Effect of four organic acids on iron uptake from iron-binding proteins derived from Tegillarca granosa using an in vitro digestion/Caco-2 cell culture model.

Iron deficiency anemia (IDA) has been brought to worldwide attention, highlighting the need for a deeper understanding of iron absorption from dietary sources. This study evaluated the effects of four organic acids, including ascorbic acid (AA), citric acid (CA), phytic acid (PA), and tannic acid (TA), on the iron absorption of iron-binding proteins (hemoglobin and ferritin) from Tegillarca granosa. AA and CA significantly enhanced iron solubility (5.82-78.02 %), while PA and TA reduced it (11.47-93.43 %) in digests. Moreover, the micromorphology of proteins transformed into dense network structures when mixed with AA/CA and ordered particle or sheet structures when mixed with PA/TA. Cellular absorption studies revealed that AA and CA enhanced iron bioavailability, while PA and TA inhibited iron absorption. This could be attributed to AA and CA disrupting hydrogen bonds within proteins and inducing disordered secondary structures, making the protein more easily digestible and promoting the release of soluble iron-AA/CA complexes.