Symposium on 'Geographical and geological influences on nutrition': Iodine deficiency in industrialised countries

Agronomic Biofortification of Plants with Iodine and Selenium: A Potential Solution for Iodine and Selenium Deficiencies

Iodine and selenium deficiencies are widespread both in developed countries and developing countries. The soil is the fundamental source of iodine and selenium for plants, and iodine and/or selenium-depleted soil restrains the cultivation of crops to cover recommended daily intakes of iodine and selenium. Although food fortification strategies, including salt iodization, increase the dietary intake of these minerals, their global deficiencies have not been eliminated. Therefore, new strategies have been developed to prevent iodine and selenium deficiencies, and biofortification is one of them. The aim of this review is to assert the outcomes of the studies that investigate the optimum conditions for biofortification with iodine and selenium and to recognize the role of biofortification practices as a potential solution for preventing iodine and selenium deficiencies. The findings of studies show that biofortification with iodine and selenium can be a solution for iodine and selenium deficiencies. Agronomic biofortification is currently a more convenient method to increase selenium and iodine contents in plants. However, the most effective agronomic biofortification conditions are crucial to acquire biofortified food. Moreover, increasing the awareness of the producers and consumers on biofortification has a determinative role in the achievement of biofortification practices for human health. Although research about iodine and selenium biofortification has been increased, the effectiveness of biofortified foods to meet recommended daily intakes is still unknown. More research is needed to understand most effective biofortification conditions for plants and bioavailability of biofortified foods for humans.

How animal milk and plant-based alternatives diverge in terms of fatty acid, amino acid, and mineral composition

The decline in fresh milk in the Western world has in part been substituted by an increased consumption of plant-based beverages (PBB). These are often marketed as healthy and sustainable alternatives to milk and dairy foodstuff, although studies have suggested PBB to be of lower nutrient quality. The current study considered different brands of almond-, oat-, rice-, coconut- and soya-based beverages for a comparative analysis and found that they indeed presented lower contents of total protein, lipids, amino acids, and minerals than cow and goat milk. The only exception was given by soya-based beverages which approximated the protein content (3.47% vs. 3.42 and 3.25% in cow and goat milk, respectively) and amino acid composition of animal milk, and also demonstrated high mineral content. The natural presence of phyto-compounds in PBB characterised as antinutrients and their potential to exacerbate the issue of low nutrient quality by lowering bioavailability have been discussed.

Adequacy of Iodine Status and Associations with Gut Health: A Prospective Cohort Study among Infants in 8 Low- and Middle-Income Countries

BACKGROUND

Environmental enteric dysfunction increases the likelihood of micronutrient deficiencies among infants, but few studies have assessed the potential impact of gut health on urinary iodine concentration (UIC) among this vulnerable group.

OBJECTIVES

We describe the trends of iodine status among infants from 6 to 24 mo old and examine the associations between intestinal permeability, inflammation, and UIC from 6 to 15 mo of age.

METHODS

Data from 1557 children enrolled in this birth cohort study conducted in 8 sites were included in these analyses. UIC was measured at 6, 15, and 24 mo of age by using the Sandell-Kolthoff technique. Gut inflammation and permeability were assessed using the concentrations of fecal neopterin (NEO), myeloperoxidase (MPO) and alpha-1-antitrypsin (AAT), and lactulose-mannitol ratio (LM). A multinomial regression analysis was used to assess the classified UIC (deficiency or excess). Linear mixed regression was used to test the effect of interactions among biomarkers on logUIC.

RESULTS

All studied populations had adequate (≥100 μg/L) to excess (≥371 μg/L) median UIC at 6 mo. Between 6 and 24 mo, 5 sites displayed a significant decline in the infant's median UIC. However, median UIC remained within the optimal range. An increase of NEO and MPO concentrations by +1 unit in ln scale reduced the risk of low UIC by 0.87 (95% CI: 0.78-0.97) and 0.86 (95% CI: 0.77-0.95), respectively. AAT moderated the association between NEO and UIC (P < 0.0001). The shape of this association appears to be asymmetric and in a reverse J-shape, with a higher UIC observed at both lower NEO and AAT concentrations.

CONCLUSIONS

Excess UIC was frequent at 6 mo and tended to normalize at 24 mo. Aspects of gut inflammation and increased permeability appear to reduce the prevalence of low UIC in children aged 6 to 15 mo. Programs addressing iodine-related health should consider the role of gut permeability in vulnerable individuals.

Iodine Intake and Related Cognitive Function Impairments in Elementary Schoolchildren

Iodine deficiency, the most common cause of preventable mental impairment worldwide, has been linked to poorer intellectual function in several studies. However, to our knowledge, no studies have been performed in moderate iodine-deficient schoolchildren using the complete form of Wechsler Intelligence Scale for Children (WISC-III; Portuguese version). The main purpose of this study was to ascertain whether moderate iodine deficiency would affect the cognitive function of schoolchildren (7-11 years old; 3rd and 4th grades). Raven's Colored Progressive Matrices (CPM; Portuguese version) were used for measuring the intelligence quotient (IQ) of the total population (n = 256; median UIC = 66.2 μg/L), and the WISC-III was used to study two selected subgroups: one moderately iodine-deficient (n = 30) and the other with adequate iodine intake (n = 30). WISC-III was shown to be the prime instrument for cognitive function assessment among moderate iodine-deficient schoolchildren; this subgroup had a Full-Scale IQ 15.13 points lower than the adequate iodine intake subgroup, with a magnitude effect of d = 0.7 (p = 0.013). Significant differences were also registered in 6 of the 13 Verbal-Performance IQ subtests. Moderate iodine deficiency has a substantial impact on mental development and cognitive functioning of schoolchildren, with significant impairment in both Performance IQ and Verbal IQ spectrum, adversely impacting their educational performance.

Iodine Concentration in Drinking Water in the Same or Different Seasons of the Year in Brazilian Macroregions

Objective. The aim of this study was to compare the concentration of iodine in drinking water in the same or different seasons of the year in Brazilian macroregions. Method. Water samples were collected from the Basic Health Units of eight municipalities that make up the different Brazilian macroregions and the Federal District. Sample collection took place in the summer, autumn, winter, and spring seasons. The spectrophotometric method with “leuco crystal violet” was used to determine the concentration of iodine in the water. Descriptive statistics on the data were performed. To verify if there was a difference in the concentration of iodine in the water between the climatic seasons of the year in the same place and between the same seasons in different locations, the Mann–Whitney or Kruskal–Wallis test was used and a $p<0.05$ value was considered significant. Results. Among the climatic seasons throughout the year in the same location, there was a difference in the concentration of iodine in the water in the municipality of Pinhais, state of Paraná/South macroregion, between autumn and summer ( $p=0.041$ ) and winter and summer seasons ( $p=0.003$ ). There was a difference in the concentration of iodine in the water in the summer season between the Midwest and South macroregions; Northeast and Midwest, Southeast and South; North and Midwest, Southeast and South ( $p<0.05$ ). In the autumn season, there was a difference in the concentration of iodine in the water between the Midwest and South macroregions; Northeast and Midwest, Southeast and South; North and Midwest, Northeast and South ( $p<0.05$ ). In the winter season, there was a difference in the concentration of iodine in the water between the Southeast and Midwest and Southeast and South macroregions ( $p<0.05$ ). In the spring season, there was a difference in the concentration of iodine in the water between the Southeast and Midwest and Southeast and South macroregions ( $p<0.05$ ). Conclusion. There were differences in the iodine concentrations in drinking water in different locations in Brazil, when analyzed in the same seasons, and in the municipality of Pinhais between the autumn and summer and winter and summer seasons. Thus, it is suggested to monitor the iodine concentrations in water, considering the differences in climate, characteristics of each region, and soils throughout the Brazilian territory, since the deficiency or excess of iodine can bring risks to the health of the population.

