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.

Iodine status of Indigenous and non-Indigenous young adults in the Top End, before and after mandatory fortification.

OBJECTIVE: To assess the median urine iodine concentration (UIC) of young adults in the Top End of Northern Territory, before and after fortification of bread with iodised salt became mandatory. DESIGN, SETTING: Analysis of cross-sectional data from two longitudinal studies, the Aboriginal Birth Cohort and the non-Indigenous Top End Cohort, pre- (Indigenous participants: 2006-2007; non-Indigenous participants: 2007-2009) and post-fortification (2013-15). PARTICIPANTS: Indigenous and non-Indigenous Australian young adults (mean age: pre-fortification, 17.9 years (standard deviation [SD], 1.20 years); post-fortification, 24.9 years (SD, 1.34 years). MAIN OUTCOME MEASURE: Median UIC (spot urine samples analysed by a reference laboratory), by Indigenous status, remoteness of residence, and sex. RESULTS: Among the 368 participants assessed both pre- and post-fortification, the median UIC increased from 58 µg/L (interquartile range [IQR], 35-83 µg/L) pre-fortification to 101 µg/L (IQR, 66-163 µg/L) post-fortification (P < 0.001). Urban Indigenous (median IUC, 127 µg/L; IQR, 94-203 µg/L) and non-Indigenous adults (117 µg/L; IQR, 65-160 µg/L) were both iodine-replete post-fortification. The median UIC of remote Indigenous residents increased from 53 µg/L (IQR, 28-75 µg/L) to 94 µg/L (IQR, 63-152 µg/L; p < 0.001); that is, still mildly iodine-deficient. The pre-fortification median UIC for 22 pregnant women was 48 µg/L (IQR, 36-67 µg/L), the post-fortification median UIC for 24 pregnant women 93 µg/L (IQR, 62-171 µg/L); both values were considerably lower than the recommended minimum of 150 µg/L for pregnant women. CONCLUSIONS: The median UIC of young NT adults increased following mandatory fortification of bread with iodised salt. The median UIC of pregnant Indigenous women in remote locations, however, remains low, and targeted interventions are needed to ensure healthy fetal development.

Plasma retinol and total carotenes and fracture risk after long-term supplementation with high doses of retinol.

OBJECTIVE: Observational studies suggest that moderate intakes of retinol and increased circulating retinol levels may increase fracture risk. Easy access to supplements, combined with an aging population, makes this a potentially important association. The aim of this study was to investigate plasma retinol and total carotene concentrations in relation to fracture risk after long-term supplementation with retinol and/or beta-carotene in 998 adults between 1990 and 2007. METHODS: Participants were 663 men and 335 women in a cancer prevention program who were initially randomized to a retinol (7.5 mg RE/d) or beta-carotene (30 mg/d) supplement between 1990 and 1996. After 1996, all participants received the retinol supplement only. Plasma retinol and total carotene, medication use and various lifestyle factors were measured at annual clinic visits. Fractures were identified by self-report in 2007. The risk for any fracture or osteoporotic fracture was modeled using Cox proportional hazard models. RESULTS: Over a median follow-up of 7.8 y, 123 participants with plasma samples reported an incident fracture. Although plasma retinol concentrations were markedly higher than those reported in observational studies, no association was observed between plasma retinol and risk for any fracture (hazard ratio [HR], 0.86 µmol/L; 95% confidence interval [CI], 0.65-1.14) or osteoporotic fracture (HR, 0.97 µmol/L; 95% CI, 0.66-1.43). A lower risk for any fracture was suggested with increasing plasma total carotenes (HR, 0.85 µmol/L; 95% CI, 0.71-1.01). CONCLUSIONS: This study does not support earlier reports of an increased fracture risk associated with increased plasma retinol concentration. The potential for carotenes to prevent fractures deserves further investigation.

Intraindividual variation in urinary iodine concentrations: effect of adjustment on population distribution using two and three repeated spot urine collections.

