Chronic Excess Iodine Intake Inhibits Bone Reconstruction Leading to Osteoporosis in Rats.

BACKGROUND: Although iodine modulates bone metabolism in the treatment of thyroid disease, the effect of iodine intake on bone metabolism remains less known. OBJECTIVE: This study evaluated the effect of excess iodine intake in rats on bone reconstruction in the 6th and 12th month of intervention. METHOD: Rats were treated with different doses of iodinated water: the normal group (NI, 6.15 µg/d), 5-fold high iodine group (5HI, 30.75 µg/d), 10-fold high iodine group (10HI, 61.5 µg/d), 50-fold high iodine group (50HI, 307.5 µg/d), and 100-fold high iodine group (100HI, 615 µg/d). Thyroid hormone concentrations were determined by a chemiluminescent immunoassay. Morphometry and microstructure of bone trabecula were observed by hematoxylin and eosin staining and microcomputed tomography, respectively. Alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) staining were performed to evaluate the activity of osteoblasts and osteoclasts, respectively. RESULTS: The 24-h urine iodine concentration increased with iodine intake. The rats in the HI groups had higher serum thyroid-stimulating hormone and decreased serum free thyroxine concentrations in the 12th month than the NI group (all P < 0.05). The percentage of the trabecular bone area and osteoblast perimeter in the 100HI group were significantly lower than those in the NI group (P < 0.05). Increased structure model index was observed in the 50HI and 100HI groups compared with the NI group in the 6th month and increased trabecular separation in the 12th month (all P < 0.05). ALP and TRAP staining revealed osteoblastic bone formation was reduced, and the number of TRAP+ multinucleated cells decreased with increasing iodine intake. CONCLUSIONS: Excess iodine intake may increase the risk of hypothyroidism in rats. Chronic excess iodine intake can lead to abnormal changes in skeletal structure, resulting in reduced activity of osteoblasts and osteoclasts, which inhibits the process of bone reconstruction and may lead to osteoporosis.

Iodine Metabolism in Urine and Breast Milk among Lactating Women with Adequate Iodine.

BACKGROUND: In lactating women, iodine metabolism is regulated and maintained by the kidneys and mammary glands. Limited research exists on how iodine absorbed by lactating women is distributed between the kidneys and breasts. OBJECTIVES: This study aimed to accurately evaluate the total iodine intake (TII), urinary iodine excretion (UIE), and breast milk iodine excretion (BMIE) in lactating women and explore the relationship between TII and total iodine excretion (TIE). METHODS: A 7-d iodine metabolism study was conducted on 41 lactating women with a mean age of 30 y in Yuncheng and Gaoqing, China, from December 2021 to August 2023. TII and TIE were calculated by measuring the iodine content in food, water, 24-h urine, feces, and breast milk. The urinary iodine excretion rate (UIER), breast milk iodine excretion rate (BMIER), and partitioning of iodine excretion between urine and breast milk were determined. RESULTS: Iodine metabolism studies were performed for 285 d. The median TII and TIE values were 255 and 263 µg/d, respectively. With an increase in TII, UIER, and BMIER, the UIE and BMIE to TII ratio exhibited a downward trend. The median UIER, BMIER, and proportion of iodine excreted in urine and breast milk were 51.5%, 38.5%, 52%, and 37%, respectively. When the TII was <120 µg/d, the BMIER decreased with the increase of the TII (ß: -0.90; 95% confidence interval: -1.08, -0.72). CONCLUSIONS: When maternal iodine intake is low, the proportion in breast milk increases, ensuring sufficient iodine nutrition for infants. In addition, the UIE of lactating women with adequate iodine concentrations is higher than their BMIE. This study was registered at clinicaltrials.gov as NCT04492657.

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.

Mechanism of multi-organ compensation under different iodine intake in pregnant rats: results from a repeated-measures study of iodine metabolism.

