The use of sugar as a vehicle for iodine fortification in endemic iodine deficiency

Trend of Iodine Status in the Eastern Mediterranean Region and Impact of the Universal Salt Iodization Programs: a Narrative Review

Recognizing the importance of iodine deficiency as a single most important preventable cause of brain damage, World Health Organization (WHO) urged all countries to scale up salt iodization since 1991 where iodine deficiency was declared as a global public health problem. All countries committed to report on the national iodine status of school-aged children (6-12 years), every 3 years. This paper aims to evaluate the progress of countries in Eastern Mediterranean Region (EMR) toward the eradication of iodine deficiency disorders (IDD) and recommend operational action to support implementation of the WHO Regional Nutrition Strategy (2020-2030). Salt iodization in EMR has been scaled up with significant progress in increasing the proportion of dietary salt which is adequately iodized. As a result, many countries such as Qatar, Kuwait, Bahrain, Jordan, Oman, and Iran have achieved, or are now on the threshold of achieving IDD elimination. The WHO in coordination with United Nations Children's Fund is working with member states to ensure suitability of these achievements. Hence, efficient monitoring will help member states to measure the magnitude of IDD as a public health problem and to monitor the effects of the intervention on the iodine status of a population. Policy makers should take proactive steps to enforce mandatory regulatory measures for USI, through a multi-sectoral coordination, and careful assessments and estimates of iodine nutritional status. Coordination between the two national programs of USI and salt reduction intake is necessary.

Iodine fortification of foods and condiments, other than salt, for preventing iodine deficiency disorders

BACKGROUND

Iodine deficiency disorders (IDD) affect close to 1.9 billion people worldwide, and are a major public health concern in many countries. Among children, iodine deficiency is the main cause of potentially preventable deficits of central nervous system development and impairment of cognitive function, as well as goitre and hypothyroidism in people of all ages. Salt iodisation is the preferred strategy for IDD prevention and control, however, in some instances where salt is not the major condiment, alternate vehicles for iodine fortification have been considered.

OBJECTIVES

To assess the effects of fortifying foods, beverages, condiments, or seasonings other than salt with iodine alone or in conjunction with other micronutrients, on iodine status and health-related outcomes in all populations.

SEARCH METHODS

Studies were identified through systematic searches of the following databases from their start date to January 2018: Cochrane Public Health Group Specialised Register; CENTRAL; MEDLINE; MEDLINE in Process; Embase; Web of Science; CINAHL; POPLINE; AGRICOLA; BIOSIS; Food Science and Technology Abstracts; OpenGrey; Bibliomap and TRoPHI; AGRIS; IBECS; Scielo; Global Index Medicus-AFRO and EMRO; LILACS; PAHO; WHOLIS; WPRO; IMSEAR; IndMED; and Native Health Research Database. We also searched reference list of relevant articles, conference proceedings, and databases of ongoing trials, and contacted experts and relevant organisations to identify any unpublished work. We applied no language or date restrictions.

SELECTION CRITERIA

Studies were eligible if they were randomised or quasi-randomised controlled trials (RCT) with randomisation at either the individual or cluster level (including cross-over trials), non-randomised RCTs, or prospective observational studies with a control group, such as cohort studies, controlled before-and-after studies, and interrupted time series. We included studies that examined the effects of fortification of food, beverage, condiment, or seasoning with iodine alone, or in combination with other micronutrients versus the same unfortified food, or no intervention. We considered the following measures: death (all-cause), goitre, physical development, mental development, cognitive function and motor skill development, cretinism, hypothyroidism, adverse effects (any reported by trialists), urinary iodine concentration, thyroid-stimulating hormone (TSH) concentration, and serum thyroglobulin concentration. We included all populations, including pregnant women, from any country.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study eligibility, extracted data, and assessed risk of bias of included studies.We used random-effects meta-analyses to combine data and generate an overall estimate of treatment effect, when more than one study examined the same outcome measure. The overall effect estimate was calculated as the mean difference (MD) or standardised mean difference (SMD) between the intervention group and the comparison group for continuous outcomes, and as odds ratio (OR) for dichotomous outcomes. We assessed the level of heterogeneity through the I² statistic. We conducted post-hoc subgroup analyses to explore possible sources of heterogeneity, and sensitivity analyses to check the robustness of the findings from the primary analyses. We assessed the quality of the evidence for each outcome using the GRADE framework.Where it was not possible to pool the results in a meta-analysis, we provided a narrative summary of the outcomes.

