Prospects of fortification of salt with iron and iodine

Predicting the Stability of Double Fortified Salt by Determining the Coating Quality of the Encapsulated Iron Premix

The technology to simultaneously fortify salt with iron and iodine was developed in Canada and transferred and scaled up in India. The double fortified salt has reached more than 60 million consumers so far. Double fortification of salt is a cost-effective and reliable means of improving iron and iodine deficiencies at a population level. However, high-quality iron premix is essential for the stability of iodine and the program’s success. Therefore, we developed a reliable and cost-effective method for premix coating quality evaluation in the field, especially in low-income settings. The integrity and chemical composition of the coating and exposure of iron at the surface (∼10 μm deep) were determined using scanning electron microscopy and energy-dispersive X-ray spectroscopy to predict the stability of the fortified salt. The phenanthroline colour dropper test was used to test the quality of the double fortified salt by reaction with ferrous iron present on the premix surface. Five iron premix samples were compared. Based on the iron release, coating composition, and the reaction with phenanthroline, Premix-3, and its corresponding DFS, obtained from a local shop in India had the lowest quality among all samples tested. The results of the dropper test corresponded with the analysis using sophisticated analytical tools, confirming it as a simple, reliable, and cost-effective test for iron premix coating quality and integrity. This simple test would be crucial for a successful double fortification program, especially in low-income countries, in predicting iron premix quality, a critical determinant of iodine stability during storage, distribution, and retail. These study results can help governments and NGOs to establish quality standards for iron premix used for salt fortification programs.

Fortification of salt with iron and iodine versus fortification of salt with iodine alone for improving iron and iodine status

BACKGROUND

Iron deficiency is an important micronutrient deficiency contributing to the global burden of disease, and particularly affects children, premenopausal women, and people in low-resource settings. Anaemia is a possible consequence of iron deficiency, although clinical and functional manifestations of anemia can occur without iron deficiency (e.g. from other nutritional deficiencies, inflammation, and parasitic infections). Direct nutritional interventions, such as large-scale food fortification, can improve micronutrient status, especially in vulnerable populations. Given the highly successful delivery of iodine through salt iodisation, fortifying salt with iodine and iron has been proposed as a method for preventing iron deficiency anaemia. Further investigation of the effect of double-fortified salt (i.e. with iron and iodine) on iron deficiency and related outcomes is warranted.  OBJECTIVES: To assess the effect of double-fortified salt (DFS) compared to iodised salt (IS) on measures of iron and iodine status in all age groups.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, five other databases, and two trial registries up to April 2021. We also searched relevant websites, reference lists, and contacted the authors of included studies.

SELECTION CRITERIA

All prospective randomised controlled trials (RCTs), including cluster-randomised controlled trials (cRCTs), and controlled before-after (CBA) studies, comparing DFS with IS on measures of iron and iodine status were eligible, irrespective of language or publication status. Study reports published as abstracts were also eligible.

