Selenoproteins for antioxidant systems and thyroid-hormone metabolism.
Switzerland age 18–65: 70 µg/day.
Fish, eggs, meat, whole grains and Brazil nuts; plant-food content depends strongly on soil.
Rare; severe deficiency can contribute to heart-muscle and thyroid problems and impaired immunity.
Supplements do not reliably prevent cancer or cardiovascular disease in replete people.
Hair and nails are more notable in selenium excess than in mild deficiency.
Low-selenium regions, dialysis, severe malabsorption or parenteral nutrition.
Diet and, when justified, laboratory testing; consider soil and origin differences.
Not routinely. Brazil nuts vary widely; use a targeted dose rather than “more is better”.
Selenosis causes garlic odour, nausea, neurological symptoms, and hair and nail loss/brittleness.