Iodine deficiency in women of childbearing age: not bread alone?

Iodine deficiency remains a public health concern, particularly in pregnant women and those planning pregnancy because of the risk of impaired fetal neurological development. Following implementation of strategies to improve iodine intake in Australia, there has been minimal investigation into current iodine status. We aimed to characterise iodine status in a population of women of childbearing-age in Australia.

A cross-sectional study was performed in 97 women of childbearing-age attending outpatient clinics at a tertiary hospital in Sydney. Pregnant and postmenopausal women were excluded. Iodine intake was surveyed via questionnaire. Spot urinary iodine (UI) was concurrently measured. The relationships between UI, dietary intake and use of iodine-containing multivitamins/medications were examined.

Median UI was 117 ug/L. Forty women (41%) were iodine deficient (UI <100 ug/L). The most commonly consumed source of dietary iodine was bread (29/97, 30% daily). Forty-three women took iodine-containing multivitamins but 18/43 (41.2%) remained deficient. There were no significant associations between UI and diet. There was a smaller proportion of deficient people than in our previous study (125/180 non-pregnant subjects, 69%, vs 41% in this study, p<0.001).

The overall population median is now sufficient, however, a significant proportion of this multicultural group are iodine deficient. There are similar proportions of deficiency in those using iodine supplements versus not. Contributors may include ethnicity-related dietary practices, limited awareness or poor adherence to iodine supplements. Despite public health strategies, a significant proportion of women of child-bearing age remained iodine deficient. Further research involving a larger population and contributors to iodine deficiency is warranted.