Profiling of selenium absorption and accumulation in healthy subjects after prolonged l-selenomethionine supplementation

PURPOSE: Autoimmune thyroiditis and its complications for the reproductive system are a growing problem. Selenium is a common ingredient in numerous food supplements recommended for thyroiditis and pregnancy. A fast, simple method to measure serum selenium concentration will improve knowledge of its pharmacokinetics and toxicity. AIM: To validate a useful method to measure serum selenium concentration and to study selenium absorption and accumulation in a prospective interventional study of prolonged treatment. METHODS: Thirty healthy volunteers received a single dose of L-selenomethionine one tablet (83 mcg) (Phase 1), a single dose of two tablets (Phase 2), and two tablets daily for 14 days (Phase 3). Total selenium and selenium time profiles were generated by serial sampling (T0, T3, T6, T12, and T24 hours after ingestion-Phases 1 and 2; and T0 and T24 hours-Phase 3). Selenium concentration was investigated by open-vessel acid digestion of small serum volumes followed by hydride generation atomic fluorescence spectroscopy analysis. RESULTS: There was a significant increase in serum selenium concentration (mcg/L) in all treatment phases. Significantly increased levels were reached at T3 in Phase 1 (baseline: 76.5 ± 2.47; T3: 82.8 ± 3.28) and at T6 in Phase 2 (83.8 ± 3.46). They remained significantly increased at T12 in Phase 1 and T24 in Phase 2 (79.03 ± 2.69). There was significant selenium accumulation after prolonged intake (14 days) (102.13 ± 5.61). CONCLUSIONS: Prolonged selenomethionine administration increases circulating blood selenium concentration and hydride generation atomic fluorescence spectroscopy enables its accurate quantification.