PURPOSE: This study aimed to explore the differences in iodine metabolism and expression of NIS and Pendrin in pregnant rats under different iodine nutritional status. METHODS: Female Wistar rats were divided into four groups: low iodine (LI), normal iodine (NI), ten fold high iodine (10HI), and fifty fold high iodine (50HI). The intervention began after one week of adaptive feeding. Iodine metabolism experiments were performed beginning on the 15th day of pregnancy. 24-h iodine intake and excretion were calculated. The concentrations of iodine in urine, fecal, thyroid, and placenta were measured by ICP-MS. PCR and Western Blot were used to detect the mRNA levels and cell membrane protein of sodium/iodide symporter (NIS) and Pendrin in the small intestine, thyroid, kidney, and placenta. RESULTS: Fecal iodine excretion (FIE) and urinary iodine excretion (UIE) in the 50HI group were significantly higher than those in the NI group (P < 0.05). The NIS protein and mRNA in the kidney and small intestine have an upward trend in iodine deficiency and a downward trend in iodine excess. Thyroid and placental iodine storage in the 50HI group were significantly higher than those in the NI group (P < 0.05). NIS, Pendrin protein, and mRNA in the thyroid and placenta tend to increase when iodine is deficient and decrease when there is excess. CONCLUSION: Iodine excretion and iodine stores in the placenta and thyroid gland are positively correlated with iodine intake. NIS and Pendrin are also regulated by iodine intake.

Iodine Intakes of <150 µg/day or >550 µg/day are Not Recommended during Pregnancy: A Balance Study.

BACKGROUND: Adequate iodine intake during pregnancy is critical for maintaining maternal and fetal thyroid function and development. There are only limited data from iodine-balance studies to inform iodine requirements during pregnancy. OBJECTIVES: This is an iodine-balance study conducted to explore the associations among iodine intake, excretion, and retention to provide information regarding iodine requirements during pregnancy. METHODS: A 7-d iodine-balance experiment enrolled 93 healthy pregnant Chinese women from Hebei, Tanjin, and Shandong. Duplicates of all foods and beverages consumed were systematically collected and measured for iodine content. Iodine excretion was measured by collecting 24-h urine and feces samples. Simple linear regression models were used to assess relationships between total iodine intake and iodine retention, whereas mixed effect models were used to assess the relationship between daily iodine intake and iodine retention. RESULTS: The mean ± SD age of participating pregnant women was 29 ± 2 y at a median 22 (IQR: 13-30) wk of gestation. The mean 7-d iodine retention was 43.0 ± 1060 µg/7 d. A negative iodine balance was present in 56% of women whereas 44% had a positive balance. Pregnant women with iodine intakes <150 µg/d were in negative balance whereas those with intakes >550 µg/d were in positive balance. The daily iodine intake at zero balance was 343 µg/d, which was higher in women from Shandong (492 µg/d) than in those from Hebei and Tianjin (202 µg/d). CONCLUSIONS: Iodine intake at zero balance determined in pregnant women with adequate iodine nutrition is 202 µg/d, and the calculated recommended nutrient intake (RNI) is 280 µg/d. Iodine intakes of <150 µg/d and >550 µg/d are not recommended during pregnancy. This trial was registered at clinicaltrials.gov as NCT03710148.

Iodine Nutrition in Children ≤2 years of Age in Norway.

BACKGROUND: As a component of the thyroid hormones (THs), iodine is vital for normal neurodevelopment during early life. However, both deficient and excess iodine may affect TH production, and data on iodine status in young children are scarce. OBJECTIVES: To describe iodine nutrition (iodine status and intake) in children ≤2 y of age in Innlandet County (Norway) and to describe the associations with maternal iodine nutrition. METHODS: A cross-sectional study was performed in a representative sample of mother-child pairs selected from 30 municipalities from November 2020 until October 2021. Iodine status [child urinary iodine concentration (UIC), maternal UIC, and breast milk iodine concentration (BMIC)] was measured. Child's iodine intake was estimated using 2 24-h dietary recalls (24-HR) and a food frequency questionnaire. The Multiple Source Method was used to estimate the usual iodine intake distributions from the 24-HR assessments. RESULTS: The median UIC in 333 children was 145 µg/L, indicating adequate iodine status according to the WHO cutoff (100 µg/L). The median usual iodine intake was 83 µg/d. Furthermore, 35% had suboptimal usual iodine intakes [below the proposed Estimated average requirement (72 µg/d)], whereas <1% had excessive usual iodine intakes [above the Upper intake level (200 µg/d)]. There was a positive correlation between children's iodine intake and BMIC (Spearman rank correlation coefficient r = 0.67, P < 0.001), and between children's UIC and BMIC (r = 0.43, P < 0.001), maternal UIC (r = 0.23, P = 0.001), and maternal iodine intake (r = 0.20, P = 0.004). CONCLUSION: Despite a median UIC above the cutoff for iodine sufficiency, more than a third of the children had suboptimal usual iodine intakes. Our findings suggest that many children will benefit from iodine fortification and that risk of iodine excess in this age group is low.

Systematic review and meta-analysis of iodine nutrition in modern vegan and vegetarian diets.

