Excessive Iodine Intake Research Articles

Hypothyroidism induced by excessive-iodine is associated in humans with altered hsa-miR-199a-5p/HIF-1α axis and thyroglobulin.

The adverse effect of excessive iodine intake has attracted extensive attention. However, the role of excessive iodine on hypothyroidism and detailed mechanism are not exactly known. Studies have shown that miRNAs are crucial to the occurrence and development of hypothyroidism. Nevertheless, there still limited population-based studies on the miRNA-mRNA regulation in the occurrence of hypothyroidism induced by excessive iodine. Total of 291 hypothyroidism patients and 291 controls matched by sex (1:1) and age (±3 years) were enrolled from Heze City, Shandong Province. Multiple logistic regression analysis revealed that water iodine concentration of 100-300μg/L was an independent risk factor for hypothyroidism. Additionally, excessive water iodine was associated with an increase in thyroglobulin (Tg) concentration in new-diagnosed hypothyroidism patients. Further, high-throughput miRNA sequencing indicated that hsa-miR-19b-3p, hsa-miR-199a-5p, hsa-miR-204-5p and hsa-miR-144-3p were significantly correlated with the occurrence of hypothyroidism. Q-PCR results showed that levels of hsa-miR-199a-5p and hsa-miR-204-5p in the hypothyroidism group were markedly lower than those in the control group. In addition, among the hypothyroidism patients, hsa-miR-199a-5p level in water iodine >100μg/L group was remarkably higher than that in 10-100μg/L group. Furthermore, HIF-1α and PD-L1 mRNA levels in whole blood were determined, which are the target genes regulated by miRNA-199a-5p in previous studies. Compared with the control group, HIF-1α mRNA level was significantly increased in the hypothyroidism group. In the hypothyroidism case group, compared with the 10-100µg/L group, HIF-1α mRNA level was remarkably decreased in water iodine >100µg/L group. Collectively, miR-199a-5p/HIF-1α axis may contribute to hypothyroidism induced by excessive iodine through thyroglobulin.

Effect of decitabine on PD-L2 methylation in whole blood of iodine-induced autoimmune thyroiditis rats.

Excessive iodine intake can induce autoimmune thyroiditis (AIT), and the methylation of programmed death receptor 2 (PD-L2) may be involved in the development of iodine-induced AIT. Here, we investigated the immune role of methylation of the susceptibility gene PD-L2 in the occurrence of iodine-induced AIT using the DNA methyltransferase inhibitor Decitabine (Dec) in an experimental autoimmune thyroiditis (EAT) rat model. After injecting Dec intraperitoneally into EAT rats, we performed arsenic-cerium catalytic spectrophotometry, pathological hematoxylin and eosin staining, enzyme-linked immunosorbent assay, quantitative methylation-specific polymerase chain reaction (qMSP), and quantitative real-time polymerase chain reaction (qPCR) to determine the relevant indices. The results showed that compared with the control group, the urinary iodine, thyroid lymphocyte infiltration, thyroglobulin antibody (TgAb), interferon (IFN-γ), and interleukin (IL-23) levels of the EAT rats were significantly increased. The PD-L2 methylation levels were significantly decreased in EAT rats compared to control rats, and the mRNA expression of the PD-L2 was significantly increased. Following Dec intervention, the methylation level of the PD-L2 in rats increased and interferon and interleukin-23 levels decreased, albeit not significantly. However, the mRNA expression of PD-L2 decreased significantly after Dec intervention, and the thyroid function of EAT rats also showed a gradual improvement trend. In summary, hypomethylation of PD-L2 is closely related to the development of iodine-induced AIT. Pro-inflammatory cellular factors are also involved in iodine-induced AIT progression. Although Dec shows promise in the treatment of AIT, further evaluation of its safety is necessary.

Analysis of risk factors for autoimmune thyroid disease based on blood indicators and urinary iodine concentrations.

