Myths vs facts: Selen and Langlebigkeit

Selenium is an essential trace element that acts as a cofactor for selenoproteins (e.g., glutathione peroxidases) with antioxidant and thyroid-regulating functions. Observational studies suggest that adequate selenium status is associated with reduced all-cause mortality, especially in populations with low baseline levels. However, randomized controlled trials (RCTs) have not consistently shown that selenium supplementation extends lifespan in well-nourished individuals. In fact, some trials indicate an increased risk of type 2 diabetes with high selenium intake. The evidence is therefore mixed: deficiency is harmful, but excess is also detrimental. The 'optimal' selenium level depends on soil content, diet, and genetic variants (e.g., in SELENOP). For healthy adults with a balanced diet, selenium supplements do not provide a proven longevity benefit. Safety note: The tolerable upper intake level is 300 µg/day; chronic overdose causes selenosis (hair loss, nail brittleness, neuropathy).