Direct assessment of body iron balance in women with and without iron supplementation using a long-term isotope dilution method in Benin and Switzerland.

BACKGROUND: Long-term isotopic dilution measurements of body iron may allow quantification of basal body iron balance and iron gains during an iron intervention with higher precision and accuracy than conventional iron indices. OBJECTIVES: We compared body iron balance before, during, and after oral iron supplementation in women in Benin and in Switzerland. METHODS: In prospective studies, Beninese (n = 11) and Swiss (n = 10) women previously labeled with stable iron isotopes were followed preintervention for 90-120 d, then received 50-mg iron daily for 90-120 d and were followed postintervention for 90-120 d. We used changes in blood isotopic composition to calculate iron absorption (Feabs), iron loss (Feloss), and net iron balance (Fegain). RESULTS: Compliance with supplementation was >90%. In Benin, during the preintervention, intervention, and postintervention periods, Fe means ± SDs were as follows: 1) Feabs: 0.92 ± 1.05, 3.75 ± 2.07, and 0.90 ± 0.93 mg/d; 2) Feloss: 1.46 ± 1.95, 1.58 ± 1.57, and 1.84 ± 1.61 mg/d; and 3) Fegain: -0.55 ± 1.56 mg/d, 2.17 ± 1.81 mg/d, and -0.94 ± 1.13 mg/d. In Switzerland, the corresponding values were: 1) 1.51 ± 0.37, 4.09 ± 1.52, and 0.97 ± 0.41 mg/d; 2) 0.76 ± 1.37, 2.54 ± 1.43, and 2.08 ± 1.05 mg/d; and 3) 0.75 ± 1.37, 1.55 ± 1.75, and -1.11 ± 1.06 mg/d. Inflammation was low in both settings, and isotopically calculated iron balance was comparable to that calculated from changes in conventional iron indices. CONCLUSION: Without iron supplementation, Beninese women had lower long-term dietary iron absorption and higher iron losses in the preintervention period than Swiss women. During iron supplementation, both groups had high iron absorption and similar iron gains. However, there was a 3-fold increase in iron losses in the Swiss women during the supplementation and postintervention period compared with the preintervention period. Body iron isotope dilution is a promising new method for quantifying long-term body iron balance and for assessing the impact of iron interventions. The studies were registered at clinicaltrials.gov as NCT02979080 and NCT02979132, respectively.

Estimating the Health and Economic Benefits of Universal Salt Iodization Programs to Correct Iodine Deficiency Disorders.

Background: There has been tremendous progress over the past 25 years to control iodine deficiency disorders (IDDs) through universal salt iodization (USI). In 2019, using the median urinary iodine concentration (MUIC), only 19 countries in the world are classified as iodine deficient; in contrast in 1993, using the total goiter rate (TGR), 113 countries were classified as iodine deficient. However, few analyses have tried to quantify the global health and economic benefits of USI programs, and the shift from TGR to MUIC as the main indicator of IDDs complicates assessment of progress. Methods: We used a novel approach to estimate the impact of USI on IDDs, applying a regression model derived from observational data on the relationship between the TGR and the MUIC from 24 countries. The model was used to generate hypothetical national TGR values for 2019 based on current MUIC data. TGR in 1993 and modeled TGR in 2019 were then compared for 139 countries, and using consequence modeling, the potential health and economic benefits realized between 1993 and 2019 were estimated. Results: Based on this approach, the global prevalence of clinical IDDs (as assessed by the TGR) fell from 13.1% to 3.2%, and 720 million cases of clinical IDDs have been prevented by USI (a reduction of 75.9%). USI has significantly reduced the number of newborns affected by IDDs, with 20.5 million cases prevented annually. The resulting improvement in cognitive development and future earnings suggest a potential global economic benefit of nearly $33 billion. However, 4.8 million newborns will be affected by IDDs in 2019, who will experience life-long productivity losses totaling a net present value of $12.5 billion. Conclusions: The global improvements in iodine status over the past 25 years have resulted in major health and economic benefits, mainly in low- and middle-income countries. Efforts should now focus on sustaining this achievement and expanding USI to reach the continuing large number of infants who remain unprotected from IDDs.

