Search Results (89)

Background: Iodine nutrition requires continued surveillance after changes in salt iodization policy. This study evaluated iodine status and associated factors among children and adolescents in Zhejiang Province, ten years after the national salt iodization standard was lowered. Methods: A cross-sectional survey employing a stratified, multistage cluster sampling design was conducted in 2022. A total of 688 participants aged 6–17 years with complete data on urinary iodine concentration, household salt iodine concentration, geographic classification, and key questionnaire variables were included in the analysis. Multivariate logistic regression analysis was performed to identify factors independently associated with iodine sufficiency. Results: Among 688 participants, the median household salt iodine concentration was 21.50 mg/kg, and iodized salt coverage was 64.68%. The median urinary iodine concentration (UIC) was 191.4 μg/L; however, 15.26% of participants had UIC < 100 μg/L. Participants in coastal areas had lower UIC levels and lower household iodized salt coverage than those in inland areas. Multivariate logistic regression analysis identified age, geographic region, and household use of iodized salt as factors significantly associated with iodine sufficiency. Conclusions: The overall iodine nutritional status among children and adolescents aged 6–17 years in Zhejiang Province is adequate. However, a certain proportion of iodine deficiency persists. Continued, targeted monitoring and health education on the appropriate use of qualified iodized salt are warranted, particularly in coastal areas and among younger children. Full article

Iodine is an essential micronutrient required for the synthesis of thyroid hormones and the maintenance of metabolic, neurodevelopmental and immune function. As iodine cannot be synthesized endogenously, adequate intake depends on dietary sources and environmental availability. Despite decades of progress in improving iodine supply, both iodine deficiency and excess remain significant global public health challenges. This review summarizes iodine physiology, covering both its role in thyroid hormone synthesis and emerging evidence for extrathyroidal immunomodulatory and antioxidant actions. It summarizes major dietary sources, global intake patterns and current approaches to iodine status assessment, including urinary biomarkers, salivary iodide measurement and dietary screening tools. The clinical consequences of iodine imbalance are examined, ranging from goiter, hypothyroidism and impaired neurocognitive development associated with deficiency, to iodine-induced thyroid dysfunction, autoimmunity and adverse systemic effects linked to excess intake. Special attention is given to vulnerable populations, particularly pregnant women and infants. This review further evaluates public health strategies, including salt iodization and targeted supplementation, while addressing the emerging challenge posed by salt-reduction initiatives. Achieving optimal iodine intake remains essential for thyroid health and population well-being, underscoring the need for coordinated monitoring and policy adaptation. Full article

Background/Objectives: Iodine deficiency remains an important global public health concern. Although iodized salt is the primary strategy for iodine deficiency prevention, its effectiveness depends on adequate iodine concentrations in commercially available products. However, laboratory data on the iodine content of retail salt products in Hungary are currently lacking. Therefore, this study aimed to determine the iodine concentration of commercially available iodized table salts in Hungary and to assess their compliance with the WHO-recommended range of 20–40 ppm. Methods: Twenty different brands of iodized table salt were purchased from major retail outlets in Pécs, Hungary, representing the dominant food retail sector. According to product labels, ten salts were fortified with potassium iodate (KIO₃) and ten with potassium iodide (KI). Iodine concentrations were determined by iodometric titration following WHO-recommended laboratory methods. All measurements were performed in triplicate and expressed as mean values. In addition, a small exploratory wholesale micro-survey examined purchasing patterns of iodized and non-iodized salt in the regional supply chain. Results: Measured iodine concentrations varied substantially among products, ranging from 0 to 33.9 ppm. Overall, 65% of the analyzed salt samples contained less than 20 ppm iodine, while only 35% fell within the WHO-recommended range of 20–40 ppm. Notably, several products declared iodine concentrations below recommended levels on their labels. The wholesale micro-survey showed that ten times more iodized than non-iodized salt was ordered during the observation period. Conclusions: These results suggest that the presence of iodized salt on the market does not necessarily guarantee adequate iodine supply and highlight the potential relevance of considering iodine status during the differential diagnosis of hypothyroidism. Full article

