Iodine status in Melbourne adults in the early 1990s and 2007-08

Objective: To investigate the iodine status of Melbourne adults in 1992–94 and 2007–08, and to assess dietary iodine intake to enable comparison with recommended Nutrient Reference Values. Method: A cross‐sectional study utilising 24‐hr urine samples collected at two time points in a random sample of the Melbourne Collaborative Cohort Study. Two hundred and fifty seven adults (128 males, 129 females) in 1992–94, with a mean age of 56 years, and 265 adults (132 males, 133 females) in 2007–08, with a mean age of 68 years, were assessed, all being Melbourne residents. Urinary iodine concentration (UIC) was determined and daily urinary iodine excretion and daily iodine intake were assessed. Results: In 1992–94, the median UIC was 27 μg/L and 84% had UIC <50 μg/L. The median daily iodine intake was 51 μg/d, and 83% of participants had dietary iodine intakes below the Estimated Average Requirement of 100 μg/d. In 2007–08, the median UIC was 49 μg/L, 51% had UIC <50 μg/L and the median daily iodine intake was 98 μg/d, with 52% of intakes below the EAR. Conclusion: Melbourne adults were moderately iodine deficient in 1992–94, and borderline moderately deficient in 2007–08. Implications: While iodine status appears to have improved, it remains below an adequate level for much of the adult population of Victoria. Adequate monitoring is fundamental to assess whether the mandatory use of iodised salt in bread is effective in reducing iodine deficiency across all population groups.