Iodine status in pregnant women and infants in Finland

PURPOSE

Iodine insufficiency during pregnancy may adversely influence fetal growth and development. There is a lack of information on iodine status in pregnant women and infants in many countries including Finland. The aim of this study is to determine dietary intake of iodine and the iodine status in a population of Finnish pregnant women and their infants.

METHODS

Urine samples were collected from women participating in a mother-child clinical study at early (n = 174) and late pregnancy (n = 186) and at three months of postpartum (n = 197), when infant samples were also collected (n = 123). Urine iodine concentration was measured using inductively coupled plasma mass spectrometry. Cutoffs for iodine insufficiency were < 150 µg/L during pregnancy and < 100 µg/L at postpartum and in infants. Iodine intake was assessed using 3-day food diaries.

RESULTS

Increased risk of insufficiency, based on urinary iodine concentrations, was observed in the groups investigated in this study. Of the women studied, 66% had urinary iodine concentrations indicating insufficient intakes and iodine insufficiency at early pregnancy, 70% at late pregnancy and 59% at three months of postpartum. This was also the case in 29% of the three-month-old infants. Estimation of iodine intake revealed that iodine insufficient women had lower intakes of iodine from the diet, from food supplements and from diet plus supplements than iodine sufficient women in early pregnancy and at three months of post-partum. In late pregnancy, this difference was seen for iodine intake from supplements.

CONCLUSION

The majority of the women manifested with low urine iodine concentrations both during and after pregnancy. Similarly, one-third of the infants presented with iodine insufficiency. Maternal iodine intake data support these findings. These observations may have implications for optimal child cognitive development.

Política mundial de yodación de sal: desafíos

Objetivo Identificar los desafíos que conlleva la implementación de la política mundial de yodación de sal para el consumo humano. Métodos Se realizó una revisión de la literatura publicada entre el año 2000 y 2021 en PubMed, con los términos MeSH yodo, política pública, cloruro de sodio y los términos complementarios yodo/deficiencia, exceso. Se obtuvieron 141 artículos y se revisaron 50 aplicando como criterio de inclusión el abordaje de la implementación de la política de yodación. Resultados Se identificaron siete desafíos: sostenibilidad de la política, eliminar la brecha entre la explotación y la comercialización de la sal, prevenir la fortificación indiscriminada de los alimentos, promover la educación sobre la ingesta de sal yodada, controlar la ingesta excesiva de yodo, equilibrar la ingesta óptima de yodo con la reducción del consumo de cloruro de sodio y producir suficiente información oficial sobre la política. Conclusión La yodación universal de la sal es una política que requiere mayor sensibilidad a las situaciones locales de cada país para mitigar efectivamente el problema de salud pública de los desórdenes por deficiencia y exceso en la ingesta de yodo alrededor del mundo.

Environmental and human iodine and selenium status: lessons from Gilgit-Baltistan, North-East Pakistan

Iodine and selenium deficiencies are common worldwide. We assessed the iodine and selenium status of Gilgit-Baltistan, Pakistan. We determined the elemental composition (ICP-MS) of locally grown crops (n = 281), drinking water (n = 82), urine (n = 451) and salt (n = 76), correcting urinary analytes for hydration (creatinine, specific gravity). We estimated dietary iodine, selenium and salt intake. Median iodine and selenium concentrations were 11.5 (IQR 6.01, 23.2) and 8.81 (IQR 4.03, 27.6) µg/kg in crops and 0.24 (IQR 0.12, 0.72) and 0.27 (IQR 0.11, 0.46) µg/L in water, respectively. Median iodised salt iodine was 4.16 (IQR 2.99, 10.8) mg/kg. Population mean salt intake was 13.0 g/day. Population median urinary iodine (uncorrected 78 µg/L, specific gravity-corrected 83 µg/L) was below WHO guidelines; creatinine-corrected median was 114 µg/L but was unreliable. Daily selenium intake (from urinary selenium concentration) was below the EAR in the majority (46-90%) of individuals. Iodine and selenium concentrations in all crops were low, but no health-related environmental standards exist. Iodine concentration in iodised salt was below WHO-recommended minimum. Estimated population average salt intake was above WHO-recommended daily intake. Locally available food and drinking water together provide an estimated 49% and 72% of EAR for iodine (95 µg/day) and selenium (45 µg/day), respectively. Low environmental and dietary iodine and selenium place Gilgit-Baltistan residents at risk of iodine deficiency disorders despite using iodised salt. Specific gravity correction of urine analysis for hydration is more consistent than using creatinine. Health-relevant environmental standards for iodine and selenium are needed.

Reinterpreting patterns of variation in human thyroid function: An evolutionary ecology perspective

Two hundred million people worldwide experience some form of thyroid disorder, with women being especially at risk. However, why human thyroid function varies between populations, individuals, and across the lifespan has attracted little research to date. This limits our ability to evaluate the conditions under which patterns of variation in thyroid function are best understood as 'normal' or 'pathological'. In this review, we aim to spark interest in research aimed at understanding the causes of variation in thyroid phenotypes. We start by assessing the biomedical literature on thyroid imbalance to discuss the validity of existing reference intervals for diagnosis and treatment across individuals and populations. We then propose an evolutionary ecological framework for understanding the phylogenetic, genetic, ecological, developmental, and physiological causes of normal variation in thyroid function. We build on this approach to suggest testable predictions for how environmental challenges interact with individual circumstances to influence the onset of thyroid disorders. We propose that dietary changes, ecological disruptions of co-evolutionary processes during pregnancy and with pathogens, emerging infections, and exacerbated stress responses can contribute to explaining the onset of thyroid diseases. For patients to receive the best personalized care, research into the causes of thyroid variation at multiple levels is needed.

Incidence of thyroid disorders in the second decade of adequate iodine supply in Slovenia

BACKGROUND

The incidence of thyroid disorders importantly depends on iodine supply and may change over time. There are only a few data available regarding the change in the incidence of thyroid disorders following the increase in iodine supply. Therefore, the aim of this study was to establish the incidence of thyroid disorders in the second decade of adequate iodine supply in Slovenia.

METHODS

The medical records of 17,828 adult patients who were examined at this department for the first time in the years 2011, 2012, 2013 and 2014 were reviewed. The incidence of diffuse and nodular goiter, thyroid autonomy, Graves' disease, non-hypothyroid and hypothyroid Hashimoto's thyroiditis in the stable catchment area of the University Medical Centre Ljubljana with 1,000,000 inhabitants was followed.

RESULTS

A significantly lower incidence of thyroid autonomy was observed in the year 2014 as compared to 2011 (p = 0.006), a significantly higher incidence of Hashimoto's thyroiditis in 2014 as compared to 2013 (p = 0.003), and a significantly higher incidence of non-hypothyroid Hashimoto's thyroiditis in 2014 as compared to 2011 and 2013 (p = 0.005 and p = 0.022, respectively). The incidence of other thyroid diseases did not change significantly in the observed period.

CONCLUSION

In the second decade of adequate iodine supply in Slovenia, we established a similar or even a lower incidence of most thyroid diseases in the observed 4 years with the exception of Hashimoto's thyroiditis.

Micronutrients, iodine status and concentrations of thyroid hormones: a systematic review

Context

The metabolism of thyroid hormones, which are essential for normal development, involves many proteins and enzymes. It requires iodine as a key component but is also influenced by several other micronutrients, including selenium, zinc, iron, and vitamin A.

Objective

This systematic review was designed to investigate the effect of micronutrient status and supplementation on iodine status and thyroid hormone concentrations.

Data Sources

Using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines, electronic databases were searched from their inception to April 2016.

Study Selection

Human studies published in English and reporting data on micronutrient status and iodine status and/or thyroid hormone concentrations were included. Studies that examined the effect of micronutrient supplementation on iodine status and/or thyroid hormone concentrations were also included.

