Progress in salt iodization and improved iodine nutrition in China, 1995--99

In 1993, the State Council of China announced the policy to virtually eliminate iodine-deficiency disorders (IDD) by 2000 and adopted universal salt iodization (USI) as the national strategy. Biennial province-based monitoring from 1995 onward aimed at capturing the use and iodine content of household salt, along with urinary iodine concentrations among schoolchildren from the same households. This paper reports on the progress made in China toward the goal of virtually eliminating iodine-deficiency disorders on the basis of 85 population-representative surveys in China's provinces during 1995--99. The percentage of households using adequately iodized salt (iodine > or = 20 mg/kg) increased from 43.1 % in 1995, to 82.2% in 1997, to 89.0% in 1999. In 1999, at least 90% of the households in 15 (48%) of the 31 provinces used adequately iodized salt, and a median urinary iodine concentration of less than 100 microg/L in children was reported in only one province. Across provinces, the median urinary iodine concentrations in children were positively correlated in each survey year with the median household salt iodine contents (combined r(s) = 0.74, p < .001) and with the proportions of households using adequately iodized salt (combined r(s) = 0.81, p <.001). Also in each survey year, the percentage of children with urinary iodine concentrations of at least 300 microg/L was correlated (combined r(s) = 0.69, p < .001) with the proportion of households using salt with iodine content of at least 40 mg/kg. The median urinary iodine concentration in children had reached 300 microg/L or more in 13 provinces (42%) by 1999. In a little more than five years, then, China has achieved outstanding progress toward the goal of virtual elimination of IDD through USI. Policy recommendations include improvement of quality assurance by salt manufacturers, along with a modest reduction in the mandated salt iodization levels.     

Reaching the goal of Universal Salt Iodization (USI): experience of Uttar Pradesh, India

BACKGROUND: In 2002, the percentage of households consuming iodized salt in the state of Uttar Pradesh (UP) in India dropped to as low as 6%. This implied that 3.5 million newborns in this non-salt producing state, with 180 million population, were at risk of brain damage unless universal accessibility and consumption of iodized salt was ensured and sustained. OBJECTIVES: Urgent measures were introduced in 3 phases in the statefor accelerating procurement, distribution and consumption of iodized salt. METHODS: In the first phase, a study on mapping of salt wholesalers and understanding the salt trading system--including understanding the knowledge, attitudes, and practices of salt traders was undertaken to accelerate efforts to influence availability, marketing, and accessibility of iodized salt. The study revealed that a total of only 344 primary wholesalers supplied salt to the entire state. Of these, 126 wholesalers marketed 80% of salt and were located in only 15 of the total 70 districts of the state. This finding became a very strong basis for the program in phase II, which focused on the critical group of wholesalers and set up a system to frequently interact with them. The salt wholesalers were equipped with Salt Testing Kits (STKs) to ensure adequate iodine content in the salt procured by them and adherence to the legal ban on the sale of non-iodized salt for human consumption. Simultaneously, a "child-to-community" approach was launched through involvement of middle and high school children to create demand and monitor consumption of iodized salt at the household level. Over 217,000 salt samples (about 26,000 samples per quarter) were brought in by school children and tested for iodine content. RESULTS: The school activities resulted not only in influencing consumption of iodized salt, but also galvanized the entire chain linking consumers, retailers, and wholesalers. In less than 2 years, salt procured with nil iodine decreased from 38% to 15.3%, and salt marketed with adequate iodine level increased from 28.6% to 64.9%. School data revealed an increase in consumption of iodized salt from 6% to 46.7%. In phase 3, additional standardized activities at the school level were included and the program was taken to scale in the state. CONCLUSION: The findings revealed that identification and inclusion of salt wholesalers-not only the salt manufacturers-was important for achieving a rapid positive shift in iodized salt marketing and consumption practices.     