Vegan and vegetarian diets are widely supported and adopted, but individuals following such diets remain at greater risk of iodine deficiency. This systematic review and meta-analysis was conducted to assess the iodine intake and status in adults following a vegan or vegetarian diet in the modern day. A systematic review and quality assessment were conducted from October 2020 to December 2022 according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidance. Studies were identified in Ovid MEDLINE, Web of Science, PubMed, and Scopus. Eleven articles were eligible for review containing 4421 adults (aged ≥ 18 years). Vegan groups had the lowest median urinary iodine concentration (mUIC) (12·2/l). None of the dietary groups had mUIC within the optimal range for iodine status (100-200 µg/l) (WHO). Vegan diets had the poorest iodine intake (17·3 µg/d) and were strongly associated with lower iodine intake (P = < 0·001) compared with omnivorous diets. Lower intake in vegan diets was influenced by sex (P = 0·007), the presence of voluntary or absence of Universal Salt Iodisation (USI) programmes (P = 0·01 & P = < 0·001), and living in a country with adequate iodine nutrition (P = < 0·001). Vegetarians and particularly vegans living in countries with no current USI programme continue to have increased risk of low iodine status, iodine deficiency and inadequate iodine intake. Further research into the usefulness of mandatory fortification of vegan appropriate foods is required.

Iodine status of pregnant women from the Republic of Cyprus.

Iodine supply is crucial during pregnancy to ensure that the proper thyroid function of mother and baby support fetal brain development. Little is known about iodine status or its dietary determinants in pregnant women in the Republic of Cyprus. We therefore recruited 128 pregnant women at their first-trimester ultrasound scan to a cross-sectional study. We collected spot-urine samples for the measurement of urinary iodine concentration (UIC, µg/l) and creatinine concentration (Creat, g/l), the latter of which allows us to correct for urine dilution and to compute the iodine-to-creatinine ratio (UI/Creat). Women completed a FFQ and a general questionnaire. We used a General Linear model to explore associations between maternal and dietary characteristics with UI/Creat. The median UIC (105 µg/l) indicated iodine deficiency according to the WHO criterion (threshold for adequacy = 150 µg/l), and the UI/Creat was also low at 107 µg/g. Only 32 % (n 45) of women reported the use of iodine-containing supplements; users had a higher UI/Creat than non-users (131 µg/g v. 118 µg/g), though this difference was NS in the adjusted analysis (P = 0·37). Of the dietary components, only egg intake was significantly associated with a higher UI/Creat in adjusted analyses (P = 0·018); there was no significant association with milk, dairy products or fish intake. Our results suggest that pregnant women in Cyprus have inadequate iodine status and are at risk of mild-to-moderate iodine deficiency. Further research on dietary sources in this population is required.

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.

Estimation of appropriate dietary intake of iodine among lactating women in China based on iodine loss in breast milk.

OBJECTIVE: Data on iodine loss in breast milk, which are critical for establishing the appropriate dietary iodine intake for lactating women, is currently limited. A study was conducted to assess iodine loss in breast milk among Chinese lactating women to estimate the appropriate dietary intake of iodine. METHODS: A total of 54 pairs of healthy, lactating women and their infants aged 0-6 months were recruited from Tianjin and Luoyang cities in China. A 4 days infant weighing study was conducted to assess iodine loss in the breast milk of lactating women. Mothers were required to weigh and record their infants' body weights before and after each feeding for a 24 h period from 8:00 am to 8:00 am. During the weighing study, 2812 breast milk samples and 216 24-h urine samples were collected from each lactating mother for four consecutive days. In addition, a 3 days 24 h dietary record, including salt weighing and drinking water samples collecting, was performed by each lactating mother to determine dietary iodine intake during the weighing study. RESULTS: The average dietary iodine intake of lactating women was 323 ± 80 µg/d. The median breast milk iodine concentration and 24 h urinary iodine concentration of lactating women were 154 (122-181) and 135 (104-172) µg/L, respectively. The mean volume of breast milk and the mean iodine loss in the breast milk of lactating women were 711 ± 157 mL/d and 112 ± 47 µg/d, respectively. The appropriate dietary intake of iodine among lactating Chinese women is approximately 260 µg/d. CONCLUSIONS: Based on the iodine loss in breast milk (110 µg/d) found in this study, and the estimated average requirement of iodine for adults, the appropriate dietary intake of iodine among lactating Chinese women is 260 µg/d, which is higher than the 240 µg/d recommended by the China Nutrition Science Congress in 2013.