MAIN RESULTS

Eleven studies met the criteria, providing 14 comparisons, and capturing data on 4317 participants. Seven studies were RCTs, three were cluster non-RCTs, and one was a randomised cross-over design. Seven studies were carried out among school children (N = 3636), three among women of reproductive age (N = 648), and one among infants (N = 33). The studies used diverse types of food as vehicle for iodine delivery: biscuits, milk, fish sauce, drinking water, yoghourt, fruit beverage, seasoning powder, and infant formula milk. Daily amounts of iodine provided ranged from 35 µg/day to 220 µg/day; trial duration ranged from 11 days to 48 weeks. Five studies examined the effect of iodine fortification alone, two against the same unfortified food, and three against no intervention. Six studies evaluated the effect of cofortification of iodine with other micronutrients versus the same food without iodine but with different levels of other micronutrients. We assessed one study to be at low risk of bias for all bias domains, three at low risk of bias for all domains apart from selective reporting, and seven at an overall rating of high risk of bias.No study assessed the primary outcomes of death, mental development, cognitive function, cretinism, or hypothyroidism, or secondary outcomes of TSH or serum thyroglobulin concentration. Two studies reported the effects on goitre, one on physical development measures, and one on adverse effects. All studies assessed urinary iodine concentration.The effects of iodine fortification compared to control on goitre prevalence (OR 1.60, 95% CI 0.60 to 4.31; 1 non-RCT, 83 participants; very low-quality evidence), and five physical development measures were uncertain (1 non-RCT, 83 participants; very low-quality evidence): weight (MD 0.23 kg, 95% CI -6.30 to 6.77); height (MD -0.66 cm, 95% CI -4.64 to 3.33); weight-for-age (MD 0.05, 95% CI -0.59 to 0.69); height-for-age (MD -0.30, 95% CI -0.75 to 0.15); and weight-for-height (MD -0.21, 95% CI -0.51 to 0.10). One study reported that there were no adverse events observed during the cross-over trial (low-quality evidence).Pooled results from RCTs showed that urinary iodine concentration significantly increased following iodine fortification (SMD 0.59, 95% CI 0.37 to 0.81; 6 RCTs, 2032 participants; moderate-quality evidence). This is equivalent to an increase of 38.32 µg/L (95% CI 24.03 to 52.61 µg/L). This effect was not observed in the meta-analysis of non-RCTs (SMD 0.25, 95% CI -0.16 to 0.66; 3 non-RCTs, 262 participants; very low-quality evidence). Sensitivity analyses did not change the effect observed in the primary analyses.

AUTHORS' CONCLUSIONS

The evidence on the effect of iodine fortification of foods, beverages, condiments, or seasonings other than salt on reducing goitre, improving physical development measures, and any adverse effects is uncertain. However, our findings suggest that the intervention likely increases urinary iodine concentration. Additional, adequately powered, high-quality studies on the effects of iodine fortification of foods on these, and other important outcomes, as well as its efficacy and safety, are required.

Iodine nutrition status in lactating mothers residing in countries with mandatory and voluntary iodine fortification programs: an updated systematic review

BACKGROUND

The aim of this review is to assess data available on iodine nutrition status in lactating mothers residing in countries with mandatory and voluntary iodine fortification programs and/or iodine supplementation.

SUMMARY

A systematic review was conducted by searching articles published between 1964 and 2013 in Pub Med, ISI Web, and Cochrane Library using iodine nutrition, lactation, iodine supplementation, and iodine fortification as keywords for titles and/or abstracts. Relevant articles were included if they reported urinary iodine concentration (UIC) in lactating mothers and, if determined, the type of iodine fortification program and/or iodine supplementation. Forty-two studies met the inclusion criteria. Among these, 21 studies assessed lactating mothers in countries with a mandatory iodine fortification program, 17 studies were from countries with voluntary and/or without iodine fortification programs, and four studies assessed iodine nutrition status in lactating mothers undergoing iodine supplementation. Among countries with mandatory iodine fortification programs, the range of salt iodization level in lactating mothers with a UIC <100 μg/L was between 8 and 40 ppm, whereas among lactating mothers with UIC >100 μg/L, it was between 15 and 60 ppm. Levels of UIC <100 μg/L were observed among lactating women in India, Denmark, Mali, New Zealand, Australia, Slovakia, Sudan, and Turkey, whereas in countries such as Chile, Iran, Mongolia, New Guinea, and Nigeria, the median or mean of UIC was >100 μg/L. There was a median or mean UIC <100 μg/L in nearly all lactating mothers residing in countries where implementation of universal salt iodization program was voluntary, including Switzerland, Australia, New Zealand, Ireland, and Germany. However, in some countries with voluntary iodine fortification programs, such as the United States, Spain, and Japan, a mean or median UIC of >100 μg/L has been reported.

