(P06-034-25) Co-Digestion of Iron Chlorophyllin Derivatives With Plant Proteins and Ascorbic Acid Influences Iron Uptake In Vitro

Objectives: Iron chlorophyll derivatives (ICDs), a potential iron fortificant, can better deliver iron to Caco-2 intestinal cells than the fortificant FeSO₄. More ICD-bound iron was delivered to cells when ICDs were co-digested with the protein albumin, as compared to ICDs digested alone. We sought to test whether the additions of whey, soybean, and pea protein isolates also enhanced iron bioaccessibility and delivery to Caco-2 cells. We also determined whether the addition of ascorbic acid (AA) influenced any protein effects observed.

Methods: Increasing doses of whey, soybean, and pea protein isolates (i.e. 0-154 mg) were co-digested in vitro with ICDs providing 0.5 mg Fe, n=3. This digestion was performed both with and without AA (5:1 molar ratio relative to Fe). Post-digestion, the samples were centrifuged, and the supernatant filtered, diluted 16x, and applied to confluent Caco-2 cells. Digesta iron was quantitated using ICP-MS. Cellular ferritin and total protein were quantitated using ELISA. Metabolites in the filtered digesta were separated via a HILIC column and analyzed using a UHPLC/QTOF-MS with ESI+. Masses were scanned over 50-500 m/z. Metabolites were annotated and tentatively identified via comparison with the METLIN database. Metabolite intensities were compared using either a Student’s t-test or ANOVA, followed by Tukey’s post-hoc test (P < 0.05 considered significant).

Results: Whey protein isolates increased iron bioaccessibility, while soybean and pea protein isolates decreased it, compared to ICDs digested alone. All protein isolates reduced ferritin, compared to cells treated with ICD digesta alone. AA+ICDs+whey improved ferritin but not bioaccessibility, as compared to ICDs+whey. AA did not change iron bioaccessibility nor ferritin formation when ICDs were co-digested with soybean or pea protein. Metabolomics data revealed that AA+ICDs+whey had increased glutamic acid and cysteine containing tri-/dipeptides in digesta, which can chelate iron and transport across cell membrane, as compared to ICDs+whey, which may have influenced iron uptake.

Conclusions: Overall, our results have implications for putative iron fortification strategies, and meal co-consumption strategies, if ICDs are to be used as a dietary source of iron.

Funding Sources: Bill & Melinda Gates Foundation; Steven J. Schwartz Fellowship; USDA Multistate Project