Prevalence of goiter in children 6 to 12 years of age in Ethiopia

BACKGROUND: Iodine-deficiency disorders are a major public health problem in Ethiopia. In conjunction with implementing control programs, baseline information needs to be established. OBJECTIVE: To investigate the distribution and degree of severity of iodine-deficiency disorders in terms of goiter prevalence, urinary iodine excretion (UIE) levels, and proportion of households with iodated salt in Ethiopia. METHODS: A nationwide, community-based, cross-sectional study was conducted from February to May 2005 among 10,965 children aged 6 to 12 years. A multistage, proportional-to-population-size sampling method was used. Goiters were classified by the method recommended by the World Health Organization/UNICEF/International Council for the Control of Iodine Deficiency Disorders (WHO/UNICEF/ICCIDD), in which the thyroid gland is graded as 0 (normal), 1 (palpable goiter), or 2 (visible goiter); urinary iodine was determined by the wet digestion method; and salt samples were analyzed by a rapid test kit. RESULTS: The national total goiter weighted prevalence rate among children aged 6 to 12 years was 39.9% (95% confidence interval, 38.6% to 41.2%), representing more than 4 million children. The median UIE was 2.45 microg/ dL; 45.8% of children had UIE values of 2 microg/dL or less, and 22.8% had UIE values of 2.01 to 5.0 pg/dL. Only 4.2% of the households had iodated salt. CONCLUSIONS: According to the WHO/UNICEF/ ICCIDD classification, both goiter prevalence and UIE levels indicate that the whole country appears to be severely affected by iodine deficiency. Furthermore, the virtual absence of iodated salt in the households shows that currently there is no salt iodization program in the country. Dietary sources of iodine in Ethiopia are not dependable, and hence a sustainable universal salt iodization program needs to be implemented without delay.     

Iodine fortification is related to increased weight-for-age and birthweight in children in Asia

Severe iodine deficiency causes stunting and mental retardation in utero, but the relation between mild deficiency and child growth is not well known. The use of iodated salt in relation to anthropometric data was examined from recent survey data. After potential confounding factors had been controlled for, significant associations were seen in Bangladesh, India, Nepal, and Sri Lanka. The use of iodated salt was related to increased weight-for-age and mid-upper-arm circumference, most strongly in the second year of life, mainly affecting soft tissue (thinness). The relation with weight-for-age was greater among children of mothers with lower body mass index. The use of iodated salt was related to birthweight in Sri Lanka and in the Philippines, where iodized oil capsules given during pregnancy had a negative effect when used with high levels of iodine in salt. The associations generally were concentrated in large geographic areas, possibly because of interactions with other environmental factors (e.g., selenium and arsenic). The apparent growth response to iodine may reflect functional effects of mild deficiency, which is widespread, possibly including effects on brain development.     

Iodine deficiency persists in the Zanzibar Islands of Tanzania

BACKGROUND: Iodine is an essential micronutrient for normal human growth and development. It is estimated that more than 1.6 billion people live in iodine-deficient environments, yet there are still some countries and areas where the prevalence of iodine-deficiency disorders is unknown. OBJECTIVE: To establish the prevalence of iodine-deficiency disorders in the Zanzibar Islands, a community assumed to have ready access to iodine-rich seafoods. METHODS: In a cross-sectional study, 11,967 schoolchildren were palpated for goiter prevalence, a subsample was evaluated for urinary iodine concentration, and the availability of iodated salt was assessed at the household and retail levels. RESULTS: The mean total goiter prevalence was 21.3% for Unguja and 32.0% for Pemba. The overall median urinary iodine concentration was 127.5 microg/L. For Unguja the median was 185.7 microg/L, a higher value than the median of 53.4 microg/L for Pemba (p < .01). The household availability of iodated salt was 63.5% in Unguja and 1.0% in Pemba. The community was not aware of the iodine-deficiency problem and had never heard of iodated salt. CONCLUSIONS: The inadequate intake of iodine documented in the Zanzibar Islands belies the common assumption that an island population with access to seafood is not at risk for iodine-deficiency disorders. We urge health planners to implement mandatory salt iodation and education efforts to alleviate the situation.     

