wo ist selen enthalten — what symptoms are typical?

Selenium is an essential trace mineral found in Brazil nuts (just 1–2 nuts meet daily needs), tuna, sardines, eggs, meat (especially organ meats), and mushrooms. Plant sources like broccoli, cabbage, and whole grains also contain selenium, but levels depend on soil content. Typical deficiency symptoms include fatigue, muscle weakness, cognitive decline, hair loss, and impaired immune function. Severe deficiency can lead to Keshan disease (heart muscle damage) or Kashin-Beck disease (joint degeneration). Toxicity (selenosis) presents with garlic breath, hair loss, and neurological issues. Evidence for these symptoms is human-strong, based on clinical and epidemiological data. However, effects are dose-dependent and influenced by genetics (e.g., SELENOP variants). Consumer DNA tests for selenium metabolism are not clinically validated; a blood test (serum or whole blood selenium) is more reliable. Safety note: avoid daily high intake of Brazil nuts due to toxicity risk.