Background: Adequate iodine intake during pregnancy is essential for optimal maternal thyroid function and fetal neurodevelopment. Although universal salt iodization has been implemented in Turkey, pregnant women may remain vulnerable to iodine insufficiency. This study aimed to evaluate maternal thyroid function in relation to iodine status, and to comprehensively compare the diagnostic performance of spot urinary indices and creatinine-adjusted measures against measured 24 h urinary iodine excretion (24h-UIE) in pregnant women. Methods: A total of 227 pregnant women attending family health centers in Afyonkarahisar, Turkey, provided both spot urine samples and complete 24 h urine collections. Urinary iodine concentration (UIC), creatinine-corrected UIC (UIC/UCr), and 24h-UIE were measured. Thyroid function tests were interpreted using trimester-specific reference ranges. Correlations between urinary indices were assessed, and ROC analyses were performed using 24h-UIE as the operational reference. A structured questionnaire evaluated iodine-related dietary knowledge and salt-use practices. Results: The median spot UIC was 59.0 µg/L, indicating insufficient recent iodine intake at the population level. Based on 24h-UIE, 70% of participants had excretion levels below the Estimated Average Requirement (EAR) threshold (<144 µg/day). Spot UIC showed a weak correlation with 24h-UIE (rho = 0.270, p < 0.001), whereas UIC/UCr demonstrated a stronger correlation (rho = 0.491, p < 0.001). In ROC analyses, UIC/UCr yielded a significantly higher AUC than spot UIC (0.774 [95% CI: 0.707–0.841] vs. 0.670 [95% CI: 0.593–0.748]; DeLong p = 0.016). Overt hypothyroidism was not observed; subclinical hypothyroidism was present in 16.3% of participants. While no overall association was found between iodine indices and thyroid status, in the first trimester, those with subclinical hypothyroidism had higher 24h-UIE medians than euthyroid peers (134.2 vs. 100.3 µg/day, p = 0.037), although both groups remained below the EAR threshold. Knowledge regarding iodine-rich foods and iodized salt use was limited among the study population. Conclusions: Iodine insufficiency remains highly prevalent among pregnant women in this region despite salt iodization. While spot UIC alone showed limited agreement with 24h-UIE, creatinine-adjusted UIC may offer improved interpretability under conditions of variable urine dilution. Preserved thyroid function in the presence of iodine insufficiency highlights the silent nature of this condition during pregnancy. Strengthened pregnancy-specific iodine surveillance and targeted antenatal education are warranted. Full article

Micronutrient deficiencies remain a persistent challenge to global health and food security, particularly in low- and middle-income countries where evidence-based strategies are urgently needed. Biofortification of staple crops has been promoted as a complementary intervention to supplementation and food fortification, but its effective implementation requires locally relevant studies. Such evidence is essential because the performance and adoption of biofortified crops depend on context-specific factors, including crop varieties, soil micronutrient dynamics, dietary patterns, cultural acceptability, and bioavailability, which limit the transferability of findings across settings. This perspective examines whether countries with the highest micronutrient burdens generate sufficient local research to inform biofortification policy decisions. We conducted a bibliometric mapping of peer-reviewed literature indexed in Scopus and compared country-level publication counts with indicators of iodized salt coverage, zinc deficiency, and childhood anemia, which were selected because they are prioritized metrics in global health and food security. From 776 eligible articles, most publications originated from a small group of high- and middle-income countries, whereas regions facing the greatest nutritional burdens, including parts of Sub-Saharan Africa and South Asia, contributed little to the scientific output. Countries with low iodized-salt coverage, high zinc deficiency, or childhood anemia above 40% frequently showed zero or minimal publications. This misalignment suggests that countries facing the greatest nutritional vulnerabilities may be underrepresented in the indexed scientific literature. These findings highlight the value of further strengthening research participation and visibility in high-burden settings to ensure that the evidence base more accurately reflects global needs. Full article