Data Extraction

A predesigned and piloted data extraction form was used to compile data from individual studies.

Results

A total of 57 studies were included: 20 intervention studies and 37 observational studies. Although observational evidence suggests that concentrations of selenium, zinc, and iron are positively associated with iodine status, data from randomized controlled trials fail to confirm this relationship.

Conclusions

Further studies are needed to provide greater understanding of the role of micronutrient status in iodine nutrition and thyroid function to ascertain the public health implications for populations worldwide.

Variation of iodine status during pregnancy and its associations with thyroid function in women from Rio de Janeiro, Brazil

OBJECTIVE

To assess iodine status and its effects on maternal thyroid function throughout pregnancy.

DESIGN

In the present prospective cohort study, three urinary samples were requested for urinary iodine concentration (UIC) determinations in both the first and third gestational trimesters. Serum thyrotropin (TSH) and free thyroxine (FT4) were analysed in both trimesters and thyroid antibodies were assessed once.

SETTING

Rio de Janeiro, Brazil.ParticipantsFirst-trimester pregnant women (n 243), of whom 100 were re-evaluated during the third trimester.

RESULTS

Iodine sufficiency was found in the studied population (median UIC=216·7 µg/l). The first- and third-trimester median UIC was 221·0 and 208·0 µg/l, respectively. TSH levels (mean (sd)) were higher in the third trimester (1·08 (0·67) v. 1·67 (0·86) mIU/l; P&lt;0·001), while FT4 levels decreased significantly (1·18 (0·16) v. 0·88 (0·12) ng/dl; P&lt;0·001), regardless the presence of iodine deficiency (UIC&lt;150 µg/l) or circulating thyroid antibodies. UIC correlated (β; 95% CI) independently and negatively with age (-0·43; -0·71, -0·17) and positively with multiparity (0·15; 0·02, 0·28) and BMI (0·25; 0·00, 0·50). Furthermore, median UIC per pregnant woman tended to correlate positively with TSH (0·07; -0·01, 0·14). Women with median UIC≥250 µg/l and at least one sample ≥500 µg/l throughout pregnancy had a higher risk of subclinical hypothyroidism (OR=6·6; 95% CI 1·2, 37·4).

CONCLUSIONS

In this cohort with adequate iodine status during pregnancy, excessive UIC was associated with an increased risk of subclinical hypothyroidism.

Iodine fortification of foods and condiments, other than salt, for preventing iodine deficiency disorders

BACKGROUND

Iodine deficiency disorders (IDD) affect close to 1.9 billion people worldwide, and are a major public health concern in many countries. Among children, iodine deficiency is the main cause of potentially preventable deficits of central nervous system development and impairment of cognitive function, as well as goitre and hypothyroidism in people of all ages. Salt iodisation is the preferred strategy for IDD prevention and control, however, in some instances where salt is not the major condiment, alternate vehicles for iodine fortification have been considered.

OBJECTIVES

To assess the effects of fortifying foods, beverages, condiments, or seasonings other than salt with iodine alone or in conjunction with other micronutrients, on iodine status and health-related outcomes in all populations.

SEARCH METHODS

Studies were identified through systematic searches of the following databases from their start date to January 2018: Cochrane Public Health Group Specialised Register; CENTRAL; MEDLINE; MEDLINE in Process; Embase; Web of Science; CINAHL; POPLINE; AGRICOLA; BIOSIS; Food Science and Technology Abstracts; OpenGrey; Bibliomap and TRoPHI; AGRIS; IBECS; Scielo; Global Index Medicus-AFRO and EMRO; LILACS; PAHO; WHOLIS; WPRO; IMSEAR; IndMED; and Native Health Research Database. We also searched reference list of relevant articles, conference proceedings, and databases of ongoing trials, and contacted experts and relevant organisations to identify any unpublished work. We applied no language or date restrictions.

SELECTION CRITERIA

Studies were eligible if they were randomised or quasi-randomised controlled trials (RCT) with randomisation at either the individual or cluster level (including cross-over trials), non-randomised RCTs, or prospective observational studies with a control group, such as cohort studies, controlled before-and-after studies, and interrupted time series. We included studies that examined the effects of fortification of food, beverage, condiment, or seasoning with iodine alone, or in combination with other micronutrients versus the same unfortified food, or no intervention. We considered the following measures: death (all-cause), goitre, physical development, mental development, cognitive function and motor skill development, cretinism, hypothyroidism, adverse effects (any reported by trialists), urinary iodine concentration, thyroid-stimulating hormone (TSH) concentration, and serum thyroglobulin concentration. We included all populations, including pregnant women, from any country.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility, extracted data, and assessed risk of bias of included studies.We used random-effects meta-analyses to combine data and generate an overall estimate of treatment effect, when more than one study examined the same outcome measure. The overall effect estimate was calculated as the mean difference (MD) or standardised mean difference (SMD) between the intervention group and the comparison group for continuous outcomes, and as odds ratio (OR) for dichotomous outcomes. We assessed the level of heterogeneity through the I² statistic. We conducted post-hoc subgroup analyses to explore possible sources of heterogeneity, and sensitivity analyses to check the robustness of the findings from the primary analyses. We assessed the quality of the evidence for each outcome using the GRADE framework.Where it was not possible to pool the results in a meta-analysis, we provided a narrative summary of the outcomes.

MAIN RESULTS

Eleven studies met the criteria, providing 14 comparisons, and capturing data on 4317 participants. Seven studies were RCTs, three were cluster non-RCTs, and one was a randomised cross-over design. Seven studies were carried out among school children (N = 3636), three among women of reproductive age (N = 648), and one among infants (N = 33). The studies used diverse types of food as vehicle for iodine delivery: biscuits, milk, fish sauce, drinking water, yoghourt, fruit beverage, seasoning powder, and infant formula milk. Daily amounts of iodine provided ranged from 35 µg/day to 220 µg/day; trial duration ranged from 11 days to 48 weeks. Five studies examined the effect of iodine fortification alone, two against the same unfortified food, and three against no intervention. Six studies evaluated the effect of cofortification of iodine with other micronutrients versus the same food without iodine but with different levels of other micronutrients. We assessed one study to be at low risk of bias for all bias domains, three at low risk of bias for all domains apart from selective reporting, and seven at an overall rating of high risk of bias.No study assessed the primary outcomes of death, mental development, cognitive function, cretinism, or hypothyroidism, or secondary outcomes of TSH or serum thyroglobulin concentration. Two studies reported the effects on goitre, one on physical development measures, and one on adverse effects. All studies assessed urinary iodine concentration.The effects of iodine fortification compared to control on goitre prevalence (OR 1.60, 95% CI 0.60 to 4.31; 1 non-RCT, 83 participants; very low-quality evidence), and five physical development measures were uncertain (1 non-RCT, 83 participants; very low-quality evidence): weight (MD 0.23 kg, 95% CI -6.30 to 6.77); height (MD -0.66 cm, 95% CI -4.64 to 3.33); weight-for-age (MD 0.05, 95% CI -0.59 to 0.69); height-for-age (MD -0.30, 95% CI -0.75 to 0.15); and weight-for-height (MD -0.21, 95% CI -0.51 to 0.10). One study reported that there were no adverse events observed during the cross-over trial (low-quality evidence).Pooled results from RCTs showed that urinary iodine concentration significantly increased following iodine fortification (SMD 0.59, 95% CI 0.37 to 0.81; 6 RCTs, 2032 participants; moderate-quality evidence). This is equivalent to an increase of 38.32 µg/L (95% CI 24.03 to 52.61 µg/L). This effect was not observed in the meta-analysis of non-RCTs (SMD 0.25, 95% CI -0.16 to 0.66; 3 non-RCTs, 262 participants; very low-quality evidence). Sensitivity analyses did not change the effect observed in the primary analyses.