Excess iodine intake: sources, assessment, and effects on thyroid function.

Iodine is essential for thyroid hormone synthesis. High iodine intakes are well tolerated by most healthy individuals, but in some people, excess iodine intakes may precipitate hyperthyroidism, hypothyroidism, goiter, and/or thyroid autoimmunity. Individuals with preexisting thyroid disease or those previously exposed to iodine deficiency may be more susceptible to thyroid disorders due to an increase in iodine intake, in some cases at intakes only slightly above physiological needs. Thyroid dysfunction due to excess iodine intake is usually mild and transient, but iodine-induced hyperthyroidism can be life-threatening in some individuals. At the population level, excess iodine intakes may arise from consumption of overiodized salt, drinking water, animal milk rich in iodine, certain seaweeds, iodine-containing dietary supplements, and from a combination of these sources. The median urinary iodine concentration (UIC) of a population reflects the total iodine intake from all sources and can accurately identify populations with excessive iodine intakes. Our review describes the association between excess iodine intake and thyroid function. We outline potential sources of excess iodine intake and the physiological responses and consequences of excess iodine intakes. We provide guidance on choice of biomarkers to assess iodine intake, with an emphasis on the UIC and thyroglobulin.

Reducing micronutrient deficiencies in Pakistani children: are subsidies on fortified complementary foods cost-effective?

OBJECTIVE: To estimate the cost-effectiveness of price subsidies on fortified packaged complementary foods (FPCF) in reducing iodine deficiency, iron-deficiency anaemia and vitamin A deficiency in Pakistani children. DESIGN: The study proceeded in three steps: (i) we determined the current lifetime costs of the three micronutrient deficiencies with a health economic model; (ii) we assessed the price sensitivity of demand for FPCF with a market survey in two Pakistani districts; (iii) we combined the findings of the first two steps with the results of a systematic review on the effectiveness of FPCF in reducing micronutrient deficiencies. The cost-effectiveness was estimated by comparing the net social cost of price subsidies with the disability-adjusted life years (DALY) averted. SETTING: Districts of Faisalabad and Hyderabad in Pakistan. SUBJECTS: Households with 6-23-month-old children stratified by socio-economic strata. RESULTS: The lifetime social costs of iodine deficiency, iron-deficiency anaemia and vitamin A deficiency in 6-23-month-old children amounted to production losses of $US 209 million and 175 000 DALY. Poor households incurred the highest costs, yet even wealthier households suffered substantial losses. Wealthier households were more likely to buy FPCF. The net cost per DALY of the interventions ranged from a return per DALY averted of $US 783 to $US 65. Interventions targeted at poorer households were most cost-effective. CONCLUSIONS: Price subsidies on FPCF might be a cost-effective way to reduce the societal costs of micronutrient deficiencies in 6-23-month-old children in Pakistan. Interventions targeting poorer households are especially cost-effective.

Societal Costs of Micronutrient Deficiencies in 6- to 59-month-old Children in Pakistan.

BACKGROUND: In Pakistan, nearly half of children younger than 5 years are stunted, and 1 in 3 is underweight. Micronutrient deficiencies, a less visible form of undernutrition, are also endemic. They may lead to increased morbidity and mortality as well as to impaired cognitive and physical development. OBJECTIVE: To estimate the lifetime costs of micronutrient deficiencies in Pakistani children aged between 6 and 59 months. METHODS: We develop a health economic model of the lifetime health and cost consequences of iodine, iron, vitamin A, and zinc deficiencies. We assess medical costs, production losses in terms of future incomes lost, and disability-adjusted life-years (DALYs). The estimation is based on large population surveys, information on the health consequences of micronutrient deficiencies extracted from randomized trials, and a variety of other sources. RESULTS: Total societal costs amount to US$46 million in medical costs, US$3,222 million in production losses, and 3.4 million DALYs. Costs are dominated by the impaired cognitive development induced by iron-deficiency anemia in 6- to 23-month-old children and the mortality caused by vitamin A deficiency. Costs are substantially higher in poorer households. CONCLUSIONS: Societal costs amounted to 1.44% of gross domestic product and 4.45% of DALYs in Pakistan in 2013. These costs hinder the country's development. They could be eliminated by improved nutrition of 6- to 59-month-old children and public health measures. Our results may contribute to the design of cost-effective interventions aiming to reduce micronutrient deficiencies in early childhood and their lifetime consequences.

Stable Isotope Techniques for the Assessment of Host and Microbiota Response During Gastrointestinal Dysfunction.

The International Atomic Energy Agency convened a technical meeting on environmental enteric dysfunction (EED) in Vienna (October 28-30, 2015; https://nucleus.iaea.org/HHW/Nutrition/EED_Technical_Meeting/index.html) to bring together international experts in the fields of EED, nutrition, and stable isotope technologies. Advances in stable isotope-labeling techniques open up new possibilities to improve our understanding of gastrointestinal dysfunction and the role of the microbiota in host health. In the context of EED, little is known about the role gut dysfunction may play in macro- and micronutrient bioavailability and requirements and what the consequences may be for nutritional status and linear growth. Stable isotope labeling techniques have been used to assess intestinal mucosal injury and barrier function, carbohydrate digestion and fermentation, protein-derived amino acid bioavailability and requirements, micronutrient bioavailability and to track microbe-microbe and microbe-host interactions at the single cell level. The noninvasive nature of stable isotope technologies potentially allow for low-hazard, field-deployable tests of gut dysfunction that are applicable across all age groups. The purpose of this review is to assess the state-of-the-art use of stable isotope technologies and to provide a perspective on where these technologies can be exploited to further our understanding of gut dysfunction in EED.

Maximizing the benefits and minimizing the risks of intervention programs to address micronutrient malnutrition: symposium report.

Interventions to address micronutrient deficiencies have large potential to reduce the related disease and economic burden. However, the potential risks of excessive micronutrient intakes are often not well determined. During the Global Summit on Food Fortification, 9-11 September 2015, in Arusha, a symposium was organized on micronutrient risk-benefit assessments. Using case studies on folic acid, iodine and vitamin A, the presenters discussed how to maximize the benefits and minimize the risks of intervention programs to address micronutrient malnutrition. Pre-implementation assessment of dietary intake, and/or biomarkers of micronutrient exposure, status and morbidity/mortality is critical in identifying the population segments at risk of inadequate and excessive intake. Dietary intake models allow to predict the effect of micronutrient interventions and their combinations, e.g. fortified food and supplements, on the proportion of the population with intakes below adequate and above safe thresholds. Continuous monitoring of micronutrient intake and biomarkers is critical to identify whether the target population is actually reached, whether subgroups receive excessive amounts, and inform program adjustments. However, the relation between regular high intake and adverse health consequences is neither well understood for many micronutrients, nor do biomarkers exist that can detect them. More accurate and reliable biomarkers predictive of micronutrient exposure, status and function are needed to ensure effective and safe intake ranges for vulnerable population groups such as young children and pregnant women. Modelling tools that integrate information on program coverage, dietary intake distribution and biomarkers will further enable program makers to design effective, efficient and safe programs.

Optimization of a New Mass Spectrometry Method for Measurement of Breast Milk Iodine Concentrations and an Assessment of the Effect of Analytic Method and Timing of Within-Feed Sample Collection on Breast Milk Iodine Concentrations.

