Overview
Selenium is an essential trace mineral that plays a critical role in human health through its incorporation into selenoproteins, such as glutathione peroxidases, which are key components of the body's antioxidant defense system [4][5]. These selenoproteins help protect cells from oxidative stress, support immune function, and regulate inflammation, with emerging evidence highlighting selenium's potential in disease prevention, including cardiovascular disease and certain cancers. Low selenium status has been associated with increased risk of heart disease, impaired immune response, and worse outcomes in critically ill patients, particularly those with sepsis or COVID-19 [4][2][7]. While selenium shows pleiotropic effects in preclinical models, including antitumor and antidiabetic properties [1], clinical trials have yielded mixed results, especially in cancer prevention [5]. In ICU settings, selenium supplementation may improve outcomes in deficient patients, though evidence remains inconsistent [2][6].
Dosage Guide
Recommended Daily Allowance
For generally healthy individuals
Therapeutic Doses
For treatment of specific conditions
Upper Intake Limit
Maximum safe daily intake
400 mcg— Tolerable Upper Intake Level for adults; higher doses risk selenosis
Special Forms
Alternative forms for specific needs
Highly bioavailable form, commonly used in supplements
Inorganic form, often used in IV formulations and clinical settings
Contains mixed organic selenium compounds, including selenomethionine
Clinical Notes
- High-dose selenium supplementation (>400 mcg/day) may lead to selenosis, with symptoms including hair loss, nail brittleness, gastrointestinal disturbances, and neurological issues
- Monitor selenium levels in long-term supplementation, especially in ICU or chronic disease settings
- Avoid high doses without medical supervision, particularly in individuals with renal impairment or those receiving parenteral nutrition
Research
Selenium exhibits pleiotropic effects, particularly in antitumor and antidiabetes applications via selenium-based nanomedicines.
Selenium supplementation in ICU patients shows potential for improved clinical outcomes, though results are mixed; no significant harm was reported.
Global clinical trials on selenium have evolved over 48 years, with emphasis on intervention studies and product development needing stronger clinical validation.
Adequate selenium intake supports cardiac health by enhancing antioxidant defenses via selenoproteins like glutathione peroxidase.
Selenium has chemopreventive potential in cancer, but human trials show contradictory results despite strong mechanistic rationale.
Critically ill patients often have low selenium levels, but clinical trial evidence for supplementation improving outcomes is inconsistent.
Selenium deficiency is linked to worse outcomes in COVID-19, suggesting a long-term toxic relationship between deficiency and viral severity.
Zinc and selenium are under investigation for COVID-19 prevention and treatment, but high-quality RCTs are needed to confirm efficacy.
