(P30-022-25) Plant-Based Iron Boosts Intestinal Iron Status In Vitro

Objectives: Iron chlorophyll derivatives (ICDs) contain iron bound in a porphyrin backbone, analogous to heme, the most bioavailable form of iron. However, the ability of ICDs and leghemoglobin (LegH, a plant heme-containing protein) to deliver iron under physiological conditions is poorly studied. This study compared intestinal iron delivery from ICDs, LegH, FeSO₄, and hemoglobin (Hb), using ferritin as a surrogate measure. We also assessed the expression of heme oxygenase 1 (HO-1), the intracellular protein which facilitates iron removal from the heme backbone, to help dilucidated the iron assimilation pathway for these compounds.

Methods: ICDs, LegH, FeSO₄ and Hb were digested (providing 50 µg Fe /mL of digesta, n = 6 per treatment type) in vitro to simulate the gastric, duodenal, and jejunal phases. Digesta was centrifuged, and the supernatant was filtered, diluted 16x, and applied to differentiated Caco-2 cells. The cells were incubated for 2 h, after which fresh iron-depleted media was added, and the cells were incubated for an additional 22 h before harvest. Digesta iron was tested using inductively coupled plasma mass spectrometry. Cellular ferritin, HO-1, and total protein levels were tested using commercial ELISA kits. Levels were compared using ANOVA, followed by Tukey’s post-hoc test (P<0.05 considered significant).

Results: The iron bioaccessibility in digesta containing LegH or ICDs was comparable to digesta containing FeSO₄. In contrast, the iron in digesta containing ICDs and LegH was 4.2x and 1.6x more bioaccessible, respectively, than the iron in digesta containing Hb. Ferritin in the Caco-2 cells incubated with digesta containing either ICDs or LegH increased by 5x and 13x, respectively, compared to cells treated with digesta containing FeSO₄. However, either ICDs or LegH performed slightly worse than Hb (1.7x and 1.6x lower respectively). HO-1 in cells incubated with digesta containing LegH was lower than the amount of HO-1 in cells incubated with digesta containing Hb, but not FeSO₄.

Conclusions: Data demonstrates that ICDs and LegH better deliver iron to intestinal cells as compared to FeSO_4, although the absorption mechanism(s) are still unknown. These novel iron sources show great potential as future dietary fortificants or supplements.

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