DATA COLLECTION AND ANALYSIS

Three review authors applied the study selection criteria, extracted data, and assessed risk of bias. Two review authors rated the certainty of the evidence using GRADE. When necessary, we contacted study authors for additional information. We assessed RCTs, cRCTs and CBA studies using the Cochrane RoB 1 tool and Cochrane Effective Practice and Organisation of Care (EPOC) tool across the following domains: random sequence generation; allocation concealment; blinding of participants and personnel; blinding of outcome assessment; incomplete outcome data; selective reporting; and other potential sources of bias due to similar baseline characteristics, similar baseline outcome assessments, and declarations of conflicts of interest and funding sources. We also assessed cRCTs for recruitment bias, baseline imbalance, loss of clusters, incorrect analysis, and comparability with individually randomised studies. We assigned studies an overall risk of bias judgement (low risk, high risk, or unclear).  MAIN RESULTS: We included 18 studies (7 RCTs, 7 cRCTs, 4 CBA studies), involving over 8800 individuals from five countries. One study did not contribute to analyses. All studies used IS as the comparator and measured and reported outcomes at study endpoint.  With regards to risk of bias, five RCTs had unclear risk of bias, with some concerns in random sequence generation and allocation concealment, while we assessed two RCTs to have a high risk of bias overall, whereby high risk was noted in at least one or more domain(s). Of the seven cRCTs, we assessed six at high risk of bias overall, with one or more domain(s) judged as high risk and one cRCT had an unclear risk of bias with concerns around allocation and blinding. The four CBA studies had high or unclear risk of bias for most domains. The RCT evidence suggested that, compared to IS, DFS may slightly improve haemoglobin concentration (mean difference (MD) 0.43 g/dL, 95% confidence interval (CI) 0.23 to 0.63; 13 studies, 4564 participants; low-certainty evidence), but DFS may reduce urinary iodine concentration compared to IS (MD -96.86 μg/L, 95% CI -164.99 to -28.73; 7 studies, 1594 participants; low-certainty evidence), although both salts increased mean urinary iodine concentration above the cut-off deficiency. For CBA studies, we found DFS made no difference in haemoglobin concentration (MD 0.26 g/dL, 95% CI -0.10 to 0.63; 4 studies, 1397 participants) or urinary iodine concentration (MD -17.27 µg/L, 95% CI -49.27 to 14.73; 3 studies, 1127 participants). No studies measured blood pressure. For secondary outcomes reported in RCTs, DFS may result in little to no difference in ferritin concentration (MD -3.94 µg/L, 95% CI -20.65 to 12.77; 5 studies, 1419 participants; low-certainty evidence) or transferrin receptor concentration (MD -4.68 mg/L, 95% CI -11.67 to 2.31; 5 studies, 1256 participants; low-certainty evidence) compared to IS. However, DFS may reduce zinc protoporphyrin concentration (MD -27.26 µmol/mol, 95% CI -47.49 to -7.03; 3 studies, 921 participants; low-certainty evidence) and result in a slight increase in body iron stores (MD 1.77 mg/kg, 95% CI 0.79 to 2.74; 4 studies, 847 participants; low-certainty evidence). In terms of prevalence of anaemia, DFS may reduce the risk of anaemia by 21% (risk ratio (RR) 0.79, 95% CI 0.66 to 0.94; P = 0.007; 8 studies, 2593 participants; moderate-certainty evidence). Likewise, DFS may reduce the risk of iron deficiency anaemia by 65% (RR 0.35, 95% CI 0.24 to 0.52; 5 studies, 1209 participants; low-certainty evidence).  Four studies measured salt intake at endline, although only one study reported this for both groups. Two studies reported prevalence of goitre, while one CBA study measured and reported serum iron concentration. One study reported adverse effects. No studies measured hepcidin concentration.

AUTHORS' CONCLUSIONS

Our findings suggest DFS may have a small positive impact on haemoglobin concentration and the prevalence of anaemia compared to IS, particularly when considering efficacy studies. Future research should prioritise studies that incorporate robust study designs and outcome measures (e.g. anaemia, iron status measures) to better understand the effect of DFS provision to a free-living population (non-research population), where there could be an added cost to purchase double-fortified salt. Adequately measuring salt intake, both at baseline and endline, and adjusting for inflammation will be important to understanding the true effect on measures of iron status.

The Potential of Iodine and Iron Double-Fortified Salt Compared with Iron-Fortified Staple Foods to Increase Population Iron Status

The potential of double-fortified salt (DFS) to improve population iron status is compared with the potential of iron-fortified wheat flour, maize flour, rice grains, and milk products. The potential for a positive impact on iron status is based on reported efficacy studies, consumption patterns, the extent of industrialization, and whether there are remaining technical issues with the fortification technologies. Efficacy studies with DFS, and with iron-fortified wheat flour, maize flour, and rice, have all reported good potential to improve population iron status. Iron-fortified milk powder has shown good impact in young children. When these foods are industrially fortified in modern, automated facilities, with high-level quality control and assurance practices, high-quality raw materials, and a wide population coverage, all vehicles have good potential to improve iron status. Relative to other fortification vehicles, fortification practices with wheat flour are the most advanced and iron-fortified wheat flour has the highest potential for impact in the short- to medium-term in countries where wheat flour is consumed as a staple. Liquid milk has the least potential, mainly because an acceptable iron fortification technology has not yet been developed. Maize is still predominantly milled in small-scale local mills and, although the extruded rice premix technology holds great promise, it is still under development. Salt has a proven record as an excellent vehicle for iodine fortification and has demonstrated good potential for iron fortification. However, technical issues remain with DFS and further studies are needed to better understand and avoid color formation and iron-catalyzed iodine losses in both high- and low-quality salts under different storage conditions. There is currently a risk that the introduction of DFS may jeopardize the success of existing salt iodization programs because the addition of iron may increase iodine losses and cause unacceptable color formation.

