wo ist selen enthalten — when to see a doctor?

Selenium is an essential trace element found mainly in animal-based foods: Brazil nuts (very rich, but limit to 1–2 nuts per day), fish (tuna, sardines, salmon), meat (beef, chicken, liver), eggs, and dairy. Plant sources like lentils, sunflower seeds, and mushrooms also contain selenium, but levels depend heavily on soil content. In many European regions, soils are low in selenium, making plant-based intake insufficient. When to see a doctor? Persistent fatigue, muscle weakness, hair loss, brittle nails, or a weakened immune system may indicate selenium deficiency. Also, thyroid issues (selenium is crucial for thyroid hormone metabolism) or chronic inflammation warrant a blood test. Diagnosis is via serum or whole blood selenium measurement. Caveat: High-dose selenium supplements can cause selenosis (garlic breath, hair loss, nerve damage). The recommended daily intake is about 55–70 µg for adults. The provided context lacks specific selenium data, so this answer is based on general medical knowledge.