Stability of iodine in salt fortified with iodine and iron

BACKGROUND: Determining the stability of iodine in fortified salt can be difficult under certain conditions. Current methods are sometimes unreliable in the presence of iron. OBJECTIVE: To test the new method to more accurately estimate iodine content in double-fortified salt (DFS) fortified with iodine and iron by using orthophosphoric acid instead of sulfuric acid in the titration procedure. METHODS: A double-blind, placebo-controlled study was carried out on DFS and iodized salt produced by the dry-mixing method. DFS and iodized salt were packed and sealed in color-coded, 0.5-kg, low-density polyethylene pouches, and 25 of these pouches were further packed and sealed in color-coded, double-lined, high-density polyethylene bags and transported by road in closed, light-protected containers to the International Council for the Control of Iodine Deficiency Disorders (ICCIDD), Delhi; the National Institute of Nutrition (NIN), Hyderabad; and the Orissa Unit of the National Nutrition Monitoring Bureau (NNMB), Bhubaneswar. The iodine content of DFS and iodized salt stored under normal room conditions in these places was measured by the modified method every month on the same prescribed dates during the first 6 months and also after 15 months. The iodine content of DFS and iodized salt stored under simulated household conditions was also measured in the first 3 months. RESULTS: After the color code was broken at the end of the study, it was found that the DFS and iodized salt stored at Bhubaneswar, Delhi, and Hyderabad retained more or less the same initial iodine content (30-40 ppm) during the first 6 months, and the stability was not affected after 15 months. The proportion of salt samples having more than 30 ppm iodine was 100% in DFS and iodized salt throughout the study period. Daily opening and closing of salt pouches under simulated household conditions did not result in any iodine loss. CONCLUSIONS: The DFS and iodized salt prepared by the dry-mixing method and stored at normal room conditions had excellent iodine stability for more than 1 year.     

Stability of salt double-fortified with ferrous fumarate and potassium iodate or iodide under storage and distribution conditions in Kenya

The stability of table salt double-fortified with iron as ferrous fumarate, and with iodine as potassium iodide or potassium iodate, has been investigated under actual field conditions of storage and distribution in the coastal and highland regions of Kenya. Seven 200-g sample packets of double-fortified salt in sealed polyethylene bags and a similar packet containing a datalogger for monitoring temperature and humidity were packaged with 21 sample bags of salt from another study into a bundle, which then entered the distribution network from a salt manufacturer's facility to the consumer. Iodine retention values of up to 90% or more were obtained during the three-month study. Double-fortified salt was prepared using ferrous fumarate microencapsulated with a combination of binders and coloring agents and coated with soy stearine, in combination with either iodated salt or salt iodized with potassium iodide microencapsulated with dextrin and coated with soy stearine. Most of the ferrous iron was retained, with less than 17% being oxidized to the ferric state. The polyethylene film overwrap of salt packs in the bundles provided significant protection from ambient humidity. Salt double-fortified with iodine and microencapsulated iron ferrous fumarate premix was generally quite stable, because both iodine and ferrous iron were protected during distribution and retail in typical tropical conditions in Kenya's highlands and humid lowlands.     

Combating iodine deficiency: lessons from China,Indonesia, and Madagascar

This study investigated the factors contributing to a successful and sustainable elimination of iodine-deficiency disorders, drawing from salt fortification experiences in China, Indonesia, and Madagascar. Government officials, salt farmers, salt producers, and wholesalers were interviewed to collect data during field visits. Analyses used in the study include simple correlation, and wherever data permit, regression. The study found that measures crucial for combating iodine deficiency include raising public awareness of the disorders, ensuring easy access to iodated salt, promoting compliance in the salt industry, and monitoring and enforcement. Factors that ensure a reliable supply of iodated salt are equally important as those that create the demand for it. Governments must ensure that surveillance and enforcement mechanisms are functioning right from the time that salt iodation is made compulsory. For sustainability during later years, the adequacy of iodine in iodated salt must be monitored, and incentives must be modified as needed to increase compliance rates in the salt industry. Once national coverage of iodated salt reaches over 90%, the government can concentrate on fine-tuning and targeting resources at areas with a low consumption of iodated salt. Elimination of micronutrient deficiencies has a long-term impact on public health; moreover, poorer segments of the population, who are more vulnerable to such deficiencies, have more to gain from fortification programs. Thus, lessons from the successful elimination of iodine-deficiency disorders are valuable for future similar micronutrient activities.     