AUTHORS' CONCLUSIONS

The evidence on the effect of iodine fortification of foods, beverages, condiments, or seasonings other than salt on reducing goitre, improving physical development measures, and any adverse effects is uncertain. However, our findings suggest that the intervention likely increases urinary iodine concentration. Additional, adequately powered, high-quality studies on the effects of iodine fortification of foods on these, and other important outcomes, as well as its efficacy and safety, are required.

A systematic review of iodine deficiency among women in the UK

OBJECTIVE

The present study reviewed the literature on iodine status among women of childbearing age and pregnant women in the UK. Particular attention was given to study quality and methods used to assess iodine status.

DESIGN

A systematic review was conducted to examine the literature and critically evaluate study design.

SETTING

Studies were identified in PubMed, Web of Science, Scopus and Ovid MEDLINE databases, as well as from secondary references.

PARTICIPANTS

Women of childbearing age or pregnant, living in the UK.

RESULTS

Fifty-seven articles were identified and twelve articles were selected, including a total of 5283 women. Nine studies conducted urinary iodine assessments, three studies conducted dietary assessments only, and seven studies classified their target population as iodine deficient according to WHO criteria.

CONCLUSIONS

No single study from the selected articles could produce nationally representative results regarding the prevalence of iodine deficiency among the female population in the UK. Consideration of the evidence as a whole suggests that women of childbearing age and pregnant women in the UK are generally iodine insufficient. Further large-scale research is required for more accurate and reliable evidence on iodine status in the UK.

Language delay and poorer school performance in children of mothers with inadequate iodine intake in pregnancy: results from follow-up at 8 years in the Norwegian Mother and Child Cohort Study

Purpose

Some studies indicate that mild-to-moderate iodine deficiency in pregnant women might negatively affect offspring neurocognitive development, including previous results from the Norwegian Mother and Child Cohort study (MoBa) exploring maternally reported child development at age 3 years. The aim of this follow-up study was to investigate whether maternal iodine intake in pregnancy is associated with language and learning at 8 years of age.

Methods

The study sample includes 39,471 mother–child pairs participating in MoBa with available information from a validated food frequency questionnaire covering the first half of pregnancy and a questionnaire on child neurocognitive development at 8 years. Multivariable regression was used to explore associations of iodine intake from food and supplements with maternally reported child outcomes.

Results

Maternal iodine intake from food less than ~ 150 µg/day was associated with poorer child language skills (p-overall = 0.013), reading skills (p-overall = 0.019), and writing skills (p-overall = 0.004) as well as poorer school test result in reading (p < 0.001), and increased likelihood of the child receiving special educational services (p-overall = 0.042) (in non-iodine supplement users). Although significant, differences were generally small. Maternal use of iodine supplements in pregnancy was not significantly associated with any of the outcomes.

Conclusions

Low habitual iodine intake in pregnant women, i.e., lower than the recommended intake for non-pregnant women, was associated with mothers reporting poorer child language, school performance, and increased likelihood of special educational services. We found no indications of benefits or harm of using iodine-containing supplements in pregnancy. Initiating use in pregnancy might be too late.

Electronic supplementary material

The online version of this article (10.1007/s00394-018-1850-7) contains supplementary material, which is available to authorized users.

Low Iodine Intake from Dairy Foods Despite High Milk Iodine Content in Israel

BACKGROUND

Milk is a major source of iodine in human nutrition. Because both iodine content and the consumption of milk and dairy vary widely over time and populations, their contribution to iodine intake must be evaluated regularly. A recent national iodine survey found Israel's population to be mildly iodine deficient, possibly due to unmonitored changes in the food content of dietary iodine. Accounting for dairy iodine content can help guide efforts to prevent iodine deficiency.

OBJECTIVES

This study aimed to determine the iodine concentration of dairy products typically consumed in the Israeli diet, and to estimate iodine intake from dairy products among Israeli adults.

METHODS

Iodine was analyzed in 33 selected dairy products that account for 89% of the total population's dairy intake according to the "MABAT" Israeli National Health and Nutrition survey. Based on these data, the distribution of iodine intake from milk, dairy, and dairy-based foods in the adult population was calculated.

RESULTS

Israeli milk is rich in iodine, with a mean concentration of 22 μg/100 g. However, due to low dairy consumption, the mean iodine intake from milk and dairy was only 34 μg/day (median 23 μg/day; range: 0-337 μg/day) or 22% of the recommended daily allowance. Self-reported intake among poor, male, and Arab subgroups was even lower.

CONCLUSIONS

Because Israeli milk and dairy products are iodine rich, their contribution to the population's iodine intake would increase if they were consumed in greater amounts, particularly by high-risk groups. Dairy's potential contribution to iodine nutrition should be considered in recommendations for dairy consumption and iodine prophylaxis.

Oral bioaccessibility of toxic and essential elements in raw and cooked commercial seafood species available in European markets

The oral bioaccessibility of several essential and toxic elements was investigated in raw and cooked commercially available seafood species from European markets. Bioaccessibility varied between seafood species and elements. Methylmercury bioaccessibility varied between 10 (octopus) and 60% (monkfish). Arsenic (>64%) was the toxic element showing the highest bioaccessibility. Concerning essential elements bioaccessibility in raw seafood, selenium (73%) and iodine (71%) revealed the highest percentages. The bioaccessibility of elements in steamed products increased or decreased according to species. For example, methylmercury bioaccessibility decreased significantly after steaming in all species, while zinc bioaccessibility increased in fish (tuna and plaice) but decreased in molluscs (mussel and octopus). Together with human exposure assessment and risk characterization, this study could contribute to the establishment of new maximum permissible concentrations for toxic elements in seafood by the European food safety authorities, as well as recommended intakes for essential elements.

Primordial and Primary Preventions of Thyroid Disease

BACKGROUND

Primordial and primary preventions of thyroid diseases are concerned with avoiding the appearance of risk factors, delaying the progression to overt disease, and minimizing the impact of illness.

SUMMARY

Using related key words, 446 articles related to primordial and primary, preventions of thyroid diseases published between 2001-2015 were evaluated, categorized and analyzed. Prevention and elimination of iodine deficiency are major steps that have been successfully achieved and maintained in many countries of the world in last 2 decades. Recent investigations related to the effect of cigarette smoking, alcohol consumption, and autoimmunity in the prevention of thyroid disorders have been reviewed.

CONCLUSIONS

The cornerstone for successful prevention of thyroid disease entails timely implementation of its primordial and primary preventions, which must be highly prioritized in related health strategies by health authorities.

Review of Iodine Nutrition in Iranian Population in the Past Quarter of Century

CONTEXT

Iodine deficiency is one of the most important health problems worldwide. The overall aim of this study was a narrative review of the past and present status of iodine nutrition in the Iranian population to gather and provide valuable background data in this field for future studies.

EVIDENCE ACQUISITION

For this narrative literature review study, published internal (SID, Iran doc, Iran medex) and international (Web of knowledge, Pubmed, SCOPUS) source studies were searched using the following medical subject heading terms: Iodine, IDD (iodine deficiency disorders), UIC (urinary iodine concentration), Goiter, IQ (intelligence quotient), thyroid hormone, Iodine and pregnancy, Iodine and breast feeding, as well as Iodized salt, reporting the prevalence of iodine deficiency and iodine nutrition status of different target populations in Iran over 25 years, between 1988 - 2014, were assessed. We found 185 abstracts by literature search, of which, 161 papers that were as case reports, animal study, with lack of regional or national data were excluded after full text evaluation. Finally 24 full papers covering regional or national data on iodine nutrition of the study population were eligible for our review.

