Iodine status in the Nordic countries - past and present

Assessing the impact of short-term Lugol's solution on toxic nodular thyroid disease: a pre-post-intervention study

Purpose

Preoperative iodine therapy in toxic nodular goiter (TNG) is discouraged as iodine may cause aggravation of hyperthyroidism. We aimed to examine if a short course of iodine treatment is safe to administer in TNG.

Methods

Patients with TNG (n=20) and subclinical to mild hyperthyroidism (free (f)T4 <30 pmol/L) without complicating illnesses were included in this pre-post-intervention study at Karolinska University Hospital. All participants received Lugol's solution 5%, three oral drops thrice daily for 10 days. Heart rate, TSH, fT4, fT3 concentrations were collected before (day 0) and after treatment (day 10). Thyroid hormone concentrations were also measured at two time points during treatment to discover aggravations of hyperthyroidism. ThyPRO39se, a quality-of-life questionnaire, was filled out day 0 and day 10. Differences in heart rate, thyroid hormone concentrations, and quality-of-life before and after treatment were compared. Adverse reactions were reported.

Results

The median age was 63.5 years. Female to male ratio 19:1. FT4 and fT3 concentrations decreased (both p<0.001), and TSH concentration increased (p<0.001) after 10 days of treatment. There was no difference in heart rate. No aggravations of thyrotoxicosis were noticed in any of the participants. ThyPRO39se scores improved on three scales, including hyperthyroid symptoms, while the remaining scale scores were unchanged. Mild and transient symptoms related to or possibly related to treatment were observed in six participants.

Conclusion

A short course of Lugol's solution improved thyroid hormone concentrations, reduced patient-reported hyperthyroid symptoms and was safe in TNG. Lugol's solution might be an option for preoperative treatment in TNG.

Clinical trial registration

https://www.clinicaltrials.gov, identifier NCT04856488.

A nationwide registry-based observational study of thyroid disease incidence in the Faroe Islands

OBJECTIVE

The occurrence of thyroid disease varies among populations. While the iodine nutrition level of the Faroese seems to have been decreasing over the past decades, there is no systematic evaluation of the thyroid disease pattern in the Faroe Islands. Such knowledge of thyroid disease occurrence in the North Atlantic region may support healthcare planning and prevention. To investigate incidence rates, including subtypes of thyroid diseases, and demographic characteristics of thyroid disease patients in the Faroe Islands, to improve understanding of the patterns and trends of these disorders.

DESIGN AND METHOD

A registry-based observational study was conducted over 10 years, encompassing all adult Faroese individuals.

PATIENTS AND MEASUREMENTS

Health records from general practitioners and hospitals were used to identify incident cases of thyroid diseases. Validation was performed using multiple data sources. The incidence rates were standardised using population data from the middle of the study period 2006-2018.

RESULTS

Among the 1152 individuals diagnosed with thyroid disease, the standardised incidence rates per 100,000 person-years were 55 for hyperthyroidism and 112 for hypothyroidism, and around four times higher in women than in men. Hashimoto's thyroiditis was the dominant cause of hypothyroidism, while Graves' disease was the leading cause of hyperthyroidism. The incidence of hypothyroidism increases with age. A decreasing trend was observed over time for both hypothyroidism and hyperthyroidism.

CONCLUSION

Considering the decrease in iodine nutrition levels over the past decades, we were surprised by the high incidence of autoimmune thyroid disease. The findings highlight the need for continuous monitoring of thyroid disease occurrence in coastal areas of the North Atlantic Ocean.

Supplementation with selenium and coenzyme Q10 in an elderly Swedish population low in selenium - positive effects on thyroid hormones, cardiovascular mortality, and quality of life

BACKGROUND

Selenium-dependent deiodinases play a central role in thyroid hormone regulation and metabolism. In many European countries, insufficient selenium intake may consequently lead to adverse effects on thyroid function. In this randomised placebo-controlled double-blind study, we examined the effect of supplementation with selenium and coenzyme Q10 on thyroid hormonal status, cardiovascular (CV) mortality and health-related quality of life (Hr-QoL).

METHODS

Free T3, free T4, reverse T3, and TSH were determined in 414 individuals at baseline, and the effect of selenium yeast (200 µg/day) and coenzyme Q10 (200 mg/day) supplementation on hormone concentrations, CV mortality and Hr-QoL was evaluated after 48 months using Short Form 36 (SF-36). Pre-intervention plasma selenium was low, mean 67 µg/L, corresponding to an estimated intake of 35 µg/day. Changes in concentrations of thyroid hormones following the intervention were assessed using T-tests, repeated measures of variance, and ANCOVA analyses.

RESULTS

In the total population, the group with the lowest selenium concentration at baseline presented with significantly higher levels of TSH and lower levels of fT3 as compared to subjects with the highest selenium concentration. Supplementation with selenium and coenzyme Q10 for 4 years significantly increased fT3 and rT3, decreased fT4, and diminished the increase in TSH levels compared with placebo treatment (p = 0.03, all). In the placebo group, TSH and fT4 values above the median were associated with an increase in 10-year CV mortality, as compared with the mortality rate among those with TSH and fT4 below the median (p < 0.04, both), with no difference in mortality rate according to TSH and fT4 levels in the active intervention group. Similarly, TSH > median and fT3 < median were associated with a decline in mental Hr-QoL measures vs. TSH < and fT3 > median in the placebo group during 4 years of follow-up, but this was wiped out in the active group.

CONCLUSIONS

Supplementation with selenium and coenzyme Q10 had a beneficial effect on thyroid hormones with respect to CV mortality and Hr-QoL outcomes. The initial deficient selenium status was associated with an impaired thyroid function and the changes in thyroid hormone levels can be explained by increased activity of deiodinases. We conclude that a substantial part of the elderly study population might suffer from suboptimal thyroidal function with adverse clinical implications due to selenium deficiency.

TRIAL REGISTRATION

This study was registered at ClinicalTrials.gov and has the identifier NCT01443780. Since it was not mandatory to register at the time the study began, the study has been registered retrospectively.

Iodine status and determinants in adults in Norway - results from a population-based health examination survey (The HUNT Study)

Background

In Norway, there is a lack of knowledge about the iodine status in the general and older adult population, and there is no established national monitoring programme for iodine. Several studies have indicated that iodine deficiency is prevalent in subgroups of the population. Salt iodisation is currently being considered as a measure to increase the population iodine status. In this cross-sectional study, the aim was to evaluate iodine status and determinants in the adult and older adult population in Mid-Norway, before salt iodisation is likely to be initiated.

Methods

The study sample was a subsample of participants in the fourth wave of the population-based Trøndelag Health Study (HUNT4, 2017-2019) with available spot-urine samples. This subsample included participants with 25-64 years (n = 500) and 70-79 years (n = 250). The urine samples were analysed for iodine and creatinine. Information on the habitual intake of milk/yoghurt, fish, supplement use, use of thyroid medication and relevant background factors was collected through a general questionnaire. Multivariable quantile regression was used to model differences in the median urinary iodine concentration (UIC) by determinants. Estimates were weighted to match the age and sex distribution of the Norwegian population aged 25-79 years in 2019.

Results

Median UIC was 97 µg/L (95% confidence interval [CI]: 92, 103) indicating borderline iodine deficiency at a group level. The median UIC increased with age, and iodine status was insufficient in participants below age 55 years (median 92 µg/L [95% CI: 85, 99]). Important determinants of UIC were habitual milk/yoghurt intake, daily supplement use and current use of thyroid medication, but not intake of lean or fatty fish. Risk of mild-to-moderate iodine deficiency was seen in those with a low intake of milk/yoghurt, no supplement use and who did not use thyroid medication. No group was identified as being at risk of iodine excess.

Conclusion

Iodine status was adequate in older adults but mildly deficient in adults under 55 years. Milk intake, supplement use and use of thyroid medication are important determinants of iodine intake in Norway.

Iodine and plant-based diets: a narrative review and calculation of iodine content

An increasing number of food-based recommendations promote a plant-based diet to address health concerns and environmental sustainability in global food systems. As the main sources of iodine in many countries are fish, eggs and dairy products, it is unclear whether plant-based diets, such as the EAT-Lancet reference diet, would provide sufficient iodine. This is important as iodine, through the thyroid hormones, is required for growth and brain development; adequate iodine intake is especially important before, and during, pregnancy. In this narrative review, we evaluated the current literature and estimated iodine provision from the EAT-Lancet reference diet. There is evidence that those following a strict plant-based diet, such as vegans, cannot reach the recommended iodine intake from food alone and are reliant on iodine supplements. Using the EAT-Lancet reference diet intake recommendations in combination with iodine values from UK food tables, we calculated that the diet would provide 128 μg/d (85 % of the adult recommendation of 150 μg/d and 51–64 % of the pregnancy recommendation of 200–250 μg/d). However, if milk is replaced with unfortified plant-based alternatives, total iodine provision would be just 54 μg/d (34 % and 22–27 % of the recommendations for adults and pregnancy, respectively). Plant-based dietary recommendations might place consumers at risk of iodine deficiency in countries without a fortification programme and where animal products provide the majority of iodine intake, such as the UK and Norway. It is essential that those following a predominantly plant-based diet are given appropriate dietary advice to ensure adequate iodine intake.

Unfavorable nutrient intakes in children up to school entry age: results from the nationwide German KiESEL study

Background

Nutrition in the first years of life is a cornerstone for child development and long-term health, yet there is a lack of current data on energy and nutrient intake among toddlers and preschoolers in Germany.