Fast and reliable salt iodine measurement: evaluation of the WYD Iodine Checker in comparison with iodometric titration

Iodine deficiency persists as the leading cause of preventable brain damage and reduced intellectual capacity in the world. The most effective method for the elimination of iodine deficiency is the consumption of adequately iodized salt. Ensuring that a population receives adequately iodized salt demands careful monitoring of the salt iodine content. We evaluated the WYD Iodine Checker, a hand-held instrument that quantitatively measures the salt iodine content on the basis of a colorimetric method, and compared its performance with iodometric titration. Performance testing results indicated that the WYD Iodine Checker is a highly precise, accurate, and sensitive tool for measuring salt iodine content. It is a user-friendly instrument that is based on a simple methodology and a straightforward salt sample preparation and testing procedure. We recommend further testing to examine the field performance of the WYD Iodine Checker when measuring iodate salt samples.     

Adding an oxidant increases the stability of iodine in iodized salt

It has been shown that moisture plays a critical role in the stability of iodine and that reducing agents in iodized salt reduce the stability of iodine. We question whether this is valid in all cases, and have found that the reducing agent may play a more important role than moisture in decreasing the stability of iodine. We reviewed current methods to enhance iodine retention in iodized salt, and propose methods to produce stable iodized salt and to analyze its stability. Our experiments showed that when reducing impurities are removed, iodine remains stable in iodized salt, even when the salt is "wet." We suggest that the stability of iodine in iodized salt can be improved by oxidizing iodized salt with sodium hypochloride, and that the iodine content of iodized salt, after heating at 120 degrees C for one hour, can be used to reflect the quality of iodized salt. We have demonstrated that reducing agents play a critical role in the stability of iodine in iodized salt. We have shown a method of purifying salt by removing reducing materials, which can be used to produce iodized salt with sufficient stability at lower cost. We also propose an analytical method to determine the stability of iodine in iodized salt. These methods could be further developed to achieve better accuracy, precision, and reliability and be applied to a greater variety of iodized salts.     

Difference in goiter rates between regular and occasional users of iodized salt in Mongolia

In Mongolia many households use iodized salt only occasionally. We investigated whether the occasional use of iodized salt had an impact on the reduction of goiter size. We examined 685 children (8-11 years old) in five groups of households that (1) used iodized salt regularly, (2) used more than 10 kg of iodized salt annually, (3) used 6 to 10 kg annually, (4) used less than 6 kg annually, (5) and regularly used noniodized salt. The prevalence of goiter as determined by ultrasound in these five groups was 31.1%, 30.3%, 40.6%, 52.1%, 56.6%, respectively. There was no difference between goiter rates among the first three groups, but these groups had significantly lower rates than the last two groups. We concluded that annual use of more than 6 kg of iodized salt, preferably more than 10 kg, by a household had a beneficial effect on the rate of goiter. In addition, the possibility was suggested that households that consumed only iodized salt consumed less salt than other households.     

