together. Thus, selenium-containing compounds may help overcome breast cancer patients’ multi-drug resistance via overlapping multiple mechanisms: read more

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Selenium and Pregnancy and Thyroid Function

What Do We Know About Pregnancy and Selenium Deficiency?

First of all, during pregnancy, biomarkers of selenium status decline considerably. In some pregnancies, the blood level of selenium falls to critically low levels [Schomburg 2021].

Pregnant woman
In some studies, low selenium status in pregnancy links to a higher risk of postpartum thyroiditis, particularly in TPO-antibody positive women.

Secondly, the decline in selenium status during pregnancy reflects an increased need for selenium. During the pregnancy, both the mother and the developing fetus need selenium. The mother transfers selenium to the fetus via the placenta [Schomburg 2021].

Thirdly, low selenium status during pregnancy is associated with health risks [Schomburg 2021; Shreenath et al 2023]:

  • impaired immune system function
  • increased vulnerability to autoimmune diseases
  • increased risk of miscarriage, pre-eclampsia, fetal growth restriction, preterm labor, and gestational diabetes

Fourthly, selenium supplementation may be necessary in some cases. To date, the evidence base in support of selenium supplementation during pregnancy is somewhat limited. At this point, we need more randomized controlled trials. However, it is clear that adequate selenium status during pregnancy is important for good immune system function and for preventing the development of autoimmune conditions [Schomburg 2021]. read more