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Special Issue "Iodine and Health throughout the Lifecourse"

A special issue of Nutrients (ISSN 2072-6643).

Deadline for manuscript submissions: closed (1 February 2018)

Special Issue Editors

Guest Editor
Dr. Emilie Combet

Human Nutrition, School of Medicine, College of Medical, Veterinary and Life Sciences, 10–16 Alexandra Parade, University of Glasgow, Glasgow G31 2ER, UK
Website | E-Mail
Phone: +44 (0) 141 201 8527
Interests: iodine; lifecourse; nutrition; polyphenolics; nutrient profiling; glycation; oxidative stress; biomarkers; metabolic health; obesity
Guest Editor
Dr. Karen Charlton

School of Medicine, Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW, 2522, Australia
Website | E-Mail
Interests: nutritional epidemiology; chronic disease; nutrition, health and ageing; food and nutrition monitoring; food security; salt reduction; micronutrient status of populations; dietary methodology

Special Issue Information

Dear Colleagues,

Iodine is a key nutrient required for the formation of the thyroid hormones. Iodine deficiency, a preventable cause of brain damage and impaired development, remains a challenge to lifelong health globally. Design and implementation of successful strategies to prevent iodine insufficiency requires an in-depth understanding of the personal and societal factors influencing food choices, dietary behaviour and policy-making, as well as key physiological and molecular events linking iodine, metabolism and physical and cognitive development.

This Special Issue of Nutrients, entitled "Iodine and Health Throughout the Lifecourse", welcomes the submission of manuscripts describing either original research or systematic reviews and meta-analyses.

Potential topics may include, but are not limited to:

  • Prevention of iodine deficiency instead of Iodine prophylaxis
  • Iodine and cognitive function in older adults
  • Iodine and neurocognitive development in pregnancy and childhood
  • Health promotion and interventions to improve iodine status in vulnerable groups
  • Effectiveness of iodine fortification policies
  • Epidemiological and health economics studies
  • Animal and in vitro models supporting novel molecular understanding of the role of iodine in development and ageing
  • Novel methods to better determine iodine status of individuals
Dr. Emilie Combet
Dr. Karen Charlton
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nutrients is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • iodine
  • thyroid
  • neurodevelopment
  • lifecycle
  • supplementation

Published Papers (16 papers)

