Iodine Intake Trends in United States Girls and Women between 2011 and 2020.

BACKGROUND: Usual intakes of iodine in United States girls and women, including pregnant and lactating women have not been adequately studied. Adequate intake of iodine is critical for neurodevelopment of girls, thyroid functions, and reproductive health of women. OBJECTIVES: This study aimed to examine the adequacy and trends of iodine intake of United States girls and women between 2011 and 2020. METHODS: We mapped the sources of United States girls and women's iodine intake from the 29 food groups between 2011 and 2020 using United States Department of Agriculture's iodine data release 2. The total food intakes from 2 d of dietary recall of the United States National Health and Nutritional Examination Survey and estimated iodine concentrations of the food groups were used to calculate the usual iodine intakes of female participants. Trends of usual intakes, urinary iodine concentrations (UIC), and estimated intake adequacy were calculated. RESULTS: Median usual intakes of iodine estimated from diet and supplements and UIC of United States girls and nonpregnant, nonlactating women declined between 2011 and 2020 in all 3 age groups: ≤14 y, 15-49 y old, and ≥50 y. Median usual intakes of iodine for pregnant and lactating United States women declined as well. Inadequacy levels of usual iodine intake were 9.9% for nonpregnant, nonlactating women of reproductive age 15-49 y old, 40.3% for lactating, and 10.2% for pregnant women in the 2017-2020 period. Intake insufficiencies estimated from UIC were 48.8%, 63.2%, and 31.3% for nonpregnant, nonlactating women of reproductive age 15-49 y old, pregnant and lactating women, respectively, in the 2017-2020 period. A significant decline in milk consumption might be one of the major contributors to the dietary iodine decline in United States women. CONCLUSIONS: Iodine intake of United States girls and women were on the decline between 2011 and 2020 and the increased inadequacy of iodine intake deserves public health attention.

Salivary iodide status as a measure of whole body iodine homoeostasis?

Iodine is a trace element required to produce the thyroid hormones, which are critical for development, growth and metabolism. To ensure appropriate population iodine nutrition, convenient and accurate methods of monitoring are necessary. Current methods for determining iodine status either involve a significant participant burden or are subject to considerable intra-individual variation. The continuous secretion of iodide in saliva potentially permits its use as a convenient, non-invasive assessment of status in populations. To assess its likely effectiveness, we reviewed studies analysing the association between salivary iodide concentration (SIC) and dietary iodine intake, urinary iodide concentration (UIC) and/or 24-h urinary iodide excretion (UIE). Eight studies conducted in different countries met the inclusion criteria, including data for 921 subjects: 702 healthy participants and 219 with health conditions. SIC correlated positively with UIC and/or UIE in four studies, with the strength of relationship ranging from r = 0·19 to r = 0·90 depending on sampling protocol, age, and if salivary values were corrected for protein concentration. Additionally, SIC positively correlated with dietary intake, being strongest when saliva was collected after dinner. SIC varied with external factors, including thyroid function, use of some medications, smoking and overall health status. Evidence provided here supports the use of SIC as a viable, low-burden method for determining iodine status in populations. However, small sample sizes and high variability indicates the need for more extensive analyses across age groups, ethnicities, disease states and dietary groups to clarify the relative accuracy and reliability in each case and standardise procedure.

Survey of iodized salt coverage in areas with different water iodine concentrations and the iodine status of local women.

