A new bio-enhanced iron formulation with improved iron bioaccessibility modulates intestinal pathways involved in iron uptake, storage and export

Abstract Iron deficiency remains a major global health concern, and the efficacy of oral iron supplementation is often limited by poor bioavailability and gastrointestinal intolerance. In this context, biofortified biological matrices may represent an alternative strategy to improve iron delivery while providing additional functional properties. The present study investigated an innovative nutraceutical formulation composed of iron-biofortified Arthrospira platensis (Nordstedt) Gomont, commonly known as spirulina, combined with thermally inactivated Saccharomyces cerevisiae , used as a potential post-biotic agent. We evaluated the ability of iron-enriched spirulina (ES), non-enriched spirulina (NES), the nutraceutical formulation containing enriched spirulina and yeast (NF), and sucrosomial iron (SI), used as a positive control, to effectively deliver iron and modulate the expression of key regulators of intestinal iron handling. Iron quantification showed higher iron levels in the biofortified samples (ES: 21.01 ± 0.62; NF: 19.68 ± 0.77 mg Fe/g formulation) compared to NES (12.43 ± 0.55 mg Fe/g), while SI (22.37 ± 1.06 mg Fe/g) was used as a positive control. Following simulated gastrointestinal digestion, iron bioaccessibility was 97.15% for ES, 37.90% for NES, 56.02% for SI, and 95.99% for NF. In the in vitro Caco-2 + HT-29 Transwell model, NF displayed the highest transepithelial iron permeation, reaching 90.67 ± 3.41% after 1 h and 98.87 ± 4.39% after 4 h, compared with 48.54 ± 1.26% and 81.63 ± 2.34% for ES, 77.01 ± 2.02% and 75.66 ± 1.97% for NES, and 70.69 ± 3.98% and 82.86 ± 2.74% for SI. At the molecular level, all formulations reduced DMT1 expression after 3 h, with the strongest effect observed for NF (Log2FC < -2), while NF also promoted a coordinated protective response involving the upregulation of FTH1, SLC40A1, and SOD2 gene expression. Overall, NF emerged as the most promising formulation under the tested experimental conditions, combining intestinal tolerability with efficient, tightly regulated iron delivery.