成本-效益分析法在食物铁强化项目中的应用现状

食物铁强化已经被越来越多的国家作为预防和控制铁缺乏和缺铁性贫血的主要策略。本文就各国食物铁强化项目的成本-效益分析报告进行了综述。目前成本-效益分析的运用范围和影响日益加剧,但是成本-效益方法广泛应用于食物铁强化项目尚待进一步的研究。     

Iron Compounds for Food Fortification: Guidelines for Latin America and the Caribbean 2002

Iron deficiency is the most prevalent micronutrient deficiency in the world today. It affects millions of individuals throughout the life cycle, particularly infants and pregnant women, but also older children, adolescents, and women of reproductive age. Living organisms require iron for their cells to function normally. Iron is needed for the development of vital tissues - including the brain - and for transporting and storing oxygen in hemoglobin and muscle myoglobin. Iron deficiency anemia is the severe form of iron deficiency. It can result in low resistance to infection, impaired psychomotor development, and cognitive function in children, poor academic performance, as well as fatigue and poor physical/work endurance. In addition to the above, iron deficiency anemia in pregnancy can result in a low-birth-weight infant. Three intervention strategies are available to prevent iron deficiency and, therefore, iron deficiency anemia. These are supplementation, dietary diversification, and both targeted and untargeted food fortification. Nineteen countries in the Americas have a national food fortification program, in which iron and other micronutrients are added to at least one widely consumed food that is often wheat and/or corn flour. Table 1 shows the iron compounds added to the flours. Each iron compound has different properties and characteristics, which influence its bioavailability, as is discussed later. A number of countries also currently implement fortification programs targeted to specific groups of the population, primarily infants and young children age 6 to 24 months and school-age children.     

Linking the bioavailability of iron compounds to the efficacy of iron-fortified foods

The bioavailability (relative bioavailability value; RBV) of iron compounds relative to ferrous sulfate has proven useful in ranking the potential of iron compounds for food fortification. The efficacy of iron-fortified foods however depends on the absolute iron absorption from the fortified food and not on the RBV of the iron compound. Compounds of lower RBV can be used to design efficacious fortified foods by adding them at an appropriately higher level. Efficacy thus depends on the amount of iron added to the food vehicle as well as the daily consumption of the fortified food by the target population, the amount of iron lacking in the diet of the target population in relation to their needs, and the prevalence of widespread infections and other micronutrient deficiencies. The World Health Organization has recently published guidelines for food fortification, which include recommendations for iron fortification compounds and a method of how to define the iron fortification level. The same organization has also published guidelines on the iron status methods to be used to monitor interventions. Recent efficacy studies, which have to a large extent followed these guidelines, have shown good efficacy of iron-fortified salt, fish sauce, wheat flour, and rice in improving the iron status of target populations. However, although we now know how to design an efficacious iron-fortified food, efficacy cannot be ensured in populations with widespread infections and other micronutrient deficiencies. In such situations, other public health measures may be necessary before we can ensure an improvement in iron status.     