Re-exploring the requirement of dietary iodine intake in Chinese female adults based on 'iodine overflow theory'.

PURPOSE: We re-explored the basal iodine requirement based on healthy Chinese female and a new iodine overflow theory was proposed for iodine balance study. METHODS: Thirty-six Chinese healthy female adults (age 20.7 ± 1.1) were recruited for this study, which included 40 days low iodine depletion period and six stages of 30 days supplementation period. Uniform diets with low iodine were provided and the content of iodine in the diet was regulated by dairy products. The total iodine intake from food and the total iodine excretion through 24-h urine and staged feces were completely gathered and monitored. The incremental (Δ) intake and excretion over the range were calculated. RESULTS: The iodine intake and excretion were 13.6 µg/day and 48.6 µg/day at the first stage, respectively. The incremental iodine intakes and excretions were 21.1 µg/day to 120.3 µg/day and 25.8 µg/day to 105.4 µg/day for the supplementation stages, respectively. According to the 'iodine overflow theory', the zero iodine balance (Δ iodine intake = Δ iodine excretion) derived from a mixed effect model indicated a mean iodine intake of 52.2 µg/d (1.0 µg/d kg). The RNI for iodine to healthy Chinese female adult was 73.1 µg/d (1.4 µg/d kg). CONCLUSION: A daily iodine intake of 52.2 µg/d may meet the basal iodine requirement for healthy Chinese female adults, and Chinese female may need more than 20% iodine intake than male based on the 'iodine overflow theory'. The trial was registered at the Chinese Clinical Trial Registry in May 2018 (No: ChiCTR1800016184).

Iodine intake assessment in the staff of a Porto region university (Portugal): the iMC Salt trial.

PURPOSE: Iodine deficiency disorder (IDD) is an ongoing worldwide recognized problem with over two billion individuals having insufficient iodine intake. School-aged children and pregnant women are often target groups for epidemiological studies, but there is a lack of knowledge on the general adult population. The aim of this study was to assess the iodine status among a Portuguese public university staff as a proxy for the adult working population. METHODS: The population study covered 103 adults within the iMC Salt randomized clinical trial, aged 24-69 years. Urinary iodine concentration was measured spectrophotometrically using the Sandell-Kolthoff reaction. Iodine food intake was assessed using a 24-h dietary recall. The contribution of discretionary salt to the iodine daily intake was assessed through 24-h urinary sodium excretion (UIE) and potentiometric iodine determination of household salt. RESULTS: The mean urine volume in 24 h was 1.5 L. The median daily iodine intake estimated from 24-h UIE was 113 µg/day, being lower among women (p < 0.05). Only 22% of participants showed iodine intake above the WHO-recommended cutoff (150 µg/day). The median daily iodine intake estimated from the 24-h dietary recall was 58 µg/day (51 and 68 µg/day in women and men, respectively). Dairy, including yoghurt and milk products, were the primary dietary iodine source (55%). Iodine intake estimated from 24-h UIE and 24-h dietary recall was moderately correlated (Spearman rank correlation coefficient r = 0.34, p < 0.05). The average iodine concentration in household salt was 14 mg I/kg, with 45% of the samples below the minimum threshold preconized by WHO (15 mg I/kg). The contribution of discretionary salt to the daily iodine intake was around 38%. CONCLUSION: This study contributes new knowledge about iodine status in Portuguese working adults. The results revealed moderate iodine deficiency, particularly in women. Public health strategies and monitoring programs are needed to ensure iodine adequacy in all population groups.

Factors associated with recent iodine intake level among household food handlers in Southwest Ethiopia: a cross-sectional study.