OBJECTIVES: To determine the effect of adjustment for intraindividual variation on estimations of urinary iodine concentrations (UIC), prevalence of iodine deficiency and population distribution of iodine status. SETTING: Community-dwelling older adults from New South Wales, Australia. PARTICIPANTS: 84 healthy men and women aged 60-95 years were recruited prior to introduction of the mandatory iodine fortification programme. PRIMARY AND SECONDARY OUTCOME MEASURES: UIC data were collected from three spot urine samples, each 1 week apart. Repeated measures analysis of variance were determined between-person (sb) and total (sobs) SDs. Adjusted UIC values were calculated as ((person's UIC-group mean)×(sb/sobs))+group mean, and a corrected UIC distribution was calculated. RESULTS: The sb/sobs for using three samples and two samples were 0.83 and 0.79, respectively. Following adjustment for intraindividual variation, the proportion with UIC <50 µg/L reduced from 33% to 19%, while the proportion with UIC ≥100 µg/L changed from 21% to 17%. The 95th centile for UIC decreased from 176 to 136 µg/L. Adjustment by taking averages yielded a lesser degree of contraction in the distribution than the analysis of variance method. CONCLUSIONS: The addition of information about intraindividual variability has potential for increasing the interpretability of UIC data collected to monitor the iodine status of a population.

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.

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.

Risk assessment to underpin food regulatory decisions: an example of public health nutritional epidemiology.

The approach used by food regulation agencies to examine the literature and forecast the impact of possible food regulations has many similar features to the approach used in nutritional epidemiological research. We outline the Risk Analysis Framework described by FAO/WHO, in which there is formal progression from identification of the nutrient or food chemical of interest, through to describing its effect on health and then assessing whether there is a risk to the population based on dietary exposure estimates. We then discuss some important considerations for the dietary modeling component of the Framework, including several methodological issues that also exist in research nutritional epidemiology. Finally, we give several case studies that illustrate how the different methodological components are used together to inform decisions about how to manage the regulatory problem.

Australian Aboriginal Birth Cohort study: follow-up processes at 20 years.

BACKGROUND: In 1987, a prospective study of an Australian Aboriginal Birth Cohort was established focusing on the relationships of fetal and childhood growth with the risk of chronic adult disease. However as the study is being conducted in a highly marginalized population it is also an important resource for cross-sectional descriptive and analytical studies. The aim of this paper is to describe the processes of the third follow up which was conducted 20 years after recruitment at birth. METHODS: Progressive steps in a multiphase protocol were used for tracing, with modifications for the expected rural or urban location of the participants. RESULTS: Of the original 686 cohort participants recruited 68 were untraced and 27 were known to have died. Of the 591 available for examination 122 were not examined; 11 of these were refusals and the remainder were not seen for logistical reasons relating to inclement weather, mobility of participants and single participants living in very remote locations. CONCLUSION: The high retention rate of this follow-up 20 years after birth recruitment is a testament to the development of successful multiphase protocols aimed at overcoming the challenges of tracing a cohort over a widespread remote area and also to the perseverance of the study personnel. We also interpret the high retention rate as a reflection of the good will of the wider Aboriginal community towards this study and that researchers interactions with the community were positive. The continued follow-up of this life course study now seems feasible and there are plans to trace and reexamine the cohort at age 25 years.

Dietary patterns identified using factor analysis and prostate cancer risk: a case control study in Western Australia.

PURPOSE: Dietary patterns offer an alternative method for analyzing dietary intakes that take into account the whole diet. We investigated empirical dietary patterns and prostate cancer risk in Western Australia (WA) using a population-based case-control study. METHODS: Incident prostate cancer cases were identified via the WA Cancer Registry. Controls were sourced from the WA electoral roll, frequency matched on age. A food frequency questionnaire (FFQ) estimated usual dietary intake from 10 years earlier. Factor analysis identified dietary patterns in FFQ data. Effects of independent dietary patterns on prostate cancer risk were examined using unconditional logistic regression, adjusting for potential confounders. RESULTS: A total of 546 cases and 447 controls provided data. Three distinct dietary patterns were identified, which we labeled vegetable, Western, and health-conscious. An increased risk for prostate cancer was observed with the Western pattern, which consisted of high intakes of red and processed meats, fried fish, hamburgers, chips, high-fat milk, and white bread. Men in the highest quartile for Western pattern score had an odds ratio of 1.82 (95% confidence interval 1.15-2.87, trend p = 0.02). Results were similar for aggressive cases and attenuated for non-aggressive cancers. CONCLUSIONS: A western style diet may lead to increased risks for prostate cancer, especially aggressive prostate cancer.