Objective

To analyze energy and nutrient intake in toddlers (1- to 2-year-olds) and preschoolers (3- to 5-year-olds) in Germany and compare the results with the Dietary Reference Values (DRVs) by the European Food Safety Authority.

Design

Dietary intake was assessed by weighed food record data (3 + 1 day) of 890 children from the representative cross-sectional Children's Nutrition Survey to Record Food Consumption (KiESEL), carried out in 2014-2017 as a module of the German Health Interview and Examination Survey for Children and Adolescents Wave 2. For the calculation of energy and nutrient intake, the German Nutrient Database BLS 3.02, LEBTAB, and a supplement database were used.

Results

Median intakes of energy and most nutrients met or exceeded the DRVs in both toddlers and preschoolers. However, low intakes relative to DRVs were found for vitamin D (6-9% of DRV, including supplements) and iodine (57-65% of DRV). Age specific downward deviations were observed for iron intake in toddlers (75% of DRV) and for calcium intake in preschoolers (67-77% of DRV). In contrast, intakes were high for saturated fatty acids (SFA) (14-16 E%), mono-/disaccharides (60-87 g/day), and protein [2.1-2.6 g/(kg body weight*day)].

Conclusion

Nutrient imbalances in toddlers and preschoolers in Germany, which are partly age-related, give rise to concern. Research is needed to determine if routine vitamin D supplementation should be extended beyond infancy. Public health efforts to increase the rate of use of iodized salt and to reduce the intake of SFA and mono-/disaccharides in children's diets are to be strengthened.

Iodine: a scoping review for Nordic Nutrition Recommendations 2023

Iodine is essential for the synthesis of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). As in many other parts of the world, insufficient iodine intake and consequently insufficient iodine status is a public health challenge in the Nordic and Baltic countries. The main dietary sources of iodine in the Nordic and Baltic countries include cow's milk, saltwater fish, eggs, products containing iodised salt, and iodised table salt. Only Denmark (DK), Finland (FI) and Sweden (SE) have implemented mandatory (DK) or voluntary (SE, FI) salt iodisation. New data, as well as recent studies from the Nordic and Baltic countries, strengthen the evidence that the main health challenges related to insufficient iodine intake remain thyroid function and thyroid disease, mental development, and cognitive function. Excessive intakes can also cause hyperthyroidism, autoimmune thyroid disease, and thyroid cancer.

Adjusting the Iodine Content of Iodized Salt to Meet the Recommended Intake for Females of Reproductive Age: A Simulation Study with a Reduced Sodium Scenario

BACKGROUND

The use of iodized salt is a key strategy to increase iodine intake worldwide. In many countries, including New Zealand, females of reproductive age are still at risk of being mildly iodine deficient.

OBJECTIVE

This study aimed to determine the level of iodization of salt needed to ensure that females aged 18 to 40 y have an adequate intake of iodine in 2 scenarios: current discretionary salt intake and reduced discretionary salt intake.

METHOD

Data from nonpregnant, nonlactating females aged 18 to 40 y (n = 795) who took part in the 2008/09 New Zealand Adult Nutrition Survey and completed a 24-h dietary recall were used. Iodine intake was determined from all foods except bread and discretionary salt, which are fortified with iodine. Iodine from bread and salt was estimated at different levels of salt iodization, starting at 25 mg iodine/kg salt and increasing incrementally by 5 mg/kg, and added to calculate total iodine intake. The simulation concluded when the appropriate iodine content in salt was found using the estimated average requirement (EAR) cut-point method.

RESULTS

In the 2 scenarios, current discretionary salt intake (i.e., 400 mg/d) and reduced discretionary salt intake (i.e., 304 mg/d), the iodine concentration of salt is required to be 55 mg/kg and 70 mg/kg for no more than 2% of females to have an iodine intake below the EAR of 100 μg of iodine/d, respectively. In both scenarios and at all levels of iodine concentration, no one was above the upper level of intake of iodine of 1100 μg/d.

CONCLUSIONS

This study found that females of reproductive age need to consume iodized salt at the higher end of the legislated range of 25 to 65 mg/kg. If strategies to reduce sodium intake were adopted, the range would need to increase, or iodized salt would need to be included in a wider range of staple foods.

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

Background

Iodine deficiency is a major public health problem in pregnant women. Serum iodine (SI) may represent a useful biomarker for iodine nutrition evaluation. We aimed to assess the relationship between serum iodine concentration (SIC) and urinary iodine concentration (UIC), dietary iodine, thyroid function, and thyroid diseases in pregnant women in the southeast coast of China, and to provide a normal reference range of SIC for pregnant women.

Methods

A multistage random sampling method was used to select the study population. We collected urine and blood samples from pregnant women and determined UIC and SIC as well as thyroid function using Arsenic-Cerium Catalytic Spectrophotometry, inductively coupled plasma mass spectrometry, and Beckman Coulter Access2 chemiluminescent immunoanalyzer and kit, respectively, and administered a questionnaire on dietary iodine intake in pregnant women.

Results

There was a significant negative correlation between SI and thyroid-stimulating hormone (TSH) (r = -0.141) and a significant positive correlation between SI and free triiodothyronine (FT3) (r = 0.106), free thyroxine (FT4) (r = 0.236), triiodothyronine (TT3) (r = 0.229), total thyroxine (TT4) (r = 0.433), and dietary iodine intake (r = 0.068). There was a significant difference in SI levels of pregnancy between the second (78.13 μg/L) and third trimester (75.37 μg/L) (p = 0.018). SI levels between inadequate intake (74.58 μg/L) and appropriate intake (77.92 μg/L) groups were statistically different (p = 0.036). Low SIC was a risk factor for the development of hypothyroxinemia (adjusted OR = 3.14, 95% confidence interval: 1.75-5.66). The reference range for SIC in normal pregnant women is 45.03-112.44 μg/L.

Conclusion

SI may be a composite indicator of iodine nutritional status and thyroid function.

Case report of congenital goitre in a goat kid: Clinical and pathological findings

Congenital goitre is a deadly thyroid metabolic disorder characterised by low thyroid hormone levels, subsequent secretion of excess Thyroid-Stimulating Hormone (TSH) from the pituitary gland, and compensatory thyroid gland hyperplasia. This study aimed to summarise the clinical and pathological features of congenital goitre in a goat kid. In April 2019, a dead female goat kid with a history of dystocia was referred to Ferdowsi University of Mashhad Veterinary Teaching Hospital, Mashhad, Iran, to examine the carcass and find the reason for death. The necropsy were performed, along with histopathology examination, and clinical signs were recorded. Examination of the foetus revealed the presence of an enlarged thyroid gland, and the skin was thick with myxedema, pale, and without hair. After cutting the skin, the swelling showed a significantly enlarged thyroid gland with two asymmetrical lobes, with the right lobe 3.9×7.1 cm and the left 3.7×7.5 cm in size. In the histopathological examination, a severe proliferation of follicular cells was observed, which caused the thyroid gland to be microscopically dense. In conclusion, this study highlights the importance of recognising and addressing congenital goitre in goat kids. To prevent such tragic outcomes, it is crucial to focus on early detection and intervention. Furthermore, the agents of goitre need to find out and be clear.

Urinary iodine excretion and optimal time point for sampling when estimating 24-h urinary iodine

Iodine deficiency may cause thyroid dysfunction. The iodine intake in a population is measured by urinary iodine concentration (UIC) in spot samples or 24-h urinary iodine excretion (24UIE). 24UIE is considered the gold standard and may be estimated using an equation including UIC, urinary creatinine concentration, sex and age (e24UIE). The aims of this study were to evaluate the preferable timing of UIC when using this equation and assess the variability of UIE. Sixty healthy non-smoking women (n 31) and men (n 29) were included in Gothenburg, Sweden. Twelve urine samples were collected at six fixed times on two separate days. Variability was calculated for UIC, 24UIE, e24UIE, iodine excretion per hour (iHr) and UIC adjusted for creatinine and specific gravity. Median 24UIE was 156 µg/24 h and the median UIC (all spot samples) was 104 µg/l. UIC (P < 0·001), 24UIE (P = 0·001) and e24UIE (P < 0·001) were significantly higher in men. e24UIE was relatively similar to 24UIE. However, when e24UIE was calculated from UIC in the first void, it was about 15 % lower than 24UIE (P < 0·001). iHr was lowest in the morning and highest in the afternoon. Median iHr was higher in men (7·4 v. 5·3 µg/h, P < 0·001). The variability of UIE was higher within individuals than between individuals. This study suggests that most time points for estimation of individual 24UIE are appropriate, but they should preferably not be collected in the first void.

National monitoring of iodine, sodium, and vitamin D status in toddlers and women of childbearing age - results and lessons learned from a pilot study in Norway

Background

Norway is lacking a population-based national monitoring program for iodine, sodium, and vitamin D status.

Objective

The aim of this study was to pilot-test a study design for collecting biological samples from a country-representative sample of 2-year-old children and their mothers and to report results for iodine, salt, and vitamin D at baseline, before initiation of salt iodization in Norway.

Design

In a cross-sectional study, we recruited 2-year-old children and their mothers during the routine 2-year check-up through 38 randomly selected health clinics in 2021. Spot urine samples were analyzed for iodine, creatinine, and sodium, and dried blood spots from the mothers were analyzed for thyroglobulin (Tg) and 25-hydroxyvitamin D (25(OH)D).

