Effect of food-to-food fortification of African-type wholegrain maize porridge with moringa leaf and baobab fruit powders on ferritin formation in Caco-2 cells

This study determined food-to-food fortification effects of wholegrain maize-based porridge with moringa leaves (rich in iron) and baobab fruit (rich in iron absorption enhancers– ascorbic and citric acids) on ferritin formation in a coupled in vitro digestion/Caco-2 cell assay in comparison with conventional iron fortification and ascorbic acid inclusion. Unlike the in vitro dialysability assay, the coupled in vitro digestion/Caco-2 cell assay can predict iron absorption by accurately predicting the correct direction of response for all major iron modifiers.

Surprisingly in this study, the food-to-food fortification of maize-based porridge with the moringa and baobab both substantially reduced the total and percentage soluble iron and ferritin formation by the Caco-2 cells, when compared to conventional iron fortification (FeSO₄) and ascorbic acid inclusion, respectively. This is most likely because moringa is high in calcium, phytate and polyphenols, which can form insoluble complexes with iron, hence, inhibiting iron uptake by the cells. Baobab-fortified porridge had lower ascorbic acid content and ascorbic acid: iron molar ratio compared to its control, which may be responsible for its lower iron solubility, and consequently lower ferritin formation. Also, baobab’s high polyphenols likely formed small polyphenol-iron complexes of low availability.