Can Double Fortification of Salt with Iron and Iodine Reduce Anemia, Iron Deficiency Anemia, Iron Deficiency, Iodine Deficiency, and Functional Outcomes? Evidence of Efficacy, Effectiveness, and Safety

BACKGROUND

Anemia, iron deficiency, and iodine deficiency are problems of important public health concern in many parts of the world, with consequences for the health, development, and work capacity of populations. Several countries are beginning to implement double fortified salt (DFS) programs to simultaneously address iodine and iron deficiencies.

OBJECTIVE

Our objective was to summarize the evidence for efficacy and effectiveness of DFS on the full range of status and functional outcomes and across different implementation and evaluation designs essential to successful interventions.

METHODS

We conducted a systematic review and meta-analysis of published and gray literature examining the effects of DFS on nutritional status, cognition, work productivity, development, and morbidity of all population groups. We searched for articles in Medline, Embase, CINAHL, Cochrane Central Register, and ProQuest for randomized trials, quasi-randomized trials, and program effectiveness evaluations.

RESULTS

A total of 22 studies (N individuals = 52,758) were included. Efficacy studies indicated a significant overall positive effect on hemoglobin concentration [standardized mean difference (95% CI): 0.33 (0.18, 0.48)], ferritin [0.42 (0.08, 0.76)], anemia [risk ratio (95% CI): 0.80 (0.70, 0.92)], and iron deficiency anemia [0.36 (0.24, 0.55)]. Effects on urinary iodine concentration were not significantly different between DFS and iodized salt. The impact on functional outcomes was mixed. Only 2 effectiveness studies were identified. They reported programmatic challenges including low coverage, suboptimal DFS quality, and storage constraints.

CONCLUSIONS

Given the biological benefits of DFS across several populations in efficacy research, additional evaluations of robust DFS programs delivered at scale, which consider effective implementation and measure appropriate biomarkers, are needed.

Impact of Double-Fortified Salt with Iron and Iodine on Hemoglobin, Anemia, and Iron Deficiency Anemia: A Systematic Review and Meta-Analysis

Double-fortified salt (DFS) containing iron and iodine has been proposed as a feasible and cost-effective alternative for iron fortification in low- and middle-income countries (LMICs). We conducted a systematic review and meta-analysis from randomized and quasi-randomized controlled trials to 1) assess the effect of DFS on biomarkers of iron status and the risk of anemia and iron deficiency anemia (IDA) and 2) evaluate differential effects of DFS by study type (efficacy or effectiveness), population subgroups, iron formulation (ferrous sulfate, ferrous fumarate, and ferric pyrophosphate), iron concentration, duration of intervention, and study quality. A systematic search with the use of MEDLINE, EMBASE, Cochrane, Web of Science, and other sources identified 221 articles. Twelve efficacy and 2 effectiveness studies met prespecified inclusion criteria. All studies were conducted in LMICs: 10 in India, 2 in Morocco, and 1 each in Côte d'Ivoire and Ghana. In efficacy studies, DFS increased hemoglobin concentrations [standardized mean difference (SMD): 0.28; 95% CI: 0.11, 0.44; P < 0.001] and reduced the risk of anemia (RR: 0.59; 95% CI: 0.46, 0.77; P < 0.001) and IDA (RR 0.37; 95% CI: 0.25, 0.54; P < 0.001). In effectiveness studies, the effect size for hemoglobin was smaller but significant (SMD: 0.03; 95% CI: 0.01, 0.05; P < 0.01). Stratified analyses of efficacy studies by population subgroups indicated positive effects of DFS among women and school-age children. For the latter, DFS increased hemoglobin concentrations (SMD: 0.32; 95% CI: 0.03, 0.60; P < 0.05) and reduced the risk of anemia (SMD: 0.48; 95% CI: 0.34, 0.67; P < 0.001) and IDA (SMD: 0.37; 95% CI: 0.25, 0.54; P < 0.001). Hemoglobin concentrations, anemia prevalence and deworming at baseline, sample size, and study duration were not associated with effect sizes. The results indicate that DFS is efficacious in increasing hemoglobin concentrations and reducing the risk of anemia and IDA in LMIC populations. More effectiveness studies are needed.