RESULTS

Iodine deficiency, as a nutritional problem, had been identified in Iran since 1968. In the years 1987 - 1989, a few studies were done to define the prevalence of iodine deficiency in the country. The first nation-wide survey was performed in 14 provinces. Based on this survey all provinces were suffering of endemic goiter. In 1989, iodine deficiency was recognized as a major problem for community health. In 1990, salt factories began to produce iodized salt and in 1996, the second national survey was performed in 26 provinces. This survey indicated that 40% of boys and 50% of girls have goiter, with a median urinary iodine excretion of 205 µg/L. The 3rd national survey in 2001 showed that the total goiter rate is 9.8% and median UIC of 165 μg/L. In 2007, the 3th national survey was conducted 17 years after iodized salt consumption by Iranian households. In this study the total goiter rate and median urinary iodine was 5.7% and 145 μg/L, respectively. The 5th national survey conducted in 2013, showed household consumption of iodized salt for all provinces was 98% and the median urinary iodine of school children was 161 μg/L. Following the 5th national survey, the 1st national survey of the iodine status and thyroid function of pregnant women, conducted in 10 provinces in the different region of the country, documented a median UIC for pregnant women of 87.3 µg/L, results of this national survey clarified that despite iodine sufficiency of school children in Iran, pregnant women have moderate iodine deficiency and need iodine supplementation.

CONCLUSIONS

The success of iodine deficiency control program depends on well designed programmatic steps and mandatory iodized salt consumption in certain situations. The iodine intake of school children is sufficient, however, Iranian pregnant women are suffering from moderate iodine deficiency and need iodine supplementation.

Iodine Intakes of Victorian Schoolchildren Measured Using 24-h Urinary Iodine Excretion

Mandatory fortification of bread with iodized salt was introduced in Australia in 2009, and studies using spot urine collections conducted post fortification indicate that Australian schoolchildren are now replete. However an accurate estimate of daily iodine intake utilizing 24-h urinary iodine excretion (UIE μg/day) has not been reported and compared to the estimated average requirement (EAR). This study aimed to assess daily total iodine intake and status of a sample of primary schoolchildren using 24-h urine samples. Victorian primary school children provided 24-h urine samples between 2011 and 2013, from which urinary iodine concentration (UIC, μg/L) and total iodine excretion (UIE, μg/day) as an estimate of intake was determined. Valid 24-h urine samples were provided by 650 children, mean (SD) age 9.3 (1.8) years (n = 359 boys). The mean UIE of 4–8 and 9–13 year olds was 94 (48) and 111 (57) μg/24-h, respectively, with 29% and 26% having a UIE below the age-specific EAR. The median (IQR) UIC was 124 (83,172) μg/L, with 36% of participants having a UIC < 100 μg/L. This convenience sample of Victorian schoolchildren were found to be iodine replete, based on UIC and estimated iodine intakes derived from 24-h urine collections, confirming the findings of the Australian Health Survey.

Iodine in dairy milk: Sources, concentrations and importance to human health

Milk and dairy products are major iodine sources in industrialized countries. However, consumption of milk and dairy, as well as their iodine concentrations, vary widely, making them an unpredictable iodine source. Milk iodine concentrations in industrialized countries range from 33 to 534 μg/L and are influenced by the iodine intake of dairy cows, goitrogen intake, milk yield, season, teat dipping with iodine-containing disinfectants, type of farming and processing. We estimate milk and dairy contribute ≈13-64% of the recommended daily iodine intake based on country-specific food intake data. To ensure adequate iodine levels but avoid the risk of iodine excess through milk and dairy, it is crucial to reduce the wide variations in milk iodine. If iodine intakes from iodized salt fall because of public health efforts to reduce salt intake, milk and dairy products may become increasingly important sources of dietary iodine in the future.

First Israeli National Iodine Survey Demonstrates Iodine Deficiency Among School-Aged Children and Pregnant Women

BACKGROUND

National data on iodine status in Israel are lacking. Reliance on iodine-depleted desalinated water, the absence of a salt iodization program, and reports of increased use of thyroid medication in Israel suggest that the population's iodine intake is likely inadequate. The aims of this study were therefore to determine the iodine status of Israeli school-age children (SAC) and pregnant women (PW) in a nationally representative sample obtained by a novel approach of using pre-discard urinalysis samples collected from a centralized national laboratory.

METHODS

Spot urine samples from 1023 SAC and 1074 PW, representing all regions and major sectors in Israel, were collected during 2016 at the Maccabi Healthcare Services central laboratory. Urinary iodine concentration (UIC) was measured, and the results were analyzed by trimester, sex, region, and sector.

RESULTS

SAC were iodine deficient, with a median (interquartile range [IQR]) UIC of 83 μg/L (52-127 μg/L); 62% of SAC UICs were below the World Health Organization adequacy range for SAC (100-199 μg/L). PW were also iodine deficient, with a median (IQR) UIC of 61 μg/L (36-97 μg/L); 85% of PW UICs were below the adequacy range for PW (150-249 μg/L). For both SAC and PW, the median UIC was below the World Health Organization's adequacy range across all sectors, sexes, and districts. Among SAC, the median (IQR) UIC was lower among females (75 μg/L; 48-119 μg/L) than males (92 μg/L; 59-133 μg/L; p < 0.05). Median UIC values of PW correlated significantly with the median UIC for SAC by sub-district (R² = 0.3, p < 0.05).

CONCLUSIONS

Urine sampling via a centralized national laboratory was efficient and cost-saving. Iodine deficiency in Israeli SAC and PW is a serious public-health concern. A national program of salt iodization and iodine supplementation of PW should be urgently considered.

Iodine Deficiency, Still a Global Problem?

Iodine Deficiency Disorders are a major public health problem worldwide affecting all groups of people of which children and lactating women are the most vulnerable categories. At a global scale, aproximately 2 billion people suffer of iodine deficiency (ID) of which aproximately 50 million present with clinical manifestations. Assesing iodine levels through different methods has proven to have a key role when discussing treatment options. Screening programs, and early ID diagnostic is important for pregnant women’s follow-up, especially in known countries with iodine dificiency. Universal salt iodization programs have been proposed over the world, but unfortunately have covered about 71% of the world’s population. The aim of this article is to adress the current standings of iodine status and influence on general population with a general focus on newborns and pregnant women and to review the worldwide perspective on available prevention methods.

The effect of growth hormone replacement on the thyroid axis in patients with hypopituitarism: in vivo and ex vivo studies

OBJECTIVE

Alterations in the hypothalamic-pituitary-thyroid axis have been reported following growth hormone (GH) replacement. The aim was to examine the relationship between changes in serum concentration of thyroid hormones and deiodinase activity in subcutaneous adipose tissue, before and after GH replacement.

DESIGN

A prospective, observational study of patients receiving GH replacement as part of routine clinical care.

PATIENTS

Twenty adult hypopituitary men.

MEASUREMENTS

Serum TSH, thyroid hormones - free and total thyroxine (T4) and triiodothyronine (T3) and reverse T3, thyroglobulin and thyroid-binding globulin (TBG) levels were measured before and after GH substitution. Changes in serum hormone levels were compared to the activity of deiodinase isoenzymes (DIO1, DIO2 and DIO3) in subcutaneous adipose tissue.

RESULTS

The mean daily dose of growth hormone (GH) was 0·34 ± 0·11 mg (range 0·15-0·5 mg). Following GH replacement, mean free T4 levels declined (-1·09 ± 1·99 pmol/l, P = 0·02). Reverse T3 levels also fell (-3·44 ± 1·42 ng/dl, P = 0·03) and free T3 levels increased significantly (+0·34 ± 0·15 pmol/l, P = 0·03). In subcutaneous fat, DIO2 enzyme activity declined; DIO1 and DIO3 activities remained unchanged following GH substitution. Serum TSH, thyroglobulin and TBG levels were unaltered by GH therapy.

CONCLUSIONS

In vitro analysis of subcutaneous adipose tissue from hypopituitary human subjects demonstrates that GH replacement is associated with significant changes in deiodinase isoenzyme activity. However, the observed variation in enzyme activity does not explain the changes in the circulating concentration of thyroid hormones induced by GH replacement. It is possible that deiodinase isoenzymes are differentially regulated by GH in other tissues including liver and muscle.