Results

We aimed at including 400 mother-child pairs but recruited only 55 pairs. Major challenges were closed health clinics due to the COVID-19 pandemic, lack of motivation of the health personnel to prioritize recruiting, missing information about non-participation, and high workload for participants. The median urinary iodine concentration (UIC) was 123 (95% CI: 76, 228) µg/L in the toddlers and 83 (95% CI: 72, 99) µg/L in the mothers. The median urinary sodium concentration (UNaC) was 62 (95% CI: 37, 91) mmol/L in the toddlers and 93 (95% CI: 77, 107) mmol/L in the mothers. Of the mothers, 18% had levels of 25(OH)D <50 nmol/L (suboptimal status).

Discussion and conclusion

Lessons learned from the pilot study will be used to design a national monitoring program for toddlers and women of childbearing age in Norway. The results indicate that 2-year-old children and women of childbearing age in Norway may have inadequate iodine intakes at the group level, while for vitamin D, most of the mothers had adequate status.

Long-term stability of thyroid peroxidase antibody (anti-TPO) in serum in the Danish General Suburban Population Study

OBJECTIVES

We evaluated the long-term stability of thyroid peroxidase antibody (anti-TPO).

METHODS

In the Danish General Suburban Population Study (GESUS), serum samples were biobanked at -80 °C during 2010-2013. In a paired design with 70 subjects, we compared anti-TPO (30-198 U/mL) measured on fresh serum on Kryptor Classic in 2010-2011 (anti-TPOfresh) with anti-TPO remeasured on frozen serum (anti-TPOfrozen) on Kryptor Compact Plus in 2022. Both instruments used the same reagents and the anti-TPOn automated immunofluorescent assay, which was calibrated against the international standard NIBSC 66/387, based on the Time Resolved Amplified Cryptate Emission (TRACE) technology from BRAHMS. Values greater than 60 U/mL are regarded as positive in Denmark with this assay. Statistical comparisons included Bland-Altman, Passing-Bablok regression, and Kappa statistic.

RESULTS

The mean follow-up time was 11.9 years (SD: 0.43). For anti-TPOfrozen vs. anti-TPOfresh, the line of equality was within the confidence interval of the absolute mean difference [5.71 (-0.32; 11.7) U/mL] and the average percentage deviation [+2.22% (-3.89%; +8.34%)]. The average percentage deviation of 2.22% did not exceed analytical variability. Passing-Bablok regression revealed both a statistically significant systematic and proportional difference: Anti-TPOfrozen=-22.6 + 1.22*(anti-TPOfresh). Frozen samples were correctly classified as positive in 64/70 (91.4%; Kappa=71.8%).

CONCLUSIONS

Anti-TPO serum samples in the range 30-198 U/mL were stable after 12-years of storage at -80 °C with an estimated nonsignificant average percentage deviation of +2.22%. This comparison is based on Kryptor Classic and Kryptor Compact Plus, which used identical assays, reagents, and calibrator, but for which the agreement in the range 30-198 U/mL is unclarified.

Iodine Deficiency, Maternal Hypothyroxinemia and Endocrine Disrupters Affecting Fetal Brain Development: A Scoping Review

This scoping review critically discusses the publications of the last 30 years on the impact of mild to moderate iodine deficiency and the additional impact of endocrine disrupters during pregnancy on embryonal/fetal brain development. An asymptomatic mild to moderate iodine deficiency and/or isolated maternal hypothyroxinemia might affect the development of the embryonal/fetal brain. There is sufficient evidence underlining the importance of an adequate iodine supply for all women of childbearing age in order to prevent negative mental and social consequences for their children. An additional threat to the thyroid hormone system is the ubiquitous exposure to endocrine disrupters, which might exacerbate the effects of iodine deficiency in pregnant women on the neurocognitive development of their offspring. Ensuring adequate iodine intake is therefore essential not only for healthy fetal and neonatal development in general, but it might also extenuate the effects of endocrine disruptors. Individual iodine supplementation of women of childbearing age living in areas with mild to moderate iodine deficiency is mandatory as long as worldwide universal salt iodization does not guarantee an adequate iodine supply. There is an urgent need for detailed strategies to identify and reduce exposure to endocrine disrupters according to the "precautional principle".

Inadequate Iodine Intake in Mothers of Young Children in Innlandet County, Norway

Background

Iodine has an essential role in child growth and brain development. Thus, sufficient iodine intake is particularly important in women of childbearing age and lactating women.

Objectives

This cross-sectional study aimed to describe iodine intake in a large random sample of mothers of young children (aged ≤2 y) living in Innlandet County, Norway.

Methods

From November 2020 to October 2021, 355 mother-child pairs were recruited from public health care centers. Dietary data were obtained using two 24-h dietary recalls (24-HRs) per woman and an electronic FFQ. The Multiple Source Method was used to estimate the usual iodine intake from the 24-HR assessment.

Results

Based on the 24-HRs, the median (P25, P75) usual iodine intake from food was 117 μg/d (88, 153) in nonlactating women and 129 μg/d (95, 176) in lactating women. The median (P25, P75) total usual iodine intake (from food combined with supplements) was 141 μg/d (97, 185) in nonlactating women and 153 μg/d (107, 227) in lactating women. Based on the 24-HRs, 62% of the women had a total iodine intake below the recommendations (150 μg/d in nonlactating women and 200 μg/d in lactating women), and 23% of them had an iodine intake below the average requirement (100 μg/d). The reported use of iodine-containing supplements was 21.4% in nonlactating women and 28.9% in lactating women. In regular users of iodine-containing supplements (n = 63), supplements contributed to an average of 172 μg/d of iodine. Among regular iodine supplement users, 81% reached the recommendations compared with 26% of nonsupplement users (n = 237). The iodine intake estimated by FFQ was substantially higher than that estimated by 24-HRs.

Conclusions

Maternal iodine intake in Innlandet County was inadequate. This study confirms the need for action to improve iodine intake in Norway, particularly among women of childbearing age.

Iodine status in Danish pregnant women after an increase in iodine fortification

OBJECTIVE

Iodine fortification programmes are implemented in many countries and often associated with an increase in population iodine intake. However, the initial attempt may not be sufficient and in Denmark the level of iodine added to salt was increased in 2019. Sparse evidence is available on the impact of such modification in iodine fortification. The aim of this study was to evaluate iodine status in Danish pregnant women in 2021 after this increase in iodine fortification and compare to iodine status in 2012.

DESIGN

Cross-sectional study.

PATIENTS

Pregnant women in the North Denmark Region referred for routine obstetric ultrasound in 2021.

MEASUREMENTS

Participants filled out a questionnaire and delivered a spot urine. Median urinary iodine concentration (UIC) was calculated and assessed according to the recommended range in pregnancy (150-249 µg/L).

RESULTS

Altogether 147 pregnant women were included and 88% used iodine-containing supplements. Median UIC was overall 77 µg/L [95% confidence interval (CI): 61-96 µg/L], which was lower than in 2012 (101 µg/L [95% CI: 89-111 µg/L]) (p < 0.001). Considering sources of iodine intake in pregnancy, lower daily intake of dairy products (p = 0.008) and bread (p < 0.001) and a lower content of iodine in the supplement used (p < 0.001) was seen in 2021 compared to 2012.

CONCLUSION

Despite an increase in iodine fortification and frequent use of iodine-containing supplements, iodine status in pregnant women in the North Denmark Region was insufficient. Results call for continued monitoring and attention to ensure adequate iodine status during pregnancy in Denmark.

The Effect of a Vegan Diet on the Coverage of the Recommended Dietary Allowance (RDA) for Iodine among People from Poland

The aim of this research was to estimate the effect of a vegan diet on the Recommended Dietary Allowance (RDA) coverage for iodine in people from Poland. It was hypothesized that the problem of iodine deficiency is a concern, especially among vegans. The survey study was conducted in the years 2021-2022 on 2200 people aged 18-80 with omnivore and vegan diets. The exclusion criteria in the study were pregnancy and lactation. The study found that the coverage of RDA for iodine among people with a vegan diet was lower than among people with an omnivore diet (p < 0.05); 90% of the participants with a vegan diet had an iodine intake below 150 µg/day. Plant-based dairy and meat analogs were consumed by vegans frequently and in large portions, but none were fortified with iodine. It was found that iodized salt was each group's primary source of iodine. However, it was observed that the iodine supply from this source was limited among vegans, especially in female subjects, who consumed less salt and smaller portions of meals. That is why consideration should be given to the iodine fortification of plant-based foods commonly consumed by vegans.

Midwives and public health nurses' knowledge and clinical practice in securing sufficient iodine status in relation to pregnancy. A cross-sectional study

AIM

To investigate midwives' (MWs) and public health nurses' (PHNs) clinical practice and knowledge related to nutrition, with a particular focus on iodine in northern parts of Norway. Maternal iodine status prior to and during pregnancy, and the lactating period, is crucial for brain development and growth of the foetus and infant, from conception up until the first two years of life. In Norway, studies have documented mild to moderate iodine deficiency in this group.

DESIGN/METHODS

MWs (n = 128) and PHNs (n = 154) responded to a survey regarding nutrition and iodine. Descriptive data and non-parametric tests were used to analyse data.

RESULTS

Around half of the participants provided dietary guidance to a great extent. Practice of iodine-specific recommendations was lower, particularly regarding lactating women. Compared to other nutrients, iodine was not a priority.

CONCLUSION

The study indicates a lack of knowledge and poor clinical practice about iodine among MWs and PHNs.