The aim of this study was to elucidate the relationships between thyroid hormones, lifestyle factors, biochemical markers, and autoimmune thyroid disease (AITD), thereby identifying the factors influencing the development of these diseases. The study encompassed 517 patients with AITD and 549 patients with non-autoimmune thyroid disease. Demographic and clinical data were collected, and various laboratory indicators, including urinary iodine and thyroid hormones, were measured and compared between the groups. Lasso regression was employed to select the independent variables, while logistic regression analysis determined the factors associated with the development of AITD. The prevalence of drinking alcohol history, median urinary iodine, and TSH concentrations proved significantly greater in the AITD group compared to the control group, while FT3 levels demonstrated lower values within the AITD group (p<0.05). Furthermore, there was a significant difference in the distribution of iodine nutrition status between the two groups (p<0.05). Both univariate and multivariate logistic regression analyses revealed significant associations among excessive iodine intake, drinking alcohol history, TSH, FT3, and the development of AITD. Excessive iodine intake and drinking alcohol history are implicated in an augmented risk of developing AITD. The prevention of AITD may necessitate the regular monitoring of TSH and FT3 concentrations.

Salivary iodine concentrations can estimate iodine intake and diagnose abnormal thyroid function: a cross-sectional study in pregnant and lactating women in iodine-deficient areas.

Salivary iodine concentrations (SIC) and urinary iodine concentrations are correlated. This study aimed to verify the use of SIC as a biomarker for estimating iodine intake in pregnant and lactating women and to diagnose abnormal thyroid function. A cross-sectional study was conducted in northern Xinjiang, China. Participants provided venous blood, random urine, saliva and milk samples. A total of 607 pregnant and 171 lactating women volunteered to participate in the study. The average daily iodine intake was calculated for each participant. Pregnant women were divided according to trimester. The median daily iodine intake was 436·41 μg/d in the first trimester, 425·83 μg/d in the second trimester and 430·56 μg/d in the third trimester. The average daily iodine intake in lactating women was 416·16 μg/d. Different indicators were used to diagnose excessive iodine intake (> 500 μg/d). Among pregnant women, SIC had an AUC of 0·62 (P < 0·01), sensitivity of 51·75 % and specificity of 65 %. Among lactating women, SIC had an AUC of 0·63 (P = 0·03), sensitivity of 43·52 % and specificity of 85 %. SIC was an effective biomarker for diagnosing abnormal thyroid function (P = 0·03). In conclusion, this study demonstrated that SIC is a reliable biomarker for evaluating both iodine nutrition status and abnormal thyroid function in pregnant and lactating women.

Consequences of acute and long-term excessive iodine intake: A literature review focusing on seaweed as a potential dietary iodine source.

Macroalgae, also called seaweed, are becoming more widespread as food in Western diets. Seaweed can accumulate iodine, an essential nutrient for humans. However, some species of seaweed may contain very high amounts of iodine, and therefore, iodine has been identified as one of the major hazards in the seaweed food chain. Macroalgae may be consumed regularly, though many consumers report eating macroalgae only occasionally. The aim of this paper is to explore possible health consequences of excessive iodine intake according to long-term (chronic) or occasional (acute) excessive exposure to iodine, relating to a regular (chronic) or occasional (acute) seaweed intake, respectively. Furthermore, through a modeling exercise, we add different amounts of seaweed to the diet in a population group to explore the possible safe amounts that can be added without exceeding excessive iodine intakes and risking detrimental health effects. Chronic excessive iodine intakes were associated with several negative health outcomes at variable doses in various studies. For acute excessive iodine exposure, negative health effects seemed to be associated with higher iodine exposures. However, the research on this topic was limited. The chronic and acute iodine exposures needed to result in negative health outcomes may easily be ingested by macroalgae consumption. Adding seaweed to the diet must be done thoughtfully to avoid the risk of exceeding thresholds for excessive iodine intake.

Characteristics of exposure to radioactive iodine during a nuclear incident.