Background/Objectives: Iodine plays a central role in thyroid hormone synthesis and neurodevelopment. Its deficiency and excessive intake have been identified as risk factors for thyroid diseases and their consequences. The objective of the study was to analyze dietary iodine intake (dIi) and the factors that determine its intake among post-primary school students from northern Poland, specifically those from coastal areas and lake districts. Methods: The study was conducted on a sub-national sample of 3102 adolescents (1751 females and 1351 males) aged 14–20 years, recruited from schools located in the Northern (N) and North-Western (N-W) macroregions of Poland. Dietary iodine intake was assessed using the Iodine Dietary Intake Evaluation-Food Frequency Questionnaire. Based on the data obtained, the adequacy of the intake of this micronutrient was assessed. Statistical analysis was performed using the Shapiro-Wilk, U Mann-Whitney, and Kruskal-Wallis tests and Spearman’s correlation analysis. Results: The median dIi was 66.83 µg daily, including 53 µg from natural sources. This value was below the recommended dietary allowance of 150 µg and below the estimated average requirement of 95 µg of iodine in 85% and 68% of the study participants, respectively. Milk and dairy products provided the highest iodine intake (26.4%). Iodine-enriched salt (16.2%) also significantly impacted iodine intake. However, 60% of respondents did not use iodized salt. The median iodine levels from natural sources were found to be low (dairy products: 15.02 µg, fish and fish products: 2.38 µg, and eggs: 2.10 µg). Dietary iodine intake was significantly lower in adolescents from the N than N-W macroregion of Poland (median: 65.63 vs. µg daily, 74.2 p < 0.001). However, dIi did not depend on sex (p = 0.10), age (p = 0.80), school location (p = 0.80), body mass index classification (p = 0.76), or iodine supplementation (p = 0.90). Conclusions: The study results indicate that insufficient iodine intake among adolescents in northern Poland can be attributed to a limited intake of iodine from natural food sources. A pressing need exists to closely monitor iodine intake and status among Polish adolescents and to implement nutritional education, focusing on the role of iodine, potential risks associated with iodine deficiency, and dietary sources of iodine. Full article

Background/Objectives: Despite salt iodization, iodine deficiency during pregnancy and lactation is re-emerging in many industrialized countries, necessitating an evaluation of the role of dairy in supporting iodine status during these critical periods. Methods: We conducted a systematic review and meta-analysis in accordance with PRISMA guidelines. Ten databases were searched through March 2025 using ProQuest Dialog™ (Version 75.0). Study quality was assessed using either the Quality Evaluation for Observational Studies tool or the Risk of Bias 2 tool, depending on study design. Random-effects models were applied, with certainty of evidence rated using the GRADE framework. Publication bias, sensitivity analyses, and subgroup analyses were also performed. Results: Fifty-one publications met the eligibility criteria, including 50 publications of observational studies and 1 publication of a randomized controlled trial (RCT), with most studies conducted on pregnant women. Higher dairy intake was associated with significantly greater urinary iodine concentration (UIC), (23 studies; standardized mean difference: 0.326; 95% confidence interval [CI]: 0.228, 0.424; p < 0.001; I² = 57.31%; low-certainty), and significantly lower odds of iodine deficiency (11 studies; odds ratio: 0.58; 95% CI: 0.48, 0.70; p < 0.001; I² = 0%; moderate-certainty). Associations were stronger in studies conducted during later pregnancy, in higher-quality studies, and when the dairy food was specifically milk. Dairy contributed to ~27% of iodine intake from foods. Breast milk iodine concentration (BMIC) findings were inconsistent, though in one RCT, iodine-fortified milk improved BMIC and UIC. Conclusions: Dairy intake supports adequate iodine status during pregnancy and lactation. RCTs would be valuable in further investigating the role of dairy in supporting iodine status, particularly in lactating women. (PROSPERO CRD420251054576) Full article