浅谈加碘盐碘含量测定方法中仲裁法的确定

根据对GB／T13025．7—1999次氯酸钠氧化法和GB／T13025．7—91饱和溴水氧化法测定碘盐碘含量方法的比对，建议用GB／T13025．7—91饱和溴水氧化法作为测定碘盐碘含量的仲裁法。     

Stability of iodine in iodized fresh and aged salt exposed to simulated market conditions

BACKGROUND: The salt iodization law of the Philippines required that iodized salt sold at retail not be exposed to direct sunlight, high temperature and relative humidity, and contamination with moisture and dust from the environment. However, because the majority of local consumers buy salt displayed in open heaps, it was suggested that iodized salt should be sold in the same manner for greater accessibility and availability. Objective. We aimed to provide evidence on the stability of iodine in local aged and fresh salt iodized at 100 ppm iodine and exposed to various market and storage conditions. METHODS: Samples of salt in open heaps and repacked salt were exposed for 4 weeks, and salt packed in woven polypropylene bags was stored for 6 months. The iodine content of the salt was determined by the iodometric titration method, and the moisture content was determined by the oven-drying method. RESULTS: For all types of exposed salt, iodine levels were above 60 ppm after the end of the study (4 weeks). Within each salt type, losses were greater for open-heap salt than for repacked salt. The greatest drop in moisture content occurred in the first week for most types of salt and exposure combinations. Moisture content was linearly correlated with iodine content. Iodine levels in stored salt remained above 60 ppm even after 6 months. CONCLUSIONS: Iodized salt is able to retain iodine above the recommended levels despite exposure to an open environment and use of ordinary packaging materials while being sold at retail and kept in storage.     

碘盐在食品工业中应用的研究

我国缺碘区域广泛 ,并大面积流行碘缺乏症。在食盐中加碘是防治碘缺乏症的有效措施 ,为此 ,世界各国先后都将在食盐中加碘列为法规。在我国 ,虽然在民用盐中成功地应用了加碘盐 ,然而对于加工食品 ,特别是腌制食品仍然未应用加碘盐。我国腌制食品种类多 ,生产量大 ,其用盐量占有很大比例。为了在我国全面推广加碘盐 ,彻底防治碘缺乏症 ,有助于碘盐法规在我国的实施 ,为此我们进行了碘盐在食品工业中应用的研究。本研究结果表明 ,加碘盐适合于食品工业使用 ,对腌制食品不会产生任何不良影响。     

Lessons from successful micronutrient programs. Part III: program impact

Micronutrient-deficiency control programs have been greatly extended at the national level in the last 10 to 15 years. However, rigorous evaluations of these are scarce, so that conclusions on impact are tentative and based mainly on indirect evidence. The coverage of vitamin A capsule distribution programs has exceeded 70% in most study countries. In countries implementing national iodized salt programs, the coverage reaches 60% to 90% of households with adequately iodized salt. Of the three micronutrients, coverage of iron tablet supplementation is the least well documented due to inadequate program monitoring systems and population survey data. Supplementation of preschool children 6 to 59 months of age with vitamin A capsules has plausibly contributed to the reduction in clinical vitamin A deficiency and its near-elimination in many countries. The impact of vitamin A capsule supplementation on children's biochemical vitamin A status (serum retinol) in national programs may be less. National data on salt iodization show a consistent relation to reduced prevalence of iodine-deficiency disorder symptoms (goiter); the rates of cretinism and other results of iodine deficiency are almost certainly falling too. The evaluation of the impact of salt iodization programs on biochemical iodine status is limited by a lack of data. Although trials have demonstrated the efficacy of iron supplementation in reducing the prevalence of anemia, the interpretation of national-level data is not so clear. Given the substantial financial and technical commitment required to implement national micronutrient-deficiency control programs, it is vital that investment enable the evaluation of the impact of these programs. It is becoming increasingly important to collect data on subclinical deficiency (e.g., biochemical data) to assess program impact.     

加碘食盐中碘损失的实验研究(Ⅱ)

采用氯化钠增敏光度法研究了在模拟烹饪条件下加碘食盐中碘的稳定性.实验结果表明,碘盐中碘的稳定性并不理想,加碘食盐中碘的稳定性受温度与受热时间的影响较大,受热温度越高,碘损失越多;受热时间越长,碘损失越多.     