Iron Fortification: Its Efficacy and Safety in Relation to Infections

Iron-fortification programs are efficacious and effective provided recent guidelines are followed: the iron compound is carefully chosen and its level in the food is based on target population requirements, the amount lacking in the diet, and the iron bioavailability of the diet and the compound. For monitoring, serum ferritin and transferrin receptor should be included in addition to hemoglobin. Thus, recent studies of provision of iron-fortified salt to children in Morocco, rice to children in India, wheat flour to women in Thailand, and fish sauce in Vietnam have demonstrated efficacy and effectiveness. All were in nonmalarious areas, and intestinal parasites were uncommon except in India, where the children were dewormed. C-reactive protein was used to eliminate high ferritin values due to infection. An efficacy study of iron-fortified salt in dewormed school-aged children in Côte d'Ivoire, where the prevalence of malaria parasitemia was 55%, found no change in hemoglobin after 6 months, but serum ferritin increased and transferrin receptor decreased significantly, and the increase in body iron and estimated iron absorbed compared favorably with the results of a study of similar design in Morocco, where the prevalence of iron-deficiency anemia decreased from 30% to 5% after 10 months. Hence, iron-fortification programs in malarious areas may not decrease anemia prevalence but will improve iron status and, presumably, iron-dependent health outcomes. Eight studies in nonmalarious areas, all but one in infants receiving iron-fortified formula, have found no evidence of increase in infections and some evidence of a decrease in respiratory infection. There have been no studies in malarious areas.

Concept of double salt fortification; a tool to curtail micronutrient deficiencies and improve human health status

Fortification of food with micronutrients such as vitamins and minerals is one of the main strategies used to combat micronutrient deficiencies. Fortification in common salt is a fruitful strategy because of the daily consumption of 5-12 g salt per person globally. Therefore double fortification of salt with iodine and iron could be a reasonable approach to prevent both iodine and iron deficiencies. It is reckoned that about two billion people are iodine-deficient worldwide. Iodine deficiency during pregnancy may affect the health status of both mother and fetus and increase infant mortality. Deficiencies of both these micronutrients during childhood affect somatic growth and cognitive and neurological function. Thyroid metabolism is negatively affected by iron deficiency and reduced effectiveness of iodine prophylaxis in areas of endemic goiter. High prevalence of iron deficiency among children may be reduced by the application of effective iodized salt programs. However, ensuring the stability and bioavailability of both iron and iodine as double-fortified salt is difficult. Iodine present in iodide or iodate form in dual-fortified salt is oxidized to free iodine in the presence of ferrous ions and oxygen and consequently loses its characteristics. Moreover, ferrous iron is more bioavailable but is readily oxidized to the less bioavailable ferric form. However, both forms of iron may lead to discoloration of the final product, which can be reduced by providing a physical barrier around the iron. Salt encapsulation is one of the best tools to provide a physical barrier for undesirable reactions and interactions during storage. In this review the concept of dual salt fortification, the impact of fortification on curing various life-threatening maladies, latest assessments of mineral deficiencies and the choice of fortificants are discussed.

Effect of iron-fortified foods on hematologic and biological outcomes: systematic review of randomized controlled trials

BACKGROUND

The utility of iron fortification of food to improve iron deficiency, anemia, and biological outcomes is not proven unequivocally.

OBJECTIVES

The objectives were to evaluate 1) the effect of iron fortification on hemoglobin and serum ferritin and the prevalence of iron deficiency and anemia, 2) the possible predictors of a positive hemoglobin response, 3) the effect of iron fortification on zinc and iron status, and 4) the effect of iron-fortified foods on mental and motor development, anthropometric measures, and infections.

DESIGN

Randomized and pseudorandomized controlled trials that included food fortification or biofortification with iron were included.

RESULTS

Data from 60 trials showed that iron fortification of foods resulted in a significant increase in hemoglobin (0.42 g/dL; 95% CI: 0.28, 0.56; P < 0.001) and serum ferritin (1.36 μg/L; 95% CI: 1.23, 1.52; P < 0.001), a reduced risk of anemia (RR: 0.59; 95% CI: 0.48, 0.71; P < 0.001) and iron deficiency (RR: 0.48; 95% CI: 0.38, 0.62; P < 0.001), improvement in other indicators of iron nutriture, and no effect on serum zinc concentrations, infections, physical growth, and mental and motor development. Significant heterogeneity was observed for most of the evaluated outcomes. Sensitivity analyses and meta-regression for hemoglobin suggested a higher response with lower trial quality (suboptimal allocation concealment and blinding), use of condiments, and sodium iron edetate and a lower response when adults were included.