Iodine is an essential micronutrient that is required for thyroid hormone (TH) synthesis. However, adequate maternal thyroid function is critical for fetal growth and neurodevelopment. Pregnancy increases iodine requirements due to enhanced renal clearance, higher maternal TH production, and transplacental transfer, making pregnant women especially vulnerable to iodine deficiency. In this review, we examine the molecular mechanisms of TH synthesis and regulation, placental transport and metabolism, and the physiological adaptations of thyroid function during gestation. We also analyze the clinical and public health consequences of iodine imbalances, ranging from deficiency to excess. Evidence indicates that mild iodine deficiency—which is common even in developed countries—can lead to maternal thyroid overstimulation, increased thyroglobulin levels, altered T3/T4 ratios, and enlarged thyroid volume, while severe deficiency results in maternal and fetal hypothyroidism with irreversible neurocognitive impairment in the offspring. Conversely, excessive iodine intake may impair fetal thyroid function through mechanisms such as the Wolff–Chaikoff effect. In conclusion, ensuring balanced iodine intake through iodized salt, supplementation, and routine thyroid monitoring during pregnancy is essential to protect maternal health and optimize early neurodevelopment. Full article

Background/Objectives: With the rising trend of out-of-home dining in China, the use of iodized salt (IS) in eating-out venues plays a key role in preventing iodine deficiency disorders (IDDs). However, the coverage rate of iodized salt (CRIS) and the utilization rate of adequately iodized salt (URAIS) in these venues in China remain underexplored, potentially undermining IDD prevention strategies. This study aims to assess the CRIS and URAIS in such venues across China and identify the factors influencing their prevalence. Methods: From 2021 to 2024, a nationwide cross-sectional study was conducted in China, involving 19,346 venues. A 50 g sample of cooking salt was collected from each venue, and the iodine content was measured. The CRIS and URAIS were calculated, and associations with various factors were assessed using Chi-square tests, the Cochran–Armitage trend test, and multivariate logistic regression. Results: Of the 19,346 samples, 18,519 tested positive for IS, and 17,588 contained adequately iodized salt (AIS), resulting in a CRIS of 95.7% and a URAIS of 90.9%. Significant regional differences were found, with coastal areas showing a lower CRIS and URAIS than inland areas (87.0% vs. 97.8%; 81.0% vs. 93.2%) and urbanized areas having lower rates compared to less urbanized areas (94.1% vs. 97.3%; 88.9% vs. 92.9%). Higher per capita income was associated with a lower CRIS and URAIS (Z = −19.72, p < 0.0001; Z = −13.85, p < 0.0001). Lower per capita income (OR = 3.24, OR = 1.36, p < 0.0001), inland areas (OR = 4.14, OR = 2.68, p < 0.0001), and mountainous areas (OR = 2.48, OR = 1.27, p < 0.0001) were associated with a higher likelihood of IS and AIS use. Conclusions: While the CRIS and URAIS in dining venues meet national standards, regional disparities persist, particularly in coastal, plain, and economically advanced areas. Strengthening regulatory oversight and public education on iodized salt’s health benefits is essential. Full article

Background: Hashimoto’s thyroiditis (HT) is characterized by the loss of tolerance to thyroid autoantigens [thyroid peroxidase (TPO) and thyroglobulin (Tg)], usually identifying circulating antibodies (Abs) against these thyroid autoantigens (TPOAb and/or TgAb), together with a significant lymphocytic infiltration, causing an increased risk of hypothyroidism. Among the multiple mechanisms described for the development of HT is the nutritional status of several micronutrients, including iodine. Iodine deficiency or excess is associated with thyroid function disorders and, likely, thyroid autoimmunity. Thus, iodized salt intake [especially through universal salt iodization (USI) programs] may be influencing the prevalence of HT. The objectives of this systematic review are to describe and analyze changes over time in the prevalence of HT following the implementation of USI programs. Methods and results: The following databases were consulted for articles published from January 1965 to January 2025: Pubmed/Medline; ProQuest; Scopus; Biosis; Web of Science; and Google Scholar. The search terms were as follows: “iodine”, “salt”, “intake”, “prevalence”, AND Hashimoto’s thyroiditis. Only English language articles were taken into account, and each of them was scrutinized according to the JBI Critical Appraisal Checklist. Only those studies in which the design, study population, number of participants, country, evaluation post-USI (years), and the prevalence of thyroid Abs positivity were described were included. In total, 74 studies were identified, of which 31 evaluated thyroid Abs values post-USI. Conclusions: Excess iodine intake, mediated by USI programs without an adequate follow-up and monitoring plan, may explain (at least in part) the prevalence and distribution of HT; therefore, it is a real challenge to establish a balance between healthy salt intake, USI program strategies, and possible functional outcomes and thyroid autoimmunity in the population. Registration number: INPLASY202540074. Full article

