Iodine status of adults in Taiwan 2005–2008, 5 years after the cessation of mandatory salt iodization

Background/Purpose Iodine deficiency causes a broad spectrum of disorders across all ages. Mandatory salt iodization in Taiwan successfully reduced the goiter rate from 21.6% to 4.3% in schoolchildren surveyed in 1971. The program continued until 2003 when salt iodization was changed from mandatory to voluntary. The purpose of this study was to investigate the iodine status of Taiwanese individuals after the change in the iodine policy. Methods Urinary iodine (UI) was measured in samples from adults in the Nutrition and Health Survey in Taiwan 2005–2008. Results The median UI level was 100 μg/L, and the percentage of populations with UI levels below 100 μg/L and 50 μg/L was 50.1% and 15.1%, respectively, indicating that the iodine status was borderline adequate. Men had a higher UI level than women (102 μg/L vs. 98 μg/L, p = 0.003), and older individuals (age > 60 years) had a lower UI level than younger people, particularly in women. The iodine status of the population < 50 years was sufficient, but it was insufficient in older groups. Mild iodine insufficiency was noted in all areas of Taiwan except the Southern area and Penghu islands, with the lowest UI level of 79 μg/L in the Mountain area. Although the UI level of women of childbearing age (19–44 years) was 103 μg/L, there may be a risk of iodine deficiency during pregnancy. Conclusion The iodine nutrition of the Taiwanese population in 2005–2008 was borderline adequate, with insufficiency in some subgroups. Further monitoring of the iodine status is necessary.