Iodine nutrition with North Atlantic living: the Faroese adolescents

Iodine nutrition is critical for human health. While iodine excretion was low within the recommended range among adult Faroese, younger generations tend to abandon local foods. Such changes raise a concern about iodine intake, which led us to perform this first study of iodine nutrition among teenagers in the North Atlantic islands. We used samples from a nationwide collection of urine samples in 14-year-olds following iodine fortification of salt in 2000. Urine was analysed for iodine and creatinine to adjust for dilution by iodine/creatinine, and a food frequency questionnaire was used to record the intake of iodine-rich foods. The 129 participants yielded a 90 % precision of the estimated iodine nutrition level. The median urinary iodine concentration (UIC) was 166 μg/l (bootstrapped 95 % confidence interval 156–184 μg/l). The median creatinine-adjusted UIC was 132 μg/g (bootstrapped 95 % CI 120–138 μg/g). Fish and whale meat dinners were more frequent among residents of villages compared with the capital: median fish dinners, 3 v. 2 per week (P = 0⋅001), and whale meat, 1 v. 0⋅4 per month (P < 0⋅001). UIC decreased with fewer fish dinners (P = 0⋅03). Our study demonstrated that Faroese teenagers were iodine-replete. The changing dietary habits emphasise the need for continuous monitoring of iodine nutrition and surveying iodine deficiency disorders.

Mild-to-moderate iodine deficiency and symptoms of emotional distress and depression in pregnancy and six months postpartum - Results from a large pregnancy cohort

BACKGROUND

The relationship between iodine intake and depression is unknown. The aim of the present study was to investigate whether iodine intake was associated with symptoms of perinatal emotional distress and depression in a mild- to moderately iodine deficient population.

METHODS

The study population comprised 67,812 women with 77,927 pregnancies participating in the Norwegian Mother, Father and Child Cohort Study. Self-reported emotional distress and depressive symptoms were reported in pregnancy and at six months postpartum. Iodine intake was assessed by a food frequency questionnaire in mid-pregnancy. Urinary iodine concentration (UIC) was available for 2792 pregnancies.

RESULTS

The median iodine intake from food was 121 μg/day and the median UIC was 68 μg/L. The prevalence of high scores for emotional distress was 6.6 % in pregnancy and 5.8 % six months postpartum, and for high scores on postpartum depression it was 10.3 %. In non-users of iodine supplements (63 %), a low maternal iodine intake from food (lower than ~100-150 μg/day) was associated with increased risk of high scores of emotional distress and depression both in pregnancy and six months postpartum (p < 0.001). Iodine supplement use was associated with increased risk of high scores of emotional distress in pregnancy compared to no supplement use or use of supplements without iodine.

LIMITATIONS

Observational design, self-report information, and short scales to assess symptoms of emotional distress and depression.

CONCLUSION

A low habitual iodine intake was associated with increased prevalence of perinatal emotional distress and depression. The potential non-beneficial effect of iodine supplements may have biological explanations. More studies are needed.

Macromineral and trace element concentrations in milk from Finnish Ayrshire cows fed microalgae (Spirulina platensis) and rapeseed (Brassica napus)

Given the lack of research regarding the effect of microalgal supplementation in dairy cows on milk mineral concentrations, this study investigated the effect of feeding different protein supplements in dairy cow diets on milk, feces, and blood plasma mineral concentrations, associated milk and blood plasma transfer efficiencies, and apparent digestibility. Lactating Finnish Ayrshire cows (n = 8) were allocated at the start of the trial to 4 diets used in a replicated 4 × 4 Latin square design experiment: (1) control diet (CON), (2) a pelleted rapeseed supplement (RSS; 2,550 g/d), (3) a mixture of rapeseed and Spirulina platensis (RSAL; 1,280 g of RSS + 570 g of S. platensis per day), and (4) S. platensis (ALG; 1,130 g of S. platensis per day). In each of the 4 experimental periods, a 2-wk adaptation to the experimental diets was followed by a 7-d sampling and measurement period. Feed samples were composited per measurement period, milk, and feed samples (4 consecutive days; d 17-20), and blood plasma samples (d 21) were composited for each cow period (n = 32). Data were statistically analyzed using a linear mixed effects model with diet, period within square, square and their interaction as fixed factors, and cow within square as a random factor. Cows fed ALG were not significantly different in their milk or blood plasma mineral concentrations compared with CON, although feeding ALG increased fecal concentrations of macrominerals (Ca and Mg) and trace elements (Co, Cu, Fe, I, Mn, and Zn), and reduced their apparent digestibility, compared with CON. When compared with CON and ALG, milk from cows fed RSAL and RSS had lower milk I concentrations (-69.6 and -102.7 μg/kg of milk, respectively), but total plasma I concentrations were not affected significantly. Feeding S. platensis to dairy cows did not affect mineral concentrations in cows' blood or milk, but care should be taken when rapeseed is fed to avoid reducing milk I concentrations which may in turn reduce consumers' I intake from milk and dairy products.

Cancer-specific mortality in breast cancer patients with hypothyroidism: a UK population-based study

PURPOSE

Epidemiological studies have indicated a higher prevalence of hypothyroidism in breast cancer patients, possibly related to shared risk factors and breast cancer treatments. However, few studies have evaluated how hypothyroidism impacts survival outcomes in breast cancer patients. We aimed to determine the association between hypothyroidism and breast cancer-specific and all-cause mortality.

METHODS

We conducted a population-based study using the Scottish Cancer Registry to identify women diagnosed with breast cancer between 2010 and 2017. A matched comparison cohort of breast cancer-free women was also identified. Using hospital diagnoses and dispensed prescriptions for levothyroxine, we identified hypothyroidism diagnosed before and after breast cancer diagnosis and determined associations with breast cancer-specific and all-cause mortality. Cox proportional hazards regression was used to calculate hazard ratios (HR) and 95% confidence intervals (CI) adjusted for potential confounders.

RESULTS

A total of 33,500 breast cancer patients were identified, of which 3,802 had hypothyroidism before breast cancer diagnosis and 565 patients went on to develop hypothyroidism after. Breast cancer patients had higher rates of hypothyroidism compared with cancer-free controls (HR 1.14, 95% CI 1.01-1.30). Among breast cancer patients, we found no association between hypothyroidism (diagnosed before or after) and cancer-specific mortality (before: HR 0.99, 95% CI 0.88-1.12, after: HR 0.97, 95% CI 0.63-1.49). Similar associations were seen for all-cause mortality.

CONCLUSION

In a large contemporary breast cancer cohort, there was little evidence that hypothyroidism, either at diagnosis or diagnosed after breast cancer, was associated with cancer-specific or all-cause mortality.

Antenatal thyroid hormone therapy and antithyroid drug use in Norway from 2004 to 2018

OBJECTIVE

Thyroid disease during pregnancy is associated with adverse pregnancy outcomes and suboptimal fetal development. During the last decades, guidelines for diagnosing thyroid disease during pregnancy have changed considerably and there has been increased awareness. This study aimed to describe the prevalence of thyroid disease treatment over time among pregnant women in Norway.

DESIGN

Nationwide register-based study.

METHODS

We combined historical data from the Medical Birth Registry of Norway and the Norwegian Prescription Database, identifying pregnant women using thyroid therapy from 2004 to 2018.

RESULTS

A total of 855,067 pregnancies were included in the analyses. The proportion of women using thyroid hormone replacement therapy during pregnancy increased from 1.46% (n = 800) in 2004 to 3.57% (n = 1940) in 2018. The proportion of women using antithyroid medications also increased from 0.04% (n = 20) in 2004 to 0.10% (n = 56). During these 15 years, the mean maternal age increased by 0.9 years. When adjusting for age, the risk for being on thyroid hormone replacement therapy during pregnancy increased by an average of 5% per year (odds ratio: 1.05, 95% CI: 1.05-1.05).

CONCLUSION

During the recent 15 years, there has been a substantial increase in the use of thyroid hormone therapy in Norwegian pregnant women. We speculate that this could be due to an increased awareness in combination with overdiagnosis because of inappropriate diagnostic criteria. To truly understand the possible causes and consequences of this development, further research is warranted.

Disparities in Nutritional Adequacy of Diets between Different Socioeconomic Groups of Finnish Adults

Information on dietary adequacy is needed to assess food and nutrition security in a modern society, especially in the transition towards climate-friendly food systems. In this study, differences in the nutritional adequacy of diets among Finnish adults were evaluated in population groups of different education, income and urbanisation levels. The study used data from the FinDiet 2017 Survey (n = 1655, 18-74 years). Modelled usual intakes of foods and nutrients were evaluated relative to food-based dietary guidelines issued by the National Nutrition Council of Finland (FNNC) and with respect to nutrient adequacy following the Nordic Nutrition Recommendations and FNNC. For about half of the nutrients studied, intakes were found to be adequate. Intakes of protein, fat, saturated fatty acids and salt were estimated to be high. By contrast, inadequate intakes were seen in folate and vitamins A, D, B1, B2 and C in almost all groups studied. Groups with a higher education and income, groups that lived in urban areas and, in particular, women adhered more closely to recommended food consumption and nutrient intakes than others. However, major challenges posed by the Finnish diet are common to all groups studied, and only certain dietary features evaluated in view of nutritional adequacy are associated with socioeconomic differences.

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.

