Dietary iodine intake and urinary iodine excretion in normal Korean adults

Korea is a region abundant in foods containing iodine such as seaweed and fish. An adequate amount of iodine consumption is extremely important as both a deficiency and excess of iodine can result in health problems. This study was undertaken to assess the iodine nutritional status of normal Korean adults who consume seaweed and fish, and to determine the relationship between the dietary iodine intake and the urinary excretion of iodine. The dietary assessment of iodine using a food frequency questionnaire and a urinary iodine excretion examination were carried out in 278 healthy adults. The iodide selective electrode (ISE) method was used to determine urinary iodine excretion. The average usual iodine intake of Korean adults was 479 µg per day (ranging from 61 µg to 4086 µg). There was no significant difference in sex or age. The major food sources of dietary iodine included seaweed (66%), milk and dairy products (11%), and fish (9%). The contribution of seaweed to the total iodine intake tended to increase with age while the contribution of milk decreased. The average urinary excretion of iodine was 674 µg/g creatinine and there was no significant difference in sex or age. The dietary iodine intake was positively correlated with the urinary excretion of iodine (γ = 0.60, p < 0.01). The study data indicated that the iodine intake and excretion of Koreans depends mostly on the amount of seaweed consumption like sea tangle and sea mustard. As well, the current iodine intake and urinary iodine excretion by Koreans seems to be higher than in other countries.