BACKGROUND: Iodine deficiency is a global public health threat, affecting an estimated two billion people. The median urinary iodine concentration is more reliable in determining recent iodine intakes and the risks of iodine deficiency. Therefore, this study was aimed to identify the factors associated with recent iodine intake level using median urinary iodine concentration as an indicator among household food handlers in southwest Ethiopia. METHODS: A community-based survey was conducted with selected households using a pretested interviewer-administered questionnaire in southwest Ethiopia. A 20-gram sample of table salt and a 5 ml causal urine samples were also collected and analyzed using rapid test kit and a Sandell-Kolthoff reaction, respectively. A salt iodine concentration above 15 ppm was classified as adequately iodized and a median urinary iodine concentration between 100 and 200µgl- 1 was considered as adequate iodine intake. A bivariable and multivariable logistic regression model was fitted. Crude and adjusted odds ratios with their 95% confidence levels were reported. Associations with a p-value ≤ 0.05 were used to declare statistical significance. RESULTS: A total of 478 women were included, with a mean age of 33.2 (± 8.4 years). Only 268 (56.1%) of the households had adequately iodized salt (> 15 ppm). The median urinary iodine concentration (interquartile range) was 87.5 µg l- 1 (45.6-107.6). In a fitted multivariable logistic regression model (p-value = 0.911), illiterate women (AOR = 4.61; 95% CI: 2.17, 9.81), poorly iodized salt in the household (AOR = 25.0; 95% CI: 13-48), salt purchased from open market (AOR = 1.93; 95% CI: 1.0, 3.73) and women who do not read the label during purchasing the salt (AOR = 3.07; 95% CI: 1.31, 7.17) were important predictors of the risk of Iodine deficiency. CONCLUSION: Despite public health efforts to improve iodine intake, its deficiency is still a major public health problem among southwest Ethiopian women.

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 Based on a Survey from a Cohort of Women at Their Third Trimester of Pregnancy from the Bosque County Chile.

Adequate iodine nutrition is fundamental for all humans and is critical during pregnancy and lactation due to iodine forms part of the structure of thyroid hormones (THs) and it is required for THs function. Iodine is a scarce micronutrient that must be obtained from the diet. Sufficient iodine can be found in the nature from seafood and given it is not frequently consumed by Chileans, public health policies state that table salt in Chile must be iodized. Health plans must be monitored to determine if the intake of iodine is being appropriated and the population has not fallen in deficiency or excess. The aim of this work was to evaluate iodine intake in 26 women at the third trimester of pregnancy. Pregnant women are resident from El Bosque a low-income County located in Santiago de Chile. These Chilean pregnant women were recruited by nutritionist at the Centros de Salud familiar (CESFAM). A 24 h dietary recall (24 h-DR) was applied to them to evaluate iodine intake. Samples of urine and blood were taken by health professionals to analyze parameters of thyroid function and to measure urine iodine concentration (UIC). The survey analysis showed that the iodine consumption in these pregnant women derived mainly from salt, bread and milk and not from seafood. The survey analysis indicated that iodine intake was above the requirements for pregnant women. However, the average UIC indicated that iodine intake was adequate, suggesting the need to find a better parameter to determine iodine intake in pregnant women.

Iodine Status of Mother-Infant Dyads from Montréal, Canada: Secondary Analyses of a Vitamin D Supplementation Trial in Breastfed Infants.

BACKGROUND: Most pregnant or lactating women in Canada will not meet iodine requirements without iodine supplementation. OBJECTIVES: To assess the iodine status of 132 mother-infant pairs based on secondary analyses of a vitamin D supplementation trial in breastfed infants from Montréal, Canada. METHODS: Maternal iodine status was assessed using the breastmilk iodine concentration (BMIC). Singleton, term-born infants were studied from 1-36 months of age. Usual (adjusted for within-person variation) iodine intakes were estimated from urinary iodine and creatinine concentrations. Iodine status was assessed using median urinary iodine concentrations (UICs) and by estimating inadequate intakes by the cut-point method using a proposed Estimated Average Requirement for infants 0-6 months of age (72 µg/d). RESULTS: At 1, 3, and 6 months of age, 70%, 63%, and 3% of infants, respectively, were exclusively breastfed. From 1-36 months of age (n = 82-129), the median UICs were ≥100 µg/L (range, 246-403 µg/L), which is the cutoff for adequate intakes set by the WHO for children <2 years. Almost all (98%-99%) infants at 1 and 2 months, 2 and 3 months, and 3 and 6 months of age had usual creatinine-adjusted iodine intakes ≥ 72 µg/d. The median BMIC was higher (P < 0.001) at 1 month compared to 6 months of lactation [1 month, 198 µg/kg (IQR, 124-274; n = 105) and 6 months, 109 µg/kg (IQR, 67-168; n = 78)]. At 1 and 6 months, 96% and 79% of mothers, respectively, had a BMIC ≥ 60 µg/kg, the lower limit of a normal reference range. The percentages of mothers that used a multivitamin-mineral (MVM) supplement containing iodine were 90% in pregnancy and 79% and 59% at 1 and 6 months of lactation, respectively. CONCLUSIONS: The iodine status of infants was adequate throughout infancy. These results support a recommendation that all women who could become pregnant, who are pregnant, or who are breastfeeding take a daily MVM supplement containing iodine.

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.

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.