The Iodine Content in Urine, Faeces and Selected Organs of Rats Fed Lettuce Biofortified with Iodine Through Foliar Application

Iodine is an essential trace element for humans. Foliar application of micronutrients is successfully used in order to increase the concentration of essential elements in vegetables. The aim of this study was to evaluate the iodine absorption in the rat organism fed foliar biofortified lettuce. The presented study was consisted of the vegetative and animal experiment. In the vegetative experiment with lettuce, two combinations of foliar application were used: (1) control-without iodine application and (2) iodine application in the potassium iodide (KI) form. In the animal experiment, Wistar rats were divided to four groups, which received one of four diets: (1) C-control diet containing iodine in the KI form, (2) D-diet deficient in iodine, (3) D + BL-diet containing biofortified lettuce, and (4) D + CL-diet containing control lettuce (as the only source of iodine in diet, respectively). The diets contained 0.260, 0.060, 0.254 and 0.075 mg I/kg, respectively. In order to determine the iodine absorption in the rat organisms, the content of this trace element was measured in urine, faeces and in selected organs with the use of the ICP-OES technique. Foliar application of the KI increased the content of iodine in lettuce. The rats from the D + BL group excreted significantly less iodine in their urine and faeces and also accumulated more iodine in the organs than the rats from the C group. Iodine with biofortified lettuce was much bioavailable for rodents than iodine from control diet. Biofortified lettuce can be a source of iodine in a diet of human and can improve iodine nutrition.

Iodine deficiency and associated factors among school children: a cross-sectional study in Ethiopia

Background

Iodine deficiency remains a public health problem in the world. It is the leading cause of preventable mental retardation and brain damage worldwide. Though 12 million school age children are at risk of developing iodine deficiency, there is a scarcity of literature showing the magnitude of iodine deficiency in Ethiopia. Therefore, this study aimed to determine the prevalence and associated factors of iodine deficiency among school children in Robe District, southeast Ethiopia.

Methods

A school based cross–sectional study was conducted from February to June, 2015. A structured interviewer-administered questionnaire was used to collect data. A systematic random sampling technique was employed to select 422 children. A multivariate logistic regression analysis was carried out to identify factors associated with iodine deficiency. In the multivariate analysis, variables with a P-value of <0.05 were considered statistically significant.

Results

A total of 393 school children participated in the study. The median urinary iodine level was 78 μg/l. About 57 and 43.5 % of the children were found with low urinary iodine level and goiter, respectively. Only 29 % of the households utilized adequately iodized salt. The result of the multivariate analysis revealed that the odds of iodine deficiency were higher among female [AOR = 2.23; 95 % CI: 1.54, 3.55] and older (10–12 years) [AOR = 2.21; 95 % CI: 1.44, 3.42] children.

Conclusion

In this community, the prevalence of goiter and low urine iodine level is high. Thus, iodine deficiency exists as severe public health problem. In addition, there is a low utilization of iodized salt in the setting. Therefore, it is crucial to intensify efforts in the implementation of iodized salt. Moreover, attention should be given to school children to address ID.

Median Urinary Iodine Concentrations Are Indicative of Adequate Iodine Status among Women of Reproductive Age in Prey Veng, Cambodia

Iodine deficiency disorders are estimated to affect over 1.9 million people worldwide. Iodine deficiency is especially serious for women during pregnancy and lactation because of the negative consequences for both mother and infant. The aim of this cross-sectional study was to determine the median urinary iodine concentration (UIC) as a population-level indicator of iodine status among rural women farmers of reproductive age (18-45 years) in the province of Prey Veng, Cambodia. A total of 450 women provided a spot morning urine sample in 2012. Of those women, 93% (n = 420) were non-pregnant and 7% (n = 30) were pregnant at the time of collection. UIC was quantified using the Sandell-Kolthoff reaction with modifications. The median UIC of non-pregnant (139 μg/L) and pregnant women (157 μg/L) were indicative of adequate iodine status using the WHO/UNICEF/ICCIDD epidemiological criteria for both groups (median UIC between 100-199 and 150-249 μg/L, respectively). We conclude that non-pregnant and pregnant women in rural Prey Veng, Cambodia had adequate iodine status based on single spot morning urine samples collected in 2012. More research is warranted to investigate iodine status among larger and more representative populations of women in Cambodia, especially in light of recent policy changes to the national program for universal salt iodization.

Ensuring Effective Prevention of Iodine Deficiency Disorders

BACKGROUND

Programs initiated to prevent iodine deficiency disorders (IDD) may not remain effective due to changes in government policies, commercial factors, and human behavior that may affect the efficacy of IDD prevention programs in unpredictable directions. Monitoring and outcome studies are needed to optimize the effectiveness of IDD prevention.

SUMMARY

Although the need for monitoring is compelling, the current reality in Europe is less than optimal. Regular and systematic monitoring surveys have only been established in a few countries, and comparability across the studies is hampered by the lack of centralized standardization procedures. In addition, data on outcomes and the cost of achieving them are needed in order to provide evidence of the beneficial effects of IDD prevention in countries with mild iodine deficiency.

CONCLUSION

Monitoring studies can be optimized by including centralized standardization procedures that improve the comparison between studies. No study of iodine consumption can replace the direct measurement of health outcomes and the evaluation of the costs and benefits of the program. It is particularly important that health economic evaluation should be conducted in mildly iodine-deficient areas and that it should include populations from regions with different environmental, ethnic, and cultural backgrounds.

Iodine intake as a risk factor for thyroid cancer: a comprehensive review of animal and human studies

Thyroid cancer (TC) is the most common endocrine malignancy and in most countries, incidence rates are increasing. Although differences in population iodine intake are a determinant of benign thyroid disorders, the role of iodine intake in TC remains uncertain. We review the evidence linking iodine intake and TC from animal studies, ecological studies of iodine intake and differentiated and undifferentiated TC, iodine intake and mortality from TC and occult TC at autopsy, as well as the case–control and cohort studies of TC and intake of seafood and milk products. We perform a new meta-analysis of pooled measures of effect from case–control studies of total iodine intake and TC. Finally, we examine the post-Chernobyl studies linking iodine status and risk of TC after radiation exposure. The available evidence suggests iodine deficiency is a risk factor for TC, particularly for follicular TC and possibly, for anaplastic TC. This conclusion is based on: a) consistent data showing an increase in TC (mainly follicular) in iodine deficient animals; b) a plausible mechanism (chronic TSH stimulation induced by iodine deficiency); c) consistent data from before and after studies of iodine prophylaxis showing a decrease in follicular TC and anaplastic TC; d) the indirect association between changes in iodine intake and TC mortality in the decade from 2000 to 2010; e) the autopsy studies of occult TC showing higher microcarcinoma rates with lower iodine intakes; and f) the case control studies suggesting lower risk of TC with higher total iodine intakes.

Dietary ratio of animal:plant protein is associated with 24-h urinary iodine excretion in healthy school children

Adequate dietary iodine intake in children is essential for optimal physical and neurological development. Whether lower dietary animal food and salt intake may adversely affect iodine status is under discussion. We examined the association between dietary animal:plant protein ratio with 24-h urinary iodine excretion (24-h UI, μg/d), and whether this is modified by salt intake. A 24-h UI was measured in 1959 24-h urine samples from 516 6- to 12-year-old participants of the Dortmund Nutritional and Anthropometric Longitudinally Designed Study. Parallel 3 d weighed food records were used to estimate dietary intakes. Protein sources were classified as dairy, animal and plant. A repeated-measures regression model (PROC MIXED) was used to analyse the effect of animal:plant protein ratios on 24-h UI.

