Nano-iron oral supplements emerged as efficient supplements with reduced gastrointestinal side effects. Very recently, nanorods of β-FeOOH was introduced as the most efficient shape of nano-iron to be employed as oral supplement. Developed technologies in the fabrication of nanostructures provides the ability to synthesize β-FeOOH nanorods in various lengths while the other features are constant. As we all know, particles' length has an immense impact on the biologic properties of nanorods. But there are no in vivo data about the impacts of particles length on the bioavailability and possible toxicity of β-FeOOH nanorods. So, in this study, different lengths of β-FeOOH nanorods were fabricated and employed as oral iron supplements. In this order, β-FeOOH nanorods with two lengths (mean length 50 nm and 100 nm) were successfully synthesized via hydrolysis reaction. Oral supplementation of Sprague-Dawley rats with the synthesized nanorods and FeSO₄ was performed in two dosages, 10 and 20 mg/Kg. After 1-month daily treatment, blood and tissue samples were collected for hematologic, toxicologic, and pathologic analyses. Compared to FeSO₄, β-FeOOH nanorods demonstrated greater efficiency to improve serum iron levels (~ threefold increase) and also hematological parameters. Similar to FeSO₄, nanorods exhibited any adverse effect on liver and spleen tissues. With the same level of biocompatibility, short nanorods provided better bioavailability than the long nanorods. These data approved the short β-FeOOH nanorods as efficient and safe nanostructures to be employed in nano-based formulation of iron supplements.

Keywords: Akageneite; Anemia; Iron deficiency; Nano-formulations; Toxicity.

© 2025. The Author(s), under exclusive licence to Society for Biological Inorganic Chemistry (SBIC).