PURPOSE: There were only two definitions of iodine-deficient (water iodine concentration < 10 µg/L) and iodine-excess areas (water iodine concentration > 100 µg/L) in China before 2020. Areas with water iodine concentration between 10 and 100 µg/L implement the same policy as iodine-deficient areas to provide iodized salt. The definition of iodine-adequate areas was formulated in 2020 for the first time. The paper aims to investigate the coverage rate of iodized salt (CR) in different areas defined according to the latest national standards, evaluate the iodine status of local women, and provide a basis for the revision and improvement of relevant policies. METHODS: A total of 1948 women aged 18-60 were recruited from the iodine extra-high areas (IEHA), iodine-excess areas (IEA), iodine-adequate areas (IAA), inland iodine-deficient areas (IIDA), and coastal iodine-deficient areas (CIDA). Information on daily diet was collected with the Food Frequency Questionnaire. Drinking water, salt, food, and urine samples were collected and tested in our laboratory. Based on the recommended daily iodine intake, we assessed whether the subjects' daily iodine intake levels were adequate. RESULTS: The CR and the median urinary iodine concentrations (UICs) were 4.02% and 98.03 µg/L in CIDA, 89.74% and 144.93 µg/L in IIDA, 26.55% and 178.60 µg/L in IAA, 8.78% and 446.5 µg/L in IEA, 3.95% and 605.4 µg/L in IEHA, respectively. The differences among these five areas were statistically significant (P < 0.0001). The daily dietary iodine intakes were mainly from drinking water in IAA (63.92%), IEA (92.29%), and IEHA (92.93%), and were mainly from iodized salt in IIDA (59.22%) and food in CIDA (86.6%). CONCLUSION: Women in IAA and IIDA were in an adequate iodine state. Women in IEA and IEHA were in an iodine-excess state, and it is necessary to carry out water improvements projects. Women in CIDA were in a slight iodine-deficient state, and health education on scientific iodine fortification should be strengthened to increase iodine intake.

Relationship between iodine knowledge and dietary iodine intake in pregnant and lactating women: a cross-sectional study.

OBJECTIVE: This study assessed the iodine knowledge of pregnant and lactating women and the relationship to dietary iodine intake and iodine status. The factors influencing iodine intake were analysed. DESIGN: Basic information and iodine knowledge were collected via a questionnaire. A FFQ assessed dietary iodine intake. The urinary iodine concentration (UIC) was measured using the arsenic-cerium catalytic spectrophotometric determination of iodine in urine (WS/T 107 -2016). SETTING: A cross-sectional study involving pregnant and lactating women in Xinjiang, China was conducted. PARTICIPANTS: A total of 1181 pregnant women and 504 lactating women were enrolled in the study. RESULTS: The median UIC for pregnant and lactating women was 179·27 and 192·81 µg/l, respectively, and the dietary iodine intake was 407·16 and 356·89 µg/d, respectively. Of the pregnant and lactating women, 73·4 % and 82·5 % had medium iodine knowledge, respectively. In pregnant women, iodine knowledge and dietary iodine intake were positively correlated. High iodine knowledge and iodine education were shown to be protective factors for excessive iodine intake in pregnant women. CONCLUSION: This study demonstrated that the iodine nutritional status of women in Xinjiang was appropriate, and iodine knowledge was at a medium level, but there was confusion about iodine nutrition. Public education is needed to improve iodine knowledge and active iodine supplementation awareness among these populations of women.

Iodine intake in healthy Japanese aged from 6 to 70 years residing in the same district.

Iodine is an essential component of thyroid hormones and a dietary micronutrient for humans, and adequate iodine intake is necessary to maintain thyroid function. A population's iodine intake and nutritional status are assessed based on urinary iodine excretion. There are few studies on iodine nutritional status for all age groups residing in the same area in Japan. Between 2010 and 2017, a total of 769 healthy subjects aged 6.4-73 years in three sites in Yokohama City, were enrolled in the survey. The urinary iodine concentration (UIC), iodine to creatinine (Cr) ratio (UI/Cr) and estimated 24-h urinary iodine excretion (UIE) in single spot urine samples were measured, and habitual dietary iodine intake was assessed by food frequency questionnaires. The estimated 24-h UIE was calculated using individual predicted 24-h creatinine excretion by the validated equations developed for healthy Japanese children and adults which vary by age, gender and anthropometry. The median UIC for all participants was 219 µg/L, suggesting adequate iodine intake for this population. There was an increasing trend in median UI/Cr and estimated 24-h UIE by age. A significant correlation between UIC and UI/Cr (r = 0.6378), UIC and estimated 24-h UIE (r = 0.6804), and UI/Cr and estimated 24-h UIE (r = 0.5756) were observed. These estimates can be feasible, convenient and alternative methods to 24-h urine collection in order to assess iodine status in some populations such as ethnically or racially homogeneous and well-nourished people. Additional studies are required to validate these findings.

Studies on urinary excretion and variability of dietary iodine in healthy Japanese adults.

The daily consumption of iodine in Japan is higher than in most countries, and there are few reports on iodine metabolism and variance of habitual iodine ingestion in an iodine-sufficient area. To elucidate the patterns of short-term urinary iodine excretion (UIE) and long-term variability of habitual iodine intake, the urinary iodine excretion process after a high dietary iodine load of 3 mg was observed in eight Japanese adults under strict supervision with complete urine collections for three days. In addition, estimated UIE and dietary iodine intake (DII) were assessed in 24 university students using repeated spot urine samples of ten consecutive days and a food frequency questionnaire in each of the four seasons. Approximately 50, 75 and 90% of orally ingested iodine was excreted into the urine at 8, 13 and 22 hours after ingestion, respectively. Almost an equal amount of ingested iodine in meals was cleared within 33.5 h after eating with a maximum excretion rate at 3-4 h. There was a high fluctuation in the UIE and DII in the university students. The intra- and inter-individual crude coefficients of variation were 123 or 294.7% for UIE, and 58.3 or 88.7% for DII, respectively, indicating a higher variance of habitual iodine intake than in other countries. The frequency of occurrence for UIE above 3 mg was every 43 days. Rapid renal clearance of iodine and high variability as well as low frequency of dietary iodine intake might prevent people from being exposed to an excess iodine intake over the long term in Japan.

Korean-specific biokinetic model for iodine in radiological protection.

The International Commission on Radiological Protection (ICRP) recently adopted a detailed biokinetic model for systemic iodine with reference transfer coefficients based on typical worldwide dietary intakes of stable iodine. The regional data provided demonstrate that the ICRP reference thyroidal biokinetics may differ substantially across regions with atypically low or high dietary intakes of stable iodine. Importantly, the design of the ICRP model facilitates modifications of reference thyroidal kinetics based on regional dietary iodine intake. The present study extended the ICRP model to the South Korean population, whose dietary iodine intake is much higher than the global mean. The following three transfer coefficients were selected as targets for Korean-specific values: thyroidal uptake rate (λ1), hormonal secretion rate (λ4) and leakage rate of thyroidal organic iodine as inorganic iodide (λ5). The Korean-specific values forλ1,λ4andλ5were determined to be 4.48, 0.0086 and 0.0171 d-1, respectively, to yield the measurements of thyroidal iodine and physiological status of Korean adults. The determinedλ1andλ5values differed noticeably from the ICRP values, whereas theλ4value was comparable to that of the ICRP. Compared with the ICRP reference model, the Korean model, in which the Korean-specific transfer coefficients were adopted, predicted noticeably lower thyroidal uptake and faster decrease of thyroidal iodine. In addition, the predicted cumulative activities of radioiodine in the thyroid were substantially lower (40-80%) than those predicted by the ICRP model. The Korean model developed in this study demonstrates that the iodine biokinetics for Koreans (i.e. a population with a high iodine consumption) obviously differ from the prediction of the ICRP model. Hence, the Korean model may serve to improve the accuracy of thyroid dose estimation for Koreans and will lead to practical changes in matters concerned with radiological protection.

[Iodine nutritional status and intake levels in adult from different water iodine content areas of Xinjiang Uygur Autonomous Region in 2017].

OBJECTIVE: To understand the iodine nutrition status of adults in Xinjiang Uygur Autonomous Region under the effective control of iodine deficiency disease. METHODS: Using stratified cluster random sampling method, in the district to determine water iodine median<10 µg/L and ≥10 µg/L of urban and rural areas, a total of 10 survey points, deals from the collecting water deals of extracting water iodine content detection. Adults over 18 years old were randomly selected from 30 households at each survey site to carry out a survey on dietary iodine intake, and the contents of dietary salt iodine and adult urine iodine were tested. RESULTS: The median iodine content in water in Xinjiang Uygur Autonomous Region was 4. 4(2. 3, 13. 6)µg/L. The median iodine content of household salt was 27(24, 30) mg/kg. The median urinary iodine content in adults was 168(103, 259)µg/L. The average dietary iodine intake of adults in the region was 312 µg/d. CONCLUSION: The water iodine content in the environment outside Xinjiang Uygur Autonomous Region is relatively low, and the iodine nutritional status and dietary iodine intake of adults are generally at the appropriate level. However, urban adults with relatively low water iodine content and good economic status have a higher risk of iodine deficiency. Iodized salt is the main source of dietary iodine for adults in Xinjiang Uygur Autonomous Region. Adults in poorer rural and urban areas rely more heavily on iodized salt.