BACKGROUND: Breast milk iodine concentration (BMIC) may be an indicator of iodine status during lactation, but there are few data comparing different analytical methods or timing of sampling. The aims of this study were: (i) to optimize a new inductively coupled plasma mass spectrometry (ICP-MS) method; and (ii) to evaluate the effect of analytical method and timing of within-feed sample collection on BMIC. METHODS: The colorimetric Sandell-Kolthoff method was evaluated with (a) or without (b) alkaline ashing, and ICP-MS was evaluated using a new (129)I isotope ratio approach including Tellurium (Te) for mass bias correction (c) or external standard curve (d). From iodine-sufficient lactating women (n = 97), three samples were collected within one breast-feeding session (fore-, mid-, and hind-feed samples) and BMIC was analyzed using (c) and (d). RESULTS: Iodine recovery from NIST SRM1549a whole milk powder for methods (a)-(d) was 67%, 24%, 105%, and 102%, respectively. Intra- and inter-assay coefficients of variation for ICP-MS comparing (c) and (d) were 1.3% versus 5.6% (p = 0.04) and 1.1% versus 2.4% (p = 0.33). The limit of detection (LOD) was lower for (c) (0.26 µg/kg) than it was for (d) (2.54 µg/kg; p = 0.02). Using (c), the median [95% confidence interval (CI) obtained by bootstrap] BMIC (µg/kg) in foremilk (179 [CI 161-206]) and in mid-feed milk (184 [CI 160-220]) were not significantly different (p = 0.017), but were higher than in hindmilk (175 [CI 153-216]; p < 0.001). In foremilk using (d), BMIC was 199 ([CI 182-257]; p < 0.001 vs. (c)). The variation in BMIC comparing (c) and (d) (13%) was greater than variation within feeding (5%; p < 0.001). CONCLUSIONS: Because of poor recoveries, (a) and (b) should not be used to measure BMIC. Compared with (d), (c) has the advantages of higher precision and a lower LOD. In iodine-sufficient women, BMIC shows low variation within a breast-feeding session, so timing of sampling is not a major determinant of BMIC.

Ensuring Effective Prevention of Iodine Deficiency Disorders.

BACKGROUND: Programs initiated to prevent iodine deficiency disorders (IDD) may not remain effective due to changes in government policies, commercial factors, and human behavior that may affect the efficacy of IDD prevention programs in unpredictable directions. Monitoring and outcome studies are needed to optimize the effectiveness of IDD prevention. SUMMARY: Although the need for monitoring is compelling, the current reality in Europe is less than optimal. Regular and systematic monitoring surveys have only been established in a few countries, and comparability across the studies is hampered by the lack of centralized standardization procedures. In addition, data on outcomes and the cost of achieving them are needed in order to provide evidence of the beneficial effects of IDD prevention in countries with mild iodine deficiency. CONCLUSION: Monitoring studies can be optimized by including centralized standardization procedures that improve the comparison between studies. No study of iodine consumption can replace the direct measurement of health outcomes and the evaluation of the costs and benefits of the program. It is particularly important that health economic evaluation should be conducted in mildly iodine-deficient areas and that it should include populations from regions with different environmental, ethnic, and cultural backgrounds.

Development and Validation of a New Low-Cost Enzyme-Linked Immunoassay for Serum and Dried Blood Spot Thyroglobulin.

BACKGROUND: Thyroglobulin (Tg), a biomarker of iodine nutrition, can be measured on dried blood spots (DBS), which simplifies collection and transport in surveys. The World Health Organization recommends DBS-Tg for monitoring iodine status in children. It could also be a useful iodine biomarker during pregnancy. However, the Tg antibody (Ab) used in earlier DBS-Tg assays is no longer commercially available. The aims of the present study were: (i) to develop a new low-cost serum and DBS-Tg sandwich enzyme-linked immunosorbent assay for assessment of Tg in population studies; (ii) to check the stability of DBS-Tg during long-term storage; and (iii) to assess within-subject variability in DBS-Tg. METHODS: Serum and DBS samples were measured from healthy pregnant women (n = 424) with the new assays, as well as the Immulite 2000 (Siemens), including TgAb positive (n = 150) and TgAb negative (n = 274) women. DBS-Tg stability was tested over 15 weeks of storage at -20 °C. Within-subject variability was evaluated over four weeks in four healthy adults. RESULTS: Intra-assay and interassay variability was 4.4-7.3% and 10.1-12.9% for the new serum Tg assay, and 7.6-12.3% and 7.6-16.5% for the DBS-Tg assay. Correlation between the two serum methods was high (r = 0.68, p < 0.01). Assay performance in all women and those TgAb negative was comparable. Correlation between the new serum Tg assay and the DBS-Tg assay was high (r = 0.78, p < 0.01), and agreement expressed as a function of the average Tg concentration for the two methods (X) was 0.59X -4.59 µg/L. DBS-Tg was stable for 15 weeks stored at -20 °C. Within-subject variability in DBS-Tg was 21.1%. Reagents and antibodies costs for the new serum and DBS assays are ∼ US$1. CONCLUSIONS: These new low-cost serum and DBS-Tg assays perform well over a wide range of Tg concentrations, and the field-friendly DBS assay may be particularly useful in population studies of iodine nutrition.