Infant Iodine and Selenium Status in Relation to Maternal Status and Diet During Pregnancy and Lactation

Iodine and selenium are essential trace elements. Recent studies indicate that pregnant and lactating women often have insufficient intake of iodine and selenium, but the impact on fetal and infant status is unclear. Here, we assessed iodine and selenium status of infants in relation to maternal intake and status of these trace elements in the birth cohort NICE, conducted in northern Sweden (n = 604). Iodine was measured in urine (UIC) in gestational week 29, and in breast milk and infant urine 4 months postpartum, while selenium was measured in maternal plasma and erythrocytes in gestational week 29, and in breast milk and infant erythrocytes 4 months postpartum, in both cases using ICP-MS. Maternal intake was assessed with semi-quantitative food frequency questionnaires in gestational week 34 and at 4 months postpartum. The median intake of iodine and selenium during pregnancy (98 and 40 μg/d, respectively) and lactation (108 and 39 μg/d, respectively) was below recommended intakes, reflected in insufficient status (median UIC of 113 μg/L, median plasma selenium of 65 μg/L). Also, breast milk concentrations (median iodine 77 μg/L, median selenium 9 μg/L) were unlikely to meet infant requirements. Median UIC of the infants was 114 μg/L and median erythrocyte selenium 96 μg/kg, both similar to the maternal concentrations. Infant UIC correlated strongly with breast milk levels (rho = 0.64, p < 0.001). Their erythrocyte selenium correlated with maternal erythrocyte selenium in pregnancy (rho = 0.38, p < 0.001), but not with breast milk selenium, suggesting formation of prenatal reserves. Our results indicate that the transport of iodine and selenium to the fetus and infant is prioritized. Still, it is uncertain whether most infants had sufficient intakes. Further, the results might indicate an involvement of iodine in asthma development during the first year of life, which is essential to follow up. The low maternal and infant dietary intake of both iodine and selenium, especially when the mothers did not use supplements or iodized table salt, suggest a need for a general screening of women and young children.

New Reference Values for Thyroid Volume and a Comprehensive Assessment for Influencing Factors in Chinese Adults with Iodine Sufficiency

OBJECTIVES

The reference values for thyroid volume (Tvol) determined by ultrasound require supportive data of normal Tvol from local iodine-sufficient populations. This study aimed to explore new reference values for Tvol in Chinese adults and comprehensively evaluate the factors associated with enlarged Tvol.

METHODS

A cross-sectional study was conducted in Tianjin, China. Tvol was measured by ultrasound in adults with long-term iodine sufficiency. Blood and urine samples were collected to evaluate biochemical indexes, thyroid function, and iodine status.

RESULTS

A total of 1,991 adults from the urban and suburban areas were analysed. The trend of Tvol increasing with age was observed in men under age 40 years and in women under age 52 years. In the quantile regression analyses, we found that body surface area (BSA) (β = 7.22, 95% CI: 5.33, 9.12), thyroid-stimulating hormone (TSH) (β = -1.48, 95% CI: -2.39, -0.57), thyroid nodules (TNs) (β = 6.70, 95% CI: 2.19, 11.22), and metabolic syndrome (MetS) (β = 1.40, 95% CI: 0.63, 2.17) had a strong effect on Tvol at higher percentiles in males. The dominant factors influencing Tvol were BSA (β = 9.64, 95% CI: 2.66, 16.61), TSH (β = -0.78, 95% CI: -1.16, -0.39), and TNs (β = 1.11, 95% CI: 0.43, 1.79) in females. The largest reference values for Tvol based on BSA were 20.18 (17.79, 24.32) mL in males and 15.31 (14.05, 16.70) mL in females.

CONCLUSIONS

Quantile regression analyses showed that a high BSA index, a decreased TSH level, and the prevalence of TNs were essential factors associated with the enlargement of the thyroid gland. Our findings reported the new reference values for Tvol determined by ultrasound based on gender and BSA in Chinese adults.

Changes in organoleptic, microbiological and biochemical properties of kefir with iodine addition during the storage

Iodine is a vital trace element that must be constantly and daily supplied with food to the organism. Currently, the amount of food that can provide the organism with the required amount of iodine is insufficient. The purpose of the study was to investigate changes in organoleptic, microbiological, and biochemical parameters of kefir made with the addition of iodine during its refrigeration storage. It was found that during the storage of samples of kefir with iodine there is a slowdown in the reproduction of lactic acid bacteria, compared with the control sample. In particular, the number of lactic acid bacteria during the first two days of storage increased 1.3 times in the experimental sample and 1.5 times in the control sample of kefir. After 12 days of storage, the number of lactobacilli in the test sample of kefir increased 2.5 times, and in the control 3.2 times, compared with the amount in fresh kefir. Similar patterns were observed in determining the development of yeast. In particular, the reproduction rate of yeast in the control sample of kefir was, on average, 1.3 times faster (8 – 12 days), compared with yeast in the experimental sample. It was also found that during the 12-day storage period at a temperature of +6 °C, the titrated acidity in kefir with iodine increased 1.4 times, and in the control 1.6 times and was 130.5 °T and 154.1 °T, respectively. At such acidity values, the test sample of kefir still met the requirements of the standard, and the control was 24.1 °T higher. In this case, kefir containing iodide had better organoleptic characteristics during 12 days of storage. Produced kefir with the addition of iodine can be considered a functional product to provide the population with sufficient iodine.

Iodine and thyroid status during pregnancy and risk of stillbirth: A population-based nested case-control study

Prior research suggests that severe iodine deficiency in pregnancy may be associated with stillbirth. However, the relationship between mild to moderate iodine insufficiency, which is prevalent even in developed countries, and risk of stillbirth is unclear. We thus examined associations of iodine status and risk of stillbirth in a prospective population‐based nested case–control study in Finland, a mild to moderately iodine insufficient population. Stillbirth cases (n = 199) and unaffected controls (n = 249) were randomly selected from among all singleton births in Finland from 2012 to 2013. Serum samples were collected between 10 and 14 weeks gestation and analysed for iodide, thyroglobulin (Tg) and thyroid‐stimulating hormone (TSH). Odds ratios (ORs) and 95% confidence intervals (CIs) for stillbirth were estimated using logistic regression. After adjusting for maternal age, prepregnancy body mass index, socio‐economic status and other factors, neither high nor low serum iodide was associated with risk of stillbirth (Q1 vs. Q2–Q3 OR = 0.92, 95% CI = 0.78–1.09; Q4 vs. Q2–Q3 OR = 0.78; 95% CI = 0.45–1.33). Tg and TSH were also not associated with risk of stillbirth in adjusted models. Maternal iodine status was not associated with stillbirth risk in this mildly to moderately iodine‐deficient population. Tg and TSH, which reflect functional iodine status, were also not associated with stillbirth risk. The lack of associations observed between serum iodide, TSH and Tg and risk of stillbirth is reassuring, given that iodine deficiency in pregnancy is prevalent in developed countries.

Functional Meat Products as Oxidative Stress Modulators: A Review

High meat consumption has been associated with increased oxidative stress mainly due to the generation of oxidized compounds in the body, such as malondialdehyde, 4-hydroxy-nonenal, oxysterols, or protein carbonyls, which can induce oxidative damage. Meat products are excellent matrices for introducing different bioactive compounds, to obtain functional meat products aimed at minimizing the pro-oxidant effects associated with high meat consumption. Therefore, this review aims to summarize the concept and preparation of healthy and functional meat, which could benefit antioxidant status. Likewise, the key strategies regarding meat production and storage as well as ingredients used (e.g., minerals, polyphenols, fatty acids, walnuts) for developing these functional meats are detailed. Although most effort has been made to reduce the oxidation status of meat, newly emerging approaches also aim to improve the oxidation status of consumers of meat products. Thus, we will delve into the relation between functional meats and their health effects on consumers. In this review, animal trials and intervention studies are discussed, ascertaining the extent of functional meat products' properties (e.g., neutralizing reactive oxygen species formation and increasing the antioxidant response). The effects of functional meat products in the frame of diet-gene interactions are analyzed to 1) discover target subjects that would benefit from their consumption, and 2) understand the molecular mechanisms that ensure precision in the prevention and treatment of diseases, where high oxidative stress takes place. Long-term intervention-controlled studies, testing different types and amounts of functional meat, are also necessary to ascertain their positive impact on degenerative diseases.

Effect of Dietary Seaweed Supplementation in Cows on Milk Macrominerals, Trace Elements and Heavy Metal Concentrations

This study investigated the effect of seaweed supplementation in dairy cow diets on milk yield, basic composition, and mineral concentrations. Thirty-seven Icelandic cows were split into three diet treatments: control (CON, no seaweed), low seaweed (LSW, 0.75% concentrate dry matter (DM), 13–40 g/cow/day), and high seaweed (HSW, 1.5% concentrate DM, 26–158 g/cow/day). Cows were fed the same basal diet of grass silage and concentrate for a week, and then were introduced to the assigned experimental diets for 6 weeks. The seaweed mix of 91% Ascophyllum nodosum: 9% Laminaria digitata (DM basis), feed, and milk samples were collected weekly. Data were analyzed using a linear mixed effects model, with diet, week, and their interaction as fixed factors, cow ID as random factor, and the pre-treatment week data as a covariate. When compared with CON milk, LSW and HSW milk had, respectively, less Se (−1.4 and −3.1 μg/kg milk) and more I (+744 and +1649 μg/kg milk), while HSW milk also had less Cu (−11.6 μg/kg milk) and more As (+0.17 μg/kg milk) than CON milk. The minimal changes or concentrations in milk for Se, Cu, and As cannot be associated with any effects on consumer nutrition, but care should be taken when I-rich seaweed is fed to cows to avoid excessive animal I supply and milk I concentrations.

