Micronutrient Fortification  
Iron Bioavailability Screening Tool

Accurate and cost effective bioavailability screening is essential to the selection/specification of optimal iron forms in foods fortified to address the global health challenge of iron deficiency. To help differentiate among different iron products used in food fortification, SUSTAIN developed a simple laboratory tool for initial screening of elemental iron powders and other iron fortificants.

A variety of screening methods were evaluated for their accuracy and utility in predicting the biological absorption of elemental iron powders, globally the most commonly used iron fortificants. The dissolution rate of iron powders in dilute hydrochloric acid was found to be the most accurate and efficient means of predicting the biological absorption of these products. Several human efficacy studies that utilized standardized samples of iron powders SUSTAIN assembled for its Elemental Iron Studies project indicate that those powders with relatively higher dissolution rates are better absorbed from fortified snacks than those with lower dissolution rates.

To develop a standardized bioavailability screening protocol based on product dissolution rate, iron powder dissolution was studied under different pH, time, and temperature conditions. Parameters with the most consistent values and closest linear correlation to iron absorption in rats were identified. Nine laboratories initially evaluated and confirmed the replicability of the preliminary protocol in a collaborative study. Based on results, key parameters (e.g., time, temperature, speed) were optimized by industry partners. We now seek funds to ensure that the protocol is sufficiently rugged, validate its replicability in a second collaborative study, and have it accredited by an appropriate standards organization.

The screen will have immediate applications as a low-cost, reliable means to assess the quality of new and/or improved iron fortificants (spurring innovation). The screening tool can also be used as a basis for establishing new measurable standards for iron fortificants that correspond to bioavailability. This would help to weed out poor performers and assure use of the most efficacious iron forms in food fortification initiatives.

Project related publications include: