Bovine ferritin iron bioavailability in man

Area of Science:

• Nutritional Biochemistry
• Human Physiology
• Pharmacology

Background:

• Ferritin is the primary intracellular iron storage protein.
• Understanding ferritin iron bioavailability is crucial for nutritional and therapeutic applications.

Purpose of the Study:

• To evaluate the bioavailability of iron from ferritin in human subjects.
• To compare iron absorption from ferritin versus ferrous sulfate.
• To assess the suitability of ferritin as a pharmaceutical iron preparation.

Main Methods:

• Human subjects ingested radiolabelled [55Fe]ferritin derived from bovine spleen and liver.
• Iron absorption was quantified using gamma counting.
• Comparisons were made between ferritin iron and ferrous sulfate iron under fed and fasted conditions.
• Dose-response effects were investigated by varying iron intake.

Main Results:

• Geometric mean absorption of 5 mg ferritin iron was 3.8% (fasted) and 3.2% (fed), significantly lower than ferrous sulfate (24.1% fasted, 8.2% fed).
• At a 10-fold higher iron dose, ferritin iron absorption was 0.6-0.7%, compared to 7.9% (fasted) and 2.6% (fed) for ferrous sulfate.
• No significant difference in absorption was found between bovine spleen ferritin (4.0%) and liver ferritin (2.7%).

Conclusions:

• Ferritin iron exhibits poor bioavailability in humans.
• Iron absorption from ferritin is substantially less efficient than from ferrous sulfate.
• Ferritin is not recommended for use as a pharmaceutical iron preparation due to its low absorption efficiency.