Predictive modelling of interventions to improve iodine intake in New Zealand

The potential effects of four interventions to improve iodine intakes of six New Zealand population groups are assessed.

A model was developed to estimate iodine intake when (i) bread is manufactured with or without iodized salt, (ii) recommended foods are consumed to augment iodine intake, (iii) iodine supplementation as recommended for pregnant women is taken and (iv) the level of iodization for use in bread manufacture is doubled from 25-65 mg to 100 mg iodine/kg salt.

New Zealanders have low and decreasing iodine intakes and low iodine status. Predictive modelling is a useful tool to assess the likely impact, and potential risk, of nutrition interventions.

Food consumption information was sourced from 24 h diet recall records for 4576 New Zealanders aged over 5 years.

Most consumers (73-100 %) are predicted to achieve an adequate iodine intake when salt iodized at 25-65 mg iodine/kg salt is used in bread manufacture, except in pregnant females of whom 37 % are likely to meet the estimated average requirement. Current dietary advice to achieve estimated average requirements is challenging for some consumers. Pregnant women are predicted to achieve adequate but not excessive iodine intakes when 150 μg of supplemental iodine is taken daily, assuming iodized salt in bread.

The manufacture of bread with iodized salt and supplemental iodine for pregnant women are predicted to be effective interventions to lift iodine intakes in New Zealand. Current estimations of iodine intake will be improved with information on discretionary salt and supplemental iodine usage.