wo ist selen enthalten — which blood markers matter?

Selenium is an essential trace mineral found in Brazil nuts (1–2 nuts meet daily needs), tuna, sardines, eggs, meat (especially liver), and mushrooms. Plant content depends on soil selenium. Key blood markers for selenium status include: serum selenium (short-term intake), selenoprotein P (longer-term status), and glutathione peroxidase activity (functional marker). Deficiency can impair immunity, thyroid function, and antioxidant defense. Caution: excess selenium (e.g., from Brazil nuts or supplements) causes selenosis – garlic breath, hair loss, nerve damage. The safe upper limit is 300–400 µg/day. Evidence for these markers is solid (human-moderate), but inflammation or kidney disease can alter results. A single test should be confirmed by a clinician. No direct context was provided; this answer is based on established nutritional science.