During a nuclear accident, numerous products of nuclear fission are released, including isotopes of radioactive iodine. Among them is iodine-131, with a half-life of 8.02 days, which emits β radiation. For decades, it has been effectively and safely used in medicine. However, in the event of a nuclear accident, uncontrolled exposure can have harmful biological effects. The main sources of internal contamination with iodine-131 are contaminated air, food and water. The most exposed organ is the thyroid gland, where radioactive iodine accumulates via the Na+/I- symporter (NIS). NIS does not distinguish between radioactive iodine isotopes and the stable isotope iodine-127, which is essential for the synthesis of thyroid hormones. Exposure to radioactive iodine during a nuclear accident is primarily associated with papillary thyroid cancer, whose incidence begins to increase a few years after exposure. Children and adolescents are at the highest risk, and the risk is particularly significant for individuals living in iodine-deficient areas. Ensuring an adequate iodine supply is therefore crucial for lowering the risk of the harmful effects of exposure to radioactive iodine at the population level. Protecting the thyroid with potassium iodide tablets significantly reduces radiation exposure, as stable iodine prevents the entry of radioactive iodine into the thyroid. Such protection is effective only within a narrow time window - a few hours before and after the exposure and is recommended only for those under 40 years of age, as the risks of excessive iodine intake outweigh the potential benefits in older individuals.

The Role of miRNA in Hyperthyroidism Induced by Excessive Iodine in Drinking Water.

In recent years, iodine deficiency-related diseases have been effectively controlled; the prevalence of excessive iodine-induced thyroid diseases has increased, such as hyperthyroidism. However, there are still several controversial outcomes regarding the relationship between excessive iodine intakes and hyperthyroidism. MicroRNAs (miRNAs) extensively participate in the progression of thyroid diseases; nevertheless, the relationship and mechanism between iodine exposure and miRNAs have not been explored in hyperthyroidism patients. In this study, a total of 308 pairs of hyperthyroidism patients and healthy controls were enrolled in. Logistic regression analysis showed that level of water iodine >100 μg/L was an independent risk factor for hyperthyroidism. Compared with the healthy control, the serum thyroglobulin (Tg) content and levels of interferon-γ (IFN-γ), interleukin 6 (IL-6), and tumor necrosis factor-α (TNF-α) were significantly elevated in hyperthyroidism patients. Further, high-throughput miRNA sequencing was applied to find crucial miRNAs involved in the occurrence of hyperthyroidism related to excessive water iodine. Based on the fold change and Q value, miR-144-3p, miR-204-5p, miR-346, miR-23b-5p, and miR-193b-3p were selected for validation by qRT-PCR. Our results showed that miR-346 and miR-204-5p in the case group were significantly lower than those of the control group, and the similar results found under the level of water iodine >300 μg/L. Nonetheless, no significant difference was found at 10-100 μg/L level of water iodine. Furthermore, the ROC curve indicated that miR-346 and miR-204-5p had the ability to diagnose hyperthyroidism patients. Taken together, excessive water iodine may decrease the expression of miR-346 and miR-204-5p, which mediate the elevation of Tg and cytokines, ultimately making contribution to the development of hyperthyroidism.

Evaluation of the Bioavailability of Iodine and Arsenic in Raw and Cooked Saccharina japonica Based on Simulated Digestion/Caco-2 Cell Model.