Iodine nutrition among the adult population of the Faroe Islands: a population-based study

The WHO recommends monitoring iodine status in all populations with median urinary iodine concentration (UIC) below 100 µg/l suggesting iodine deficiency. There are no data on the iodine intake among the population of the Faroe Islands. This study aimed to provide data on iodine nutrition in a representative sample of the general adult population from the Faroe Islands. We conducted a population-based cross-sectional survey in 2011–2012 and measured iodine in urine from 491 participants (294/197 men/women) using the ceri/arsen method after alkaline ashing. Participants include about 100 subjects in each of four adult decades and included participants from both the capital city and villages. The median UIC was low within the recommended range 101 µg/l (range 21–1870 µg/l). No samples were in the range suggesting severe iodine deficiency, but half of the samples were in the range of just adequate or mildly insufficient iodine intake with UIC markedly lower in women than in men (86 v. 115 µg/l; P < 0·001). Intake of fish and whale meals affected the UIC. In conclusion, nearly half of the population had an iodine excretion in the range of borderline or mild iodine deficiency. The lowest iodine nutrition level among Faroese women is a concern as it may extend to pregnancy with increased demands on iodine nutrition. In addition, we found that large variations and the intermittently excessive iodine intakes warrant follow-up on thyroid function in the population of the Faroe Islands.

The Increased Trend of Medical Treatment for Thyroid Diseases during Pregnancy: A 13-Year National Study

OBJECTIVE

Thyroid dysfunction affects up to 5-7% of all pregnancies. The rates of thyroid hormone use in nonpregnant population have substantially increased in recent years. The aim of this study was to assess possible changes in the use of levothyroxine substitution and antithyroid drugs over time in pregnant women.

METHODS

The study data consisted of all singleton pregnancies (N = 736,873) between 2004 and 2016 in Finland collected from the Finnish Medical Birth Register. The Prescription Register and Special Refund Entitlement Register provided information on levothyroxine and antithyroid drug purchases. The annual rates of levothyroxine and antithyroid drug prescription redemptions were explored to estimate changes in exposure rates to thyroid medication from 2004 to 2016. Joinpoint regression analyses were performed to explore interannual variability in levothyroxine and antithyroid drug treatment.

RESULTS

There was more than a five-fold increase in levothyroxine use during the study period; in 2004, 1.1% of pregnant women had levothyroxine treatment, and by 2016, the prevalence increased to 6.2%. In addition, we observed a slight increase in antithyroid medication during pregnancy, but antithyroid drug use during pregnancy overall was very rare. In 2004, 0.05% of pregnant women used antithyroid drugs, and by 2016, this percentage had increased to 0.14%.

CONCLUSIONS

Our study shows that the rate of levothyroxine use in pregnancy has markedly increased. This suggests that tracing and screening relevant patients and awareness of thyroid disorders on pregnancy and their significance for the pregnancy outcome have increased and the threshold to treat thyroid disorders has declined.

Adequate Urinary Iodine Concentration among Infants in the Inland Area of Norway

Considering the importance of iodine to support optimal growth and neurological development of the brain and central nervous system, this study aimed to assess and evaluate iodine status in Norwegian infants. We collected data on dietary intake of iodine, iodine knowledge in mothers, and assessed iodine concentration in mother’s breast milk and in infant’s urine in a cross-sectional study at two public healthcare clinics in the inland area of Norway. In the 130 mother–infant pairs, the estimated infant 24-h median iodine intake was 50 (IQR 31, 78) µg/day. The median infant urinary iodine concentration (UIC) was 146 (IQR 93, 250) µg/L and within the recommended median defined by the World Health Organization for this age group. Weaned infants had a higher UIC [210 (IQR 130, 330) µg/L] than exclusively breastfed infants [130 (IQR 78, 210) µg/L] and partially breastfed infants [135 (IQR 89, 250) µg/L], which suggest that the dietary data obtained in this study did not capture the accurate iodine intake of the included infants. The iodine status of infants in the inland area of Norway seemed adequate. Weaned infants had higher UIC compared to breastfed infants, suggesting early access and consumption of other sources of iodine in addition to breast milk.

Iodine status in UK-An accidental public health triumph gone sour

The improvement in iodine status among the UK population from the 1930s onwards has been described as an 'accidental public health triumph' despite the lack of any iodine fortification program. However, iodine deficiency in the UK has re-emerged in vulnerable groups and is likely due to a combination of changing farming practices, dietary preferences and public health priorities. The UK is now among only a minority of European countries with no legislative framework for iodine fortification. The experience of folic acid fortification and the 28-year delay in its implementation lays bare the political difficulties of introducing any fortification program in the UK. If iodine fortification is not an imminent possibility, then it is important to explore other options: how to change farming practice especially on organic farms; encourage dairy intake; protect and expand our public health programs of milk provision for vulnerable groups and embark on education programs for women of childbearing potential and healthcare professionals. This review explores how the UK may have arrived at this juncture and how the iodine status of the nation may be improved at this time of major political and public health upheaval.

Iodine status five years after the adjustment of universal salt iodization: a cross-sectional study in Fujian Province, China

Background

Universal salt iodization program was introduced to China to eliminate iodine deficiency disorders in 1995. In 2012, Fujian Province decreased the concentration of iodized table salt according to the national unified requirement. This study aimed to assess the effect on iodine status after the adjustment, providing evidence for further adjustment in Fujian Province.

Methods

Sampling units were selected by multistage cluster sampling method. In each sampling unit, table salt was collected from 30 households. A total of 2,471 people in 2009 and 4,806 people in 2017 provided urine samples and were included in this cross-sectional analysis. Median iodized salt concentration and median urine iodine concentration were present by median and interquartile range.

Results

Median iodized salt decreased from 29.8 mg/kg in 2009 to 23.9 mg/kg in 2017. The median urinary iodine concentrations for school-age children in 2017 in coastal urban area, non-coastal urban area, coastal rural area and non-coastal rural area were 163.6µg/L (interquartile range = 100.1–252.0µg/L), 198.9µg/L (interquartile range = 128.0-294.0µg/L), 181.8µg/L (interquartile range = 114.1–257.0µg/L) and 218.2µg/L (interquartile range = 148.1-306.5µg/L), respectively. The median urinary iodine concentrations for adults in 2017 in these areas were 151.1µg/L (interquartile range = 98.3-231.7µg/L), 168.7µg/L (interquartile range = 109.6–242.0µg/L), 167.7µg/L (interquartile range = 105.7-245.7µg/L) and 182.7µg/L (interquartile range = 117.1-258.9µg/L). The median urinary iodine concentrations for pregnant women in 2017 in these areas were 157.7µg/L (interquartile range = 106.9-223.8µg/L), 141.5µg/L (interquartile range = 97.7-207.6µg/L), 127.3µg/L (interquartile range = 90.0-184.5µg/L) and 144.8µg/L (interquartile range = 99.9-184.5µg/L). The median urinary iodine concentrations for lactating women in 2017 in these areas were 122.7µg/L (interquartile range = 84.1–172.0µg/L), 123.7µg/L (interquartile range = 70.7-184.7µg/L), 105.8µg/L (interquartile range = 67.1-152.3µg/L) and 110.2µg/L (interquartile range = 74.1-170.3µg/L).

Conclusions

The overall urinary iodine concentrations among school-age children, adults and lactating women dramatically decreased after implementing the new standard. Almost all of them were iodine adequate, suggesting we reached the expected aim of iodized salt adjustment. However, pregnant women were iodine insufficient after adjustment. Therefore, we should continue the surveillance of iodine status of populations and focus on the additional iodine supplement strategies for pregnant women.

Lower iodine storage in the placenta is associated with gestational diabetes mellitus

BACKGROUND

The micronutrient iodine is essential for a healthy intrauterine environment and is required for optimal fetal growth and neurodevelopment. Evidence linking urinary iodine concentrations, which mainly reflects short-term iodine intake, to gestational diabetes mellitus (GDM) is inconclusive. Although the placental concentrations would better reflect the long-term gestational iodine status, no studies to date have investigated the association between the placental iodine load and the risk at GDM. Moreover, evidence is lacking whether placental iodine could play a role in biomarkers of insulin resistance and β-cell activity.

METHODS

We assessed the incidence of GDM between weeks 24 and 28 of gestation for 471 mother-neonate pairs from the ENVIRONAGE birth cohort. In placentas, we determined the iodine concentrations. In maternal and cord blood, we measured the insulin concentrations, the Homeostasis Model Assessment (HOMA) for insulin resistance (IR) index, and β-cell activity. Logistic regression was used to estimate the odds ratios (OR) of GDM, and the population attributable factor (PAF) was calculated. Generalized linear models estimated the changes in insulin, HOMA-IR, and β-cell activity for a 5 μg/kg increase in placental iodine.

RESULTS

Higher placental iodine concentrations decreased the risk at GDM (OR = 0.82; 95%CI 0.72 to 0.93; p = 0.003). According to the PAF, 54.2% (95%CI 11.4 to 82.3%; p = 0.0006) of the GDM cases could be prevented if the mothers of the lowest tertile of placental iodine would have placental iodine levels as those belonging to the highest tertile. In cord blood, the plasma insulin concentration was inversely associated with the placental iodine load (β = - 4.8%; 95%CI - 8.9 to - 0.6%; p = 0.026).

CONCLUSIONS

Higher concentrations of placental iodine are linked with a lower incidence of GDM. Moreover, a lower placental iodine load is associated with an altered plasma insulin concentration, HOMA-IR index, and β-cell activity. These findings postulate that a mild-to-moderate iodine deficiency could be linked with subclinical and early-onset alterations in the normal insulin homeostasis in healthy pregnant women. Nevertheless, the functional link between gestational iodine status and GDM warrants further research.

Use of Thyroid Hormones in Hypothyroid and Euthyroid Patients: A 2020 THESIS Questionnaire Survey of Members of the Swedish Endocrine Society

BACKGROUND

The standard treatment of hypothyroidism is levothyroxine (LT-4). However, there are several controversies regarding treatment of hypothyroid patients.