Ensuring the Efficacious Iron Fortification of Foods: A Tale of Two Barriers

Iron fortification of foods has always been a challenge. This is because iron fortification compounds vary widely in relative absorption; because many foods undergo unacceptable changes in color or flavor from the addition of iron; and because many of the iron-fortified foods contain potent inhibitors of iron absorption. These technical barriers have largely been overcome, and efficacious iron-fortified foods, that maintain or improve the iron status of women or children in long-term feeding studies, can be designed. Commercially fortified infant foods are efficacious, and other commercial iron-fortified foods targeted at women and children will provide a useful amount of iron provided the fortification level is adjusted according to the relative absorption of the iron compound. Technologies for the large-scale fortification of wheat and maize flour are also well established, and iron fortification of rice, using the recently developed extruded premix technique, is showing great promise. However, some important knowledge gaps still remain, and further research and development is needed in relation to iron (and iodine)-fortified salt and iron-fortified liquid milk. The usefulness of less-soluble iron compounds, such as ferrous fumarate, to fortify foods for infants and young children in low- and middle-income countries (LMICs) also needs further investigation. A more formidable barrier to efficacious iron-fortified food has been reported in recent years. This is the infection-initiated inflammation barrier, which inhibits iron absorption in response to infection. This barrier is particularly important in LMICs where infections such as malaria and HIV are widespread, and gastrointestinal infections are common due to poor quality water supplies and sanitation. Another source of inflammation in such countries is the high prevalence of obesity in women. Most countries in sub-Saharan Africa have high inflammation which not only decreases the efficacy of iron-fortified and iron-biofortified foods but complicates the monitoring of large-scale iron fortification programs. This is because iron deficiency anemia cannot be differentiated from the more prominent anemia of inflammation and because inflammation confounds the measurement of iron status. There is an urgent need to better quantify the impact of inflammation on the efficacy of iron-fortified foods. However, at present, in LMICs with high inflammation exposure, infection control, cleaner water, improved sanitation, and a decrease in obesity prevalence will undoubtedly have a greater impact on iron status and anemia than the iron fortification of foods.     

PHYSICAL ACCEPTABILITY AND BIOAVAILABILITY OF IRON FORTIFIED FOOD

Nutritionally significant iron fortification of foods is needed to meet the pressing problem of insufficient intake of dietary iron. Consideration must be made of an iron compound's effect on the physical properties of a food as well as of its bioavailability. Encapsulation or selection of small particles may permit use of otherwise unacceptable iron sources for food fortification.     

National food fortification: a dialogue with reference to Asia: policy in evolution

Food fortification generally refers to the addition of micronutrients and other favourably bio-active food components to food-stuffs where there are recognised deficiencies in the target population. Each forticant has had or could have regulatory implications. It is understandable, although arguable, in the face of a limited food supply skewed, for the majority, in the direction of starchy staples of low essential nutrient density. Efforts, with plant breeding, to biofortify such foods are underway and likely to be safer, more sustainable and affordable than chemical additions. Unfortunately, with an increasingly refined and naturally tasteless food supply (salty, fatty, sugary and starchy), and where energy requirements are falling because of physical inactivity, micronutrient fortification is being used as a nutritional "fix-it' strategy. In Asia, there are several critical micro- nutrients. No one national fortification program can deal with all deficiencies is likely to be highly selective for the nutrients which have the greatest advocacy or are most recognisable. They also leave the other health promoting food properties like intactness, nutrient spectrum, and phytonutrient content un-addressed. A variety of food-stuffs, with different biological origins, is the preferred approach. Where an optimal food system is not in place, there may be justification for fortification if there is regular monitoring and surveillance of the food supply and health outcomes occurs; is a clear cost-risk-benefit advantage in such a strategy; are programs in place to improve the nutritional value of the basic food supply and is an "exit strategy' for the fortification program.     