Kelp is a traditional healthy food due to its high nutritional content; however, its relatively high contents of iodine and arsenic have raised concerns about its edible safety. This study explored the effects of different cooking treatments on the contents of iodine and arsenic in kelp, evaluated the bioaccessibility and bioavailability of iodine and arsenic in kelp using in vitro digestion, and compared the differences in the transport characteristics of iodine in kelp and KIO3 using a Caco-2 monolayer cell transport model. The results show that the content of target elements that reached systemic circulation could be reduced by cooking and gastrointestinal digestion. The highest reductions in iodine and arsenic were 94.4% and 74.7%, respectively, which were achieved by boiling for 10 min. The bioaccessibility and bioavailability of iodine and arsenic were significantly improved by a cooking treatment. However, the contents of iodine and arsenic decreased significantly, with the bioaccessibility of iodine reducing from 3188.2 μg/L to 317.0 μg/L and that of arsenic reducing from 32.5 μg/L to 18.1 μg/L in the gastric phase after boiling. The findings also show that the efficiency of iodine transport in kelp and KIO3 was positively correlated with the transport time and negatively correlated with the concentration of iodine. With the increase in the iodine concentration, the rate of iodine transport in kelp decreased from 63.93% to 3.14%, but that of KIO3 was stable at around 35%, which indicates that the absorption efficiency of iodine from kelp was limited, even when too much kelp was ingested. In conclusion, the edible safety of kelp is significantly improved after cooking. The risk of excessive iodine and arsenic intake caused by consuming kelp is extremely low, and as an effective iodine supplement source, kelp has higher edible safety compared with KIO3. This study clarifies the safety of algae based on iodine and arsenic contents and also provides a basis for the formulation of food safety standards.

Iodinated Contrast Induced Hypothyroidism in the Infant After Enteral Contrast Enema: A Case Report and Systematic Review.

Excessive iodine intake triggers the Wolff-Chaikoff effect resulting in downregulation of thyroid hormone synthesis to prevent hyperthyroidism. Failure to escape the Wolff-Chaikoff effect can be seen especially in (premature born) infants and may result in prolonged iodine induced hypothyroidism. We describe a rare case of a preterm infant who developed severe iodinated contrast induced hypothyroidism after the use and prolonged stasis of enteral iodinated contrast media (ICM). In addition a systematic literature search was performed to evaluate all available data on this complication. A systematic literature search was performed in PubMed and Embase. Studies describing the effect of enteral ICM on thyroid function were considered eligible. The primary outcome was to determine the frequency of contrast induced hypothyroidism in infants after administration of enteral ICM. The premature infant in our center developed severe iodinated contrast induced hypothyroidism after enteral ICM. In total, only two studies met our eligibility data, reporting eight patients. Out of these eight patients, four premature infants developed a contrast induced hypothyroidism after enteral administration of ICM. Data on severity, length and frequency of contrast induced hypothyroidism after exposure to enteral ICM is very scarce. The herein reported case and literature search illustrate the potential severity of the complication and underline the necessity of future studies on this topic. We recommend standardized monitoring of thyroid function after exposure to enteral ICM in newborns to prevent delayed diagnosis of severe contrast induced hypothyroidism until evidence based recommendations can be made.

A review of groundwater iodine mobilization, and application of isotopes in high iodine groundwater.

Excessive intake of iodine will do harm to human health. In recent years, high iodine groundwater has become a global concern after high arsenic and high fluorine groundwater. A deep understanding of the environmental factors affecting iodine accumulation in groundwater and the mechanism of migration and transformation is the scientific prerequisite for effective prevention and control of iodine pollution in groundwater. The paper comprehensively investigated the relevant literature on iodine pollution of groundwater and summarized the present spatial distribution and hydrochemical characteristics of iodine-enriched groundwater. Environmental factors and hydrogeological conditions affecting iodine enrichment in aquifers are systematically summarized. An in-depth analysis of the hydrologic geochemistry, physical chemistry, biogeochemistry and human impacts of iodine transport and transformation in the surface environment was conducted, the results and conclusions in the field of high iodine groundwater research are summarized comprehensively and systematically. Stable isotope can be used as a powerful tool to track the sources of hydrochemical components, biogeochemistry processes, recharge sources and flow paths of groundwater in hydrogeological systems, to provide effective research methods and means for the study of high iodine groundwater system, anddeepen the understanding of the formation mechanism of high iodine groundwater, the application of isotopic technique in high iodine groundwater is also systematically summarized, which enriches the method and theory of high iodine groundwater research. This paper provides more scientific basis for the prevention and control of groundwater iodine pollution and the management of groundwater resources in water-scarce areas.