CONCLUSION

Consumption of iron-fortified foods results in an improvement in hemoglobin, serum ferritin, and iron nutriture and a reduced risk of remaining anemic and iron deficient.

Critical evaluation of strategies for mineral fortification of staple food crops

Staple food crops, in particular cereal grains, are poor sources of key mineral nutrients. As a result, the world's poorest people, generally those subsisting on a monotonous cereal diet, are also those most vulnerable to mineral deficiency diseases. Various strategies have been proposed to deal with micronutrient deficiencies including the provision of mineral supplements, the fortification of processed food, the biofortification of crop plants at source with mineral-rich fertilizers and the implementation of breeding programs and genetic engineering approaches to generate mineral-rich varieties of staple crops. This review provides a critical comparison of the strategies that have been developed to address deficiencies in five key mineral nutrients-iodine, iron, zinc, calcium and selenium-and discusses the most recent advances in genetic engineering to increase mineral levels and bioavailability in our most important staple food crops.

Development of field test kits for determination of microencapsulated iron in double-fortified salt

BACKGROUND

Efficacy studies have shown that salt double-fortified with iodine and iron can significantly reduce the incidence rates of iron-deficiency anemia and iodine-deficiency disorders. Double-fortified salt can be prepared by mixing microencapsulated iron compounds into conventionally iodated salt. Effective implementation of a double fortification program requires field-based analytical methods to ensure iron levels in double-fortified salt.

OBJECTIVE

To develop semiquantitative and qualitative field test kits by adopting standard analytical methods for iron determination to the analysis of iron in double-fortified salt.

METHODS

Thermal, mechanical, and chemical strategies were assessed to enable contact between analytical reagents and the encapsulated iron compounds during the analysis. A chemical approach using nonpolar solvents was adopted in semiquantitative and qualitative field tests. The fat coating of the iron premix was removed by solvents, releasing the iron for subsequent colorimetric determination.

RESULTS

Both semiquantitative and qualitative field tests were based on initial removal of the microencapsulant, followed by iron quantitation. Solvent dissolution of the coating layer was most useful for rapid release of iron. A semiquantitative field test kit was developed using a mixture of 5% heptane and 95% tetrachloroethylene to free the iron, which was then determined by the 1,10-phenanthroline method. The field test had a useful detection range of 0 to 2,000 ppm of iron. Statistical analyses revealed that the results obtained with the kit correlated well with those obtained by standard laboratory methods (p < .001). A qualitative field test kit was developed to identify the presence of iron. Microencapsulated iron was freed with the use of tetrachloroethylene and then reacted with phenanthroline to form a visually observable coloration on the salt sample.

CONCLUSION

Semiquantitative and qualitative field test kits for iron determination in double-fortified salt have been developed and tested. These kits could be useful in quality control of double fortification of salt in small salt-production facilities and in the field, particularly in developing countries.

Naturally occurring iodine in humic substances in drinking water in Denmark is bioavailable and determines population iodine intake

Iodine intake is important for thyroid function. Iodine content of natural waters is high in some areas and occurs bound in humic substances. Tap water is a major dietary source but bioavailability of organically bound iodine may be impaired. The objective was to assess if naturally occurring iodine bound in humic substances is bioavailable. Tap water was collected at Randers and Skagen waterworks and spot urine samples were collected from 430 long-term Randers and Skagen dwellers, who filled in a questionnaire. Tap water contained 2 μg/l elemental iodine in Randers and 140 μg/l iodine bound in humic substances in Skagen. Median (25; 75 percentile) urinary iodine excretion among Randers and Skagen dwellers not using iodine-containing supplements was 50 (37; 83) μg/24 h and 177 (137; 219) μg/24 h respectively (P < 0·001). The fraction of samples with iodine below 100 μg/24 h was 85·0 % in Randers and 6·5 % in Skagen (P < 0·001). Use of iodine-containing supplements increased urinary iodine by 60 μg/24 h (P < 0·001). This decreased the number of samples with iodine below 100 μg/24 h to 67·3 % and 5·0 % respectively, but increased the number of samples with iodine above 300 μg/24 h to 2·4 % and 16·1 %. Bioavailability of iodine in humic substances in Skagen tap water was about 85 %. Iodine in natural waters may be elemental or found in humic substances. The fraction available suggests an importance of drinking water supply for population iodine intake, although this may not be adequate to estimate population iodine intake.

