Iron deficiency poses a major global health problem affecting an estimated two billion people. In 2002, the World Health Organization ranked iron deficiency as the seventh most important preventable global risk for disease, disability and death. However, the elimination of iron deficiency has not proved easy.
Dietary diversification, promoting the consumption of iron-rich foods, is hindered by the difficulty of achieving behavioral change as well as by the predominance of plant-based diets characteristic of developing countries – diets deficient in the more bioavailable heme form of iron.
Pharmaceutical supplementation has been mainly targeted at high-risk groups such as pregnant women and young children. However, supplementation efforts have been compromised by side effects, low compliance and supply or distribution problems in developing countries.
In many countries, food fortification has been adopted as a cost-effective approach to providing additional iron. However, even though fortification or enrichment can improve iron dietary intake, the low bioavailability of added fortificant iron threatens the effectiveness of these programs. In 2003, Sharing Science & Technology to Aid in the Improvement of Nutrition (SUSTAIN) established and facilitated a task force,
consisting of nutritional, medical, industry and government experts, to consider strategies for enhancing the absorption of fortification iron and to assess the cost.
BARRIERS TO IRON FORTIFICATION
The SUSTAIN task force concluded that while infant formulas, infant cereals, soy sauce and fish sauce are generally effective vehicles for food fortification, some doubt remains as to the usefulness of iron fortified cereal flours.
The initial technical barrier is finding an iron fortificant compound that is sufficiently bioavailable but causes no adverse sensory changes to the food vehicle.
While highly soluble compounds of iron like ferrous sulfate are desirable food fortificants, the SUSTAIN task force found that they are not used in many food vehicles because of sensory issues. Thus, potentially less well-absorbed forms of iron are commonly used in food fortification.
After reviewing a previous SUSTAIN evaluation of elemental iron powders commonly used in cereal flour fortification, the Task Force concluded that of the five iron powders sold, only electrolytic iron had been demonstrated to be a useful iron fortificant.
Since electrolytic iron was judged to be only half as well absorbed as ferrous sulfate, the Task Force recommended that it should be added to foods at twice the level of ferrous sulfate.
A second technical barrier to successful food fortification is overcoming the inhibitory effect of dietary components, such as phytate, phenolic compounds and calcium.
These are often present in the food vehicle itself or in the accompanying diet — particularly in the cereal and tuber based diets common in the developing world. For example, iron absorption may be unacceptably low from highphytate whole grain cereal flours even when fortified with highly absorbable iron compounds such as ferrous sulfate.
A consensus on appropriate uses of iron enhancing technologies was reached after expert review of extensive presentations by science and industry representatives and rigorous discussion of background review papers at a SUSTAIN Workshop in Washington, DC, U.S. (March 9-12, 2003).
The Task Force’s consensus recommendations concluded that the bioavailability of iron fortificants can be enhanced with innovative ingredient technologies to increase the bioavailability of fortification iron in diets containing significant amounts of iron absorption inhibitors, while, at the same time, not causing adverse sensory changes in the chosen vehicles.
The reducing and chelating properties of ascorbic acid can improve iron absorption for iron-fortified dry food preparations, such as pre-cooked com-
plementary infant foods (e.g. cereal and legume-based blends), powdered milk and other dry beverage products made for reconstitution.
In meals high in iron absorption inhibiting compounds, sodium iron EDTA (NaFeEDTA )has been shown to be two to three times better absorbed than iron in ferrous sulphate. While research is needed on its sensory effects on flour-based food staples, the Task Force recommends NaFeEDTA for use in soy, fish sauces and potentially and other condiments.
The iron in ferrous bisglycinate, a patented product, appears to be well absorbed from milk, milk products, beverages and high-phytate cereal products. However, there is very little published data on stability and organoleptic effects during processing, storage and cooking.
With further development, dephytinization as well as encapsulation may be possible for low-cost cereal-based complementary foods in developing countries. While commercial phytase products are commonly used in animal feed to free phosphates, increase mineral availability and protein conversion, their use in food products for humans has been limited. Encapsulation may improve the shelf life of fortified products by preventing iron mediated fat oxidation and thereby allow the addition of iron compounds with high relative bioavailability into foods where organoleptic changes would otherwise pose problems. Table 1 reviews the pros and cons of the various strategies.
While effective fortification depends primarily on the selection of technically feasible and biologically efficacious strategies, cost is critical to sustainability. Manufacturers and consumers in developing countries can absorb only minimal increases in production costs and governmental subsidies are usually not sustainable.
Defining a relatively low strategy with the high impact through bioavailable iron is a critical component of a successful fortification program. However, current fortification regulations in most of the world specify the amount of iron added to the food vehicle but do not account for bioavailability.
The task force asserted that it is essential to calculate cost with reference to the delivery of bioavailable iron — rather than simply on the amount of iron added. From a health benefit point of view, smaller quantities of highly bioavailable iron are equivalent to larger amount of a less bioavailable product. Therefore, price per unit of iron alone may therefore be misleading.
Table 1 shows estimates of relative cost of using various iron absorption enhancers based both on iron addition level and the expected improvement in iron bioavailability based on delivering a level of absorbable iron equivalent to 10 mg daily of iron from ferrous sulphate.
While the ingredient technologies recommended by the SUSTAIN task force may add to the cost of fortification, in many cases they may represent the only strategy that can make real improvement in iron status of iron deficient populations around the world. In addition, increased bioavailability offered by these technologies may make it possible to achieve an equivalent biological impact with a lower level of iron – and lower levels could theoretically offset the cost increase to some extent.
Ultimately, as long as the cost is affordable to producers and consumers, the use of technologies to enhance iron bioavailability will be crucial to the success of iron fortification as a strategy to reduce iron deficiency in developing countries. WG
The full report "Enhancing the Absorption of Fortification Iron, A SUSTAIN Task Force Report,"which includes efficacy, details of the consensus statement on appropariate uses of iron enhancing technologies, and full references will be available at