The Impact of Selenium Supplementation on Human Health and the Course of Diseases, Including Breast Cancer Prevention and Treatment

Introduction and purpose: Selenium is a trace element that plays a huge role in the human body. It acts mainly through enzymes—selenoproteins—which protect cells from oxidative stress, participate in thyroid hormone metabolism, and also have anti-inflammatory properties. The aim of this review is to discuss the impact of selenium levels and the effects of selenium supplementation on human health, including breast cancer prevention and treatment. Description of the state of knowledge: Selenium supplementation plays an important role in thyroid diseases and may influence the development and course of type II diabetes, neurological and psychiatric diseases. Selenium and its supplementation have been shown to influence female and male fertility, as well as the course of pregnancy and the health of the mother and fetus. Selenium is involved in the activation of the immune system and has the ability to modulate lipid metabolism, which is beneficial in cardiovascular diseases. Research is ongoing on the effect of selenium supplementation in the prevention and treatment of cancer, including breast cancer. Some studies show a reduction in incidence and improved prognosis in patients supplementing with selenium. Conclusions: Current data from numerous studies indicate the benefits of selenium supplementation, especially in patients with selenium deficiency. Further detailed clinical and experimental studies on large groups of patients are needed to confirm the effectiveness and clearly determine the potential benefits or harms associated with selenium supplementation in various health conditions.