The importance of bioavailability of dietary iron in relation to the expected effect from iron fortification

BACKGROUND

The most common method of combating iron deficiency is iron fortification, especially in developing countries. However, few studies have shown a significant effect on iron status following iron fortification of low bioavailability diets.

OBJECTIVE

To investigate how iron fortification and dietary modifications affect iron absorption and rates of changes in iron stores.

METHODS

Research has made it possible to predict both iron absorption and the effects of iron fortification and diet modifications on iron stores using recently developed algorithms. Iron absorption and rate of change in iron stores were calculated from nine diets representing a broad range of iron bioavailability and iron contents. The calculations were related to the main target group for iron fortification, that is, women of reproductive age having empty stores but normal haemoglobin concentrations.

RESULTS

As the only measure, iron fortification has practically no effect on iron status if the original diet has low bioavailability. However, after dietary modifications such a diet shows a positive effect on iron stores. The combined action of fortification (6 mg/day) and modest bioavailability changes in a low bioavailability diet results approximately in 40 and 70% greater increases in iron stores than through iron fortification or dietary modification alone.

CONCLUSIONS

It is difficult to achieve good effects on iron status from iron fortification as the only measure if the diet has low bioavailability. Both dietary modifications as well as iron fortification are required to improve effectively the iron status of a population.

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.

The Influence of Iron Status on Iodine Utilization and Thyroid Function

Despite significant progress, deficiencies of iron and iodine remain major public health problems affecting > or =30% of the global population. These deficiencies often coexist in children. Recent studies have demonstrated that a high prevalence of iron deficiency among children in areas of endemic goiter may reduce the effectiveness of iodized salt programs. These findings argue strongly for improving iron status in areas of overlapping deficiency, not only to combat anemia but also to increase the efficacy of iodine prophylaxis. The dual fortification of salt with iodine and iron may prove to be an effective and sustainable method to accomplish these important goals.

Salt dual-fortified with iodine and micronized ground ferric pyrophosphate affects iron status but not hemoglobin in children in Cote d'Ivoire

Deficiencies of iron and iodine are common in West Africa, and salt is one of very few food vehicles available for fortification. Salt dual-fortified with iodine and micronized ground ferric pyrophosphate (FePP) was tested for its efficacy in rural, tropical Côte d'Ivoire. First, salt and iron intakes, and iron bioavailability were estimated using 3-d weighed food records in 24 households. Local iodized salt was then fortified with 3 mg Fe/g salt as ground FePP (mean particle size = 2.5 mum), and stability, sensory and acceptability trials were done. The dual fortified salt (DFS) was distributed to households and its efficacy compared with that of iodized salt (IS) in a 6-mo, double-blind trial in 5- to 15-y-old iron-deficient children (n = 123). All children were dewormed at baseline. After 6 mo, serum ferritin (SF) and transferrin receptor (TfR) concentrations as well as body iron stores improved significantly in the DFS group but not in the IS GROUP (P < 0.05). Body iron increased from 4.6 +/- 2.7 to 5.9 +/- 2.7 mg/kg (mean +/- SD) in the DFS group; concentrations before and after treatment in the IS group were 5.5 +/- 2.9 and 5.6 +/- 3.1 mg/kg, respectively. The hemoglobin concentration and the prevalence of anemia did not change in either group. The prevalences of malaria, soil-transmitted helminths, and riboflavin deficiency were 55, 14, and 66%, respectively. In tropical West Africa, low-grade salt fortified with micronized ground FePP increased body iron stores but not hemoglobin in children. Iron utilization may have been impaired by the high prevalence of malaria and concurrent nutrient deficiencies.

Triple fortification of salt with microcapsules of iodine, iron, and vitamin A

BACKGROUND

In many developing countries, children are at high risk of goiter, vitamin A deficiency, and iron deficiency anemia.

OBJECTIVE

We aimed to develop a stable, efficacious salt fortified with iodine, iron, and vitamin A.

DESIGN

A novel spray-cooling technique was used with hydrogenated palm oil to package potassium iodate, micronized ferric pyrophosphate, and retinyl palmitate into microcapsules (mean particle size: 100 mum). We used the microcapsules to create triple-fortified salt (TFS) with 30 mug I, 2 mg Fe, and 60 mug vitamin A/g salt. After storage trials, we compared the efficacy of TFS with that of iodized salt in a 10-mo, randomized, double-blind trial in goitrous schoolchildren (n = 157) who had a high prevalence of vitamin A deficiency and iron deficiency anemia.

