Selenium
Selenium
Snapshot
Selenium is a vital trace mineral that supports antioxidant defenses, thyroid hormone metabolism, immune function, and reproductive health, with potential roles in cancer prevention and cardiovascular protection.
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What is Selenium?
Selenium is an essential micronutrient incorporated into selenoproteinsโenzymes such as glutathione peroxidase and thioredoxin reductaseโthat protect cells from oxidative damage and regulate thyroid hormone activation.
Where It Comes From
Dietary selenium is found in foods like Brazil nuts, seafood (tuna, sardines), organ meats, eggs, whole grains, and legumes. Soil selenium content influences plant and animal selenium levels, so geographic variation affects dietary intake.
Key Nutrients & Compounds
Provides selenium primarily in the forms of selenomethionine and selenocysteine, which are incorporated into selenoproteins critical for redox balance and thyroid enzyme function.
Health Benefits
Selenium enhances antioxidant defenses by supporting glutathione peroxidase activity; optimizes thyroid function through iodothyronine deiodinases; bolsters immune responses by promoting lymphocyte proliferation; and may lower risk of certain cancers and cardiometabolic disorders.
Recommended Dosage
Adults require approximately 55โฏยตg per day (RDA), with a tolerable upper intake level of 400โฏยตg/day to avoid toxicity. Supplementation often provides 100โ200โฏยตg/day, depending on dietary adequacy and health goals.
How to Use It
Take selenium supplements (as selenomethionine or selenium yeast) with meals to enhance absorption and reduce gastrointestinal upset. Maintain consistent daily intake, and avoid exceeding recommended upper limits.
Who Should Use It?
Individuals in regions with low soil selenium, those following vegan or vegetarian diets, patients with thyroid disorders, or anyone at risk for selenium deficiency may benefit from supplementation under healthcare guidance.
Possible Interactions or Cautions
Excessive selenium can lead to selenosis (hair loss, nail brittleness, gastrointestinal distress). It may interact with chemotherapy agents and anticoagulants; monitor levels in those with existing heart disease or diabetes.
Final Thoughts
Selenium is a cornerstone trace mineral for antioxidant protection and endocrine health. Achieving balance through diet or targeted supplementation can support overall wellness, but care is needed to avoid toxicity.
Scientific Studies
ClarkโฏLC, etโฏal. Effects of selenium supplementation for cancer prevention: a randomized controlled trial. JAMA. 1996;276(24):2011โ2018. https://doi.org/10.1001/jama.1996.03540240055030
RaymanโฏMP. The importance of selenium to human health. Lancet. 2000;356(9225):233โ241. https://doi.org/10.1016/S0140-6736(00)02490-9
HawkesโฏWC, AlkanโฏZ, GarlandโฏT. Selenium supplementation increases glutathione peroxidase activity in humans. J Nutr. 2002;132(6):1401โ1403. https://doi.org/10.1093/jn/132.6.1401