The correlation between urinary iodine levels and gallstone risk: elevated iodine intake linked to gallstone occurrence.

Essential trace elements are vital for human growth and development. Nevertheless, excessive intake can pose risks. As of yet, no research has looked at the possibility of a relationship between the prevalence of gallstones and urinary concentrations of nickel, molybdenum, and iodine. The purpose of this study was to examine the correlation between urinary levels of iodine, molybdenum, and nickel and the occurrence of gallstones in a U.S. population and to verify whether excessive iodine intake is associated with the occurrence of gallstones. Data from 2,734 participants that were gathered between 2017 and 2020 were examined. Employing inductively coupled plasma mass spectrometry (ICP-MS), the levels of nickel (Ni), iodine (I), and molybdenum (Mo) in the urine were determined. Gallstones presence was determined using a standardized questionnaire. Restricted cubic spline analysis, subgroup analysis, and logistic regression analysis were used to evaluate the relationship between the occurrence of gallstones and urinary essential trace elements. The logistic regression analysis indicated an increased risk of gallstone development in Quartiles 2, Quartiles 3, and Quartiles 4 groups in comparison to the Quartiles 1 group, based on urinary iodine levels (OR = 1.69, 95% CI: 1.11-2.56; OR = 1.68, 95% CI: 1.10-2.55; OR = 1.65, 95% CI: 1.09-2.51). Urinary iodine levels were nonlinearly positively linked with the development of gallstones, according to restricted cubic spline analysis (P-Nonlinear = 0.032). Subgroup analyses showed that high levels of urinary iodine were associated with a high risk of gallstones in different populations, and were more pronounced in adults aged 60 years and older, in women, with a BMI ≥ 25, and in diabetic patients. Our research revealed a correlation between an increased risk of gallstones and increasing urinary iodine levels. Urinary iodine levels serve as indicators of the body's iodine status, thus suggesting that excessive iodine intake may be linked to an elevated risk of gallstone formation.

Iodine and selenium: Dietary sources and nutritional status of the population of the Kurdistan Region in Northern Iraq

AimThe primary aim of this study was to determine the selenium (Se) and iodine (I) food concentrations and dietary intake of the population living in the Kurdish controlled region of northern Iraq. We also assessed the extent to which iodised salt contributes to dietary iodine intake. MethodologyFoods and samples of salt and drinking water were analysed, including 300 crops samples from 40 local farms. The results, supplemented by food composition data, were used to assess dietary Se and I intake for 410 volunteers using a semi-quantitative food questionnaire. To directly investigate the nutritional status of individuals, urine samples were also collected from participants. ResultsSelenium intake was mainly supplied by protein and cereal sources. Calculated median dietary intake of Se was 62.7 µg d−1 (mean = 66.3 µg d−1) with c. 72 % of participants meeting or exceeding dietary reference intake recommendations for age. Median dietary intake of I, excluding salt consumption, was 94.6 µg d−1 (mean 100.2 µg d−1), increasing to 607.2 µg d−1 when salt (of which >90 % was iodized) was included. Salt intake was estimated to be c.13.5 g d−1 (5400 mg Na d−1) which greatly exceeds WHO recommended intake (< 2000 mg d−1 of Na). Urine iodine concentrations indicated that 98 % of school aged children had excessive iodine intake (≥300 µg L−1) and 80–90 % of all study participants had above average or excessive iodine intake (≥200 µg L−1). ConclusionsPoultry and rice are the main sources of dietary Se to this population but around a third of children receive an inadequate Se intake. Fresh fruit and vegetables are the main sources of dietary I, but consumption of local foods cannot supply adequate I without iodised salt supplementation. Consumption of iodized salt well above recommended amounts is supplying this population with substantial iodine intake. Interventions to reduce salt intake would help to limit excessive iodine intake whilst also reducing cardio-vascular risks from Na consumption.