RESULTS

After storage for 6 mo, losses of iodine and vitamin A from the TFS were approximately 12-15%, and color was stable. In the TFS group, mean hemoglobin increased by 15 g/L at 10 mo (P < 0.01), iron status indexes and body iron stores improved significantly (P < 0.05), and mean serum retinol, retinol-binding protein, and the ratio of retinol-binding protein to prealbumin increased significantly (P < 0.01). At 10 mo, prevalences of vitamin A deficiency and iron deficiency anemia were significantly lower in the TFS group than in the iodized salt group (P < 0.001).

CONCLUSION

Newly developed microcapsules containing iodine, iron, and vitamin A are highly stable when added to local African salt. TFS was efficacious in reducing the prevalence of iron, iodine, and vitamin A deficiencies in school-age children.

Dual fortification of salt with iodine and micronized ferric pyrophosphate: a randomized, double-blind, controlled trial

BACKGROUND

In many developing countries, children are at high risk for both goiter and anemia. In areas of subsistence farming in rural Africa, salt is one of the few regularly purchased food items and could be a good fortification vehicle for iodine and iron, provided that a stable yet bioavailable iron fortificant is used.

OBJECTIVE

We tested the efficacy of salt dual-fortified with iodine and micronized ferric pyrophosphate for reducing the prevalence of iodine and iron deficiencies in children.

DESIGN

In rural northern Morocco, we fortified local salt with 25 microg I (as potassium iodate)/g salt and 2 mg Fe (as micronized ferric pyrophosphate; mean particle size = 2.5 microm)/g salt. After storage and acceptability trials, we compared the efficacy of the dual-fortified salt (DFS) with that of iodized salt in a 10-mo, randomized, double-blind trial in iodine-deficient 6-15-y-old children (n = 158) with a high prevalence of anemia.

RESULTS

After storage for 6 mo, there were no significant differences in iodine content or color lightness between the DFS and iodized salt. During the efficacy trial, the DFS provided approximately 18 mg Fe/d; iron absorption was estimated to be approximately 2%. After 10 mo of treatment in the DFS group, mean hemoglobin increased by 16 g/L (P < 0.01), iron status and body iron stores increased significantly (P < 0.01), and the prevalence of iron deficiency anemia decreased from 30% at baseline to 5% (P < 0.001). In both groups, urinary iodine (P < 0.001) and thyroid volume (P < 0.01) improved significantly from baseline.

CONCLUSION

A DFS containing iodine and micronized ferric pyrophosphate can be an effective fortification strategy in rural Africa.

Essential metals--case study on iron

Iron is a vital element in life. Because of the insolubility of iron oxides and sulfides the implication is that dissolved iron was fairly abundant and that oxygen and sulfide were rare in the atmosphere and ocean. Iron and its compounds present as pollutants in the atmosphere can cause deleterious effects to humans, animals, and materials. Analyses of urban air samples show that the iron content averages 1.6 microg/m(3), with the iron and steel industry probably the most likely source of emission. Iron is a natural component of soils and its concentration can be influenced by some industries. Iron concentration in surface water varies greatly, from 61 ppm to 2680 ppm. The disposition of iron in the human body is regulated by a complex mechanism to maintain homeostasis. Iron concentrations in body tissues must be tightly regulated because excessive iron leads to tissue damage, as a result of formation of free radicals. Iron has the capacity to accept and donate electrons readily. The content of body iron is regulated primarily by absorption since humans have no physiological mechanism by which excess iron is excreted. Iron has been identified as a component of asbestos and other mineral and synthetic fibers. Inhalation of iron oxide fumes or dust by workers in the metal industries may result in deposition of iron particles in lungs, producing an X-ray appearance resembling silicosis. During the last decades efforts regarding dietary iron supply focused mostly on the prevention of deficiencies, especially during growth and pregnancy. The chemical form of the iron influences absorption, as do interrelationships with other dietary components.

Dual fortification of salt with iodine and microencapsulated iron: a randomized, double-blind, controlled trial in Moroccan schoolchildren

BACKGROUND

In many developing countries, children are at high risk of both goiter and iron deficiency anemia.

OBJECTIVE

In a series of studies in northern Morocco, we developed and tested a dual-fortified salt (DFS) containing iodine and microencapsulated iron.

