Impact of Ascorbic Acid on the In Vitro Iron Bioavailability of a Casein-Based Iron Fortificant.

Magalie Sabatier,Stéphane Dubascoux,Raymond P Glahn,Harjinder Singh,Marine Nicolas,Anant Dave,Mary Bodis,Joeska Husny,Andreas Rytz

doi:10.3390/nu12092776

Abstract

A new iron–casein complex (ICC) has been developed for iron (Fe) fortification of dairy matrices. The objective was to assess the impact of ascorbic acid (AA) on its in vitro bioavailability in comparison with ferrous sulfate (FeSO4) and ferric pyrophosphate (FePP). A simulated digestion coupled with the Caco-2 cell culture model was used in parallel with solubility and dissociation tests. Under diluted acidic conditions, the ICC was as soluble as FeSO4, but only part of the iron was found to dissociate from the caseins, indicating that the ICC was an iron chelate. The Caco-2 cell results in milk showed that the addition of AA (2:1 molar ratio) enhanced iron uptake from the ICCs and FeSO4 to a similar level (p = 0.582; p = 0.852) and to a significantly higher level than that from FePP (p < 0.01). This translated into a relative in vitro bioavailability to FeSO4 of 36% for FePP and 114 and 104% for the two ICCs. Similar results were obtained from water. Increasing the AA to iron molar ratio (4:1 molar ratio) had no additional effect on the ICCs and FePP. However, ICC absorption remained similar to that from FeSO4 (p = 0.666; p = 0.113), and was still significantly higher than that from FePP (p < 0.003). Therefore, even though iron from ICC does not fully dissociate under gastric digestion, iron uptake suggested that ICCs are absorbed to a similar amount as FeSO4 in the presence of AA and thus provide an excellent source of iron.

Highlights

Iron is an essential micronutrient with well-established contributions to body functions such as the formation of red blood cells and hemoglobin, oxygen transport, cell division, energy metabolism, immunity and cognition [1]
As part of its iron did not dissociate from the casein under acidic conditions, the iron–casein complex (ICC) can be classified as an iron chelate
The demonstrated impact of ascorbic acid (AA) on iron uptake from the ICC showed that part of the iron that dissociates under simulated digestion is exchangeable in the gut lumen; the similar quantity of ferritin generated by the cells when exposed to ICC and FeSO4 would suggest that the part of iron from

Summary

Introduction

Iron is an essential micronutrient with well-established contributions to body functions such as the formation of red blood cells and hemoglobin, oxygen transport, cell division, energy metabolism, immunity and cognition [1]. According to the most recent estimates, 25% and 37% of anemia is associated with iron deficiency in preschool children and women of reproductive age, respectively [2]. Food fortification with iron is generally regarded as the most cost-effective and sustainable long-term approach for reducing the risk of iron deficiency [3]. Adding a bioavailable form of iron in some food products (e.g., with either a high moisture, and/or a low pH, and/or containing fat, polyphenols) in a relevant nutritional quantity remains a technological challenge, as soluble forms of Nutrients 2020, 12, 2776; doi:10.3390/nu12092776 www.mdpi.com/journal/nutrients. The less soluble forms of iron (e.g., iron pyrophosphate (FePP)) are generally more stable in difficult-to-fortify products but are less well absorbed. A highly water-soluble iron–casein complex (ICC) with improved organoleptic properties [4,5], i.e., a sodium caseinate-ferric (Fe3+ ) phosphate complex, has recently been developed

Methods

Discussion

Conclusion