Enhancing the absorption of fortification iron. A SUSTAIN Task Force report

Iron deficiency remains a major global health problem affecting an estimated 2 billion people. The World Health Organization ranked it as the seventh most important preventable risk for disease, disability, and death in 2002. Since an important factor in its causation is the poor bioavailability of iron in the cereal-based diets of many developing countries, SUSTAIN set up a Task Force, consisting of nutritional, medical, industry, and government experts to consider strategies for enhancing the absorption of fortification iron. This paper summarizes the findings of this Task Force. Detailed reviews of each strategy follow this overview. Highly soluble compounds of iron like ferrous sulfate are desirable food fortificants but cannot be used in many food vehicles because of sensory issues. Thus, potentially less well-absorbed forms of iron commonly are used in food fortification. The bioavailability of iron fortificants can, however, be enhanced with innovative ingredient technologies. Ascorbic acid, NaFeEDTA, ferrous bisglycinate, and dephytinization all enhance the absorption of fortification iron, but add to the overall costs of fortification. While all strategies cannot be recommended for all food fortification vehicles, individual strategies can be recommended for specific foods. For example, the addition of ascorbic acid is appropriate for dry blended foods such as infant foods and other dry products made for reconstitution that are packaged, stored, and prepared in a way that maximizes retention of this vitamin. NaFeEDTA can be recommended for fortification of fish sauce and soy sauce, whereas amino acid chelates may be more useful in milk products and beverages. With further development, dephytinization may be possible for low-cost, cereal-based complementary foods in developing countries. Encapsulation of iron salts in lipid coatings, while not an iron absorption-enhancing strategy per se, can prevent soluble forms of iron from interacting undesirably with some food vehicles and hence broaden the application of some fortificants. Research relevant to each of these strategies for enhancing the bioavailability or utility of iron food fortificants is reviewed. Individual strategies are evaluated in terms of enhancing effect and stability, organoleptic qualities, cost, and regulatory issues of interest to the nutrition community, industry, and consumers. Recommendations are made on potential usages and further research needs. Effective fortification depends on the selection of technically feasible and efficacious strategies. Once suitable strategies have been identified, cost becomes very important in selecting the best approach to implement. However it is essential to calculate cost in relation to the amount of bioavailable iron delivered. An approach to the calculation of cost using a conservative estimate of the enhancing effects of the innovative technologies discussed in the supplement is given in the final section.     

Lessons Learned with Iron Fortification in Central America

The countries of Central America have been pioneers in the developing world regarding food fortification initiatives. Salt fortification with iodine was introduced since the late 40s and 50s; sugar fortification with vitamin A is carried out in national programs in Guatemala, Honduras, El Salvador, and Nicaragua, beginning in the 70s; and cereal flour fortification with iron and B vitamins was introduced in the 60s. Salt and sugar fortification have been carefully characterized and evaluated, and the impact of these two interventions to prevent and to control iodine and vitamin A deficiency, respectively, is well established. This did not happen with cereal flour fortification, however, and the effect of this intervention is unknown. Nevertheless, some lessons can be extracted from our experience; these will be discussed in this review.     

A comparison of physical properties, screening procedures and a human efficacy trial for predicting the bioavailability of commercial elemental iron powders used for food fortification

Elemental iron powders are widely used to fortify staple foods. Experimental evidence indicates that there is considerable variation in the bioavailability of different products. For some powders, it may be too low to permit a significant impact on iron status. This study was designed to evaluate possible approaches to screening commercial iron powders for predicted bioavailability, to identify products that have the potential to improve iron status, and to ascertain whether bioavailability is related to the method of manufacture. Nine commercial iron powders were allocated to one of five types based on the production process; carbonyl, electrolytic, hydrogen-reduced (H-reduced), carbon monoxide-reduced (CO-reduced), and other reduced. Structure by scanning electron microscopy and physical properties (pycnometric and apparent density, particle size distribution, Fisher subsieve size, and surface area) were determined on all samples. Selected samples (one or more of each type depending on the cost of the assay) were then subjected to five screening procedures that have previously been advocated for predicting bioavailability in humans--issolution rate in 0.1 mol/L HCl, dialyzability and Caco-2 cell iron uptake, both after simulated in vitro gastrointestinal digestion, relative bioavailability (RBV) with respect to ferrous sulfate by the AOAC rat hemoglobin repletion method, and plasma iron tolerance tests in human volunteers. The results for particle size distribution, surface area, Fisher subsieve size, dissolution rate in 0.1 mol/L HCl, and RBV in rats were significantly correlated and consistent for powders of the same type. However, values for different powder types were significantly different. There was no correlation between either dialyzability or Caco-2 cell uptake and the predicted bioavailability estimates based on the physical properties, dissolution rates, RBV in rats, or human efficacy data. Although human plasma iron tolerance tests were in general agreement with the other measures of predicted bioavailability, they did not provide information that would have improved the precision of bioavailability estimates based on physical properties, dissolution in HCl and/or RBV in rats. Our observations indicate that the dissolution rate in 0.1 mol/L HCI under standardized conditions is highly predictive of potential bioavailability and that it would be the most practical approach to developing a reliable and sensitive screening procedure for predicting and monitoring the bioavailability of commercial elemental iron powder products. Some, but not all, of the carbonyl and electrolytic iron powders had the highest predicted bioavailability values. The predicted bioavailability for the reduced iron products was lower and variable, with the lowest values being recorded for the carbon monoxide and other reduced iron products. Two powder types were selected for a human efficacy trial, electrolytic (because it is the iron powder type recommended by WHO) and hydrogen-reduced (because of its widespread use). Electrolytic/A131 and H-reduced/AC-325 had relative efficacies compared with ferrous sulfate monohydrate of 77% and 49%, respectively, based on the change in body iron stores in Thai women with low iron stores, who received an additional 12 mg iron per day, six days per week for 35 weeks in wheat-based snacks. We conclude that there is significant variability in the bioavailability of the commercial iron powders that we evaluated (those used for food fortification at the time that our studies were initiated), and that bioavailability is related in part to production method. The bioavailability of some carbonyl and electrolytic iron powders may be adequate for effective food fortification. The reduced iron powders that we tested are unlikely to have an adequate impact on iron nutrition at the fortification levels currently employed, although preliminary analysis of a new H-reduced product indicates that it may be possible to improve the bioavailability of individual powders of this type of product. We did find significant differences among products in both the electrolytic and carbonyl categories. Therefore, all products should be screened rigorously.     