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Research

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Open AccessArticle
Iodine Status Assessment in South African Adults According to Spot Urinary Iodine Concentrations, Prediction Equations, and Measured 24-h Iodine Excretion
Nutrients 2018, 10(6), 736; https://doi.org/10.3390/nu10060736
Received: 12 May 2018 / Revised: 31 May 2018 / Accepted: 1 June 2018 / Published: 7 June 2018
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Abstract
The iodine status of populations is conventionally assessed using spot urinary samples to obtain a median urinary iodine concentration (UIC) value, which is assessed against standard reference cut-offs. The assumption that spot UIC reflects daily iodine intake may be flawed because of high [...] Read more.
The iodine status of populations is conventionally assessed using spot urinary samples to obtain a median urinary iodine concentration (UIC) value, which is assessed against standard reference cut-offs. The assumption that spot UIC reflects daily iodine intake may be flawed because of high day-to-day variability and variable urinary volume outputs. This study aimed to compare iodine status in a sample of South African adults when determined by different approaches using a spot urine sample (median UIC (MUIC), predicted 24 h urinary iodine excretion (PrUIE) using different prediction equations) against measured 24 h urinary iodine excretion (mUIE). Both 24 h and spot urine samples were collected in a subsample of participants (n = 457; median age 55 year; range 18–90 year) in the World Health Organization Study on global AGEing and adult health (SAGE) Wave 2 in South Africa, in 2015. Kawasaki, Tanaka, and Mage equations were applied to assess PrUIE from predicted urinary creatinine (PrCr) and spot UIC values. Adequacy of iodine intake was assessed by comparing PrUIE and mUIE to the Estimated Average Requirement of 95 µg/day, while the MUIC cut-off was <100 µg/L. Bland Altman plots assessed the level of agreement between measured and predicted UIE. Median UIC (130 µg/L) indicated iodine sufficiency. The prediction equations had unacceptable bias for PrUIE compared to measured UIE. In a sample of adult South Africans, the use of spot UIC, presented as a group median value (MUIC) provided similar estimates of inadequate iodine status, overall, when compared to EAR assessed using measured 24 h iodine excretion (mUIE). Continued use of MUIC as a biomarker to assess the adequacy of population iodine intake appears warranted. Full article
(This article belongs to the Special Issue Iodine and Health throughout the Lifecourse)
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Open AccessArticle
Regression Analysis to Identify Factors Associated with Urinary Iodine Concentration at the Sub-National Level in India, Ghana, and Senegal
Nutrients 2018, 10(4), 516; https://doi.org/10.3390/nu10040516
Received: 20 February 2018 / Revised: 13 April 2018 / Accepted: 16 April 2018 / Published: 21 April 2018
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Abstract
Single and multiple variable regression analyses were conducted using data from stratified, cluster sample design, iodine surveys in India, Ghana, and Senegal to identify factors associated with urinary iodine concentration (UIC) among women of reproductive age (WRA) at the national and sub-national level. [...] Read more.
Single and multiple variable regression analyses were conducted using data from stratified, cluster sample design, iodine surveys in India, Ghana, and Senegal to identify factors associated with urinary iodine concentration (UIC) among women of reproductive age (WRA) at the national and sub-national level. Subjects were survey household respondents, typically WRA. For all three countries, UIC was significantly different (p < 0.05) by household salt iodine category. Other significant differences were by strata and by household vulnerability to poverty in India and Ghana. In multiple variable regression analysis, UIC was significantly associated with strata and household salt iodine category in India and Ghana (p < 0.001). Estimated UIC was 1.6 (95% confidence intervals (CI) 1.3, 2.0) times higher (India) and 1.4 (95% CI 1.2, 1.6) times higher (Ghana) among WRA from households using adequately iodised salt than among WRA from households using non-iodised salt. Other significant associations with UIC were found in India, with having heard of iodine deficiency (1.2 times higher; CI 1.1, 1.3; p < 0.001) and having improved dietary diversity (1.1 times higher, CI 1.0, 1.2; p = 0.015); and in Ghana, with the level of tomato paste consumption the previous week (p = 0.029) (UIC for highest consumption level was 1.2 times lowest level; CI 1.1, 1.4). No significant associations were found in Senegal. Sub-national data on iodine status are required to assess equity of access to optimal iodine intake and to develop strategic responses as needed. Full article
(This article belongs to the Special Issue Iodine and Health throughout the Lifecourse)
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Open AccessArticle
Iodine Deficiency in a Study Population of Norwegian Pregnant Women—Results from the Little in Norway Study (LiN)
Nutrients 2018, 10(4), 513; https://doi.org/10.3390/nu10040513
Received: 22 March 2018 / Revised: 14 April 2018 / Accepted: 18 April 2018 / Published: 20 April 2018
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Abstract
Iodine sufficiency is particularly important in pregnancy, where median urinary iodine concentration (UIC) in the range of 150–250 µg/L indicates adequate iodine status. The aims of this study were to determine UIC and assess if dietary and maternal characteristics influence the iodine status [...] Read more.