DESIGN

To establish the DFS fortification concentration, we measured salt intake by 3-d weighed food records and estimated iron bioavailability from the local diet by using published algorithms. We then formulated a DFS containing 25 micro g iodine/g salt (as potassium iodide) and 1 mg iron/g salt (as ferrous sulfate hydrate encapsulated with partially hydrogenated vegetable oil). After storage and acceptability trials, we compared the efficacy of the DFS to that of iodized salt in a 9-mo, randomized, double-blind trial in iodine-deficient, 6-15-y-old children (n = 377).

RESULTS

Mean salt intake in school-age children was 7-12 g/d, and estimated iron bioavailability from the local diet was 0.4-4.3%. After storage for 20 wk, the DFS and iodized salt were not significantly different in iodine content, and color stability was acceptable when the compounds were added to local meals. During the efficacy trial, urinary iodine concentrations and thyroid volumes improved significantly (P < 0.001 and < 0.05, respectively) from baseline in both groups. At 40 wk, mean hemoglobin concentrations in the DFS group had increased by 14 g/L (P < 0.01), and serum ferritin, transferrin receptor, and zinc protoporphyrin concentrations were significantly better (P < 0.05) in the DFS group than in the iodized salt group. The prevalence of iron deficiency anemia in the DFS group decreased from 35% at baseline to 8% at 40 wk (P < 0.001).

CONCLUSION

A DFS containing iodine and encapsulated iron can be an effective fortification strategy.

Double fortified salt at crossroads

Iron Deficiency Anemia (IDA) and Iodine Deficiency Disorders (IDD) are the major public health problems often co-existing in many regions in our country. National Institute of Nutrition (NIN) has promoted the technology of double fortification of common salt with iodine and iron as a strategy to control both deficiencies under food-based approaches. Two other formulations of double fortified salt (DFS) have been subsequently developed by other agencies. NIN formulation & Nutrisalt have a stabilizer/promoter to maintain the stability of iodine in the presence of iron. The Micronutrient Initiative (MI) formulation uses physical separation of iodine by microencapsulation. NIN carried out extensive studies on stability, bioavailability, acceptability, safety and impact (including in community) of DFS. Feasibility both at factory level production and community level implementation have been worked out. MI salt had also undergone stability, acceptability and impact studies. No data is reported on the stability of Nutrisalt except that good stability is claimed in the available reports. In principle, the strategy of double fortification of salt with iron and iodine is sound with uniformly good impact on urinary iodine excretion and prevention of anemia. However, striking increments in hemoglobin (Hb) were not readily demonstrated since the intended purpose of DFS was only to provide iron at maintenance level and not therapeutic level. Complexities in the experimental designs, confounding variables and quality of the ingredients in salts also contributed to difficulties in interpretation of Hb status in studies involving DFS. Along with improvements contemplated in formulation to enhance the stability and bioavailibility, DFS should be able to fulfil the promise and realise its potential in reducing iron and iodine deficiency amongst our poor population in the next few years.

Fortification: overcoming technical and practical barriers

The main barriers to successful iron fortification are the following: 1) finding an iron compound that is adequately absorbed but causes no sensory changes to the food vehicle; and 2) overcoming the inhibitory effect on iron absorption of dietary components such as phytic acid, phenolic compounds and calcium. These barriers have been successfully overcome with some food vehicles but not with others. Iron-fortified fish sauce, soy sauce, curry powder, sugar, dried milk, infant formula and cereal based complementary foods have been demonstrated to improve iron status in targeted populations. The reasons for this success include the use of soluble iron such as ferrous sulfate, the addition of ascorbic acid as an absorption enhancer or the use of NaFeEDTA to overcome the negative effect of phytic acid. In contrast, at the present time, it is not possible to guarantee a similar successful fortification of cereal flours or salt. There is considerable doubt that the elemental iron powders currently used to fortify cereal flours are adequately absorbed, and there is an urgent need to investigate their potential for improving iron status. Better absorbed alternative compounds for cereal fortification include encapsulated ferrous sulfate and NaFeEDTA, which, unlike ferrous sulfate, do not provoke fat oxidation of cereals during storage. Encapsulated compounds also offer a possibility to fortify low grade salt without causing off-colors or iodine loss. Finally, a new and useful additional approach to ensuring adequate iron absorption from cereal based complementary foods is the complete degradation of phytic acid with added phytases or by activating native cereal phytases.