Iodine knowledge is positively associated with dietary iodine intake among women of childbearing age in the UK and Ireland.

Adequate I intake is important before conception and during pregnancy for optimal infant neurodevelopment. Recent studies have highlighted the prevalence of I deficiency in the UK and Ireland. It is possible that optimal I intake may be impeded by a poor knowledge of I nutrition. This study aimed to investigate I knowledge among women of childbearing age in the UK and Ireland and to determine whether a relationship exists between I knowledge and dietary I intake. Females (aged 18-45 years) were invited to complete an online questionnaire, which assessed knowledge of I and estimated dietary I intake using a FFQ. A total of 520 females of childbearing age completed the study. I knowledge was poor; only one-third (32 %) of the participants correctly identified pregnancy as the most important stage of the lifecycle for I, and 41 % of participants could not correctly identify any health problem related to I deficiency. The median daily I intake was estimated as 152 µg/d. Almost half (46 %) of the participants failed to meet dietary recommendations (140 µg/d) for I. A higher dietary I intake was positively associated with greater I knowledge (r 0·107; P=0·016). This study suggests that knowledge of I nutrition is low among women of childbearing age, and those with a greater knowledge of I nutrition had a higher dietary I intake. Initiatives to educate women of childbearing age on the importance of I nutrition should be considered as part of a larger public health strategy to address I deficiency.

Dietary Iodine Intake and Sources among Residents in Zhejiang Province 10 Years after Reducing Iodine Concentration in Iodized Salt.

We aimed to assess dietary iodine intake and sources in Zhejiang Province a decade after a reduction in iodine concentration in iodized salt. Three-day 24 h dietary recall and household weighing were used, complemented by "Chinese Food Composition" data. Household water and salt samples were collected from 5890 residents and analyzed. Differences in iodized salt consumption rates were observed across the following regions: inland (84.20%), subcoastal (67.80%), and coastal (37.00%) areas. The median (P25, P75) iodine concentration in water and diet were 2.2 (0.9, 4.0) µg/L and 142.05 (58.94, 237.11) µg/d, respectively, with significant regional differences in dietary concentration (inland [185.61 µg/d], subcoastal [153.42 µg/d], and coastal [75.66 µg/d]). Males (149.99 µg/d) and iodized salt consumers (191.98 µg/d) had a significantly higher dietary iodine intake than their counterparts. Regions were ranked as follows based on the proportions of individuals meeting the recommended dietary iodine intake: inland (69.40%), subcoastal (56.50%), and coastal (34.10%) areas. Dietary sources included salt (48.54%), other foods (32.06%), drinking water (8.84%), laver (4.82%), kelp (3.02%), and other seafood (2.32%). The qualified iodized salt consumption rate was significantly lower than the national standard. Zhejiang Province should continue implementing measures to control iodine deficiency through salt iodization, education efforts, and increasing the qualified iodized salt consumption rate.

Iodine Intake From Diet and Supplements and Urinary Iodine Concentration in a Cohort of Pregnant Women in the United States.

BACKGROUND: The DRI Estimated Average Requirement (EAR) in pregnancy for Iodine (I), an essential nutrient for fetal neurodevelopment, is 160 µg/d. Supplementation with 150 µg/d I/day is recommended during pregnancy, however, neither dietary intake or the combination of diet and supplement intake has been reported in US pregnant women. OBJECTIVE: Determine iodine intake from diet and supplements and iodine status in pregnancy by urinary iodine concentration in a large cohort of pregnant women. DESIGN: Pregnant women (n=750) completed the Diet History Questionnaire 2.0 from the National Institute of Cancer or multiple 24-hour recalls at baseline and identified their prenatal supplement(s). Dietary iodine intake was estimated using the USDA, FDA and ODS-NIH Database for the Iodine Content of Common Foods at enrollment, supplemental iodine intake throughout the study using content databases, and urinary iodine concentration (UIC) by the modified Sandell-Kolthoff reaction in samples collected between 14-20 weeks gestation (n=966). RESULTS: The median intake of iodine from diet was 108.8 µg/d, and 63% (473/750) were below the Estimated Average Requirement (EAR). Furthermore, 65% (529/818) took a supplement containing iodine, however, only 32% (259/818) took ≥150 µg/d. Median intake increased to 188.5 µg/d with the inclusion of I from supplements, however , 41% (380/925) remained below the EAR even after supplementation suggesting inadequate intake in nearly half of the cohort. A similar 48% (467/966) had UIC ≤150 µg/L. CONCLUSIONS: Assessment of iodine status by UIC and intake of iodine from diet and supplements support a high prevalence of iodine insufficiency during pregnancy in this large cohort of US women.