Sodium iron (III) ethylenediaminetetraacetic acid synthesis to reduce iron deficiency globally

Despite major interest in sodium iron (III) ethylenediaminetetraacetic acid's (EDTA) potential use in food fortification programs in potentially curbing the global problem of iron deficiency and its anemia, synthesis methods of stable isotope-labeled sodium iron (III) EDTA for use in human bioavailability studies are incomplete, incorrect or totally lacking. Owing to a number of clinical research groups requiring this compound in bioavailability studies, in both developing and already developed countries, we simplified and optimized the synthesis of sodium iron (III) EDTA from a block of isotopically enriched iron metal, in order that it be easily reproduced, cheaply, using simple basic laboratory apparatus. The resulting product is of high purity (>99.0%), and may be used for human stable isotope bioavailability studies. The simplicity of this method allows for the many research groups, currently doing such studies, to perform their own syntheses. Additionally, more uniformity in this synthesis will reduce the variation observed between such studies.     

Iron bioavailability from iron-fortified Guatemalan meals based on corn tortillas and black bean paste

BACKGROUND: Corn masa flour is widely consumed in Central America and is therefore a potentially useful vehicle for iron fortification. OBJECTIVE: The goal was to evaluate the bioavailability of iron from meals based on corn tortillas and black bean paste that were fortified with ferrous fumarate, ferrous sulfate, or NaFeEDTA and to investigate the potential of Na(2)EDTA to increase the bioavailability of iron from ferrous fumarate. DESIGN: With use of a crossover study design, iron bioavailability was measured in Guatemalan girls aged 12-13 y by a stable-isotope technique based on erythrocyte incorporation 14 d after intake. RESULTS: Geometric mean iron bioavailability from test meals fortified with ferrous fumarate was 5.5-6.2% and was not improved significantly by the addition of Na(2)EDTA at molar ratios of 1:1 relative to fortification iron or to the total iron content of the fortified corn masa flour. Geometric mean iron bioavailability from test meals fortified with ferrous sulfate was 5.5% and was significantly higher in test meals fortified with NaFeEDTA (9.0%; P = 0.009, paired t test). CONCLUSIONS: The bioavailability of iron from ferrous fumarate was not improved by the addition of Na(2)EDTA, contrary to what was previously shown for ferrous sulfate in other cereal-based meals. However, the bioavailability of iron from the test meal was significantly enhanced when NaFeEDTA replaced ferrous sulfate. These results support the use of NaFeEDTA in the fortification of inhibitory staple foods such as corn masa flour.     