The role of iodine in thyroid function and iodine impact on the course of Hashimoto’s thyroiditis - review

Introduction: Iodine is one of the most important micronutrients necessary for the proper functioning of the thyroid gland. It is an essential component of thyroxine and triiodothyronine, hormones produced and secreted by the thyroid gland. Severe iodine deficiency impairs thyroid hormone synthesis and can lead to gland enlargement. This deficiency results in various disorders collectively termed iodine deficiency disorders. Not only iodine deficiency but also excess iodine intake can be harmful and affect thyroid function. Doses of iodine above physiological levels can result in both hypothyroidism and hyperthyroidism. Numerous studies have linked chronic high iodine intake to an increased frequency of autoimmune thyroiditis. This review examines the mechanisms of iodine regulation and the role of excess iodine can play in the development of Hashimoto’s thyroiditis. Aim of the study: The aim of the study is to present and summarize the role of iodine in thyroid function and its impact on the course of Hashimoto’s thyroiditis. This review explains the potential increased risk of thyroid autoimmune disorder connected with iodine over-supplementation. Materials and Methods: For this current literature review, the important studies published from 1986-2024 in PubMed database was searched. The literature available in the PubMed database was reviewed with the following keywords: iodine, Hashimoto’s thyroiditis, autoimmune thyroiditis. Conclusion: Iodine is crucial for thyroid health and fetal development, but its excessive intake can be harmful. Maintaining optimal levels of this microelement is essential to prevent both iodine deficiency and autoimmune disorders. Iodine supplementation is recommended only for pregnant and lactating women.

Urinary iodine concentrations in preschoolers and cognitive development at 4 and 6 years of age, the Rhea mother-child cohort on Crete, Greece

BackgroundEvidence regarding child iodine intake and neurodevelopment is scarce. MethodsWe aimed to assess the impact of child iodine intake at 4 years of age on cognitive and motor development at 4 and 6 years among 304 children from the Rhea cohort on Crete, Greece. Child iodine intake was assessed via urinary iodine concentrations (UIC) measured using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and adjusted for specific gravity. Child cognitive and motor development was assessed using the McCarthy Scales of Children's Abilities (MSCA) at 4 years of age and Raven’s Coloured Progressive Matrices (RCPM), Finger Tapping Test (FTT), and Trail Making Test (TMT) at 6 years. Associations were explored using multivariable-adjusted linear regression analyses with UIC categorized according to WHO criteria [insufficient intake <100 µg/L, adequate 100–299 µg/L (reference group), excessive ≥300 µg/L]. ResultsThe children’s median UIC was 249 µg/L (25–75th percentile: 181–344 μg/L). Children with UIC <100 μg/L had lower scores in the motor scale at 4 years (MSCA-motor scale: B=-10.3; 95 %CI −19.9, −0.6; n=10) and in intelligence at 6 years (RCPM-total score: B=-3.6, 95 %CI −6.8, −0.5; n=9) than children in the reference group. No associations were found with the general cognitive scale at 4 years or with TMT and FTT scales at 6 years. Children with UIC ≥300 μg/L had lower cognitive scores both at 4 (MSCA; B= −3.5; 95 %CI −6.9, −0.1; n =101) and 6 years of age (RCPM-total score; B= −1.2; 95 %CI −2.3, −0.0; n =98) than children in the reference group. No associations were observed with the motor scale at 4 years or with TMT and FTT scales at 6 years. ConclusionOur findings indicate that both low and excessive iodine intake at preschool age may adversely affect child cognitive abilities. Additionally, low iodine intake may also impact motor abilities.

A national survey of iodine nutrition in children aged 3-6 years in China and its relationship with children's physical growth.

Iodine, an essential trace element for the human body, plays a pivotal role in sustaining health. Malnutrition has emerged as a pressing public health concern, posing a significant threat to human well-being. Iodine deficiency poses a substantial threat to the development of children, potentially leading to neurological developmental disorders and mental retardation. Conversely, excessive iodine intake can result in structural and functional abnormalities in the thyroid gland. In this study, we selected children aged 3-6 years through a stratified cluster sampling approach in six regions across China to explore the correlation between iodine nutrition and their physical growth. A total of 5920 preschool children participated in this study, with a median urinary iodine concentration (UIC) of 177.33 [107.06, 269.92] μg/L. Among these children, 250 (4.2%) exhibited stunting, 180 (3.0%) were underweight, 198 (3.3%) experienced wasting, 787 (3.3%) were overweight and 414 (7.0%) were classified as obese. The multivariate linear regression revealed that UIC exhibited a positive correlation with body mass index z-Score (BMIZ) in overweight children (β = 0.038; 95% CI: 0.001, 0.075). In normally growing children, the associations between UIC and height-for-age z-score, weight-for-age z-score and BMIZ displayed nonlinear patterns. Our findings suggest that iodine nutrition is adequate for Chinese children aged 3-6 years. Furthermore, iodine nutrition is intricately linked to the growth and development of these children. Consequently, it is imperative to implement decisive measures to prevent both iodine deficiency and excess.

Risks of Iodine Excess.

Iodine is a micronutrient that is required for thyroid hormone synthesis. The iodide cycle in thyroid hormone synthesis consists of a series of transport, oxidation, organification, and binding/coupling steps in thyroid follicular cells. Common sources of iodine include the consumption of an iodine-rich diet or iodine-fortified foods, the administration of amiodarone, iodine-containing supplements, or iodinated contrast media, and other miscellaneous sources. Methods to assess population iodine status include the measurement of urinary iodine concentrations, blood thyroglobulin levels, prevalence of elevated neonatal thyrotropin levels, and thyroid volume. Although excessive iodine intake or exposure is generally well tolerated, an acute iodine load may result in thyroid dysfunction (hypothyroidism or hyperthyroidism) in certain susceptible individuals due to the failure to escape from the Wolff-Chaikoff effect and to the Jod-Basedow phenomenon, respectively. In this review, we discuss the associations between excessive iodine intake or exposure, with particular focus on iodinated contrast media as a common source of excess iodine in health care settings, and risks of incident thyroid dysfunction. We also summarize the risks of iodine excess in vulnerable populations and review current guidelines regarding the screening and monitoring of iodinated contrast-induced thyroid dysfunction. Finally, we discuss the long-term potential nonthyroidal health risks associated with iodine excess and suggest the need for more data to define safe upper limits for iodine intake, particularly in high-risk populations.

Evaluation of Iodine and Goitrogens in Selected Vegetables from Owerri Imo State in Nigeria

The prevalence of iodine deficiency disorders remains a challenge in numerous developing nations despite widespread advocacy for iodized salt and iodine-fortified foods. As a result, this study assesses the iodine content of ten selected vegetables—water leaf, okra, green, tomatoes, lettuce, “okazi”, “ugu”, cabbage, “uha” leaf, and garden egg leaf. The result revealed varying iodine concentrations among these vegetables: 159.93±2.25 μg/kg for water leaf, 151.27±1.61 μg/kg for okra, and 160.43±4.37 μg/kg for green. Tomatoes exhibited 110.10±2.76 μg/kg, while lettuce had 181.27±1.76 μg/kg. “Okazi”, “ugu”, cabbage, “uha” leaf, and garden egg leaf showed iodine levels of 155.10±3.50 μg/kg, 153.43±2.47 μg/kg, 96.10±2.00 μg/kg, and 127.77±3.01 μg/kg, respectively. The evaluation for goitrogens demonstrated sufficient presence in these vegetables, with notable exceptions such as zinc, which was found in lower concentrations in “ugu”, lettuce, “okazi”, and cabbage, and was absent in “uha” leaf, garden egg leaf, green, water leaf, and okra. Based on these results, it was concluded that Owerri's vegetables exhibit relatively high iodine content within recommended dietary allowances. Consequently, ongoing vigilance is advised for the salt iodization program to prevent excess iodine intake, particularly among high-risk populations.

