Estimating the iodine supplementation level to recommend for pregnant and breastfeeding women in Australia.

OBJECTIVE: To identify a level of iodine supplementation to recommend for pregnant and breastfeeding women in Australia. DESIGN, SETTING AND PARTICIPANTS: Dietary modelling indicated that mandatory fortification of bread with iodine by replacing salt with iodised salt would still leave a gap in iodine intakes in pregnant and breastfeeding women in Australia. Iodine shortfall was estimated by two separate methods: (i) analysis of data from published studies reporting mean urinary iodine concentrations in populations of Australian women who were pregnant or had given birth in the past 6 months; and (ii) modelling based on the postmandatory fortification iodine intake estimates calculated by Food Standards Australia New Zealand using food consumption reported by women aged 19-44 years who participated in the 1995 National Nutrition Survey. MAIN OUTCOME MEASURE: Estimated level of daily supplementation required to provide sufficient iodine to result in a low proportion of pregnant and breastfeeding women having inadequate iodine intakes. RESULTS: Estimations from both data sources indicate that a supplement of 100-150 µg/day would increase iodine intakes to a suitable extent in pregnant and breastfeeding women in Australia. CONCLUSIONS: The final level of supplementation we recommend should be based on these calculations and other factors. There will be population subgroups for whom our general recommendation is not appropriate.

Iodine status of Aboriginal teenagers in the Darwin region before mandatory iodine fortification of bread.

OBJECTIVE: To determine the iodine status of participants in the Aboriginal Birth Cohort Study who resided in the Darwin Health Region (DHR) in the "Top End" of the Northern Territory prior to the introduction of mandatory iodine fortification of bread. DESIGN, SETTING AND PARTICIPANTS: Participants in our study had been recruited at birth and were followed up at a mean age of 17.8 years. Spot urine samples were collected and assessed for iodine concentration at a reference laboratory. The median urinary iodine concentration (MUIC) of residents of the DHR was calculated and compared with international criteria for iodine status. Analyses were conducted for subgroups living in urban areas (Darwin-Palmerston) and remote communities (rural with an Aboriginal council). We collected a repeat sample in a subset of participants to explore the impact of within-person variation on the results. MAIN OUTCOME MEASURE: MUIC for residents of the DHR. RESULTS: Urine specimens were provided by 376 participants in the DHR. Overall MUIC was 58 µg/L when weighted to the 2006 Census population. Urban boys had higher values (MUIC = 77 µg/L) than urban and remote-dwelling non-pregnant girls (MUIC = 55 µg/L), but all these groups were classified as mildly iodine deficient. Remote-dwelling boys had the lowest MUIC (47 µg/L, moderate deficiency). Pregnant girls and those with infants aged less than 6 months also had insufficient iodine status. Correction for within-person variation reduced the spread of the population distribution. CONCLUSIONS: Previously, iodine deficiency was thought to occur only in the south-eastern states of Australia. This is the first report of iodine deficiency occurring in residents of the NT. It is also the first study of iodine status in a defined Indigenous population. Future follow-up will reassess iodine status in this group after the introduction of iodine fortification of bread.

Change in Australian Vitamin A Intakes over Time.

BACKGROUND: The mean intake of vitamin A of Australians aged 2 y and older was 300 µg retinol equivalents lower in the 2011-2012 national nutrition survey than in 1995 and decreases preponderated in adults rather than young children. OBJECTIVE: This aim of this study was to identify the foods associated with this change and to examine how the method used to adjust for within-person variability affects the estimated prevalence of inadequate intakes in both surveys. METHODS: Foods contributing to vitamin A intake were calculated from the first day of data. The prevalence of inadequate intakes was calculated using a 2-d average, the Iowa State University method, and the National Cancer Institute (NCI) method and either taken from the published reports or calculated using Food Standards Australia New Zealand's in-house software. RESULTS: In adults, lower consumption of liver, yellow fat spreads, milk products, and carrots and similar root vegetables accounted for most of the change in intake. Vitamin A intake data were less right-skewed in 2011-2012 than in 1995. The prevalence of inadequate vitamin A intake depended on the adjustment method chosen: for example, in 2011-2012 it ranged between 3% and 55% in men aged 19-30 y. The NCI method prevalence (21% for this group) is taken as the preferred estimate of inadequacy because the method adjusts around the mean and accounts for several other sources of variance. However, the NCI method could not be used to analyze the 1995 survey. CONCLUSIONS: The lower vitamin A intake in Australia was related to changes in retinol intake rather than carotenoid intake and to lower consumption of several different types of food. The estimated prevalence of inadequate intake depends on the statistical method chosen for analysis. A direct measure of vitamin A status is needed to allow conclusions about the implications of the decreasing intake of this vitamin.

Growth and morbidity in children in the Aboriginal Birth Cohort Study: the urban-remote differential.

OBJECTIVES: To describe the prevalence of markers of growth, chronic and infectious disease in peripubertal Aboriginal children living in the Darwin Health Region in the "Top End" of the Northern Territory, and to compare prevalence between children living in urban and remote areas. DESIGN: Cross-sectional survey nested in a prospective birth cohort. SUBJECTS: 482 children living in the region who were recruited at birth (Jan 1987 to Mar 1990) and were followed up between 1998 and 2001, when aged 8-14 years. MAIN OUTCOME MEASURES: Selected parameters of growth and nutrition, infectious disease and potential markers of chronic adult disease were compared between children living at follow-up in suburban situations in Darwin-Palmerston (urban) and those living in rural communities with an Aboriginal council (remote). RESULTS: Remote children were shorter than urban children (mean height, 141.7 v 146.3 cm; P < 0.001), lighter (median weight, 30.3 v 37.1 kg; P < 0.001) and had lower body mass index (median, 15.3 v 17.9 kg/m(2); P < 0.001) and haemoglobin level (mean, 125.1 v 130.9 g/L; P < 0.001). Some potential markers of adult chronic disease were higher in urban than remote children: systolic blood pressure (mean, 109.6 v 106.2 mmHg; P = 0.004), and levels of total cholesterol (4.3 v 4.0 mmol/L; P < 0.001), high-density lipoprotein cholesterol (mean, 1.4 v 1.2 mmol/L; P < 0.001) and insulin (median, 7 v 4 mU/L; P = 0.007). Diastolic blood pressure, levels of red cell folate, serum glucose and low-density lipoprotein cholesterol, and urinary albumin-creatinine ratio did not differ by location. The prevalence of visible infections was also higher in remote than urban children (P < 0.05). CONCLUSION: As some markers of health differ between peripubertal Aboriginal children living in urban areas and those in remote areas, results of surveys in remote areas cannot be generalised to urban Aboriginal populations.