Iodine sufficiency is particularly important in pregnancy, where median urinary iodine concentration (UIC) in the range of 150–250 µg/L indicates adequate iodine status. The aims of this study were to determine UIC and assess if dietary and maternal characteristics influence the iodine status in pregnant Norwegian women. The study comprises a cross-sectional population-based prospective cohort of pregnant women (Little in Norway (LiN)). Median UIC in 954 urine samples was 85 µg/L and 78.4% of the samples (n = 748) were ≤150 µg/L. 23.2% (n = 221) of the samples were ≤50 µg/L and 5.2% (n = 50) were above the requirements of iodine intake (>250 µg/L). Frequent iodine-supplement users (n = 144) had significantly higher UIC (120 µg/L) than non-frequent users (75 µg/L). Frequent milk and dairy product consumers (4–9 portions/day) had significantly higher UIC (99 µg/L) than women consuming 0–1 portion/day (57 µg/L) or 2–3 portions/day (83 µg/L). Women living in mid-Norway (n = 255) had lowest UIC (72 µg/L). In conclusion, this study shows that the diet of the pregnant women did not necessarily secure a sufficient iodine intake. There is an urgent need for public health strategies to secure adequate iodine nutrition among pregnant women in Norway. Full article
(This article belongs to the Special Issue Iodine and Health throughout the Lifecourse)
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Open AccessArticle
Regression Analysis to Identify Factors Associated with Household Salt Iodine Content at the Sub-National Level in Bangladesh, India, Ghana and Senegal
Nutrients 2018, 10(4), 508; https://doi.org/10.3390/nu10040508
Received: 2 March 2018 / Revised: 2 April 2018 / Accepted: 12 April 2018 / Published: 19 April 2018
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Abstract
Regression analyses of data from stratified, cluster sample, household iodine surveys in Bangladesh, India, Ghana and Senegal were conducted to identify factors associated with household access to adequately iodised salt. For all countries, in single variable analyses, household salt iodine was significantly different [...] Read more.
Regression analyses of data from stratified, cluster sample, household iodine surveys in Bangladesh, India, Ghana and Senegal were conducted to identify factors associated with household access to adequately iodised salt. For all countries, in single variable analyses, household salt iodine was significantly different (p < 0.05) between strata (geographic areas with representative data, defined by survey design), and significantly higher (p < 0.05) among households: with better living standard scores, where the respondent knew about iodised salt and/or looked for iodised salt at purchase, using salt bought in a sealed package, or using refined grain salt. Other country-level associations were also found. Multiple variable analyses showed a significant association between salt iodine and strata (p < 0.001) in India, Ghana and Senegal and that salt grain type was significantly associated with estimated iodine content in all countries (p < 0.001). Salt iodine relative to the reference (coarse salt) ranged from 1.3 (95% CI 1.2, 1.5) times higher for fine salt in Senegal to 3.6 (95% CI 2.6, 4.9) times higher for washed and 6.5 (95% CI 4.9, 8.8) times higher for refined salt in India. Sub-national data are required to monitor equity of access to adequately iodised salt. Improving household access to refined iodised salt in sealed packaging, would improve iodine intake from household salt in all four countries in this analysis, particularly in areas where there is significant small-scale salt production. Full article
(This article belongs to the Special Issue Iodine and Health throughout the Lifecourse)
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Open AccessArticle
New Statistical Approach to Apportion Dietary Sources of Iodine Intake: Findings from Kenya, Senegal and India
Nutrients 2018, 10(4), 430; https://doi.org/10.3390/nu10040430
Received: 30 January 2018 / Revised: 13 March 2018 / Accepted: 27 March 2018 / Published: 29 March 2018
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Abstract
Progress of national Universal Salt Iodization (USI) strategies is typically assessed by household coverage of adequately iodized salt and median urinary iodine concentration (UIC) in spot urine collections. However, household coverage does not inform on the iodized salt used in preparation of processed [...] Read more.
Progress of national Universal Salt Iodization (USI) strategies is typically assessed by household coverage of adequately iodized salt and median urinary iodine concentration (UIC) in spot urine collections. However, household coverage does not inform on the iodized salt used in preparation of processed foods outside homes, nor does the total UIC reflect the portion of population iodine intake attributable to the USI strategy. This study used data from three population-representative surveys of women of reproductive age (WRA) in Kenya, Senegal and India to develop and illustrate a new approach to apportion the population UIC levels by the principal dietary sources of iodine intake, namely native iodine, iodine in processed food salt and iodine in household salt. The technique requires measurement of urinary sodium concentrations (UNaC) in the same spot urine samples collected for iodine status assessment. Taking into account the different complex survey designs of each survey, generalized linear regression (GLR) analyses were performed in which the UIC data of WRA was set as the outcome variable that depends on their UNaC and household salt iodine (SI) data as explanatory variables. Estimates of the UIC portions that correspond to iodine intake sources were calculated with use of the intercept and regression coefficients for the UNaC and SI variables in each country’s regression equation. GLR coefficients for UNaC and SI were significant in all country-specific models. Rural location did not show a significant association in any country when controlled for other explanatory variables. The estimated UIC portion from native dietary iodine intake in each country fell below the minimum threshold for iodine sufficiency. The UIC portion arising from processed food salt in Kenya was substantially higher than in Senegal and India, while the UIC portions from household salt use varied in accordance with the mean level of household SI content in the country surveys. The UIC portions and all-salt-derived iodine intakes found in this study were illustrative of existing differences in national USI legislative frameworks and national salt supply situations between countries. The approach of apportioning the population UIC from spot urine collections may be useful for future monitoring of change in iodine nutrition from reduced salt use in processed foods and in households. Full article