AIM

To investigate the Swedish endocrinologists' use of thyroid hormones in hypothyroid and euthyroid individuals.

METHODS

Physician members of the Swedish Endocrine Society (SEF) were invited by e-mail to participate in an online survey investigating this topic.

RESULTS

Out of the eligible 411 members, 116 (28.2%) responded. The majority (98.9%) stated that L-T4 is the treatment of choice. However, around 50% also prescribed liothyronine (L-T3) or a combination of L-T4+L-T3 in their practice. Combination therapy was mostly (78.5%) used in patients with persistent hypothyroid symptoms despite biochemical euthyroidism on L-T4 treatment. Most respondents prescribed L-T4 tablets and did not expect any major changes with alternative formulations such as soft-gel capsules or liquid formulations in situations influencing the bioavailability of L-T4. In euthyroid patients, 49.5% replied that treatment with thyroid hormones was never indicated, while 47.3% would consider L-T4 for euthyroid infertile women with high thyroid peroxidase (TPO) antibody levels.

CONCLUSION

The treatment of choice for hypothyroidism in Sweden is L-T4 tablets. Combination therapy with L-T4+L-T3 tablets was considered for patients with persistent symptoms despite biochemical euthyroidism. Soft-gel capsules and liquid solutions of L-T4 were infrequently prescribed. Swedish endocrinologists' deviation from endocrine society guidelines merits further study.

Inadequate iodine intake in lactating women in Sweden: A pilot 1-year, prospective, observational study

INTRODUCTION

Breastfed infants depend on breast-milk iodine for growth and brain development, as iodine is a trace element important for thyroid hormone production. Iodine need is higher during lactation; hence, mothers and children are at risk of iodine deficiency. We aimed to explore maternal iodine and thyroidal status during lactation.

MATERIAL AND METHODS

Pregnant women were recruited in Gothenburg, southwest Sweden. Maternal urine and serum were collected at pregnancy week 35-37 (n = 84) and 0.5, 4, and 12 months postpartum. Seventy mothers provided breast milk at 0.5 months.

RESULTS

Median (interquartile range) breast-milk iodine concentration was 90 (66-116) μg/L. About 58% had breast-milk iodine concentration <100 μg/L. Iodine supplement users (n = 13) had higher breast-milk iodine concentration than non-users (n = 49) (140 μg/L vs 71 μg/L, P = .001). Exclusively breastfeeding women at 4 months postpartum (n = 57) had lower median urinary iodine concentration (85 μg/L vs 133 μg/L, P = .004) and higher thyroglobulin serum concentration (22.3 μg/L vs 11.8 μg/L, P = .032) than non-exclusively breastfeeding women (n = 25). Concentrations of thyroid hormones were unaffected.

CONCLUSIONS

This pilot study suggests that lactating women in southwest Sweden present mildly inadequate iodine intake, mainly among non-iodine supplement users and exclusively breastfeeding mothers. Studies on the coverage of the iodine fortification program in breastfeeding women are warranted.

Relationship of household cooking salt and eating out on iodine status of pregnant women in environmental iodine-deficient coastal areas of China

As city residents eat out more frequently, it is unknown that if iodised salt is still required in home cooking. We analysed the relationship of household salt and eating out on urinary iodine concentration (UIC) in pregnant women. A household condiment weighing method was implemented to collect salt data for a week. A household salt sample was collected. A urine sample was taken at the end of the week. Totally, 4640 participants were investigated. The median UIC was 139·1 μg/l in pregnant women and 148·7, 140·0 and 122·9 μg/l in the first, second and third trimesters. Median UIC in the third trimester was lower than in the other trimesters (P < 0·001). The usage rates of iodised (an iodine content ≥ 5·0 mg/kg) and qualified-iodised (an iodine content ≥ 21·0 mg/kg) salt were 73·9 and 59·3 %. The median UIC in the qualified-iodised salt group was higher than in the non-iodised group (P = 0·037). The median UIC in the non-iodised group who did not eat out was lower than in qualified-salt groups who both did and did not eat out (P = 0·007, <0·001). The proportion of qualified-iodised salt used in home cooking is low, but foods eaten out have universal salt iodisation according to the national compulsory policy. Household iodised salt did not play a decisive role in the iodine status of pregnant women. Pregnant women in their third trimester who are not eating out and using non-iodised salt at home require extra iodine.

Iodine Status of Women and Infants in Russia: A Systematic Review

This systematic review presents a critical synthesis of the available information on the iodine status among women and infants in Russia. Literature search was performed in accordance with PRISMA guidelines using PubMed, Scopus Web of Science databases as well as eLIBRARY-the Russian national source. Altogether, 277 papers were identified and 19 of them were eligible for the review. The data on median urinary iodine concentration (UIC) in women and infants from 25 Russian regions were presented. A substantial variability in UIC across the country with no clear geographical pattern was observed. Despite substantial heterogeneity in research methodology and data presentation the results suggest that the iodine status among pregnant women and infants in Russia is below the recommended levels. Our findings demonstrate that iodine deficiency is a re-emerging public health problem in Russia. Urgent public health measures on national, regional and individual levels are warranted.

Iodine Intake in Norwegian Women and Men: The Population-Based Tromsø Study 2015-2016

Ensuring sufficient iodine intake is a public health priority, but we lack knowledge about the status of iodine in a nationally representative population in Norway. We aimed to assess the current iodine status and intake in a Norwegian adult population. In the population-based Tromsø Study 2015-2016, 493 women and men aged 40-69 years collected 24-h urine samples and 450 participants also completed a food frequency questionnaire (FFQ). The 24-h urinary iodine concentration (UIC) was analyzed using the Sandell-Kolthoff reaction on microplates followed by colorimetric measurement. Iodine intake was estimated from the FFQ using a food and nutrient calculation system at the University of Oslo. The mean urine volume in 24 h was 1.74 L. The median daily iodine intake estimated (UIE) from 24-h UIC was 159 µg/day (133 and 174 µg/day in women and men). The median daily iodine intake estimated from FFQ was 281 µg/day (263 and 318 µg/day in women and men, respectively). Iodine intake estimated from 24-h UIC and FFQ were moderately correlated (Spearman rank correlation coefficient r = 0.39, p < 0.01). The consumption of milk and milk products, fish and fish products, and eggs were positively associated with estimated iodine intake from FFQ. In conclusion, this shows that iodine intake estimated from 24-h UIC describes a mildly iodine deficient female population, while the male population is iodine sufficient. Concurrent use of an extensive FFQ describes both sexes as iodine sufficient. Further studies, applying a dietary assessment method validated for estimating iodine intake and repeated individual urine collections, are required to determine the habitual iodine intake in this population.

Standardized Map of Iodine Status in Europe

Background: Knowledge about the population's iodine status is important, because it allows adjustment of iodine supply and prevention of iodine deficiency. The validity and comparability of iodine-related population studies can be improved by standardization, which was one of the goals of the EUthyroid project. The aim of this study was to establish the first standardized map of iodine status in Europe by using standardized urinary iodine concentration (UIC) data. Materials and Methods: We established a gold-standard laboratory in Helsinki measuring UIC by inductively coupled plasma mass spectrometry. A total of 40 studies from 23 European countries provided 75 urine samples covering the whole range of concentrations. Conversion formulas for UIC derived from the gold-standard values were established by linear regression models and were used to postharmonize the studies by standardizing the UIC data of the individual studies. Results: In comparison with the EUthyroid gold-standard, mean UIC measurements were higher in 11 laboratories and lower in 10 laboratories. The mean differences ranged from -36.6% to 49.5%. Of the 40 postharmonized studies providing data for the standardization, 16 were conducted in schoolchildren, 13 in adults, and 11 in pregnant women. Median standardized UIC was <100 μg/L in 1 out of 16 (6.3%) studies in schoolchildren, while in adults 7 out of 13 (53.8%) studies had a median standardized UIC <100 μg/L. Seven out of 11 (63.6%) studies in pregnant women revealed a median UIC <150 μg/L. Conclusions: We demonstrate that iodine deficiency is still present in Europe, using standardized data from a large number of studies. Adults and pregnant women, particularly, are at risk for iodine deficiency, which calls for action. For instance, a more uniform European legislation on iodine fortification is warranted to ensure that noniodized salt is replaced by iodized salt more often. In addition, further efforts should be put on harmonizing iodine-related studies and iodine measurements to improve the validity and comparability of results.

Impact of Dietary Habit, Iodine Supplementation and Smoking Habit on Urinary Iodine Concentration During Pregnancy in a Catalonia Population

(1) Background: The nutritional status of women during pregnancy can have a considerable effect on maternal and fetal health, and on the perinatal outcome. Aim: to assess the changes occurring in dietary iodine intake, potassium iodide supplementation, and smoking habit, and the impact of these changes on the urinary iodine concentration (UIC) during pregnancy in a population of women in Catalonia (Spain). (2) Methods: Between 2009–2011, an observational study included a cohort of women whose pregnancies were monitored in the public health system in the Central and North Metropolitan areas of Catalonia. Women received individual educational counseling, a dietary questionnaire was completed, and a urine sample was collected for iodine determination at each trimester visit. (3) Results: 633 (67.9%) women answered the questionnaire at all 3 visits. The percentage of women with a desirable UIC (≥150 μg/L) increased from the first to the second trimester and remained stable in the third (57.3%, 68.9%, 68%; p < 0.001). Analysis of the relationship between UIC ≥ 150 μg/L and the women’s dietary habits showed that the percentage with UIC ≥ 150 μg/L increased with greater consumption of milk in the first trimester, and the same was true for iodized salt use in all three trimesters and iodine supplementation in all three. (4) Conclusion: During pregnancy, increased intake of milk, iodized salt, and iodine supplements were associated with an increase in the UIC.