The role of enriched foods in infant and child nutrition

Since the last century, fortified and enriched foods are products whose original composition has been modified-through addition of essential nutrients-to satisfy specific population needs. For the fortification of foods to have a positive impact on nutritional status, the micronutrients added must be well absorbed and utilized by the organism (bioavailability). Diverse factors affect bioavailability, such as the nutritional status of individuals, the presence in the diet of substances which facilitate or inhibit its absorption, interactions among micronutrients, illnesses, and chemical characteristics of the compound used for fortification. In countries such as Chile, Venezuela and Mexico, important effects have been demonstrated in reducing iron deficiency anaemia in children under 5 years of age. In less than a decade, the salt iodization programme has also proven its effectiveness. Other programmes have fortified foods with Zn, vitamin A and folic acid, which are deficient in infants and children of many populations. In summary, food fortification is a low-cost, relatively simple strategy that may reach a wide range of people, and contribute to reducing the high prevalence of micronutrient deficiencies affecting children, especially in poor countries. The costs due to losses of human capital and their repercussions on health and future development are very high. Building links among academic researchers, politicians, food manufacturers and consumers is essential in order for food fortification to be efficacious and effective, and therefore should be considered as part of an integral strategy to combat micronutrient deficiencies.     

Fortification and Health: Challenges and Opportunities

Fortification is the process of adding nutrients or non-nutrient bioactive components to edible products (e.g., food, food constituents, or supplements). Fortification can be used to correct or prevent widespread nutrient intake shortfalls and associated deficiencies, to balance the total nutrient profile of a diet, to restore nutrients lost in processing, or to appeal to consumers looking to supplement their diet. Food fortification could be considered as a public health strategy to enhance nutrient intakes of a population. Over the past century, fortification has been effective at reducing the risk of nutrient deficiency diseases such as beriberi, goiter, pellagra, and rickets. However, the world today is very different from when fortification emerged in the 1920s. Although early fortification programs were designed to eliminate deficiency diseases, current fortification programs are based on low dietary intakes rather than a diagnosable condition. Moving forward, we must be diligent in our approach to achieving effective and responsible fortification practices and policies, including responsible marketing of fortified products. Fortification must be applied prudently, its effects monitored diligently, and the public informed effectively about its benefits through consumer education efforts. Clear lines of authority for establishing fortification guidelines should be developed and should take into account changing population demographics, changes in the food supply, and advances in technology. This article is a summary of a symposium presented at the ASN Scientific Sessions and Annual Meeting at Experimental Biology 2014 on current issues involving fortification focusing primarily on the United States and Canada and recommendations for the development of responsible fortification practices to ensure their safety and effectiveness.     

Dietary diversification/modification strategies to enhance micronutrient content and bioavailability of diets in developing countries

Both cereal staples and household diets can be manipulated to enhance the content of micronutrients and/or alter the levels of absorption modifiers to improve micronutrient bioavailability. Strategies described range from plant breeding, use of fertilizers and genetic engineering to changes in food preparation and processing methods at the household level involving soaking, fermentation and germination. The impact of five household strategies designed to enhance the content and bioavailability of iron, zinc and calcium in a representative daily menu for rural Malawian preschool children has been calculated using food composition data. In the five strategies, relishes based on small dried fish replaced plant-based relishes, maize-based porridges prepared with maize flour soaked to reduce its hexa (IP-6)- and penta (IP-5)-inositol phosphate content replaced conventional porridges; and a pumpkin-leaf relish replaced sweet potato to increase the retinol content of the daily menu. Comparison of the calculated energy, nutrient, and phytate content, and [phytate]:[zinc] molar ratios of the five modified menus compared with the unmodified menu emphasizes that to ensure that the estimated requirements for iron and zinc are met, the optimal strategy includes dried fish relish twice daily together with porridges prepared using soaked (or fermented) maize flour to reduce their hexa- and penta-inositol phosphate content. Implementation of these household strategies has the potential to increase the bioavailability of iron and zinc in rural Malawian diets from low to high.     

Micronutrient supplementation: when is best and why?