CONCLUSIONS

Although universal salt iodization is still the most feasible and cost-effective approach for iodine deficiency control in pregnant and lactating mothers, UIC in lactating mothers of most countries with voluntary programs and in areas with mandatory iodine fortification is still within the iodine deficiency range, indicating that iodine supplementation in daily prenatal vitamin/mineral supplements in lactating mothers is warranted. However, further investigations are still recommended in this regard.

Iodine status and fish intake of Sudanese schoolchildren living in the Red Sea and White Nile regions

OBJECTIVE

To investigate iodine status and fish consumption of schoolchildren living in the Red Sea and White Nile regions of Sudan.

DESIGN

Cross-sectional study to determine urinary iodine concentration, visible goitre rate, iodine content of salt and fish consumption.

SETTING

Port Sudan (Red Sea) and Jabal Awliya (White Nile), Sudan.

SUBJECTS

Two hundred eighty (n 280) children aged 6-12 years (142 boys, 138 girls).

RESULTS

The median urinary iodine concentration in children from Port Sudan and Jabal Awliya was 553 and 160 μg/l, respectively. Goitre was detected in 17.1 % of children from Port Sudan but only in 1.4 % from Jabal Awliya, The salt samples from Port Sudan contained 150-360 mg iodine (KOI3)/kg salt, whereas those from Jabal Awliya had levels below the detection limit. Despite consuming salt devoid of iodine, children from Jabal Awliya had optimal iodine status. It is plausible that consumption of Nile fish from Jabal Awliya Reservoir, which is a good source of iodine and favoured by the locals, might have provided sufficient iodine. In contrast, children from Port Sudan were at higher risk of iodine-induced hyperthyroidism resulting from consumption of excessively iodised salt.

CONCLUSIONS

The findings of the study clearly demonstrated that (i) Sudan still has a problem with iodine nutrition and quality control and monitoring of salt iodisation and (ii) including fish in the diet could provide a sufficient amount of iodine for schoolchildren.

Iodine fortification: why, when, what, how, and who?

PURPOSE OF REVIEW

To highlight current issues regarding the role of iodine fortification in correcting and preventing iodine deficiency. Universal salt iodization (USI) is recommended, wherein all salt is iodized; however, a more graduated approach may be warranted.

RECENT FINDINGS

Iodine deficiency is widespread and has re-emerged in countries such as Australia, New Zealand and the UK. As well as supplementation in groups such as pregnant and lactating women who have increased iodine requirements, public health strategies to improve iodine intakes include voluntary or mandatory fortification of the food supply. A key player in the process of fortification is the food industry, wherein misperceptions that the addition of iodized salt to foods alters taste and colour still persist and legislation in some countries that prohibits its addition to manufactured foods, can result in a reluctance to support USI.

SUMMARY

Ameliorating iodine deficiency on a population level in countries with mild-to-moderate deficiency is warranted. Risk of both inadequate and excess iodine intakes requires regular monitoring to accompany fortification programmes as well as strategies to address subpopulations at risk. More sensitive indicators of recent iodine status are needed to rapidly assess the impact of fortification on improving the status.