Although the Universal Salt Iodization (USI) program has been highly successful, it remains relevant due to the continued risk of Iodine Deficiency Disorders (IDDs) in vulnerable groups, such as children and pregnant women. This program empowers the relevant authority to continuously monitor iodine levels in iodized salt. Our study reports on the use of a Salt Iodate Micro-Method Reagent (SIMR) detection kit for this purpose. The kit was validated, with a linearity of 5.0–60.0 mg/Kg, at a detection limit of 6.8 mg/Kg, with excellent recovery ranging from 93.0 to 108.3%, whereas the repeatability, intermediate precision, and reproducibility achieved a mean coefficient of variation (CV) of 5.3%, 6.8%, and 5.9%, respectively. The stability of the reagents used in the kit was tested using freshly prepared iodine standard quality control (QC) samples of 20.0 mg/Kg and 40.0 mg/Kg, all of which were observed to be stable, within the range of the mean ± 2 × (standard deviation, SD), for 10 days. The suitability of the kit was proven when no difference was found in the mean results of 70 salt samples, using a paired t-test and the Bland–Altman plot, compared to the reference method, at a 95% confidence interval (CI). Thus, the SIMR detection kit is a highly feasible alternative method for iodine monitoring, with a fast analysis time, as well as being cost effective, and environmentally friendly. Full article

Potassium iodate and potassium iodide are commonly fortified in iodized table salt, which must be continuously monitored to maintain quality. Our study reported an optimized detection method for total iodine in iodized table salt using 0.5 M sodium bisulfite as the reducing agent. The iodized table salt (0.5 g) was dissolved in 0.5 M sodium bisulfite solution prior to injection in ultra-high-performance liquid chromatography (UHPLC) coupled with a diode array detector using a weak anion-exchange column (2.1 mm × 150 mm, 5 μm). Iodide was eluted at 9.92 ± 0.06 min (λ = 223 nm) when an isocratic mobile phase of 1:1 (v/v) methanol/120 mM phosphate buffer mixed with tetrasodium pyrophosphate (pH 3.0) was running at 0.20 mL/min (15 min). Iodide was detected as total iodine from 10.0 to 50.0 mg/kg with a limit of detection (LOD) of 1.2 mg/kg and a limit of quantification (LOQ) of 3.7 mg/kg. The method was validated with relative standard deviations (RSDs) of 4.2%, 0.4%, 1.6%, and 0.8% for accuracy, repeatability, intermediate precision, and robustness, respectively. The determination of total iodine was successful on six (6) samples (n = 3), which recovered 87.2–106.9% of iodate and iodide spike. Thus, this study provides a validated protocol for the determination of total iodine in iodized table salt using 0.5 M sodium bisulfite. Full article