Iodine content in bread,milk and the retention of inherent iodine in commonly used Indian recipes

Iodine deficiency disorders (IDD) is still a major public health problem and iodized salt remains the most effective means to control IDD in India. Few reports indicate that vegans have inadequate iodine intake while at the same time concerns are being raised on the implementation of universal salt iodization in the country. Therefore, we investigated the iodine content in bread, milk and commonly used Indian recipes prepared without iodized salt and the retention of inherent iodine therein. Results showed considerable iodine content in bread (25 μg/100 g) and milk (303 μg/L) as a positive fallout of universal salt iodization. Iodine content in 38 vegetarian recipes prepared without iodized salt was very low (2.9 ± 2.4 μg/100 g). Retention of inherent iodine (65.6 ± 15.4%) and iodine from iodized salt (76.7 ± 10.3%) in the same recipes was comparable. Thus, universal salt iodization programme remains the single most important source of dietary iodine for the Indian population.     

富硒低钠盐中碘含量的测定

目的探讨富硒低钠加碘盐中碘含量的测定方法。方法通过不同的实验条件,优化国标GB/T13025.7-2012《制盐工业通用试验方法碘的测定》中氧化还原滴定法中的试剂用量,检测出富硒低钠加碘盐中的碘含量。结果改变碘化钾溶液量、淀粉溶液量、磷酸-草酸溶液量均无法测定富硒低钠盐中的碘含量;只有当次氯酸钠溶液用量≥5mL时,加入碘化钾溶液,才可以使富硒低钠加碘盐溶液显色,然后通过实验确定次氯酸钠的最佳用量,再滴定测定碘含量。结论富硒低钠加碘盐中含有还原性物质,测定其碘含量需加大次氯酸钠溶液的用量。     

加碘食盐中碘损失的实验研究

采用氯化钠增敏光度法研究了在模拟烹调条件下加碘食盐中碘的稳定性。实验结果表明，碘盐中碘的稳定性并不理想。在温度较高的条件下存在不同程度的损失。加碘盐中碘的损失量受温度与受热时间的影响：温度越高。碘损失越多；受热时间越长，碘损失越多。     

Urinary iodine concentration of pregnant women and female adolescents as an indicator of excessive iodine intake in Sri Lanka

BACKGROUND: Mild deficiencies and excesses of iodine have deleterious effects in both females and males. The iodine status of the population after implementation of the universal salt iodization program in Sri Lanka is not known. OBJECTIVE: This cross-sectional study was carried out to assess the iodine status of pregnant women and female adolescents, with urinary iodine concentration used as the measure of outcome. METHODS: The participants were 100 women in the first trimester of pregnancy and 99 female adolescents in Kuliyapitiya, Kurunegala District, North-Western Province, Sri Lanka. The urinary iodine concentration was measured in a casual urine sample from each subject. The iodate contents of salt samples collected from households of the adolescents participating in the study were also measured. RESULTS: The median urinary iodine concentration of 185.0 microg/L and the prevalence of values under 50 microg/L of only 1% among the pregnant women indicate adequate iodine intake and optimal iodine nutrition. The median urinary iodine concentration (213.1 microg/L) among female adolescents indicates a more than adequate iodine intake and a risk of iodine-induced hyperthyroidism. Approximately 8% and 4% of the adolescents and pregnant women, respectively, had urinary iodine concentrations in the range of mild iodine deficiency (51 to 100 microg/L). More than half of the adolescents (56%) and 39% of the pregnant women had urinary iodine concentrations higher than optimal. The median iodine content in salt samples was 12.7 ppm. Only 20.2% of the samples were adequately iodized, and 10.1% of the samples had very high iodine levels. CONCLUSIONS: Female adolescents and pregnant women had no iodine deficiency, but a considerable proportion of them, especially female adolescents, were at risk for iodine-induced hyperthyroidism. There is thus a need for proper monitoring of the salt iodization program to achieve acceptable iodine status.