Urinary iodine excretion after ingestion of dried and thinly shaved kombu

Abstract

Urinary iodine excretion was measured in seven male university students taking 3 g of kombu product (iodine content, 2.61 mg/g). Urinary iodine excretion rate increased within 2 h after the kombu ingestion, reached a maximum at 4 to 6 h, and then returned to a base-line level at 42.8 h after the ingestion. A half-life of the excretion rate was estimated to be 9.13 h. Proportion of urinary iodine excretion to the ingested iodine was estimated to be 53.1% at 16 h, 63.6% at 30 h and 65.6% at 42.8 h after the ingestion. These results indicate that at most 70% of iodine in kombu are absorbed and rapidly excreted into urine within 2 days after the ingestion.