Variation in iodine food composition data has a major impact on estimates of iodine intake in young children

Development and validation of a food frequency questionnaire to assess habitual iodine intake among women of childbearing age

BACKGROUND

Adequate iodine status is critical for thyroid hormone synthesis, which is essential for foetal brain development. Suboptimal iodine status has been reported in young women across Europe. Although urinary iodine concentration (UIC) is a good indicator of recent exposure, it does not reflect habitual iodine intake. This study aimed to develop and validate an iodine-specific food frequency questionnaire (I-FFQ) to assess habitual intake in Irish women aged 18-50 years.

METHODS

A 47-item interviewer-administered I-FFQ, informed by national food consumption data on Irish women aged 18-35 years, was developed and validated in a study of 100 nonpregnant women using a 4-day weighed food diary (FD) and UIC as the reference methods. Correlation, cross-classification and Bland-Altman analyses were used to assess agreement and bias between the I-FFQ and FD. Validity coefficients were calculated using the method of triads.

RESULTS

Median (interquartile range [IQR]) UIC was 82 (49, 139) µg/L. Median (IQR) intakes were 161 (106, 217) and 133 (98, 182) µg/day for the I-FFQ and FD, respectively (p = 0.001). Estimates were moderately correlated (r = 0.434), and the I-FFQ classified 89% of participants into the same or adjacent tertile of intake as the FD. Validity coefficients for the I-FFQ, FD and UIC were 0.542, 0.800 and 0.228, respectively. Though repeatability analyses 10 weeks later (n = 69) showed slight differences in estimates of intake (I-FFQ1: 164 (104, 210) µg/day; I-FFQ2: 132 (67, 237) µg/day), intakes were highly correlated between administrations (r = 0.627, p = 0.001).

CONCLUSIONS

The I-FFQ provides a reasonable estimate of habitual iodine intake in young women.

Addressing nutrient shortfalls in 1- to 5-year-old Irish children using diet modeling: development of a protocol for use in country-specific population health

BACKGROUND

Dietary habits formed in early childhood can track into later life with important impacts on health. Food-based dietary guidelines (FBDGs) may have a role in improving population health but are lacking for young children.

OBJECTIVES

We aimed to establish a protocol for addressing nutrient shortfalls in 1- to 5-y-old children (12-60 mo) using diet modeling in a population-based sample.

METHODS

Secondary analysis of 2010-2011 Irish National Pre-School Nutrition Survey data (n = 500) was conducted to identify typical food consumption patterns in 1- to 5-y-olds. Nutrient intakes were assessed against dietary reference values [European Food Safety Authority (EFSA) and Institute of Medicine (IOM)]. To address nutrient shortfalls using diet modeling, 4-d food patterns were developed to assess different milk-feeding scenarios (human milk, whole or low-fat cow milk, and fortified milks) within energy requirement ranges aligned with the WHO growth standards. FBDGs to address nutrient shortfalls were established based on 120 food patterns.

RESULTS

Current mean dietary intakes for the majority of 1- to 5-y-olds failed to meet reference values (EFSA) for vitamin D (≤100%), vitamin E (≤88%), DHA (22:6n-3) + EPA (20:5n-3) (IOM; ≤82%), and fiber (≤63%), whereas free sugars intakes exceeded recommendations of <10% energy (E) for 48% of 1- to 3-y-olds and 75% of 4- to 5-y-olds. "Human milk + Cow milk" was the only milk-feeding scenario modeled that predicted sufficient DHA + EPA among 1- to 3-y-olds. Vitamin D shortfalls were not correctable in any milk-feeding scenario, even with supplementation (5 µg/d), apart from the "Follow-up Formula + Fortified drink" scenario in 1- to 3-y-olds (albeit free sugars intakes were estimated at 12%E compared with ≤5%E as provided by other scenarios). Iron and vitamin E shortfalls were most prevalent in scenarios for 1- to 3-y-olds at ≤25th growth percentile.

CONCLUSIONS

Using WHO growth standards and international reference values, this study provides a protocol for addressing nutrient shortfalls among 1- to 5-y-olds, which could be applied in country-specific population health.

Iron, iodine and vitamin D deficiencies during pregnancy: epidemiology, risk factors and developmental impacts

Micronutrient deficiency persists throughout the world, and although the burden is higher in low-resource settings, it is also prevalent in wealthy countries, a phenomenon termed 'hidden hunger'. Due to their high requirements for vitamins and minerals relative to their energy intake, young women and children are particularly vulnerable to hidden hunger. As they share several risk factors and impact on overlapping outcomes, we consider how deficiency of iron, iodine and vitamin D can have profound impacts on perinatal health and infant development. We review the epidemiology of these micronutrient deficiencies during pregnancy, including social, environmental and dietary risk factors. We identify the main challenges in defining nutritional status of these nutrients using validated diagnostic criteria linked with meaningful clinical outcomes. Public health strategies are urgently required to improve the overall health and nutritional status of women of reproductive age. Obesity prevention and early detection of malnutrition with standardised screening methods would detect pregnant women at increased risk of iron deficiency. Development of sensitive, individual biomarkers of iodine status is required to protect maternal health and fetal/infant brain development. Risk assessments of vitamin D requirements during pregnancy need to be revisited from the perspective of fetal and neonatal requirements. International consensus on standardised approaches to micronutrient assessment, analysis and reporting as well as sensitive, clinically validated infant and child neuro-behavioural outcomes will enable progression of useful observational and intervention studies.