(This article belongs to the Special Issue Iodine and Health throughout the Lifecourse)
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Open AccessFeature PaperArticle
Iodine and Pregnancy—A Qualitative Study Focusing on Dietary Guidance and Information
Nutrients 2018, 10(4), 408; https://doi.org/10.3390/nu10040408
Received: 1 February 2018 / Revised: 16 March 2018 / Accepted: 23 March 2018 / Published: 26 March 2018
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Abstract
Iodine is essential for thyroid hormones synthesis and normal neurodevelopment; however, ~60% of pregnant women do not meet the WHO (World Health Organization) recommended intake. Using a qualitative design, we explored the perceptions, awareness, and experiences of pregnancy nutrition, focusing on iodine. Women [...] Read more.
Iodine is essential for thyroid hormones synthesis and normal neurodevelopment; however, ~60% of pregnant women do not meet the WHO (World Health Organization) recommended intake. Using a qualitative design, we explored the perceptions, awareness, and experiences of pregnancy nutrition, focusing on iodine. Women in the perinatal period (n = 48) were interviewed and filled in a food frequency questionnaire for iodine. Almost all participants achieved the recommended 150 μg/day intake for non-pregnant adults (99%), but only 81% met the increased demands of pregnancy (250 μg/day). Most were unaware of the importance, sources of iodine, and recommendations for iodine intake. Attitudes toward dairy products consumption were positive (e.g., helps with heartburn; easy to increase). Increased fish consumption was considered less achievable, with barriers around taste, smell, heartburn, and morning sickness. Community midwives were the main recognised provider of dietary advice. The dietary advice received focused most often on multivitamin supplements rather than food sources. Analysis highlighted a clear theme of commitment to change behaviour, motivated by pregnancy, with a desired focus on user-friendly documentation and continued involvement of the health services. The study highlights the importance of redirecting advice on dietary requirements in pregnancy and offers practical suggestions from women in the perinatal period as the main stakeholder group. Full article
(This article belongs to the Special Issue Iodine and Health throughout the Lifecourse)
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Open AccessArticle
Stakeholders’ Perceptions of Agronomic Iodine Biofortification: A SWOT-AHP Analysis in Northern Uganda
Nutrients 2018, 10(4), 407; https://doi.org/10.3390/nu10040407
Received: 31 January 2018 / Revised: 21 March 2018 / Accepted: 22 March 2018 / Published: 24 March 2018
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Abstract
Agronomic biofortification (i.e., the application of fertilizer to elevate micronutrient concentrations in staple crops) is a recent strategy recommended for controlling Iodine Deficiency Disorders (IDDs). However, its success inevitably depends on stakeholders’ appreciation and acceptance of it. By taking Northern Uganda as a [...] Read more.
Agronomic biofortification (i.e., the application of fertilizer to elevate micronutrient concentrations in staple crops) is a recent strategy recommended for controlling Iodine Deficiency Disorders (IDDs). However, its success inevitably depends on stakeholders’ appreciation and acceptance of it. By taking Northern Uganda as a case, this study aimed to capture and compare the perceptions of seven key stakeholder groups with respect to agronomic iodine biofortification. Therefore, we employed a SWOT (Strength, Weaknesses, Opportunities & Threats) analysis in combination with an Analytical Hierarchy Process (AHP). Findings show that stakeholders (n = 56) are generally positive about agronomic iodine biofortification in Uganda, as its strengths and opportunities outweighed weaknesses and threats. Cultural acceptance and effectiveness are considered the most important strengths while the high IDD prevalence rate and the availability of iodine deficient soils are key opportunities for further developing agronomic iodine biofortification. Environmental concerns about synthetic fertilizers as well as the time needed to supply iodine were considered crucial weaknesses. The limited use of fertilizer in Uganda was the main threat. While this study provides insight into important issues and priorities for iodine biofortification technology in Uganda, including differences in stakeholder views, the application of the SWOT-AHP method will guide future researchers and health planners conducting stakeholder analysis in similar domains. Full article
(This article belongs to the Special Issue Iodine and Health throughout the Lifecourse)
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Open AccessArticle
Iodine Intake Estimation from the Consumption of Instant Noodles, Drinking Water and Household Salt in Indonesia
Nutrients 2018, 10(3), 324; https://doi.org/10.3390/nu10030324
Received: 26 December 2017 / Revised: 24 February 2018 / Accepted: 7 March 2018 / Published: 8 March 2018
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Abstract
The objective of this study was to assess the contribution of iodine intake from iodised household salt, iodised salt in instant noodles, and iodine in ground water in five regions of Indonesia. Secondary data analysis was performed using the 2013 Primary Health Research [...] Read more.