ANIMAL

plant protein ratios ranged from 0.5 (95 % CI 0.4, 0.6) to 1.6 (95 % CI 1.4, 1.9) (lowest and highest quartile). After adjustment for total energy intake, main dietary iodine sources (dairy and salt intake), and further covariates, the inter-individual variation in animal:plant protein ratio was significantly associated with variation in 24-h UI. One unit higher animal:plant protein ratio predicted 6 μg/d higher 24-h UI (P= 0.002) in boys and 5 μg/d (P= 0.03) in girls. This relationship was partially mediated by a higher salt intake at higher animal:plant protein ratios. These results suggest that lower consumption of animal protein is associated with a small decline in iodine excretion, partially mediated by decreased salt intake. Because limited salt and increased intake of plant-based foods are part of a preferable healthy food pattern, effective nutrition political strategies will be required in the future to ensure appropriate iodine nutrition in adherent populations.

Iodine deficiency and thyroid disorders

Iodine deficiency early in life impairs cognition and growth, but iodine status is also a key determinant of thyroid disorders in adults. Severe iodine deficiency causes goitre and hypothyroidism because, despite an increase in thyroid activity to maximise iodine uptake and recycling in this setting, iodine concentrations are still too low to enable production of thyroid hormone. In mild-to-moderate iodine deficiency, increased thyroid activity can compensate for low iodine intake and maintain euthyroidism in most individuals, but at a price: chronic thyroid stimulation results in an increase in the prevalence of toxic nodular goitre and hyperthyroidism in populations. This high prevalence of nodular autonomy usually results in a further increase in the prevalence of hyperthyroidism if iodine intake is subsequently increased by salt iodisation. However, this increase is transient because iodine sufficiency normalises thyroid activity which, in the long term, reduces nodular autonomy. Increased iodine intake in an iodine-deficient population is associated with a small increase in the prevalence of subclinical hypothyroidism and thyroid autoimmunity; whether these increases are also transient is unclear. Variations in population iodine intake do not affect risk for Graves' disease or thyroid cancer, but correction of iodine deficiency might shift thyroid cancer subtypes toward less malignant forms. Thus, optimisation of population iodine intake is an important component of preventive health care to reduce the prevalence of thyroid disorders.

A robust method for iodine status determination in epidemiological studies by capillary electrophoresis

Iodine deficiency is the most common preventable cause of intellectual disabilities in children. Global health initiatives to ensure optimum nutrition thus require continuous monitoring of population-wide iodine intake as determined by urinary excretion of iodide. Current methods to analyze urinary iodide are limited by complicated sample pretreatment, costly infrastructure, and/or poor selectivity, posing restrictions to large-scale epidemiological studies. We describe a simple yet selective method to analyze iodide in volume-restricted human urine specimens stored in biorepositories by capillary electrophoresis (CE) with UV detection. Excellent selectivity is achieved when using an acidic background electrolyte in conjunction with dynamic complexation via α-cyclodextrin in an unmodified fused-silica capillary under reversed polarity. Sample self-stacking is developed as a novel online sample preconcentration method to boost sensitivity with submicromolar detection limits for iodide (S/N ≈ 3, 0.06 μM) directly in urine. This assay also allows for simultaneous analysis of environmental iodide uptake inhibitors, including thiocyanate and nitrate. Rigorous method validation confirmed good linearity (R(2) = 0.9998), dynamic range (0.20 to 4.0 μM), accuracy (average recovery of 93% at three concentration levels) and precision for reliable iodide determination in pooled urine specimens over 29 days of analysis (RSD = 11%, n = 87).

Biomarkers of nutrition for development--iodine review

The objective of the Biomarkers of Nutrition for Development (BOND) project is to provide state-of-the-art information and service with regard to selection, use, and interpretation of biomarkers of nutrient exposure, status, function, and effect. Specifically, the BOND project seeks to develop consensus on accurate assessment methodologies that are applicable to researchers (laboratory/clinical/surveillance), clinicians, programmers, and policy makers (data consumers). The BOND project is also intended to develop targeted research agendas to support the discovery and development of biomarkers through improved understanding of nutrient biology within relevant biologic systems. In phase I of the BOND project, 6 nutrients (iodine, vitamin A, iron, zinc, folate, and vitamin B-12) were selected for their high public health importance because they typify the challenges faced by users in the selection, use, and interpretation of biomarkers. For each nutrient, an expert panel was constituted and charged with the development of a comprehensive review covering the respective nutrient's biology, existing biomarkers, and specific issues of use with particular reference to the needs of the individual user groups. In addition to the publication of these reviews, materials from each will be extracted to support the BOND interactive Web site (http://www.nichd.nih.gov/global_nutrition/programs/bond/pages/index.aspx). This review represents the first in the series of reviews and covers all relevant aspects of iodine biology and biomarkers. The article is organized to provide the reader with a full appreciation of iodine's background history as a public health issue, its biology, and an overview of available biomarkers and specific considerations for the use and interpretation of iodine biomarkers across a range of clinical and population-based uses. The review also includes a detailed research agenda to address priority gaps in our understanding of iodine biology and assessment.

Iodine deficiency in the U.K.: an overlooked cause of impaired neurodevelopment?

This review describes historical iodine deficiency in the U.K., gives current information on dietary sources of iodine and summarises recent evidence of iodine deficiency and its association with child neurodevelopment. Iodine is required for the production of thyroid hormones that are needed for brain development, particularly during pregnancy. Iodine deficiency is a leading cause of preventable brain damage worldwide and is associated with impaired cognitive function. Despite a global focus on the elimination of iodine deficiency, iodine is a largely overlooked nutrient in the U.K., a situation we have endeavoured to address through a series of studies. Although the U.K. has been considered iodine-sufficient for many years, there is now concern that iodine deficiency may be prevalent, particularly in pregnant women and women of childbearing age; indeed we found mild-to-moderate iodine deficiency in pregnant women in Surrey. As the major dietary source of iodine in the U.K. is milk and dairy produce, it is relevant to note that we have found the iodine concentration of organic milk to be over 40% lower than that of conventional milk. In contrast to many countries, iodised table salt is unlikely to contribute to U.K. iodine intake as we have shown that its availability is low in grocery stores. This situation is of concern as the level of U.K. iodine deficiency is such that it is associated with adverse effects on offspring neurological development; we demonstrated a higher risk of low IQ and poorer reading-accuracy scores in U.K. children born to mothers who were iodine-deficient during pregnancy. Given our findings and those of others, iodine status in the U.K. population should be monitored, particularly in vulnerable subgroups such as pregnant women and children.

Australian children who drink milk (plain or flavored) have higher milk and micronutrient intakes but similar body mass index to those who do not drink milk

In Australia, 60% of children (9-16 years) are not meeting the estimated average requirement (EAR) for calcium, and milk is an important dietary source of calcium. We hypothesized that milk drinking (plain or flavored) would be associated with higher milk and nutrient intake among Australian children. Nutrient intakes reported via 24-hour recalls and anthropometric measurements collected from the 2007 Australian National Children's Nutrition and Physical Activity Survey were analyzed. Children and adolescents (cross sectional, n = 4487, 2-16 years) were classified into 4 categories according to milk intake: (i) exclusively plain milk drinkers, (ii) flavored (flavored and plain) milk drinkers, (iii) nondrinkers of milk (no plain or flavored milk as beverage), and (iv) nonconsumers of milk (total milk intake is 0 g). Total daily milk, energy and nutrient intake, body mass index, and waist circumference were compared between categories of milk drinking by analysis of variance models. Results of this study show that milk drinkers (plain or flavored) had a significantly higher total milk intake than did nondrinkers of milk. Milk drinking was associated with higher intakes of calcium, phosphorus, magnesium, potassium, and iodine in comparison with nondrinkers of milk and nonconsumers of milk (P < .05). Milk drinkers (exclusively plain or flavored) were more likely to meet the EAR for calcium than nondrinkers and nonconsumers of milk, whereas flavored milk drinkers were more likely to meet the EAR for calcium than exclusively plain milk drinkers. In particular, among children aged 9 to 16 years, flavored milk drinkers were 1.7 times more likely to meet the EAR for calcium than plain milk drinkers (P < .001). Although flavored milk drinkers had higher total sugar and energy intakes than did exclusively plain milk drinkers and nonconsumers of milk (P < .05), no between-group differences were observed in body mass index, waist circumference, or physical activity level. In conclusion, drinking milk was associated with higher total milk and micronutrient intake, and drinking both plain and flavored milk may help children meet their calcium requirements without negatively impacting body weight measures.