Geographical and seasonal variation in iodine content of cow's milk in the UK and consequences for the consumer´s supply

BACKGROUND

Dairy products provide a crucial source of dietary iodine for the majority of the UK population, contributing approximately 30-40 % of daily intake. Fluctuations in the iodine content of purchased milk both seasonally and annually implies potential fragility of iodine supply likely through fluctuating supplementation practices in cow herds. We set out to establish the level of national variation in herds and identify factors which might impact milk iodine content.

METHODS

Milk samples were obtained from 98 herds across the UK via the National Milk Laboratories in August and December 2016. Iodine concentration of samples was measured using ICP-MS. Milk samples and feed intake data were additionally taken from 22 cows from the University of Nottingham (UON) dairy herd.

RESULTS

There was considerable variation in milk iodine content from < 0.012 (Limit of Detection) to 1558 μg L^-1, with a summer median of 197 μg L^-1 and winter median 297 μg L^-1. Overall, winter values were higher than summer counterparts (P < 0.001) and this held true for samples taken from the North West (P = 0.002) and South West (P = 0.006) but not for other regions studied. Data from the UON herd showed a negative relationship between iodine content and milk yield (P = 0.03) and we found that milk iodine content varied considerably despite apparently similar iodine intakes.

CONCLUSIONS

Regional differences in milk iodine concentration between summer and winter suggests that feeding practices are far from uniform across the country. The negative association observed between iodine concentration and milk yield in UON samples, suggests that reduced summer values may be influenced by dilution in addition to seasonal differences in concentrate feed provision.

Iodine consumption and cognitive performance: Confirmation of adequate consumption

Iodine, a dynamic nutrient present in thyroid hormones, is responsible for regulating thyroid function, supporting a healthy metabolism, and aiding growth and development. Iodine is also essential for brain development during specific time windows influencing neurogenesis, neuronal and glial cell differentiation, myelination, neuronal migration, and synaptogenesis. About 1.5 billion people in 130 countries live in areas at risk of iron deficiencies (IDs). Reduced mental ability due to IDs occurs in almost 300 million people. Ensuring the consumption of minimum recommended daily allowances of iodine remains challenging. The effects of ID disorders range from high mortality of fetuses and children to inhibited mental development (cretinism). Poor socioeconomic development and impaired school performance are also notable. Currently, ID disorders are the single greatest contributor to preventable brain damage in fetuses and infants and arrested psychomotor development in children. Iodized salt may help fulfill iodine requirements. Increases in food salt iodization programs can help overcome ID disorders. Dietary plans can be well adjusted to incorporate iodinated foods. Maternal iodine supplementation for offspring requires adequate attention. Fruits, vegetables, bread, eggs, legumes (beans and peas), nuts, seeds, seafood, lean meats and poultry, and soy products provide small quantities of iodine. Nutrient-dense foods containing essential vitamins and minerals such as iodine may confer positive effects. To some extent, fortified foods and daily dietary supplements can be provided for different nutrients including iodine; otherwise, iodine may be consumed in less than the recommended amounts. This review focuses on aspects of adequate iodine consumption to avoid cognitive impairments.

New Iodine Food Composition Database and Updated Calculations of Iodine Intake among Norwegians

Iodine food composition data of Norwegian foods have been sparse and knowledge about different dietary iodine sources limited. We compiled a comprehensive iodine food composition database and estimated dietary iodine intake among adults in the latest Norwegian national dietary survey (Norkost 3). The iodine content of food and beverages were compiled using international guidelines and standards. Iodine content of 3259 food items were compiled, including analytical values, values from other food composition databases, estimated values, and values that were based on recipes. Estimated iodine intake in the Norkost 3 population ranged from 15 to 1462 µg/day. Men had significantly higher intake of iodine than women (p < 0.001). The proportion of men and women with estimated iodine intake below average requirement was 19% and 33%, respectively. In young women, 46% had estimated iodine intakes below average requirement and a high probability of inadequate iodine intake. Several dietary sources contributed to iodine intake and differences in the consumption pattern may put subgroups at risk of insufficient iodine intake. In the coming years, the determination of iodine in foods and national dietary surveys should be regularly performed to monitor the iodine intake in the Norwegian population.