The link between dietary nutrients intake and cardiovascular diseases in cold regions

Abstract Background The cold winter weather in northern China influences the dietary habits of its residents, contributing to a heightened risk of cardiovascular disorders, such as hypertension and coronary heart disease. Key factors include low vegetable consumption and high salt and fat intakes. This study aims to investigate the relationships between northern dietary nutrient intake in northern China and cardiovascular disorders during the winter season. Methods A food frequency questionnaire tailored to the actual eating habits in northern China was designed. Retrospective data from 955 Chinese adults were collected from November to March between 2014 to 2023. Logistic regression was employed to analyze the relationship between dietary nutrients and cardiovascular diseases, with model performance assessed using receiver operating characteristic (ROC) curves. Results Adjusted for gender, age, and body mass index (BMI), an inverse association was observed between vitamin A (OR = 0.706, 95% CI: 0.550, 0.907), nicotinic acid (OR = 0.584, 95% CI: 0.447, 0.762), phosphorus (OR = 0.777, 95% CI: 0.608, 0.994), selenium (OR = 0.719, 95% CI: 0.560, 0.923), zinc (OR = 0.683, 95% CI: 0.531, 0.880), methionine (OR = 0.730, 95% CI: 0.569, 0.936), arginine (OR = 0.753, 95% CI: 0.588, 0.964), lysine (OR = 0.706, 95% CI: 0.550, 0.907), aspartic acid (OR = 0.730, 95% CI: 0.569, 0.936) and hypertension. Additionally, a negative association was found between niacin (OR = 0.752, 95% CI: 0.597, 0.946) and coronary heart disease. Conversely, a positive association was identified between iodine and hypertension (OR = 1.305, 95% CI: 1.020, 1.669) and coronary heart disease (OR = 1.301, 95% CI: 1.037, 1.634). Conclusion Our study suggests that maintaining a balanced dietary intake of vitamin A, niacin, phosphorus, selenium, zinc, methionine, arginine, lysine, and aspartic acid can be beneficial in preventing hypertension. Adequate niacin intake is associated with a lower risk of coronary heart disease. However, excessive iodine intake may contribute to hypertension and coronary heart disease.

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

BackgroundAlthough iodine modulates bone metabolism in the treatment of thyroid disease, the effect of iodine intake on bone metabolism remains less known. ObjectiveThis study evaluated the effect of excess iodine intake in rats on bone reconstruction in the 6th and 12th month of intervention. MethodRats 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. ResultsThe 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. ConclusionsExcess 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.

Effects of iodine intake on gut microbiota and gut metabolites in Hashimoto thyroiditis-diseased humans and mice

Hashimoto thyroiditis (HT) is an organ-specific autoimmune disease linked to iodine intake. Emerging evidence highlights the gut microbiota’s role in HT pathogenesis via the microbiota-gut-thyroid axis. However, the process through which iodine intake modifies the microbiota and triggers HT remains unclear. This study examines how iodine affects gut dysbiosis and HT, recruiting 23 patients with HT and 25 healthy individuals to assess gut microbiota composition and metabolic features. Furthermore, we establish a spontaneously developed thyroiditis mouse model using NOD.H-2h4 mice highlighting the influence of iodine intake on HT progression. The butanoate metabolism significantly differs between these two groups according to the enrichment results, and butyric acid is significantly decreased in patients with HT compared with those in healthy individuals. Gut dysbiosis, driven by excessive iodine intake, disrupts TH17/Treg balance by reducing butyric acid. In summary, iodine intake alters intestinal microbiota composition and metabolic changes influencing the microbiota-gut-thyroid axis.