title: Urinary iodine concentration of New Zealand adults improves with mandatory fortification of bread with iodised salt but not to predicted levels.
abstract: OBJECTIVE
  To measure the iodine status and iodine intake of New Zealand adults 18-64 years of age following mandatory fortification of bread with iodine.
  
  
  METHODS
  A cross-sectional survey of NZ adults living in Dunedin and Wellington during February-November 2012. Three hundred and one men and women aged 18-64 years randomly selected from the New Zealand Electoral Roll completed a 24-h urine collection, a demographic and iodine-specific food frequency questionnaire (FFQ), and had height and weight measured. Urine collections were analysed for iodine and reported as median urinary iodine concentration (UIC) µg/L and median urinary iodine excretion (UIE) µg/day. The FFQ was used to estimate iodine intake with and without discretionary iodised salt use.
  
  
  RESULTS
  The median UIC for all adults was 73 µg/L, indicative of mild iodine deficiency. The mean urinary volume was 2.0 L. As an estimate of iodine intake, the median UIE was 127 µg/day. Estimated iodine intake, using the FFQ which included discretionary iodised salt use, was 132 µg/day. Iodine intakes were associated with UIC (P = 0.040) and UIE (P = 0.003), but not with bread iodine intake and iodised salt use.
  
  
  CONCLUSIONS
  Using the WHO/UNICEF/ICCIDD target for iodine sufficiency (a UIC of >100 µg/L) based on school-aged children with a mean urinary volume of 1.0 L, the iodine status of NZ adults does not reach adequate levels (73 µg/L). A more realistic parameter in a population with a higher urinary volume excretion (2.0 L) is the UIE. A median UIE of 127 µg/day suggests that the iodine status of NZ adults is now likely to be adequate.
authors.affiliation: Department of Human Nutrition, University of Otago, PO Box 56, Dunedin, New Zealand.
authors.forename: Julia C
authors.initials: JC
authors.lastname: Edmonds
authors.affiliation: Department of Human Nutrition, University of Otago, PO Box 56, Dunedin, New Zealand.|Department of Preventive and Social Medicine, University of Otago, PO Box 56, Dunedin, New Zealand.
authors.forename: Rachael M
authors.initials: RM
authors.lastname: McLean
authors.affiliation: Department of Preventive and Social Medicine, University of Otago, PO Box 56, Dunedin, New Zealand.
authors.forename: Sheila M
authors.initials: SM
authors.lastname: Williams
authors.affiliation: Department of Human Nutrition, University of Otago, PO Box 56, Dunedin, New Zealand. sheila.skeaff@otago.ac.nz.
authors.forename: Sheila A
authors.initials: SA
authors.lastname: Skeaff
mesh_terms: D000293:Adolescent; D000328:Adult; D015992:Body Mass Index; D001835:Body Weight; D001939:Bread / Q000032:analysis*; D016000:Cluster Analysis; D003430:Cross-Sectional Studies; D005260:Female; D005527:Food, Fortified; D006801:Humans; D007455:Iodine / Q000008:administration & dosage* / Q000032:analysis / Q000172:deficiency / Q000652:urine*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009520:New Zealand; D009752:Nutritional Status; D012959:Socioeconomic Factors; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage* / Q000032:analysis; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D017673:Sodium Chloride, Dietary; C034024:iodized salt; D007455:Iodine
keywords: Bread; Fortification; Iodine; Iodised salt; Urinary iodine