Indigenous peoples are often not routinely included in iodine programmes because of language barriers and remote access and may thus be at higher risk of iodine deficiency disorders, which could adversely impact their quality of life. We conducted this cross-sectional study in the remote Pwo Karen community of Thailand to determine the urinary iodine concentration of school-aged children and women of reproductive age and investigate the iodine content in household salt. We measured urinary iodine concentration in spot urine samples from healthy school-aged children and women of reproductive age, administered a questionnaire, estimated daily iodine intake and collected household salt samples to determine salt iodine concentration. The median urinary iodine concentration (range) of school-aged children (n 170) was 192 (136–263) µg/l, which was significantly higher than women of reproductive age (n 306) (147 (89–233) µg/l) (P < 0·001). The estimated daily iodine intake in school-aged children and women of reproductive age were 135 and 195 μg/d, respectively. The median (range) iodine concentration in rock and granulated salts consumed in the households were 2·32 (0·52–3·19) and 26·64 (20·86–31·01) ppm, respectively. Surprisingly, the use of iodised salt and the frequency of seafood consumption were NS predictors of urinary iodine concentration in these two groups. Our data suggest that school children and women of the Pwo Karen community have sufficient iodine intake, indicating the Thai salt iodisation programme is effectively reaching even this isolated Indigenous community. Sentinel surveys of remote vulnerable populations can be a useful tool in national iodine programmes to ensure that programme coverage is truly universal.

Ensuring adequate iodine nutrition during pregnancy is crucial for fetal brain development. Thus, the WHO recommend monitoring iodine nutrition in pregnant women. With changing dietary habits and declining iodine intake in coastal populations, iodine nutrition in pregnant Faroese women was a focus in newly established pregnancy cohorts. This study aimed to monitor the iodine status of pregnant women in the Faroe Islands by assessing urinary iodine concentration (UIC) and maternal iodine intake. For 2 years, all pregnant women were invited to participate in a nationwide study. Participants completed questionnaires addressing personal and lifestyle factors, supplement intake and dietary habits, Additionally, they provided spot urine samples for UIC measurements. Iodine was measured spectrophotometrically using the ceri/arsen method after alkaline-ashing. Among the 1030 invited, 654 participated and 647 provided a spot-urine sample. The average age was 30·4 years (18–47 years). The overall median UIC was 110 µg/l, declined from 117 to 101 µg/l over 2 years (P = 0·004). UIC was significantly impacted by diet. Women consuming fish and eggs had a higher median UIC compared with those whose primary iodine source was dairy: fish-dinner, 151 µg/l; dairy products, 112 µg/l (P < 0·001). Furthermore, there was a positive association between maternal age, reported intake of iodine-containing supplements and the UIC. This nationwide study of pregnant Faroese women found UIC below the WHO-recommended cut-off for pregnant women and decreasing with time. This decline highlights the importance of continuous monitoring to prompty identify shifts in iodine status, enabling timely intervention to address emerging deficiencies.

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.

Adequate iodine nutrition during infancy is required for normal thyroid function and, subsequently, brain development. However, data on infant iodine status in the first year of life are scarce. This study aimed to describe infant iodine status and further explore its associations with maternal iodine nutrition, breast-feeding status and thyroid function. In this cohort study, 113 infants were followed up at ages 3, 6 and 11 months in Norway. Infant and maternal urinary iodine concentration (UIC), maternal iodine intake, breast milk iodine concentration (BMIC), breast-feeding status and infant thyroid function tests were measured. The median infant UIC was 82 µg/l at the age of 3 months and below the WHO cut-off of 100 µg/l. Infant UIC was adequate later in infancy (median 110 µg/l at ages 6 and 11 months). Infant UIC was associated positively with maternal UIC (β = 0·33, 95 % CI (0·12, 0·54)), maternal iodine intake (β = 0·30, 95 % CI (0·18, 0·42)) and BMIC (β = 0·46, 95 % CI (0·13, 0·79)). Breastfed infants had lower median UIC compared with formula-fed infants at ages 3 months (76 v. 190 µg/l) and 6 months (105 v. 315 µg/l). Neither infant UIC nor BMIC were associated with infant thyroid function tests. In conclusion, breastfed infants in Norway are at risk of insufficient iodine intake during the first months of life. Maternal iodine nutrition is important for providing sufficient iodine intake in infants, and awareness of promoting adequate iodine nutrition for lactating women should be prioritised.

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

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.

Lack of knowledge about iodine has been suggested as a risk factor for iodine deficiency in pregnant women, but no studies have addressed this issue in Portugal. So, the aim of this study was to investigate iodine knowledge among Portuguese pregnant women and its association with iodine status. IoMum, a prospective observational study, included 485 pregnant women recruited at Centro Hospitalar e Universitário de S. João, Porto, between the 10th and 13th gestational weeks. Partial scores for knowledge on iodine importance, on iodine food sources or on iodised salt were obtained through the application of a structured questionnaire. Then, a total iodine knowledge score was calculated and grouped into low, medium and high knowledge categories. Urinary iodine concentration (UIC) was measured in spot urine samples by inductively coupled plasma MS. Of the pregnant women, 54 % correctly recognised iodine as important to neurocognitive development, 32 % were unable to identify any iodine-rich food and 71 % presented lack of knowledge regarding iodised salt. Of the women, 61 % had a medium total score of iodine knowledge. Knowledge on iodine importance during pregnancy was positively associated with iodine supplementation and also with UIC. Nevertheless, median UIC in women who correctly recognised the importance of iodine was below the cut-off for adequacy in pregnancy (150 µg/l). In conclusion, knowledge on iodine importance is positively associated with iodine status. Despite this, recognising iodine importance during pregnancy may not be sufficient to ensure iodine adequacy. Literacy-promoting actions are urgently needed to improve iodine status in pregnancy.