Lean-seafood intake increases urinary iodine concentrations and plasma selenium levels: a randomized controlled trial with crossover design

PURPOSE

Iodine deficiency due to insufficient nutritional intake is a public health challenge in several European countries, including Norway. Lean-seafood has a high iodine and arsenic (As) content and is a good source of selenium (Se). Evidence of a direct effect of increased intake of lean-seafood on iodine status is limited. The main aims were to determine the iodine status at baseline and to investigate possible dietary effects on urinary iodine concentration (UIC) after intervention with lean-seafood versus non-seafood. Plasma Se, and plasma and urinary As concentrations were also measured.

METHODS

A randomized controlled crossover study comprising two 4 weeks experimental periods with two balanced diets varied in main proteins (60% of total dietary proteins) of lean-seafood and non-seafood, separated by a 5 week washout period.

RESULTS

Twenty participants (7 males, 13 females) were included and the mean ± SD age was 50.6 ± 15.3 years for all participants. Fasting UIC was median (25th, 75th percentile) 70 (38, 110) and 79 (49, 94) µg/L in the lean-seafood and non-seafood intervention at baseline, respectively. UIC increased after 4 weeks of the lean-seafood intervention to 135 (110, 278) µg/L, but not after the non-seafood intervention [58 (33, 91) µg/L] (P diet-effect < 0.001). Fasting plasma Se increased in the lean-seafood intervention and decreased in the non-seafood intervention (P diet-effect = 0.001). Fasting urinary and plasma As increased in the lean-seafood intervention and was unchanged in the non-seafood intervention (P diet-effect < 0.001).

CONCLUSION

The participant's UIC was below the recommended median (100 µg/L) at baseline, but increased sufficiently after a 4 week intervention with lean-seafood.

Insufficient maternal iodine intake is associated with subfecundity, reduced foetal growth, and adverse pregnancy outcomes in the Norwegian Mother, Father and Child Cohort Study

BACKGROUND

Severe iodine deficiency impacts fertility and reproductive outcomes. The potential effects of mild-to-moderate iodine deficiency are not well known. The aim of this study was to examine whether iodine intake was associated with subfecundity (i.e. > 12 months trying to get pregnant), foetal growth, and adverse pregnancy outcomes in a mild-to-moderately iodine-deficient population.

METHODS

We used the Norwegian Mother, Father and Child Cohort Study (MoBa) and included 78,318 pregnancies with data on iodine intake and pregnancy outcomes. Iodine intake was calculated using an extensive food frequency questionnaire in mid-pregnancy. In addition, urinary iodine concentration was available in a subsample of 2795 pregnancies. Associations were modelled continuously by multivariable regression controlling for a range of confounding factors.

RESULTS

The median iodine intake from food was 121 μg/day and the median urinary iodine was 69 μg/L, confirming mild-to-moderate iodine deficiency. In non-users of iodine supplements (n = 49,187), low iodine intake (< 100-150 μg/day) was associated with increased risk of preeclampsia (aOR = 1.14 (95% CI 1.08, 1.22) at 75 vs. 100 μg/day, p overall < 0.001), preterm delivery before gestational week 37 (aOR = 1.10 (1.04, 1.16) at 75 vs. 100 μg/day, p overall = 0.003), and reduced foetal growth (- 0.08 SD (- 0.10, - 0.06) difference in birth weight z-score at 75 vs. 150 μg/day, p overall < 0.001), but not with early preterm delivery or intrauterine death. In planned pregnancies (n = 56,416), having an iodine intake lower than ~ 100 μg/day was associated with increased prevalence of subfecundity (aOR = 1.05 (1.01, 1.09) at 75 μg/day vs. 100 μg/day, p overall = 0.005). Long-term iodine supplement use (initiated before pregnancy) was associated with increased foetal growth (+ 0.05 SD (0.03, 0.07) on birth weight z-score, p < 0.001) and reduced risk of preeclampsia (aOR 0.85 (0.74, 0.98), p = 0.022), but not with the other adverse pregnancy outcomes. Urinary iodine concentration was not associated with any of the dichotomous outcomes, but positively associated with foetal growth (n = 2795, p overall = 0.017).

CONCLUSIONS

This study shows that a low iodine intake was associated with restricted foetal growth and a higher prevalence of preeclampsia in these mild-to-moderately iodine-deficient women. Results also indicated increased risk of subfecundity and preterm delivery. Initiating iodine supplement use in pregnancy may be too late.

Iodine status and supplementation before, during, and after pregnancy

Iodine intake is essential for the production of thyroid hormone. Iodine deficiency remains a public health problem in many regions around the world. Iodine deficiency can present as a spectrum of disorders depending on the degree of severity. Pregnant and lactating women are particularly vulnerable to iodine deficiency disorders because of their increased iodine requirements. Severe maternal iodine deficiency has been associated with cretinism or impaired neurodevelopment in children as well as obstetric complications. Universal salt iodization has been shown to prevent these disorders in severely iodine deficient areas. Recently, observational studies have demonstrated an association between mild-to-moderate iodine deficiency and poorer cognitive outcomes in children. In this review, we describe the iodine requirements for pregnant and lactating women, how population iodine status can be assessed, the effects of maternal iodine deficiency and excess, and current data regarding efficacy of iodine supplementation for women who are pregnant or lactating.

Lack of nutritional knowledge among Norwegian medical students concerning vegetarian diets

Aim

Vegetarian diets are increasingly popular, particularly among young women. However, exclusion of animal products from the diet increases the risk of micronutrient deficiencies, which is particularly unfortunate during pregnancy and childhood. A person needs a substantial amount of nutritional knowledge to achieve a nutritionally complete vegetarian diet. We have tested nutritional knowledge among well-educated young vegetarians and omnivores.

Subjects and methods

In October 2018, medical students at the University of Bergen, Norway (N = 880), were invited to take an anonymous survey to test their nutritional knowledge concerning micronutrients in vegetarian diets.

Results

The responses from the students (n = 394, 45%) were categorized according to diet: former or current vegetarians (24%) versus always omnivores (76%). Forty-five percent of the vegetarians and 28% of the omnivores did not consider it necessary to take supplements while following a vegetarian diet. Sixty-one percent of vegetarians and 38% of omnivores considered it possible to have a well-balanced vegan diet. Plant foods were wrongly considered to be a dietary source of vitamin B12 by 33% and of iodine by 20% of the students.

Conclusion

Nutritional knowledge concerning vegetarian diets was not optimal among Norwegian medical students, even if they had ever followed a vegetarian diet. As vegetarian diets are popular among the younger generation and pose a risk of micronutrient deficiencies, this is a public health concern. Nutrition education should be improved in the population. A more extensive integration of nutritional training in the medical curriculum must be implemented so doctors can give adequate nutritional guidance.

Vegans, Vegetarians, and Omnivores: How Does Dietary Choice Influence Iodine Intake? A Systematic Review

Vegan and vegetarian diets are becoming increasingly popular. Dietary restrictions may increase the risk of iodine deficiency. This systematic review aims to assess iodine intake and status in adults following a vegan or vegetarian diet in industrialised countries. A systematic review and quality assessment were conducted in the period May 2019-April 2020 according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies were identified in Ovid MEDLINE, Embase, Web of Science, PubMed, Scopus, and secondary sources. Fifteen articles met inclusion criteria. Participants included 127,094 adults (aged ≥ 18 years). Vegan groups presented the lowest median urinary iodine concentrations, followed by vegetarians, and did not achieve optimal status. The highest iodine intakes were recorded in female vegans (1448.0 ± 3879.0 µg day-1) and the lowest in vegetarians (15.6 ± 21.0 µg day-1). Omnivores recorded the greatest intake in 83% of studies. Seaweed contributed largely to diets of vegans with excessive iodine intake. Vegans appear to have increased risk of low iodine status, deficiency and inadequate intake compared with adults following less restrictive diets. Adults following vegan and vegetarian diets living in countries with a high prevalence of deficiency may be more vulnerable. Therefore, further monitoring of iodine status in industrialised countries and research into improving the iodine intake and status of adults following vegan and vegetarian diets is required.

Iodine and bromine in fish consumed by indigenous peoples of the Russian Arctic

Fish muscle may constitute one of the main sources of iodine (I) for the indigenous peoples of the Russian Arctic, although limited information is available about its content in commonly consumed fish species. In the current study, bromine (Br), I, the essential elements (copper, selenium and zinc) and other non-essential elements — specifically mercury, arsenic (As), cadmium, lead and nickel — have been quantified in 10 fish species consumed by people living in the Nenets and Chukotka Regions. Fish muscle was analysed by ICP-MS after nitric acid or tetramethylammonium hydroxide digestion. Certified reference materials were employed and concentrations are reported as geometric means (GMs). Atlantic cod (6.32 mg/kg) and navaga (0.934 mg/kg) contained substantially higher amounts of I than all other fish species, while broad whitefish had the lowest (0.033 mg/kg). By comparison, navaga contained more Br (14.5 mg/kg) than the other fish species, ranging 7.45 mg/kg in Atlantic cod to 2.39 mg/kg in northern pike. A significant inter-fish association between As and I in freshwater and marine fish was observed, suggesting common sources and perhaps parallel absorption patterns. Only Atlantic cod and, to lesser extent, navaga constituted significant dietary sources of I.