Dietary patterns and surgically treated benign prostatic hyperplasia: a case control study in Western Australia.

OBJECTIVES: To investigate dietary patterns and food intake as risk factors for surgically treated benign prostatic hyperplasia (BPH), as few risk factors have been established for BPH and recently there has been some interest in a role for diet in the development of BPH. PATIENTS, SUBJECTS AND METHODS: A case-control study was conducted in Western Australia (WA) during 2001 and 2002. BPH cases were men with a diagnosis of BPH hospitalized for their first prostatectomy. Controls were frequency matched for age and sex from the WA electoral roll. A previously evaluated food-frequency questionnaire (FFQ) collected information on usual dietary intake 10 years earlier. Factor analysis identified dietary patterns in the FFQ data. Effects of dietary patterns and food intakes on the risk of BPH were examined using unconditional logistic regression, adjusting for various confounders. RESULTS: In all, 406 cases and 462 controls (aged 40-75 years) provided data. Three dietary patterns were identified, i.e. 'Vegetable', 'Western' and 'Health Conscious'. BPH risk was not associated with the 'Health Conscious' or 'Western' patterns, but there was a lower risk with an increasing score for the 'Vegetable' pattern (odds ratio 0.78, 95% confidence interval 0.63-0.98). BPH risk was significantly and inversely related to the intake of total vegetables, dark yellow vegetables, other vegetables, tofu and red meat. There was a higher risk of BPH with increasing intake of high-fat dairy products. CONCLUSIONS: These results indicate that vegetables, soy products, red meat and high-fat dairy foods might be important in the development of BPH.

Growth outcomes for Australian Aboriginal children aged 11 years who were born with intrauterine growth retardation at term gestation.

Long-term poor growth outcomes are well documented for intrauterine growth-retarded babies (IUGR) in developed populations but there is a paucity of IUGR studies from disadvantaged populations where the greatest burden of IUGR occurs. Using a Northern Territory, Aboriginal cohort recruited at birth and followed up at a mean age of 11.4 years, comparisons of body size were made between children born at term who had been IUGR (n = 121) and those non-IUGR (n = 341), and between those IUGR babies who had an appropriate ponderal index at birth (n = 72) and those with a low ponderal index (n = 49). Compared with non-IUGR children, at follow-up the IUGR children were almost 2 cm shorter (P = 0.10), 4 kg lighter (P < 0.01) and their head circumferences were almost a 1 cm smaller (P < 0.01). For the 121 term IUGR children, there were no significant differences in growth outcomes according to ponderal index measures at birth. These findings from an Australian Aboriginal sample are consistent with other comparisons of IUGR and non-IUGR children in developed populations and suggest there may be no additional effects of IUGR on growth in childhood for disadvantaged populations similar to the Aboriginal population in the Northern Territory.

Does the store-turnover method still provide a useful guide to food intakes in Aboriginal communities?

OBJECTIVE: To consider the application of the store-turnover method as a guide to assess food intake in remote Aboriginal communities. METHOD: Food sources in a remote Aboriginal island community were documented. The contribution of quantifiable food sources to total community-level fresh fruit and vegetable availability was determined. RESULTS: The store remains the single largest supplier of fruit and vegetables overall (54%), however its contribution varies depending on the subpopulation of interest. A store-turnover alone may significantly underestimate community-level dietary intake, depending on the contribution of other food sources. CONCLUSIONS: Changes in the food supply in remote communities, coupled with methodological complexities inherent in the store-turnover method, challenge its application in a contemporary context. IMPLICATIONS: A simplified version of the store-turnover method is needed that could be widely applied by community people and health practitioners seeking to initiate and monitor interventions to improve diet quality.

