Matrix-controlled iron bioavailability in unrefined whole-pulse low-moisture extrudates

Iron deficiency remains one of the most prevalent micronutrient deficiencies globally, disproportionately affecting populations that rely on plant-based diets. Although pulses are widely consumed staple foods and often contain substantial amounts of iron, iron concentration alone is a poor predictor of nutritional value because absorption is strongly constrained by the food matrix after processing these pulses. Here, we show that unrefined pulse composition exerts a dominant influence on cellular iron uptake in extruded foods, often outweighing the effects of total iron concentration and processing method. Using low-moisture extrusion to produce ready-to-eat foods from unrefined pulse flours, we observed wide variation in cellular iron uptake among pulse types despite comparable iron contents, with Caco-2 cell ferritin formation ranging from 0.81 ± 0.04 to 32.17 ± 0.31 ng ferritin/mg cell protein. This variation was most strongly associated with matrix composition: the highest iron uptake occurred when a low level of inhibitory flavonoids coincided with a low phytate-to-iron molar ratio and abundant enhancer flavonoids, whereas a low inhibitor level alone was not sufficient for high iron uptake. Extrusion improved cellular iron uptake only modestly relative to traditional porridge preparation. Together, these findings highlight matrix-controlled bioavailability as a key factor in plant-based iron delivery and identify yellow bean-based puffed snacks as a promising, consumer-friendly strategy for improving dietary iron intake.