Salt fortification with iodine: Sudan situation analysis

Iodine deficiency disorders (IDD) constitute a severe public health problem in Sudan. IDD affects children and women throughout life. More than 2 out of 10 school age children have goiter. The prevalence reaches 40% in some regions of the country. Several interventional measures were introduced to control the IDD problem. While the situation with regard to production and supply of iodized salt was thus deteriorating, an Emergency Food Security and Nutrition Assessment Survey (EFSNA) revealed that the prevalence of IDD among adult women, as reflected in the presence of visible goiter, was as high as 25.5%. We have conducted a situation analysis survey in the Republic of Sudan to review the prevailing situation and suggest a benchmark that would help in developing effective control measures and in monitoring their implementations. SWOT analysis, questionnaire, focus groups discussion beside a combination of rapid assessment approach and qualitative method were used to critically evaluate the salt iodization situation in the country and assess the prevailing IDD situation in and propose a plan of action to overcome the bottlenecks. The survey concluded that Iodine deficiency affects children and women all through Sudan. The prevalence is even greater in some regions of the country and there is no supportive policy environment for successful universal salt iodization. To overcome this aggravated situation Sudan will need to conduct a baseline study to provide data on the prevalence of IDD, geographic distribution, knowledge, attitudes and practices relating to iodine deficiency. This will provide a benchmark that will help in developing effective control measures and in monitoring their implementation. The study recommended a set of actions to the government to overcome the prevailing situation and strengthening the current policy and implementation.

Slow-release iodine in local water supplies reverses iodine deficiency disorders: is it worth its salt?

An alternative approach to supplying iodine to isolated populations through the use of slow-release iodine in silicone matrices that float in the water supply was tested in remote desert areas of the Sudan. There was a differential impact, as judged by indicators of iodine nutriture, and these indicators provided varying indications of the iodine status of the population.

Iodine nutrition in Sudan: determination of thyroid-stimulating hormone in filter paper blood samples

In this study we examined the technique of measuring thyroid-stimulating hormone (TSH) on filter paper blood samples for use in evaluating the iodine nutrition status of newborns and adults living in iodine-deficient areas. Filter paper blood samples were obtained between the 5th and 7th day after birth from 103, 43 and 103 term newborns living in Khartoum (mild iodine deficiency), Kosti (moderate iodine deficiency) and Darfur (severe iodine deficiency), respectively. TSH was measured with a commercial assay and the levels were compared with those obtained with the same method in 1147 samples from term Swedish newborns, obtained on the 3rd to the 5th day of life. The mean (95% confidence interval) TSH levels of the three Sudanese groups and the Swedish group were 7.1 (4.8-9.4), 8.3 (6.6-10.1), 11.9 (0.9-22.9) and 4.51 (3.8-5.3) mU l-1, respectively. The mean TSH for all three Sudanese groups was higher than the Swedish mean (p < 0.001). TSH levels determined in filter paper blood samples from adults living in an iodine-deficient area showed a correlation (p < 0.001; r = 0.55) to levels in corresponding serum samples (range 0.52-14.1 mU l-1, median 3.4 mU l-1). No significant correlation was found, however, between blood spot levels and serum levels within the reference range (< 5 mU l-1). A modification of the commercial procedure consisting in using three instead of two monoclonal antibodies did not sufficiently improve the assay for measurements of TSH within the reference range. Thus, there is a need to develop the filter paper technique further to make it a useful test for monitoring iodine deficiency in populations expected to have TSH levels close to the reference range. In the examination of neonates, however, with their birth-induced surge of TSH, the current assay promises to be a convenient tool for discovering iodine deficiency within a community.

Control of iodine deficiency using iodination of water in a goitre endemic area

Salt iodination is the method of choice for prevention of iodine deficiency in most parts of the world. However, establishment of such a program frequently involves considerable changes in the marketing and distribution patterns and requires years to achieve. This study was conducted to evaluate the efficiency of using well-defined water sources containing iodine-saturated silicon matrices for providing adequate iodine supply to an iodine deficient population in Kordofan State, Western Sudan. A system of water iodination using silicon matrices containing 30% sodium iodide placed in polyethylene baskets was used in four villages using either traditional wells or hand pumps. Before and every 6 months after iodination of water, urine and blood samples were obtained for determination of iodine and thyroid-related hormones, respectively. Goitre assessment on the village populations were performed at the start and 2 years later. Improvements in iodine status were recorded in all the study villages. The water iodine concentrations increased and a higher iodine content was observed in the hand pumps compared to the traditional wells. The median urinary iodine concentrations increased significantly, from 0.19, 0.20, 0.19, 0.11 to 1.20, 1.10, 0.37, 0.30 mumol/l in the four villages, respectively. The percentages of subjects with serum TSH above 4 mU/l were decreased from more than 30% before iodination to less than 15% at 2 years after iodine supply and the mean serum thyroxine hormone values rose. The rates of goitre decreased from 69% to less than 25%. The study shows that this system is effective, cheap, safe and practically applicable under conditions prevailing in rural areas in developing countries with iodine deficiency.