EC Nutrition

Iron deficiency remains the most prevalent micronutrient deficiency worldwide, and conventional oral iron salts, while effective, are frequently limited by gastrointestinal intolerance and regulatory feedback mechanisms that constrain absorption. Ferritin- bound iron represents a physiologically distinct form of dietary iron that is absorbed through receptor-mediated pathways and may offer a differentiated pharmacokinetic profile. This study characterized the acute pharmacokinetics and short-term biological responses to a plant-based ferritin iron supplement (SloIron®) in healthy adult women and women with IDA. In a randomized, double-blind, parallel-group study, participants received a single 60 mg elemental iron dose under fasting conditions followed by daily supplementation for approximately 28 days, with iron metabolism biomarkers assessed over 24 hours and at study completion. Following the acute dose, both cohorts demonstrated sustained, time-dependent increases in serum iron and transferrin saturation, with higher systemic exposure and later peak concentrations in the IDA group, consistent with enhanced physiological uptake in iron- deficient states. Hepcidin responses were modest and variable, with lower overall exposure in IDA participants. Over 30 days, healthy subjects maintained iron biomarkers within normal physiological ranges, while IDA participants exhibited significant directional improvements in serum iron, ferritin, transferrin saturation, and hemoglobin, indicating early biological repletion without evidence of dysregulated iron homeostasis. SloIron® was well tolerated, with no serious adverse events or clinically relevant laboratory abnormalities. These findings demonstrate that ferritin-bound iron produces a sustained systemic iron signal and early biomarker improvements in iron-deficient individuals, supporting its role as a physiologically compatible iron source with a pharmacokinetic profile distinct from high-dose ferrous salts.

 Keywords: Iron; Ferritin-Bound Iron; Iron Pharmacokinetics; Iron Deficiency Anemia

1. Auerbach M., et al. “Iron deficiency in adults: A review”. The Journal of the American Medical Association 20 (2025): 1813-1823.
2. Pantopoulos K. “Oral iron supplementation: new formulations, old questions”. Haematologica 9 (2024): 2790-2801.
3. Lönnerdal B., et al. “Iron absorption from soybean ferritin in nonanemic women”. The American Journal of Clinical Nutrition1 (2006): 103-107.
4. Davila-Hicks P., et al. “Iron in ferritin or in salts (ferrous sulfate) is equally bioavailable in nonanemic women”. The American Journal of Clinical Nutrition4 (2004): 936-940.
5. Murray-Kolb LE., et al. “Women with low iron stores absorb iron from soybeans”. The American Journal of Clinical Nutrition1 (2003): 180-184.
6. Theil EC., et al. “Absorption of iron from ferritin is independent of heme iron and ferrous salts in women and rat intestinal segments”. The Journal of Nutrition3 (2012): 478-483.
7. Casgrain A., et al. “Effect of iron intake on iron status: a systematic review and meta-analysis of randomized controlled trials”. The American Journal of Clinical Nutrition4 (2012): 768-780.
8. Khurana M., et al. “Dietary nonheme iron is equally bioavailable from ferritin or ferrous sulfate in thalassemia intermedia”. Pediatric Hematology and Oncology8 (2017): 455-467.
9. Kalgaonkar S and Lönnerdal B. “Effects of dietary factors on iron uptake from ferritin by Caco-2 cells”. The Journal of Nutritional Biochemistry1 (2008): 33-39.
10. Kalgaonkar S and Lönnerdal B. “Receptor-mediated uptake of ferritin-bound iron by human intestinal Caco-2 cells”. The Journal of Nutritional Biochemistry4 (2009): 304-311.
11. San Martin CD., et al. “Caco-2 intestinal epithelial cells absorb soybean ferritin by μ2 (AP2)-dependent endocytosis”. The Journal of Nutrition4 (2008): 659-666.
12. Li JY., et al. “Scara5 is a ferritin receptor mediating non-transferrin iron delivery”. Developmental Cell1 (2009): 35-46.
13. Moretti D., et al. “Oral iron supplements increase hepcidin and decrease iron absorption from daily or twice-daily doses in iron-depleted young women”. Blood: The Journal of the American Society of Hematology17 (2015): 1981-1989.
14. Lönnerdal B. “Soybean ferritin: implications for iron status of vegetarians”. The American Journal of Clinical Nutrition5 (2009): 1680s-1685s.
15. Conrad ME and Umbreit JN. “Iron absorption and transport-an update”. American Journal of Hematology4 (2000): 287-298.
16. Gunshin H., et al. “Cloning and characterization of a mammalian proton-coupled metal-ion transporter”. Nature 6641 (1997): 482-488.