(P17-017-24) Iron-Enriched Kale Treated With Moderate Electric Field Processing Better Delivers Digested Iron to Caco-2 Cells as Compared to Iron Sulfate

Objectives: Moderate electric field (MEF) processing successfully increases the iron content of kale by ~160x, as compared to untreated kale. However, it is not known the effect of increased iron on kale concentrations of other nutritionally relevant bioactive compound concentrations. It is also not known whether this iron-enriched kale better delivers iron to epithelial cells following digestion and incubation with Caco-2 cells. This study aimed to determine the delivery of iron from the iron-enriched kale leaf, as compared to equivalent iron dose from other sources (i.e. hemoglobin, hemoglobin + ascorbic acid (AA), Fe₂SO₄, Fe₂SO₄ + AA).

Methods: Carotenoids and α-tocopherol (VE) were separated and quantitated from non-polar kale extracts using HPLC-DAD. AA concentrations found in the acidified polar fraction were analyzed by HPLC-PDA. Treatments providing 0.25 mg Fe were digested in vitro mimicking the gastric, duodenal, and jejunal phases with digestive enzymes. Post-digestion, the samples were centrifuged, and the supernatant filtered, diluted 16x, and applied to confluent Caco-2 cells (HTB 37, P32). Cells were incubated with digesta for 2 h, fresh iron deplete media applied, and incubated for an additional 22 h. Ferritin and total protein were tested using ELISA.

Results: In the MEF-treated kale, β-carotene and lutein were 4x lower, VE was comparable, and AA was 3x higher as compared to untreated kale. Iron-enriched kale led to a 4x increase in cell ferritin relative to FeSO₄ alone, and comparable to FeSO₄+AA and hemoglobin.

Conclusions: Despite the fact that MEF treatment reduced kale carotenoids, a half cup serving would still provide ~10% of the RDA as β-carotene (as provitamin A). Notably, MEF-treated kale is an iron-rich source that demonstrates high iron delivery in vitro. Thus, it should be tested as a potentially good dietary iron source for those at risk of iron deficiency, such as premenopausal women, vegetarians, etc.

Funding Sources: USDA NIFA Multistate, USDA NIFA-AFRI, Bill & Melinda Gates Foundation