Gestational changes of thyroid function and urinary iodine in thyroid antibody-negative Japanese women

Iodine is an essential nutrient for thyroid hormone synthesis, and iodine deficiency especially in pregnant and lactating women results in serious damage to their infants. To characterize iodine nutrition throughout gestation by using a food frequency questionnaire (FFQ) and urinary iodine concentration (UIC) measurement, and to establish appropriate gestational age-specific reference ranges for serum TSH and FT₄ in thyroid autoantibody (ThAb) negative euthyroid Japanese women, a total number of 563 pregnant women including 422 subjects with negative ThAbs, 105 postpartum women and their 297 newborn infants were included in the study. Dietary iodine intake (DII) was evaluated by FFQ. Serum TSH, FT₄ and UIC were sequentially determined in the three trimesters of pregnancy and at the 31st postpartum day. The overall median UICs throughout pregnancy and in the postpartum period were 224.0 and 135.0 μg/L, respectively, suggesting sufficient iodine nutrition. The median DII was 842.4 μg/day in pregnant women. The median UIC in the first trimester (215.9 μg/L) significantly decreased in the second trimester (136.0 μg/L). The prevalence of pregnant women with a UIC below 150 μg/L was 31.6% and that in lactating women with a UIC below 100 μg/L was 33.3%. The pattern of gestational change in serum TSH and FT₄ was comparable to that in iodine-sufficient areas. A substantial percentage of women might be at risk for iodine deficiency if there is a restriction of iodine-rich foods. However, iodine supplementation for pregnant women must be carefully balanced against the risk of iodine excess particularly in Japan. Further research in larger samples is needed.

The changing epidemiology of iodine deficiency

Globally, about 2 thousand million people are affected by iodine deficiency. Although endemic goitre is the most visible sign of iodine deficiency, its most devastating consequence is brain damage causing mental retardation in children. The relationship between iodine deficiency and brain damage was not clearly established until the 1980s when the term iodine deficiency disorders (IDDs), which encompass a spectrum of conditions caused by iodine deficiency, was introduced. This paradigm shift in the understanding of the clinical consequences of iodine deficiency led to a change in iodine deficiency assessment. The median urinary iodine excretion level has been recommended as the preferred indicator for monitoring population iodine deficiency status since 2001. The 2007 WHO urinary iodine data in schoolchildren from 130 countries revealed that iodine intake is still insufficient in 47 countries. Furthermore, about one-third of countries lack national estimates of the prevalence of iodine deficiency. The picture that has emerged from available data worldwide over the past two decades is that IDDs are not confined to remote, mountainous areas in developing countries, but are a global public health problem that affects most countries, including developed countries and island nations. The recognition of the universality of iodine deficiency highlights the need to develop and apply new strategies to establish and maintain sustainable IDD elimination and strengthen regular monitoring programmes.

Iodine concentration in fodder influences the dynamics of iodine levels in hen's egg components

In this study we determined the availability and accumulation of iodine in selected structures in hen's eggs: yolk, albumen, and eggshells. Iodine was administered as a yeast-derived biological complex mixed in standard fodder mix "DJ" to laying hens in their maximum egg yield period. The feeding period was sustained for 12 weeks, resulting in iodine enrichment in yolk and eggshells. These results suggest that iodine-enriched yeast can be added to fodder mix and premix (mineral-vitamin) given to monogastric animals such as poultry and pigs.

Iodine fortification: why, when, what, how, and who?

PURPOSE OF REVIEW

To highlight current issues regarding the role of iodine fortification in correcting and preventing iodine deficiency. Universal salt iodization (USI) is recommended, wherein all salt is iodized; however, a more graduated approach may be warranted.

RECENT FINDINGS

Iodine deficiency is widespread and has re-emerged in countries such as Australia, New Zealand and the UK. As well as supplementation in groups such as pregnant and lactating women who have increased iodine requirements, public health strategies to improve iodine intakes include voluntary or mandatory fortification of the food supply. A key player in the process of fortification is the food industry, wherein misperceptions that the addition of iodized salt to foods alters taste and colour still persist and legislation in some countries that prohibits its addition to manufactured foods, can result in a reluctance to support USI.

SUMMARY

Ameliorating iodine deficiency on a population level in countries with mild-to-moderate deficiency is warranted. Risk of both inadequate and excess iodine intakes requires regular monitoring to accompany fortification programmes as well as strategies to address subpopulations at risk. More sensitive indicators of recent iodine status are needed to rapidly assess the impact of fortification on improving the status.

Value and pitfalls in iodine fortification and supplementation in the 21st century

Although the number of iodine-deficient countries has been reduced by almost 50 % over the last decade, it still remains a frequently misunderstood health problem. The most devastating effects of iodine deficiency occur during fetal development and childhood, periods in which sufficient iodine delivery remains critical. Besides the determination of thyroid size, the concentration of urinary iodine, serum thyroid-stimulating hormone and serum thyroglobulin are useful biomarkers to assess iodine status. Severe iodine deficiency is associated with neurological complications, cretinism, endemic goitre development, hypothyroidism, decreased fertility and increased infant mortality. The recommended iodine supplementation strategies are based on correction of iodine deficiency, close monitoring and evaluation of iodine administration, cooperation of the salt industry, training of local health care professionals and education of the population. Besides the multiple beneficial effects of supplementation, we present in this review a critical look at the possible side effects.

Health benefits of marine foods and ingredients

The health benefits of seafood consumption have primarily been associated with protective effects against cardiovascular diseases (CVD). However, intake of seafood has also been associated with improved foetal and infant development, as well as several other diseases and medical conditions. The health promoting effects have chiefly been attributed to the long-chain n-3 polyunsaturated fatty acids (n-3 PUFA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In addition, the general fatty acid profile is considered favourable. On the other hand, recent and emerging research on seafood proteins and other seafood derived components suggest that these nutritional components contribute to the health effects. In this paper we review the nutritional characteristics and health benefits of marine foods and ingredients, and discuss some current and future trends in marine food production.

Schoolchildren in the Principality of Liechtenstein are mildly iodine deficient

OBJECTIVE

To investigate the iodine status of schoolchildren in the Principality of Liechtenstein.

DESIGN

A representative, cross-sectional principality-wide screening of iodine level in household salt and urinary iodine concentrations (UIC) in primary-school children. Data were compared with the WHO criteria and with 2009 iodine survey data from Switzerland, a neighbouring country that supplies most of the salt used in Liechtenstein.

SETTINGS

Principality of Liechtenstein.

SUBJECTS

Schoolchildren (n 228) aged 6-12 years from five different primary schools representing 11·4 % of the children at this age.

RESULTS

The median UIC was 96 (range: 10-446) μg/l; 11 %, 56 % and 1 % of children had a UIC <50, <100 and >300 μg/l, respectively. In all, 79 % of households were using adequately iodised salt (≥15 ppm). The median UIC was 20 % lower than that in children at comparable age in Switzerland (120 μg/l; P < 0·05).

CONCLUSIONS

According to the WHO criteria, schoolchildren in Liechtenstein are mildly iodine deficient and household iodised salt coverage is inadequate. Public health measures to increase iodine intakes in the Principality should be considered.