Suboptimal Iodine Status and Low Iodine Knowledge in Young Norwegian Women

Previous studies have documented mild to moderate iodine deficiency in pregnant and lactating women in Norway. This study focused on non-pregnant young women because their future children may be susceptible to the adverse effects of iodine deficiency. We assessed urinary iodine concentration (UIC), iodine intake from food and supplements, and iodine knowledge in 403 non-pregnant women, mainly students, aged 18-30 years. Iodine concentration was measured in spot urine samples analyzed by inductively coupled plasma mass spectrometry and iodine intake was calculated from a self-reported food frequency questionnaire. Knowledge about iodine was collected through the self-administered, paper-based questionnaire. Median (p25-p75) UIC was 75 (42-130) mu g/L and 31% had UIC < 50 mu g/L. Habitual iodine intake was 100 (69-136) mu g/day. In multiple regression models, supplemental iodine, use of thyroid medication, and iodine intake from food were positively associated with UIC, while vegetarian practice was negatively associated, explaining 16% of the variance. Approximately 40% of the young women had low iodine knowledge score and no differences were found between women in different study programs. Young women in Norway are mild to moderately iodine-deficient, and public health strategies are needed to improve and secure adequate iodine status.