Serum iodine concentration and its associations with thyroid function and dietary iodine in pregnant women in the southeast coast of China: a cross-sectional study.

Background: Iodine deficiency is a major public health problem in pregnant women. Serum iodine (SI) may represent a useful biomarker for iodine nutrition evaluation. We aimed to assess the relationship between serum iodine concentration (SIC) and urinary iodine concentration (UIC), dietary iodine, thyroid function, and thyroid diseases in pregnant women in the southeast coast of China, and to provide a normal reference range of SIC for pregnant women. Methods: A multistage random sampling method was used to select the study population. We collected urine and blood samples from pregnant women and determined UIC and SIC as well as thyroid function using Arsenic-Cerium Catalytic Spectrophotometry, inductively coupled plasma mass spectrometry, and Beckman Coulter Access2 chemiluminescent immunoanalyzer and kit, respectively, and administered a questionnaire on dietary iodine intake in pregnant women. Results: There was a significant negative correlation between SI and thyroid-stimulating hormone (TSH) (r = -0.141) and a significant positive correlation between SI and free triiodothyronine (FT3) (r = 0.106), free thyroxine (FT4) (r = 0.236), triiodothyronine (TT3) (r = 0.229), total thyroxine (TT4) (r = 0.433), and dietary iodine intake (r = 0.068). There was a significant difference in SI levels of pregnancy between the second (78.13 µg/L) and third trimester (75.37 µg/L) (p = 0.018). SI levels between inadequate intake (74.58 µg/L) and appropriate intake (77.92 µg/L) groups were statistically different (p = 0.036). Low SIC was a risk factor for the development of hypothyroxinemia (adjusted OR = 3.14, 95% confidence interval: 1.75-5.66). The reference range for SIC in normal pregnant women is 45.03-112.44 µg/L. Conclusion: SI may be a composite indicator of iodine nutritional status and thyroid function.

Can Mild-to-Moderate Iodine Deficiency during Pregnancy Alter Thyroid Function? Lessons from a Mother-Newborn Cohort.

Severe iodine deficiency during pregnancy has substantial hormonal consequences, such as fetal brain damage. Data on the potential effects of mild-to-moderate iodine deficiency on the thyroid function of pregnant women and their newborns are scarce and divergent. We investigated the association between iodine intake in pregnancy and maternal and neonatal thyroid function in a region with mild-to-moderate iodine deficiency. Pregnant women's iodine status was evaluated using an iodine food frequency questionnaire, serum thyroglobulin (Tg), and urinary iodine concentration (UIC). Neonatal thyrotropin (nTSH) values were measured after birth. Obstetrics and anthropometric data were also collected. Among the 178 women (median age 31 years) included in the study, median (interquartile range) estimated dietary iodine intake, Tg and UIC were 179 (94−268) µg/day, 18 (11−33) µg/L, and 60 (41−95) µg/L, respectively. There was a significant inverse association of iodine intake with Tg values among the study population (ß = −0.2, F = 7.5, p < 0.01). Women with high free triiodothyronine (FT3) values were more likely to exhibit an estimated iodine intake below the estimated average requirement (160 µg/day, odds ratio [OR] = 2.6; 95% confidence interval [CI], 1.1−6.4; p = 0.04) and less likely to consume iodine-containing supplements (OR = 0.3, 95% CI, 0.1−0.8; p = 0.01). It is possible that thyroid function may be affected by iodine insufficiency during pregnancy in regions with mild-to-moderate iodine deficiency. The relatively small sample size of the studied population warrants further investigation.

Iodine Excretion and Intake in Women of Reproductive Age in South Australia Eating Plant-Based and Omnivore Diets: A Pilot Study.