Iodine is a key micronutrient essential for the synthesis of thyroid hormone, which regulates metabolic processes and maintains overall health. Despite its importance, iodine deficiency is a global health issue, leading to disorders such as goiter, hypothyroidism, and developmental abnormalities. Biofortification of crops with iodine is a promising strategy to enhance the dietary iodine intake, providing an alternative to iodized salt. Curly kale (Brassica oleracea var. sabellica) is a nutrient-rich vegetable high in vitamins A, C, K; minerals; fiber; and bioactive compounds with antioxidant, anti-inflammatory, and detoxifying properties. This study evaluates the effects of diets containing iodine-biofortified curly kale (‘Oldenbor F₁’ and ‘Redbor F₁’) on iodine content, tissue iodine levels, and various biochemical parameters in laboratory rats. The biofortified curly kale was enriched with 5,7-diiodo-8-quinolinol. The iodine content in the AIN-93G (control) diet and the non-biofortified curly kale diets did not differ significantly. However, diets with 5,7-diiodo-8-quinolinol biofortified kale showed significantly higher iodine levels compared with the control diets. Tissue analysis revealed the highest iodine concentrations in the liver and kidneys of rats fed diets with biofortified curly kale, indicating better iodine bioavailability. Biochemical analysis showed that rats fed the biofortified kale diet had lower total cholesterol (TC) and triglyceride (TG) levels compared with rats fed the control diet. Additionally, the biofortified diet improved the liver function markers (ALAT, ASAT) and reduced oxidative stress markers (TBARS). The study also investigated the expression of thyroid-related genes (Slc5A5, Tpo, Dio1, Dio2) in response to diets containing biofortified kale. The results demonstrated significant changes in gene expression, indicating adaptive mechanisms to dietary iodine levels and the presence of bioactive compounds in the biofortified kale. The study also observed variations in uric acid levels, with lower concentrations in rats fed a diet with biofortified curly kale. Biofortified curly kale supports thyroid function and improves liver and kidney health by reducing oxidative stress and modulating key biochemical and genetic markers. These findings suggest that biofortified curly kale can effectively increase dietary iodine intake as a nutritional intervention to address iodine deficiency and promote overall health. Full article

Iodine is a critical trace element necessary for human and animal health owing to its role in thyroid hormone synthesis. Despite its importance, iodine deficiency remains a global health concern. Traditional methods to address this issue, such as salt iodization, face challenges like iodine loss during storage and cooking. The biofortification of plants, particularly carrots, offers a promising alternative. This study investigates iodine accumulation and distribution in carrots biofortified with potassium iodide (KI) and potassium iodate (KIO₃) using single extraction at elevated temperatures with tetramethylammonium hydroxide followed by iodine determination by ICP-MS. Results show that iodine biofortification significantly increases the iodine content of various parts of the carrot, especially the leaves and the root peels. Carrots treated with iodate accumulate 2.7 times more iodine than those treated with iodide. The leaves exhibit the highest iodine content, particularly in iodate-treated plants, where levels can be over 24 times higher than those of control carrots. Root peel and roots also accumulate substantial amounts of iodine, with the iodate treatment resulting in 5.42 mg·kg⁻¹ and 3.75 mg·kg⁻¹ dry weight, respectively. The potential application of biofortified carrots can help meet human dietary iodine requirements; additionally, iodine-rich carrot leaves as livestock feed offer a sustainable approach to increasing the iodine intake in animals. Full article

Background: Despite global efforts to promote universal salt iodization, iodine deficiency remains a public health issue in developing countries. Objectives: This study assessed the proportion and sociodemographic characteristics of households consuming adequately iodized salt in 49 low- and middle-income countries. Methods: Data from DHS surveys of 49 low- and middle-income countries (2005–2021) were used to analyze household iodized salt prevalence. R version 4.0 was employed for statistical analyses. A random-effects meta-analysis was conducted to estimate overall and regional prevalence. Results: We found that 83.4% of households consume adequately iodized salt, although with high heterogeneity (I² = 100.0%). The East Asia and Pacific and the Europe and Central Asia regions showed high consumption rates of 87.6% and 87.7%, respectively, while Latin America and the Caribbean presented a significantly lower proportion of 30.8%. Conclusions: The study highlights the need for enhanced public health strategies to increase iodized salt consumption, especially in low-income and rural households. Addressing disparities in access, education, and affordability is crucial for improving iodine intake and preventing deficiency disorders, particularly among vulnerable populations like children and pregnant women. Full article