For many nutrients, a systematic determination of the effects of high intakes over extended periods of time has not been conducted. Governments and scientific bodies have just begun to establish the methodology for, and to conduct, nutrient risk assessments for setting 'tolerable upper levels of intake' (UL) for nutrients. Nutrient risk assessment provides the framework for using available information to evaluate the safety of nutrients when added to foods or when consumed as supplements, in order to minimize the risks from over-consumption. When intakes are inadequate, food fortification may be the appropriate choice for some nutrients, while in other situations, when requirements are markedly higher for some population subgroups than for the general population, supplements may be the most appropriate intervention. The present paper will present some examples of how to use the UL along with food consumption data to assess the appropriateness of food fortification v. supplementation strategies and to assess their impact on nutrient intakes of the population. The important steps to be followed when evaluating which approach is best are: (a) establishing need, i.e. assessing the gap between current and desired intakes; (b) assessing safety, i.e. consider the margin of safety between requirement and UL as well as the severity and reversibility of the adverse effect that was used to establish the UL; (c) estimating exposure through statistical modelling, in which population-based estimates of intakes before and after the intervention are compared; (d) monitoring the impact of the intervention to ensure that the desired benefits are achieved and that excessive intakes are minimized. This approach can optimize the public health benefits of food fortification or supplement use while minimizing the risks due to excessive intakes.     

Enhancers of iron absorption: ascorbic acid and other organic acids

Ascorbic acid (AA), with its reducing and chelating properties, is the most efficient enhancer of non-heme iron absorption when its stability in the food vehicle is ensured. The number of studies investigating the effect of AA on ferrous sulfate absorption far outweighs that of other iron fortificants. The promotion of iron absorption in the presence of AA is more pronounced in meals containing inhibitors of iron absorption. Meals containing low to medium levels of inhibitors require the addition of AA at a molar ratio of 2:1 (e.g., 20 mg AA: 3 mg iron). To promote absorption in the presence of high levels of inhibitors, AA needs to be added at a molar ratio in excess of 4:1, which may be impractical. The effectiveness of AA in promoting absorption from less soluble compounds, such as ferrous fumarate and elemental iron, requires further investigation. The instability of AA during food processing, storage, and cooking, and the possibility of unwanted sensory changes limits the number of suitable food vehicles for AA, whether used as vitamin fortificant or as an iron enhancer. Suitable vehicles include dry-blended foods, such as complementary, precooked cereal-based infant foods, powdered milk, and other dry beverage products made for reconstitution that are packaged, stored, and prepared in a way that maximizes retention of this vitamin. The consumption of natural sources of Vitamin C (fruits and vegetables) with iron-fortified dry blended foods is also recommended. Encapsulation can mitigate some of the AA losses during processing and storage, but these interventions will also add cost. In addition, the bioavailability of encapsulated iron in the presence/absence of AA will need careful assessment in human clinical trials. The long-term effect of high AA intake on iron status may be less than predicted from single meal studies. The hypothesis that an overall increase of dietary AA intake, or fortification of some foods commonly consumed with the main meal with AA alone, may be as effective as the fortification of the same food vehicle with AA and iron, merits further investigation. This must involve the consideration of practicalities of implementation. To date, programs based on iron and AA fortification of infant formulas and cow's milk provide the strongest evidence for the efficacy of AA fortification. Present results suggest that the effect of organic acids, as measured by in vitro and in vivo methods, is dependent on the source of iron, the type and concentration of organic acid, pH, processing methods, and the food matrix. The iron absorption-enhancing effect of AA is more potent than that of other organic acids due to its ability to reduce ferric to ferrous iron. Based on the limited data available, other organic acids may only be effective at ratios of acid to iron in excess of 100 molar. This would translate into the minimum presence/addition of 1 g citric acid to a meal containing 3 mg iron. Further characterization of the effectiveness of various organic acids in promoting iron absorption is required, in particular with respect to the optimal molar ratio of organic acid to iron, and associated feasibility for food application purposes. The suggested amount of any organic acid required to produce a nutritional benefit will result in unwanted organoleptic changes in most foods, thus limiting its application to a small number of food vehicles (e.g., condiments, beverages). However, fermented foods that already contain high levels of organic acid may be suitable iron fortification vehicles.     