Women consuming a strictly vegan/plant-based diet may be at increased risk of low iodine intake due to avoidance of animal products containing iodine. The aim of this pilot study was to determine the iodine excretion and intake in women consuming vegan/plant based diets compared with women consuming omnivore diets. Fifty-seven women (n = 31 plant-based, n = 26 omnivores), provided two spot urine samples to assess urinary iodine concentration (UIC). Two days of dietary intake were also recorded by participants. As the data were not normally distributed results are reported as median (IQR). UIC was significantly different between groups, 44 (26-66) µg/L in the vegan/plant-based group versus 64 (40-88) µg/L in omnivores (p < 0.05). UIC did not meet the >100 µg/L level recommended by the World Health Organization. Iodine intake was also significantly different, 78 (62-91) µg/day in the vegan/plant-based group and 125 (86-175) µg/day in the omnivores (p = 0.000). Iodine intake and bread intake were correlated with iodine excretion (CC 0.410-4.11, p = 0.003). These data indicate iodine insufficiency in both groups of women as the median values were below the minimum WHO recommendation. A larger study assessing iodine excretion in the Australian women of reproductive age who are not pregnant or breastfeeding is needed to confirm these findings.

Nationwide Representative Survey of Dietary Iodine Intake and Urinary Excretion in Postpartum Korean Women.

Iodine is an essential component of thyroid hormones, but excessive iodine intake can lead to thyroid dysfunction. Traditionally, Korean mothers consume brown seaweed soup (miyeokguk), a high source of iodine, after childbirth. There is controversy regarding the effects of excessive postpartum iodine intake on the health of mothers and infants. Thus far, there have been no nationwide large-scale surveys regarding the status of iodine intake among postpartum women in Korea. Therefore, we conducted a nationwide survey of postpartum dietary iodine intake among Korean women. In total, 1054 Korean women aged ≥19 years, at less than 8 weeks postpartum, participated in this survey. Dietary data were collected using self-reported 2-day dietary records, along with before-and-after meal photos. To evaluate the correlation between dietary iodine and urinary iodine excretion (UIE), spot urine, and 24 h urine samples were collected from 98 and 29 participants, respectively. The mean daily iodine intake among all participants was 2945.6 µg, and it gradually decreased over time after childbirth. Dietary iodine intake was significantly correlated with 24 h UIE (r = 0.396, p < 0.05) and spot urine UIE (r = 0.312, p < 0.05). Follow-up studies are required to examine the influence of excessive postpartum iodine intake on thyroid health in mothers and their infants.

Associations between maternal urinary iodine assessment, dietary iodine intakes and neurodevelopmental outcomes in the child: a systematic review.

OBJECTIVE: Mild to moderate iodine deficiency during pregnancy has been associated with adverse neurodevelopmental outcomes in offspring. Few research studies to date combine assessment of urinary iodine (UIC and/or ICr), biomarkers that best reflect dietary intake, with reported dietary intake of iodine rich foods in their assessment of iodine deficiency. Thus, a systematic review was conducted to incorporate both these important measures. DESIGN: Using PRISMA guidelines, a comprehensive search was conducted in three electronic databases (EMBASE®, MedLine® and Web of Science®) from January 1970-March 2021. Quality assessment was undertaken using the Newcastle Ottawa Scale. Eligible studies included reported assessment of iodine status through urinary iodine (UIC and/or ICr) and/or dietary intake measures in pregnancy alongside neurodevelopmental outcomes measured in the children. Data extracted included study author, design, sample size, country, gestational age, child age at testing, cognitive tests, urinary iodine assessment (UIC in µg/L and/or ICr in µg/g), dietary iodine intake assessment and results of associations for the assessed cognitive outcomes. RESULTS: Twelve studies were included with nine reporting women as mild-moderately iodine deficient based on World Health Organization (WHO) cut-offs for urinary iodine measurements < 150 µg/l, as the median UIC value in pregnant women. Only four of the nine studies reported a negative association with child cognitive outcomes based on deficient urinary iodine measurements. Five studies reported urinary iodine measurements and dietary intakes with four of these studies reporting a negative association of lower urinary iodine measurements and dietary iodine intakes with adverse offspring neurodevelopment. Milk was identified as the main dietary source of iodine in these studies. CONCLUSION: The majority of studies classified pregnant women to be mild-moderately iodine deficient based on urinary iodine assessment (UIC and/or ICr) and/or dietary intakes, with subsequent offspring neurodevelopment implications identified. Although a considerable number of studies did not report an adverse association with neurodevelopmental outcomes, these findings are still supportive of ensuring adequate dietary iodine intakes and urinary iodine monitoring throughout pregnancy due to the important role iodine plays within foetal neurodevelopment. This review suggests that dietary intake data may indicate a stronger association with cognitive outcomes than urinary iodine measurements alone. The strength of this review distinguishes results based on cognitive outcome per urinary iodine assessment strategy (UIC and/or ICr) with dietary data. Future work is needed respecting the usefulness of urinary iodine assessment (UIC and/or ICr) as an indicator of deficiency whilst also taking account of dietary intakes.

