Myths vs facts: Selen and fertility

The question about myths vs. facts regarding selenium and fertility is relevant, but the provided context does not contain specific information on selenium. Generally, selenium is an essential trace element important for sperm production and motility as well as thyroid function, which in turn affects fertility. A common myth is that high selenium doses boost fertility; in reality, excess selenium can be toxic (selenosis) and impair fertility. Evidence for supplementation in well-nourished individuals is weak; only in cases of confirmed deficiency (via blood test) might supplementation be beneficial. DNA tests for selenium-related genes (e.g., GPX1) are considered marketing tools with limited clinical actionability, as per the context. Conclusion: Do not self-supplement without medical guidance, as the risk-benefit ratio is unclear.