Food Fortification: The Advantages,Disadvantages and Lessons from Sight and Life Programs

Deficiencies in one or more micronutrients such as iron, zinc, and vitamin A are widespread in low- and middle-income countries and compromise the physical and cognitive capacity of millions of people. Food fortification is a cost-effective strategy with demonstrated health, economic and social benefits. Despite ongoing debates globally and in some countries regarding the performance and safety of food fortification, the practice offers significant benefits across each of the main vehicles for food fortification (large-scale food fortification, biofortification and point-of-use or home fortification) ranging from reducing the prevalence of nutritional deficiencies and economic benefits to societies and economies. Using Sight and Life’s global and national experiences in implementing food fortification efforts, we demonstrate how different programs in LMICs have successfully addressed challenges with food fortification and in doing so, find that these efforts are most successful when partnerships are formed that include the public and private sector as well as other parties that can provide support in key areas such as advocacy, management, capacity building, implementation and regulatory monitoring.     

Study of industrial microencapsulated ferrous sulfate by means of the prophylactic-preventive method to determine its bioavailability

Radio-iron tests are frequently used to measure the bioavailability of different iron sources for food fortification. As the labeling procedures must be done under laboratory conditions, complementary studies should be carried out to evaluate the bioavailability of iron sources produced on an industrial scale. The iron bioavailability of SFE-171 (ferrous sulfate microencapsulated with phospholipids) was studied in previous reports using the compounds labeled with 59Fe and 55Fe; the results showed an iron bioavailability similar to that of ferrous sulfate. In the present work, the iron bioavailability of industrial SFE-171 was studied by the prophylactic-preventive method in rats using ferrous sulfate as the reference standard. Elemental iron powder was also studied by the same method for comparative purposes. The liver iron concentration of each animal was determined at the end of the experiment in order to evaluate the influence of each iron source on the liver iron stores. Relative biological values of 98 and 34% were found for SFE-171 and elemental iron powder, respectively, while the corresponding relative liver iron concentrations were 104 and 45%. The results provided by the prophylactic-preventive method show that the iron bioavailability of industrial SFE-171 is similar to that of ferrous sulfate; these results are also in agreement to those obtained with the radioactive compounds. We can conclude that the SFE-171 obtained by industrial procedures for massive use in iron food fortification has the same bioavailability as that of the SFE-171 produced and labeled under laboratory conditions.     

The potential of encapsulated iron compounds in food fortification: a review

Iron (Fe) encapsulation has the potential to help overcome several major challenges in Fe fortification of foods. It may decrease unwanted sensory changes in fortified products and reduce interactions of Fe with food components that lower Fe bioavailability. However, the effect of encapsulation per se on Fe bioavailability is a concern. Rat studies comparing encapsulated ferrous sulfate, ferric ammonium citrate, and ferrous fumarate to non-encapsulated compounds indicate that a ratio of capsule:substrate of > or = 60:40 may decrease the relative bioavailability (RBV) of the Fe by approximately 20%. At a ratio of capsule:substrate of < or = 50:50, the RBV of encapsulated ferrous sulfate appears to be similar to ferrous sulfate. Even minor changes in capsule composition may influence Fe bioavailability. Encapsulated ferrous fumarate given with ascorbic acid as a complementary food supplement and encapsulated ferrous sulfate fortified into salt have been shown to be efficacious in anemic children. For salt fortification, further refinements in Fe capsule design are needed to increase resistance to moisture and abrasion, while maintaining bioavailability. Studies evaluating the potential efficacy of encapsulated Fe in staple cereals (wheat and maize flours) are needed. A potential barrier to use of encapsulated forms of Fe in staple food fortification is the relatively low melting point of the capsules, which may cause unwanted sensory changes during food preparation. Research and development efforts to improve the quality of coatings and their resistance to high temperatures are ongoing. Process costs for encapsulation can be high, and unless they can be reduced, may limit applications. Further research is needed to determine which encapsulation technologies are most effective in ensuring iron bioavailability from encapsulated compounds.     

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.