What does a low Selen result mean?

A low selenium result in a biomarker test (e.g., blood or urine) indicates a potential deficiency of this essential trace mineral. Selenium is critical for antioxidant enzymes (glutathione peroxidases), thyroid hormone metabolism, and immune function. Low levels can stem from inadequate dietary intake (especially in regions with selenium-poor soil), malabsorption, chronic inflammation, or certain diseases. Possible consequences include fatigue, weakened immunity, hair loss, and thyroid dysfunction. However, a single low reading is not a diagnosis—it must be interpreted alongside diet, lifestyle, and other lab values. Consumer tests like MyBody-X provide a snapshot, not a clinical assessment. If low values persist or symptoms appear, medical evaluation is recommended. Supplementation (e.g., selenium yeast or sodium selenite) may be considered under medical guidance, but self-supplementation carries risks: the tolerable upper intake level is 400 µg/day, and excess selenium can be toxic (selenosis). Evidence for benefit in mild deficiency is moderate; for healthy individuals without deficiency, routine supplementation is not supported. Always consult a healthcare professional before acting on a single biomarker result.