Dietary Iodine Intake of the Australian Population after Introduction of a Mandatory Iodine Fortification Programme

To address mild iodine deficiency in Australia, a mandatory fortification program of iodised salt in bread was implemented in 2009. This study aimed to determine factors associated with achieving an adequate dietary iodine intake in the Australian population post-fortification, and to assess whether bread consumption patterns affect iodine intake in high-risk groups. Using nationally representative data of repeated 24-h dietary recalls from the 2011-2012 Australian National Nutrition and Physical Activity Survey, dietary iodine intakes and food group contributions were compared by age, socioeconomic status (SES), and geographical remoteness (N = 7735). The association between fortified bread intake and adequacy of iodine intake (meeting age and sex-specific Estimated Average Requirements) was investigated using logistic regression models in women of childbearing age 14-50 years (n = 3496) and children aged 2-18 years (n = 1772). The effect of SES on bread consumption was further investigated in a sub group of children aged 5-9 years (n = 488). Main sources of iodine intake at the time of the survey were cereal and cereal products, followed by milk products and dishes. Differences in iodine intake and dietary iodine habits according to age, SES and location were found (p < 0.001) for women of child-bearing age. Fortified bread consumption at ≥100 g/day was associated with five times greater odds of achieving an adequate iodine intake (OR 5.0, 95% CI 4.96-5.13; p < 0.001) compared to lower bread consumption in women and 12 times in children (OR 12.34, 95% CI 1.71-89.26; p < 0.001). Disparities in dietary iodine intake exist within sectors of the Australian population, even after mandatory fortification of a staple food. On-going monitoring and surveillance of iodine status is required.