The objective of this study was to assess the contribution of iodine intake from iodised household salt, iodised salt in instant noodles, and iodine in ground water in five regions of Indonesia. Secondary data analysis was performed using the 2013 Primary Health Research Survey, the 2014 Total Diet Study, and data from food industry research. Iodine intake was estimated among 2719 children, 10–12 years of age (SAC), 13,233 women of reproductive age (WRA), and 578 pregnant women (PW). Combined estimated iodine intake from the three stated sources met 78%, 70%, and 41% of iodine requirements for SAC, WRA and PW, respectively. Household salt iodine contributed about half of the iodine requirements for SAC (49%) and WRA (48%) and a quarter for PW (28%). The following variations were found: for population group, the percentage of estimated dietary iodine requirements met by instant noodle consumption was significantly higher among SAC; for region, estimated iodine intake was significantly higher from ground water for WRA in Java, and from household salt for SAC and WRA in Kalimantan and Java; and for household socio-economic status (SES), iodine intake from household salt was significantly higher in the highest SES households. Enforcement of clear implementing regulations for iodisation of household and food industry salt will promote optimal iodine intake among all population groups with different diets. Full article
(This article belongs to the Special Issue Iodine and Health throughout the Lifecourse)
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Open AccessArticle
Iodine Status during Pregnancy in a Region of Mild-to-Moderate Iodine Deficiency is not Associated with Adverse Obstetric Outcomes; Results from the Avon Longitudinal Study of Parents and Children (ALSPAC)
Nutrients 2018, 10(3), 291; https://doi.org/10.3390/nu10030291
Received: 31 January 2018 / Revised: 20 February 2018 / Accepted: 22 February 2018 / Published: 1 March 2018
Cited by 4 | PDF Full-text (270 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Severe iodine deficiency during pregnancy has been associated with pregnancy/neonatal loss, and adverse pregnancy outcomes; however, the impact of mild–to–moderate iodine insufficiency, though prevalent in pregnancy, is not well-documented. We assessed whether mild iodine deficiency during pregnancy was associated with pregnancy/infant loss, or [...] Read more.
Severe iodine deficiency during pregnancy has been associated with pregnancy/neonatal loss, and adverse pregnancy outcomes; however, the impact of mild–to–moderate iodine insufficiency, though prevalent in pregnancy, is not well-documented. We assessed whether mild iodine deficiency during pregnancy was associated with pregnancy/infant loss, or with other adverse pregnancy outcomes. We used samples and data from the Avon Longitudinal Study of Parents and Children (ALSPAC), from 3140 singleton pregnancies and from a further 42 women with pregnancy/infant loss. The group was classified as mildly-to-moderately iodine deficient with a median urinary iodine concentration of 95.3 µg/L (IQR 57.0–153.0; median urinary iodine-to-creatinine ratio (UI/Creat) 124 µg/g, IQR 82–198). The likelihood of pregnancy/infant loss was not different across four UI/Creat groups (<50, 50–149, 150–250, >250 µg/g). The incidence of pre-eclampsia, non-proteinuric gestational hypertension, gestational diabetes, glycosuria, anaemia, post-partum haemorrhage, preterm delivery, mode of delivery, being small for gestational age, and large for gestational age did not differ significantly among UI/Creat groups, nor were there any significant differences in the median UI/Creat. We conclude that maternal iodine status was not associated with adverse pregnancy outcomes in a mildly-to-moderately iodine-deficient pregnant population. However, in view of the low number of women with pregnancy/infant loss in our study, further research is required. Full article
(This article belongs to the Special Issue Iodine and Health throughout the Lifecourse)
Open AccessArticle
The Effect of Processing and Seasonality on the Iodine and Selenium Concentration of Cow’s Milk Produced in Northern Ireland (NI): Implications for Population Dietary Intake
Nutrients 2018, 10(3), 287; https://doi.org/10.3390/nu10030287
Received: 1 February 2018 / Revised: 22 February 2018 / Accepted: 25 February 2018 / Published: 1 March 2018
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Abstract
Cow’s milk is the most important dietary source of iodine in the UK and Ireland, and also contributes to dietary selenium intakes. The aim of this study was to investigate the effect of season, milk fat class (whole; semi-skimmed; skimmed) and pasteurisation on [...] Read more.
Cow’s milk is the most important dietary source of iodine in the UK and Ireland, and also contributes to dietary selenium intakes. The aim of this study was to investigate the effect of season, milk fat class (whole; semi-skimmed; skimmed) and pasteurisation on iodine and selenium concentrations in Northern Ireland (NI) milk, and to estimate the contribution of this milk to consumer iodine and selenium intakes. Milk samples (unpasteurised, whole, semi-skimmed and skimmed) were collected weekly from two large NI creameries between May 2013 and April 2014 and were analysed by inductively coupled plasma-mass spectrometry (ICP-MS). Using milk consumption data from the National Diet and Nutrition Survey (NDNS) Rolling Programme, the contribution of milk (at iodine and selenium concentrations measured in the present study) to UK dietary intakes was estimated. The mean ± standard deviation (SD) iodine concentration of milk was 475.9 ± 63.5 µg/kg and the mean selenium concentration of milk was 17.8 ± 2.7 µg/kg. Season had an important determining effect on the iodine, but not the selenium, content of cow’s milk, where iodine concentrations were highest in milk produced in spring compared to autumn months (534.3 ± 53.7 vs. 433.6 ± 57.8 µg/kg, respectively; p = 0.001). The measured iodine and selenium concentrations of NI milk were higher than those listed in current UK Food Composition Databases (Food Standards Agency (FSA) (2002); FSA (2015)). The dietary modelling analysis confirmed that milk makes an important contribution to iodine and selenium intakes. This contribution may be higher than previously estimated if iodine and selenium (+25.0 and +1.1 µg/day respectively) concentrations measured in the present study were replicable across the UK at the current level of milk consumption. Iodine intakes were theoretically shown to vary by season concurrent with the seasonal variation in NI milk iodine concentrations. Routine monitoring of milk iodine concentrations is required and efforts should be made to understand reasons for fluctuations in milk iodine concentrations, in order to realise the nutritional impact to consumers. Full article