Influence of Short-Term Dietary and Therapeutic Iodine Restriction on the Therapeutic Effects of Radioactive Iodine Therapy in Patients with Graves' Disease.

Background: Several studies have investigated the factors affecting the effects of radioactive iodine (131I) treatment (RAIT) in patients with Graves' disease. However, the influence of dietary or therapeutic iodine on the effect of RAIT has not been fully elucidated yet. The aim of this study was to investigate whether dietary or therapeutic iodine before RAIT influences the therapeutic effects of RAIT with a fixed-dose regimen and a short-term restriction of iodine intake in an iodine-sufficient area. Materials and Methods: We retrospectively analyzed 81 Japanese patients with Graves' disease treated with the following RAIT regimen: dietary iodine restriction for 7 days as well as discontinuation of antithyroid drugs (ATDs), potassium iodine (KI), or both for 5 days before RAIT. On the day of RAIT, we measured urinary iodine content to estimate daily iodine intake. After RAIT, we adjusted the dose of ATDs, KI, or both according to serum thyroid hormone levels every 1-2 months. Using the data from these patients, we investigated the effect of dietary and therapeutic iodine on the therapeutic effects of RAIT. The therapeutic effects at 1 year after RAIT were evaluated based on the necessity of ATDs, KI, or both. Results: Dietary iodine intake was weakly correlated with 131I uptake (RAIU), but the dose of therapeutic iodine was not correlated with RAIU. The therapeutic effects of RAIT were strongly negatively associated with estimated thyroid volume before RAIT. Neither dietary iodine intake nor therapeutic iodine before RAIT affected this association. Conclusion: This study did not find an association between short-term dietary or therapeutic iodine restriction before RAIT and the therapeutic effects of RAIT in an iodine-sufficient area.

Sufficient iodine status among Norwegian toddlers 18 months of age - cross-sectional data from the Little in Norway study.

BACKGROUND: Inadequate iodine intake has been identified in several population groups in the Nordic countries over the past years; however, studies of iodine status in infants and toddlers are scarce. OBJECTIVE: The aim of this study is to evaluate the iodine status and dietary iodine sources among 18-month-old toddlers from Norway. METHODS: Cross-sectional and country representative data from the Little in Norway study were used. All children who had given a spot urine sample at 18 months age were included (n = 416). Urinary iodine concentration (UIC) was determined by inductively coupled plasma mass-spectrometry. Dietary habits and supplement use were measured by a food frequency questionnaire. RESULTS: Median (25th-75th percentiles [p25-p75]) UIC was 129 (81-190) µg/L while estimated median (p25-p75) habitual iodine intake was 109 (101-117) µg/day. None of the children were below the estimated average requirement (EAR) of 65 µg/day or above the upper intake level of 180 µg/day. There were no differences in either UIC or estimated habitual iodine intake between different geographic areas in Norway. Milk was the most important iodine source, contributing an estimated 70% to the total iodine intake, while other foods rich in iodine such as seafood and enriched baby porridge contributed about 30%. CONCLUSIONS: The iodine status among 18-month-old toddlers from different geographic areas in Norway was sufficient, indicated by a median UIC above the WHO cutoff of 100 µg/L. This was further supported by the estimated habitual iodine intake, where none of the participants were below the EAR. Milk was an important iodine source in this age group; thus children with a low intake might be at risk of insufficient iodine intake.

New Statistical Approach to Apportion Dietary Sources of Iodine Intake: Findings from Kenya, Senegal and India.

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.