Nutritional mineral deficiencies (also referred to as micronutrient malnutrition) affect a large proportion of the human population and are particularly widespread in developing countries. Deficiency in iron is especially common, affecting more than two billion people world-wide, and is the only nutrient deficiency that is significantly prevalent in industrialised countries. Iron deficiency is associated with a range of health problems, including impairment of work performance, increased maternal and child mortality, and poor cognitive development in children.
Iron deficiencies originate when physiological requirements are not met by mineral absorption from the diet, for example due to low iron bioavailability. Dietary iron bioavailability may be low, for example, in populations having monotonous plant-based diets with little meat. Indeed, a major cause of low iron bioavailability is related to the presence of anti-nutritional factors that are naturally present in cereals and legumes. These factors form insoluble complexes with iron and interfere with its absorption.
Fortifying food with iron is a well known approach to increase dietary iron intake, but can pose a number of difficulties. A significant problem is caused by the general incompatibility between bioavailability and stability of iron compounds. Typically, the most bioavailable iron compounds are the most reactive within the food matrix. As such, fortifying foods with iron can lead to a number of undesirable changes in properties of the food, in particular organoleptic properties of the food. For example iron can accelerate oxidation reactions, adversely altering a food's flavour, and iron can also form complexes with phenolic chromophore compounds, leading to unwanted colour changes in the food.
For example, ferrous (i.e. Fe(II)) sulfate, which is a reference iron compound for food fortification in humans, causes sensory changes in the food vehicle in the presence of polyphenols or high amounts of lipids. In contrast, more stable iron sources, which are typically water-insoluble (e.g. ferric (i.e. Fe(III)) pyrophosphate), have relatively low bioavailability compared to water-soluble compounds.
A number of approaches have been taken during attempts to improve iron fortification of foods. Encapsulated ferrous sulfate has been considered, because it could provide a highly bioavailable iron source while maintaining stability through encapsulation of the formulation. However, bioavailability is highly dependent on the coating used and in many cases bioavailability of the coated iron source is reduced. Encapsulation also increases production costs. Moreover, most coatings used for encapsulation, which are lipid based, give rise to problems associated with melting during the different heat treatment stages of the manufacture of many food products.
Alternative approaches have used iron-containing nanoparticles that have been stabilised with biopolymers (EP 1743530), or ferric EDTA (ethylenediaminetetraacetic acid), which has good bioavailability and stability (U.S. Ser. No. 10/969,434; published as US 2005/0053696), for iron fortification. However, the use of nanotechnology and EDTA in food products is meeting with increased consumer resistance. Furthermore, sodium iron EDTA is expensive and not stable in all food matrices (e.g. chicken bouillon).
Accordingly, there remains a significant need for compositions and methods that enable fortification of foods and beverages with iron. In particular, there remains a need for compositions and methods that provide a soluble, preferably bioavailable source of iron that has minimal effect on the organoleptic properties of foods.