(This article belongs to the Special Issue Iodine and Health throughout the Lifecourse)
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Open AccessArticle
Suboptimal Iodine Status among Pregnant Women in the Oslo Area, Norway
Nutrients 2018, 10(3), 280; https://doi.org/10.3390/nu10030280
Received: 31 January 2018 / Revised: 19 February 2018 / Accepted: 22 February 2018 / Published: 28 February 2018
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Abstract
Norway has been considered iodine replete for decades; however, recent studies indicate reemergence of inadequate iodine status in different population groups. We assessed iodine status in pregnant women based on urinary iodine concentration (UIC), urinary iodine excretion (UIE), and iodine intake from food [...] Read more.
Norway has been considered iodine replete for decades; however, recent studies indicate reemergence of inadequate iodine status in different population groups. We assessed iodine status in pregnant women based on urinary iodine concentration (UIC), urinary iodine excretion (UIE), and iodine intake from food and supplements. In 804 pregnant women, 24-h iodine intakes from iodine-rich foods and iodine-containing supplements were calculated. In 777 women, iodine concentration was measured in spot urine samples by inductively coupled plasma/mass spectrometry (ICP-MS). In addition, 49 of the women collected a 24-h urine sample for assessment of UIE and iodine intake from food frequency questionnaire (FFQ). Median UIC was 92 µg/L. Fifty-five percent had a calculated iodine intake below estimated average requirement (EAR) (160 µg/day). Iodine intake from food alone did not provide the amount of iodine required to meet maternal and fetal needs during pregnancy. In multiple regression models, hypothyroidism, supplemental iodine and maternal age were positively associated with UIC, while gestational age and smoking were negatively associated, explaining 11% of the variance. This study clearly shows that pregnant women in the Oslo area are mild to moderate iodine deficient and public health strategies are needed to improve and secure adequate iodine status. Full article
(This article belongs to the Special Issue Iodine and Health throughout the Lifecourse)
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Open AccessArticle
Inadequate Iodine Intake in Population Groups Defined by Age, Life Stage and Vegetarian Dietary Practice in a Norwegian Convenience Sample
Nutrients 2018, 10(2), 230; https://doi.org/10.3390/nu10020230
Received: 29 December 2017 / Revised: 9 February 2018 / Accepted: 14 February 2018 / Published: 17 February 2018
Cited by 10 | PDF Full-text (984 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Inadequate iodine intake has been identified in populations considered iodine replete for decades. The objective of the current study is to evaluate urinary iodine concentration (UIC) and the probability of adequate iodine intake in subgroups of the Norwegian population defined by age, life [...] Read more.
Inadequate iodine intake has been identified in populations considered iodine replete for decades. The objective of the current study is to evaluate urinary iodine concentration (UIC) and the probability of adequate iodine intake in subgroups of the Norwegian population defined by age, life stage and vegetarian dietary practice. In a cross-sectional survey, we assessed the probability of adequate iodine intake by two 24-h food diaries and UIC from two fasting morning spot urine samples in 276 participants. The participants included children (n = 47), adolescents (n = 46), adults (n = 71), the elderly (n = 23), pregnant women (n = 45), ovo-lacto vegetarians (n = 25), and vegans (n = 19). In all participants combined, the median (95% CI) UIC was 101 (90, 110) µg/L, median (25th, 75th percentile) calculated iodine intake was 112 (77, 175) µg/day and median (25th, 75th percentile) estimated usual iodine intake was 101 (75, 150) µg/day. According to WHOs criteria for evaluation of median UIC, iodine intake was inadequate in the elderly, pregnant women, vegans and non-pregnant women of childbearing age. Children had the highest (82%) and vegans the lowest (14%) probability of adequate iodine intake according to reported food and supplement intakes. This study confirms the need for monitoring iodine intake and status in nationally representative study samples in Norway. Full article
(This article belongs to the Special Issue Iodine and Health throughout the Lifecourse)
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Open AccessArticle
Reduced Educational Outcomes Persist into Adolescence Following Mild Iodine Deficiency in Utero, Despite Adequacy in Childhood: 15-Year Follow-Up of the Gestational Iodine Cohort Investigating Auditory Processing Speed and Working Memory
Nutrients 2017, 9(12), 1354; https://doi.org/10.3390/nu9121354
Received: 17 November 2017 / Revised: 1 December 2017 / Accepted: 9 December 2017 / Published: 13 December 2017
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Abstract
There is increasing evidence that even mild gestational iodine deficiency (GID) results in adverse neurocognitive impacts on offspring. It’s unclear, however, if these persist long-term and whether they can be ameliorated by iodine sufficiency in childhood. We followed a unique cohort (Gestational Iodine [...] Read more.
