Estimating the impact of mandatory fortification of bread with iodine on pregnant and post-partum women

Background: Iodine deficiency has re-emerged in Australia. Pregnant and breastfeeding women need higher iodine intakes (estimated average requirements: 160 μg/day and 190 μg/day) than non-pregnant women (100 μg/day) because iodine is critical for early infant development. The impact of iodine fortification of bread on women's iodine intake is evaluated by reproductive status using 2003 Australian Longitudinal Study on Women's Health (ALSWH) food frequency data and projected onto 1995 National Nutrition Survey (NNS) daily food consumption data for women of child-bearing age. Methods: Recent iodine analyses of Australian foods were combined with reported intakes of key foods to estimate iodine intake before and after fortification for 665 pregnant, 432 zero to 6 months postpartum, 467 seven to 12 months postpartum and 7324 non-pregnant women. Differences in mean iodine intake between these groups were projected onto NNS estimates of total iodine intake for women of child-bearing age. Results: Pregnant and postpartum women reported eating more bread than did non-pregnant women. Mean iodine intakes (μg/day before; and after fortification) from key foods were higher in pregnant (78; 124), 0-6 months postpartum (75; 123) and 7-12 months postpartum (71; 117) than in non-pregnant women (65; 103). Projecting ALSWH results onto the NNS yields total mean iodine intakes of 167, 167, 160 and 146 for the same groups. Conclusion: Current iodine intakes are well below dietary recommendations. The impact of iodine fortification of bread would be greater for pregnant and postpartum women than has been previously estimated using general population intakes, but additional strategies to increase intakes by these groups are still needed.