The iodized salt programme in Bangalore, India provides adequate iodine intakes in pregnant women and more-than-adequate iodine intakes in their children.

OBJECTIVE: To compare the iodine status of pregnant women and their children who were sharing all meals in Bangalore, India. DESIGN: A cross-sectional study evaluating demographic characteristics, household salt iodine concentration and salt usage patterns, urinary iodine concentrations (UIC) in women and children, and maternal thyroid volume (ultrasound). SETTING: Antenatal clinic of an urban tertiary-care hospital, which serves a low-income population. SUBJECTS: Healthy pregnant women in all trimesters, aged 18-35 years, who had healthy children aged 3-15 years. RESULTS: Median (range) iodine concentrations of household powdered and crystal salt were 55·9 (17·2-65·9) ppm and 18·9 (2·2-68·2) ppm, respectively. The contribution of iodine-containing supplements and multi-micronutrient powders to iodine intake in the families was negligible. Adequately iodized salt, together with small amounts of iodine in local foods, were providing adequate iodine during pregnancy: (i) the overall median (range) UIC in women was 172 (5-1024) µg/l; (ii) the median UIC was >150 µg/l in all trimesters; and (iii) thyroid size was not significantly different across trimesters. At the same time, the median (range) UIC in children was 220 (10-782) µg/l, indicating more-than-adequate iodine intake at this age. Median UIC was significantly higher in children than in their mothers (P=0·008). CONCLUSIONS: In this selected urban population of southern India, the iodized salt programme provides adequate iodine to women throughout pregnancy, at the expense of higher iodine intake in their children. Thus we suggest that the current cut-off for median UIC in children indicating more-than-adequate intake, recommended by the WHO/UNICEF/International Council for the Control of Iodine Deficiency Disorders may, need to be reconsidered.

Assessment of iodine nutrition in populations: past, present, and future.

Iodine status has been historically assessed by palpation of the thyroid and reported as goiter rates. Goiter is a functional biomarker that can be applied to both individuals and populations, but it is subjective. Iodine status is now assessed using an objective biomarker of exposure, i.e., urinary iodine concentrations (UICs) in spot samples and comparison of the median UIC to UIC cut-offs to categorize population status. This has improved standardization, but inappropriate use of the crude proportion of UICs below the cut-off level of 100 µg/L to estimate the number of iodine-deficient children has led to an overestimation of the prevalence of iodine deficiency. In this review, a new approach is proposed in which UIC data are extrapolated to iodine intakes, adjusted for intraindividual variation, and then interpreted using the estimated average requirement cut-point model. This may allow national programs to define the prevalence of iodine deficiency in the population and to quantify the necessary increase in iodine intakes to ensure sufficiency. In addition, thyroglobulin can be measured on dried blood spots to provide an additional sensitive functional biomarker of iodine status.

Need for coordinated programs to improve global health by optimizing salt and iodine intake / Necesidad de programas coordinados para mejorar la salud a escala mundial mediante la optimización de la ingesta de sal y yodo

High dietary salt is a major cause of increased blood pressure, the leading risk for death worldwide. The World Health Organization (WHO) has recommended that salt intake be less than 5 g/day, a goal that only a small proportion of people achieve. Iodine deficiency can cause cognitive and motor impairment and, if severe, hypothyroidism with serious mental and growth retardation. More than 2 billion people worldwide are at risk of iodine deficiency. Preventing iodine deficiency by using salt fortified with iodine is a major global public health success. Programs to reduce dietary salt are technically compatible with programs to prevent iodine deficiency through salt fortification. However, for populations to fully benefit from optimum intake of salt and iodine, the programs must be integrated. This review summarizes the scientific basis for salt reduction and iodine fortification programs, the compatibility of the programs, and the steps that need to be taken by the WHO, national governments, and nongovernmental organizations to ensure that populations fully benefit from optimal intake of salt and iodine. Specifically, expert groups must be convened to help countries implement integrated programs and context-specific case studies of successfully integrated programs; lessons learned need to be compiled and disseminated. Integrated surveillance programs will be more efficient and will enhance current efforts to optimize intake of iodine and salt. For populations to fully benefit, governments need to place a high priority on integrating these two important public health programs.