There is increasing evidence that even mild gestational iodine deficiency (GID) results in adverse neurocognitive impacts on offspring. It’s unclear, however, if these persist long-term and whether they can be ameliorated by iodine sufficiency in childhood. We followed a unique cohort (Gestational Iodine Cohort, n = 266) where gestation occurred during a period of mild population iodine deficiency, with children subsequently growing-up in an iodine replete environment. We investigated whether associations between mild GID and reductions in literacy outcomes, observed at age 9-years, persisted into adolescence. Comparisons were made between offspring of mothers with gestational urinary iodine concentrations (UICs) ≥ 150 μg/L and < 150 μg/L. Educational outcomes were measured using Australian National Assessment Program—Literacy and Numeracy (NAPLAN) tests. Children whose mothers had UICs < 150 μg/L exhibited persistent reductions in spelling from Year 3 (10%, −41.4 points (95% Confidence Interval −65.1 to −17.6, p = 0.001)) to Year 9 (5.6%, −31.6 (−57.0 to −6.2, p = 0.015)) compared to children whose mothers had UICs ≥ 150 μg/L. Associations remained after adjustment for biological factors, socioeconomic status and adolescent UIC. Results support the hypothesis that mild GID may impact working memory and auditory processing speed. The findings have important public health implications for management of iodine nutrition in pregnancy. Full article
(This article belongs to the Special Issue Iodine and Health throughout the Lifecourse)
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Open AccessArticle
Maternal Iodine Intake and Offspring Attention-Deficit/Hyperactivity Disorder: Results from a Large Prospective Cohort Study
Nutrients 2017, 9(11), 1239; https://doi.org/10.3390/nu9111239
Received: 10 October 2017 / Revised: 3 November 2017 / Accepted: 8 November 2017 / Published: 13 November 2017
Cited by 17 | PDF Full-text (1197 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Current knowledge about the relationship between mild to moderately inadequate maternal iodine intake and/or supplemental iodine on child neurodevelopment is sparse. Using information from 77,164 mother-child pairs in the Norwegian Mother and Child Cohort Study, this study explored associations between maternal iodine intake [...] Read more.
Current knowledge about the relationship between mild to moderately inadequate maternal iodine intake and/or supplemental iodine on child neurodevelopment is sparse. Using information from 77,164 mother-child pairs in the Norwegian Mother and Child Cohort Study, this study explored associations between maternal iodine intake and child attention-deficit/hyperactivity disorder (ADHD) diagnosis, registered in the Norwegian Patient Registry and maternally-reported child ADHD symptoms at eight years of age. Pregnant women reported food and supplement intakes by questionnaire in gestational week 22. In total, 1725 children (2.2%) were diagnosed with ADHD. In non-users of supplemental iodine (53,360 mothers), we found no association between iodine intake from food and risk of child ADHD diagnosis (p = 0.89), while low iodine from food (<200 µg/day) was associated with higher child ADHD symptom scores (adjusted difference in score up to 0.08 standard deviation (SD), p < 0.001, n = 19,086). In the total sample, we found no evidence of beneficial effects of maternal use of iodine-containing supplements (n = 23,804) on child ADHD diagnosis or symptom score. Initiation of iodine supplement use in gestational weeks 0–12 was associated with an increased risk of child ADHD (both measures). In conclusion, insufficient maternal iodine intake was associated with increased child ADHD symptom scores at eight years of age, but not with ADHD diagnosis. No reduction of risk was associated with maternal iodine supplement use. Full article
(This article belongs to the Special Issue Iodine and Health throughout the Lifecourse)
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Open AccessArticle
The Impact of Iodine Status on the Recall Rate of the Screening Program for Congenital Hypothyroidism: Findings from Two National Studies in Iran
Nutrients 2017, 9(11), 1194; https://doi.org/10.3390/nu9111194
Received: 3 August 2017 / Revised: 14 October 2017 / Accepted: 18 October 2017 / Published: 30 October 2017
Cited by 3 | PDF Full-text (382 KB) | HTML Full-text | XML Full-text
Abstract
Back ground: Iodine deficiency is one of the important factors in increasing the recall rate in congenital hypothyroidism (CH) screening programs. The present study assessed whether the iodine status of the general population may predict the recall rate or vice versa. Methods: In [...] Read more.
Back ground: Iodine deficiency is one of the important factors in increasing the recall rate in congenital hypothyroidism (CH) screening programs. The present study assessed whether the iodine status of the general population may predict the recall rate or vice versa. Methods: In the current national study, among 1,382,229 live births delivered between March 2010 and March 2011, 1,288,237 neonates were screened for detecting CH by TSH (thyroid stimulating hormone) measurement via heel prick sampling. Simultaneously, a total of 11,280 school-aged children, aged 7–8 years, were selected using random multi-cluster sampling for measurement of urinary iodine. Results: A negative correlation was found between median urinary iodine (MUI) and the recall rate (r = −0.33, p = 0.03). No correlation was found between MUIC (median urinary iodine concentration) and the incidence rate of CH. Linear regression analysis showed a 0.1% increase in the recall rate for a one unit decrease in MUIC (β = −0.11, 95% CI: −0.2, −0.1, p = 0.03). MUIC, at a cut-off point of 144.7 µg/L, was predictive for a recall rate < 3% (p = 0.05). Conclusion: Frequencies of TSH ≥ 5 mU/L may be a more sensitive indicator for iodine status during pregnancy rather than in the general population. As higher recall rates reflect inadequate iodine nutrition, sufficient iodine supplementation is needed to reduce the recall rate in such communities. Full article
(This article belongs to the Special Issue Iodine and Health throughout the Lifecourse)
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Review