Leanness and type 2 diabetes in a population of indigenous Australians.

OBJECTIVE: To determine the prevalence of type 2 diabetes and its risk factors in a population of indigenous Australians. RESEARCH DESIGN AND METHODS: A cross-sectional study of 332 indigenous community residents aged 15 years and over with fasting blood samples and anthropometric measurements. RESULTS: Almost half of the study population (47.3%) was extremely lean (BMI<22 kg/m(2)). Leanness was particularly pronounced in the youngest age group (15<20 years), 78% of which had a BMI<22 kg/m(2). The prevalence of diabetes was 12%. It was highest in those 45-54 years and declined in older aged people. No cases of diabetes were detected in those aged less than 30 years. Diabetes prevalence was strongly linked to BMI and age (age-adjusted odds ratio=24.1, 95% CI 6.0-96.5, p<0.001) for BMI>or=25 kg/m(2) versus BMI<22 kg/m(2). Those with the lowest diabetes risk profile are lean (BMI<22 kg/m(2)) and/or young (age 15-34 years). CONCLUSIONS: These results highlight that strategies to prevent or delay the onset of diabetes should focus on the maintenance of leanness from adolescence and throughout adult life whilst young people are still in the process of forming lifelong habits.

24-hour national dietary survey data: how do we interpret them most effectively?

OBJECTIVE: To illustrate the effect of common mistakes when using 24-hour national dietary survey data to estimate the prevalence of inadequate nutrient intakes. DESIGN: Raw data on nutrient intake from the Australian 1995 National Nutrition Survey were adjusted for within-person variance using standard techniques and corrected for underreporting using the criteria of Goldberg et al. The distributions for six nutrients were compared with current dietary reference values from the UK, USA and Australia. SETTING: A national sample of the Australian population with a 61.4% response rate. RESULTS: Adjusting for within-person variance reduced the range of nutrient intakes to 66-80% of the raw data range and the proportion with intakes below the estimated average requirement (EAR) by up to 20%. Excluding underreporters further reduced the proportion below the EAR by up to 10%. Using the dietary reference values from different countries also resulted in some markedly different estimates. For example, the prevalence of low folate intakes ranged from < 1 to 92% for adult women depending on the reference used. Except for vitamin A and protein, the prevalence of low intakes was invariably higher for women than for men. CONCLUSIONS: Estimates of the prevalence of low nutrient intakes based on raw 24-hour survey data are invariably misleading. However, even after adjustment for within-person variance and underreporting, estimates of the prevalence of low nutrient intakes may still be misleading unless interpreted in the light of the reference criteria used and supported by relevant biochemical and physiological measures of nutritional status.

Haematocrit levels and anaemia in Australian children aged 1-4 years.

The aim of this study was to describe the prevalence of anaemia, mean haematocrit levels, and the risk factors influencing haematocrit in participants of the 1995 National Survey of Lead in Children. A nationally-representative cross-sectional survey of children aged 1-4 years inclusive was done. Mean haematocrit and the proportion with anaemia using both the US and WHO haematocrit-based criteria were calculated. Multivariate regression was used to identify factors associated with haematocrit. Mean haematocrit level was 38.8% (95% CI: 38.6 - 39.1%) and varied with age of child, state/territory of residence and whether the child was taking supplements. It did not vary by sex, Aboriginal identification, maternal birthplace, whether the child ate meat or any other selected characteristic. The factors identified explained only 4% of the variation in haematocrit levels. The prevalence of anaemia was 3.3% (95% CI: 2.4 - 4.5%) based on the US criteria and 2.0% (95% CI: 1.3 - 3.1%) based on the WHO criteria. The prevalence of anaemia in this national survey was lower than the prevalence of iron deficiency anaemia reported in several more localised studies.