The role of milk and dairy products in supplying iodine to pregnant women is unknown in Portugal. The aim of this study was to evaluate the association between milk and dairy product consumption and the iodine status of pregnant women in the IoMum cohort of the Oporto region. Pregnant women were recruited between 10 and 13 weeks of gestation, when they provided a spot urine sample and information on lifestyle and intake of iodine-rich foods. Urinary iodine concentration (UIC) was determined by inductively coupled plasma MS. A total of 468 pregnant women (269 iodine supplement users and 199 non-supplement users) were considered eligible for analysis. Milk (but not yogurt or cheese) intake was positively associated with UIC, in the whole population (P = 0·02) and in the non-supplement users (P = 0·002), but not in the supplement users (P = 0·29). In non-supplement users, adjusted multinomial logistic regression analysis showed that milk consumption <3 times/month was associated with a five times increased risk of having UIC < 50 µg/l when compared with milk consumption ≥2 times/d (OR 5·4; 95 % CI 1·55, 18·78; P = 0·008). The highest UIC was observed in supplement users who reported consuming milk once per d (160 µg/l). Milk, but not yogurt or cheese, was positively associated with iodine status of pregnant women. Despite the observed positive association, daily milk consumption may not be sufficient to ensure adequate iodine intake in this population.

I deficiency is still a worldwide public health problem, with children being especially vulnerable. No nationwide study had been conducted to assess the I status of Spanish children, and thus an observational, multicentre and cross-sectional study was conducted in Spain to assess the I status and thyroid function in schoolchildren aged 6–7 years. The median urinary I (UI) and thyroid-stimulating hormone (TSH) levels in whole blood were used to assess the I status and thyroid function, respectively. A FFQ was used to determine the consumption of I-rich foods. A total of 1981 schoolchildren (52 % male) were included. The median UI was 173 μg/l, and 17·9 % of children showed UI<100 μg/l. The median UI was higher in males (180·8 v. 153·6 μg/l; P<0·001). Iodised salt (IS) intake at home was 69·8 %. IS consumption and intakes of ≥2 glasses of milk or 1 cup of yogurt/d were associated with significantly higher median UI. Median TSH was 0·90 mU/l and was higher in females (0·98 v. 0·83; P<0·001). In total, 0·5 % of children had known hypothyroidism (derived from the questionnaire) and 7·6 % had TSH levels above reference values. Median TSH was higher in schoolchildren with family history of hypothyroidism. I intake was adequate in Spanish schoolchildren. However, no correlation was found between TSH and median UI in any geographical area. The prevalence of TSH above reference values was high and its association with thyroid autoimmunity should be determined. Further assessment of thyroid autoimmunity in Spanish schoolchildren is desirable.

Worldwide, the iodisation of salt has clearly improved iodine status. In industrialised countries, iodised salt added to processed food contributes most to iodine supply. Yet it is unclear as to what extent changes in the latter may affect the iodine status of populations. Between 2004 and 2009, 24-h urinary iodine excretions (UIE) were repeatedly measured in 278 German children (6 to 12 years old) of the Dortmund Nutritional and Anthropometric Longitudinally Designed Study (n 707). Na excretion measurements and simultaneously collected 3-d weighed dietary records provided data on intakes of the most important dietary sources of iodine in the children's diet. Actual trends of UIE (2004–9) and contributions of relevant food groups were analysed by mixed linear regression models. Longitudinal regression analysis showed a plateau of UIE in 2004–6; afterwards, UIE significantly decreased till 2009 (P = 0·01; median 24-h UIE in 2004–6: 85·6 μg/d; 2009: 80·4 μg/d). Median urinary iodine concentration fell below the WHO criteria for iodine sufficiency of 100 μg/l in 2007–9. Salt, milk, fish and egg intake (g/d) were significant predictors of UIE (P < 0·005); and the main sources of iodine were salt and milk (48 and 38 %, respectively). The present data hint at a beginning deterioration in the iodine status of German schoolchildren. A decreased use of iodised salt in industrially produced foods may be one possible reason for this development. Because of the generally known risks for cognitive impairment due to even mild iodine deficits in children, a more widespread use of iodised salt, especially in industrially processed foods, has to be promoted.

Most New Zealand soils contain relatively low concentrations of the anionic trace elements F, I and Se. Some areas of Australia also have a history of I deficiency. In view of current interest in establishing nutrient reference intakes for Se and I in New Zealand and Australia, it is timely to review current understanding of the intakes and status of these two elements. In spite of a recent increase in Se status, the status of New Zealanders remains low compared with populations of many other countries and may still be considered marginal, although the clinical consequences of the marginal Se status are unclear. There are no recent reports of blood Se levels in Australia, but earlier reports indicate that they were generally greater than those of New Zealanders. Similarly, the consequences of decreasing I status in Australia and New Zealand are unclear. Mild I deficiency in New Zealand has resulted in enlarged thyroid glands indicating an increased risk of goitre. Currently there is little evidence, however, of any associated clinical disease. Public health recommendations to reduce salt intake, together with the reduction in I content of dairy products, are likely to result in further decreases in the I status of New Zealand and Australian residents. Some action is needed to prevent this decline and it may be necessary to consider other means of fortification than iodized salt. The consequences of possible interactions between Se and I in human nutrition are also unclear and no practical recommendations can be made.