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Open AccessReview
Iodine as Essential Nutrient during the First 1000 Days of Life
Nutrients 2018, 10(3), 290; https://doi.org/10.3390/nu10030290
Received: 11 January 2018 / Revised: 22 February 2018 / Accepted: 27 February 2018 / Published: 1 March 2018
Cited by 12 | PDF Full-text (1173 KB) | HTML Full-text | XML Full-text
Abstract
Iodine is an essential micronutrient incorporated into thyroid hormones. Although iodine deficiency can lead to a broad spectrum of disorders throughout life, it is most critical in the early stages of development, as the foetal brain is extremely dependent on iodine supply. During [...] Read more.
Iodine is an essential micronutrient incorporated into thyroid hormones. Although iodine deficiency can lead to a broad spectrum of disorders throughout life, it is most critical in the early stages of development, as the foetal brain is extremely dependent on iodine supply. During the last two decades, our understanding of thyroid physiology during gestation has substantially improved. Furthermore, thyroid hormone receptors have been identified and characterised in placental and embryonic tissues, allowing us to elucidate the maternal-foetal transfer of thyroid hormones. Experimental studies have demonstrated that the cyto-architecture of the cerebral cortex can be irreversibly disturbed in iodine deficiency causing abnormal neuron migratory patterns which are associated with cognitive impairment in children. In this context, the role of iodine as key factor in the programming of foetal and infant neurodevelopment, needs to be revisited with a special focus on areas of mild to moderate iodine deficiency. The objective of this review is to summarize the available evidence from both animals and human studies, for the effect of iodine deficiency (particularly, of maternal hypothyroxinemia) on brain development and neurological or behavioural disorders, such as lower intelligence quotient (IQ) or attention deficit hyperactivity disorder (ADHD). Full article
(This article belongs to the Special Issue Iodine and Health throughout the Lifecourse)
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