El alto contenido de sal en la dieta es una causa principal de incremento de la presión arterial, el principal factor de riesgo de muerte a escala mundial. La Organización Mundial de la Salud (OMS) ha recomendado que el consumo de sal sea inferior a 5 g/d, una meta que solo logran una pequeña proporción de personas. La falta de yodo puede causar deficiencia cognoscitiva y motora y, si es grave, hipotiroidismo, con grave retraso mental y del crecimiento. Más de dos mil millones de personas en todo el mundo presentan riesgo de carencia de yodo. La prevención de la carencia de yodo mediante el empleo de sal yodada constituye una importante conquista de salud pública a escala mundial. Los programas cuyo objeto es reducir el contenido de sal en la dieta son técnicamente compatibles con los programas de prevención de la carencia de yodo mediante el enriquecimiento de la sal. Sin embargo, para que las poblaciones se puedan beneficiar plenamente de una ingesta óptima de sal y yodo, es preciso integrar ambos tipos de programa. Este estudio resume las bases científicas de los programas de reducción de sal y enriquecimiento con yodo, la compatibilidad de esos programas, y las medidas que deben adoptar la OMS, los gobiernos nacionales y las organizaciones no gubernamentales para garantizar que las poblaciones se beneficien plenamente de una ingesta óptima de sal y yodo. En concreto, es preciso reunir a grupos de expertos para ayudar a los países a aplicar programas integrados y llevar a cabo estudios de casos en contextos específicos de programas integrados eficaces; es preciso recopilar y difundir las enseñanzas extraídas. La integración de los programas de vigilancia los hará más eficaces y mejorará las iniciativas actuales para optimizar la ingesta de yodo y sal. Para que las poblaciones puedan beneficiarse plenamente, es preciso que los gobiernos asignen una alta prioridad a la integración de estos dos importantes tipos de programas de salud pública.

Need for coordinated programs to improve global health by optimizing salt and iodine intake.

High dietary salt is a major cause of increased blood pressure, the leading risk for death worldwide. The World Health Organization (WHO) has recommended that salt intake be less than 5 g/day, a goal that only a small proportion of people achieve. Iodine deficiency can cause cognitive and motor impairment and, if severe, hypothyroidism with serious mental and growth retardation. More than 2 billion people worldwide are at risk of iodine deficiency. Preventing iodine deficiency by using salt fortified with iodine is a major global public health success. Programs to reduce dietary salt are technically compatible with programs to prevent iodine deficiency through salt fortification. However, for populations to fully benefit from optimum intake of salt and iodine, the programs must be integrated. This review summarizes the scientific basis for salt reduction and iodine fortification programs, the compatibility of the programs, and the steps that need to be taken by the WHO, national governments, and nongovernmental organizations to ensure that populations fully benefit from optimal intake of salt and iodine. Specifically, expert groups must be convened to help countries implement integrated programs and context-specific case studies of successfully integrated programs; lessons learned need to be compiled and disseminated. Integrated surveillance programs will be more efficient and will enhance current efforts to optimize intake of iodine and salt. For populations to fully benefit, governments need to place a high priority on integrating these two important public health programs.

Symposium on 'Geographical and geological influences on nutrition': Iodine deficiency in industrialised countries.

Iodine deficiency is not only a problem in developing regions; it also affects many industrialised countries. Globally, two billion individuals have an insufficient iodine intake, and approximately 50% of continental Europe remains mildly iodine deficient. Iodine intakes in other industrialised countries, including the USA and Australia, have fallen in recent years. Iodine deficiency has reappeared in Australia, as a result of declining iodine residues in milk products because of decreased iodophor use by the dairy industry. In the USA, although the general population is iodine sufficient, it is uncertain whether iodine intakes are adequate in pregnancy, which has led to calls for iodine supplementation. The few available data suggest that pregnant women in the Republic of Ireland and the UK are now mildly iodine deficient, possibly as a result of reduced use of iodophors by the dairy industry, as observed in Australia. Representative data on iodine status in children and pregnant women in the UK are urgently needed to inform health policy. In most industrialised countries the best strategy to control iodine deficiency is carefully-monitored salt iodisation. However, because approximately 90% of salt consumption in industrialised countries is from purchased processed foods, the iodisation of household salt only will not supply adequate iodine. Thus, in order to successfully control iodine deficiency in industrialised countries it is critical that the food industry use iodised salt. The current push to reduce salt consumption to prevent chronic diseases and the policy of salt iodisation to eliminate iodine deficiency do not conflict; iodisation methods can fortify salt to provide recommended iodine intakes even if per capita salt intakes are reduced to <5 g/d.

Decrease in the prevalence of paediatric adiposity in Switzerland from 2002 to 2007.

OBJECTIVE: A national study in Switzerland in 2002 suggested nearly one in five schoolchildren was overweight. Since then, many programmes have been introduced in an attempt to control the problem. The aim of the present study was to determine the prevalence of childhood overweight in Switzerland five years later. DESIGN: In both studies a cross-sectional, three-stage, probability-proportional-to-size cluster sampling of schools throughout Switzerland was used to obtain a representative sample of approximately 2500 children aged 6-13 years. Height and weight were measured and BMI calculated. The BMI references from the Centers for Disease Control and Prevention were used to determine the prevalences of underweight (<5th percentile), overweight (>or=85th and <95th percentile) and obesity (>or=95th percentile). RESULTS: In 2007 the prevalences of underweight, overweight and obesity in boys were 3.5 %, 11.3 % and 5.4 %, respectively; in girls they were 2.6 %, 9.9 % and 3.2 %. Compared with 2002, there was a significant decrease in the prevalence of overweight in girls and of obesity in both genders. In contrast to 2002, where there were no differences, in 2007 the prevalence of paediatric obesity was significantly higher in communities with a population >100 000 compared with smaller communities (P < 0.05). CONCLUSIONS: In summary, over the past 5 years, the prevalence of adiposity has decreased in Swiss children. These findings suggest that increased awareness combined with mainly school-based programmes aimed at physical activity and healthy nutrition may have helped to control this public health problem. Future monitoring in Switzerland will determine if these findings are sustained.

Assessment of iodine status using dried blood spot thyroglobulin: development of reference material and establishment of an international reference range in iodine-sufficient children.

CONTEXT: Thyroglobulin (Tg) may be a valuable indicator of improving thyroid function in children after salt iodization. A recently developed Tg assay for use on dried whole blood spots (DBS) makes sampling practical, even in remote areas. OBJECTIVE: The study aim was to develop a reference standard for DBS-Tg, establish an international reference range for DBS-Tg in iodine-sufficient children, and test the standardized DBS-Tg assay in an intervention trial. DESIGN, PARTICIPANTS, AND INTERVENTIONS: Serum Tg reference material of the European Community Bureau of Reference (CRM-457) was adapted for DBS and its stability tested over 1 yr. DBS-Tg was determined in an international sample of 5- to 14-yr-old children (n = 700) who were euthyroid, anti-Tg antibody negative, and residing in areas of long-term iodine sufficiency. In a 10-month trial in iodine-deficient children, DBS-Tg and other indicators of iodine status were measured before and after introduction of iodized salt. RESULTS: Stability of the CRM-457 Tg reference standard on DBS over 1 yr of storage at -20 and -50 C was acceptable. In the international sample of children, the third and 97th percentiles of DBS-Tg were 4 and 40 microg/liter, respectively. In the intervention, before introduction of iodized salt, median DBS-Tg was 49 microg/liter, and more than two thirds of children had DBS-Tg values greater than 40 microg/liter. After 5 and 10 months of iodized salt use, median DBS-Tg decreased to 13 and 8 microg/liter, respectively, and only 7 and 3% of children, respectively, had values greater than 40 microg/liter. DBS-Tg correlated well at baseline and 5 months with urinary iodine and thyroid volume. CONCLUSIONS: The availability of reference material and an international reference range facilitates the use of DBS-Tg for monitoring of iodine nutrition in school-age children.