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Completed

NCT Number: NCT07143890

Iron Absorption From Plant Heme Iron

Heme, an iron protoporphyin IX complex, consists of a ferrous ion captured in a porphyrin ring acting as a tetradentate ligand. The unique features of heme iron -its unusually high absorption in foods and its resistance to luminal inhibitors of iron absorption- make it a potentially interesting iron fortificant. This study aims to compare fractional iron absorption from two plant-derived heme iron compounds-iron chlorophyllin and soy hemoglobin-with ferrous sulfate (negative control) and porcine hemoglobin (positive control) in iron-deficient women. All four compounds will be intrinsically labeled with stable iron isotopes. Fractional absorption will be assessed 14 days after test meal administration via erythrocyte iron incorporation.

Absorption will be tested in two matrices: water and maize porridge (an inhibitory matrix). Each participant will consume all test conditions in a randomized order, allowing for within-subject comparisons.

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Key information

Conditions

Iron Deficiency (ID) Iron Absorption Iron Deficiencies Iron Metabolism Disorders Metabolic Diseases Nutritional and Metabolic Diseases

Age range

18 year–45 year

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

ETH Zurich, Laboratoy of Clinical Biopharmacy

Zurich, 8092, Switzerland

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Serum ferritin < 45 µg/L (iron depleted)
  • Body weight < 70 kg
  • Body mass index 18,5 - 24,9 kg/m2 (normal weight)

Exclusion criteria

  • Hb < 120 g/L (anemia)
  • CRP > 5 µg/L (inflammation)
  • Strict vegan and vegetarians
  • Any metabolic, gastrointestinal kidney or chronic disease
  • Consumption of mineral and vitamin supplements since screening and over the study period until last blood sample collection
  • Blood transfusion over the past 6 months
  • blood donation over the past 6 months
  • Significant blood loss (accident, surgery) over the past 6 months
  • Women who are pregnant or breast feeding
  • Smoker (> 1 cigarette per week)
  • Continuous/long-term use of medication (except for contraceptives)
  • Therapeutic iron infusion over the past 6 months,
  • Known hypersensitivity or allergy to iron supplements,
  • Intention to become pregnant during the course of the studies,
  • Known or suspected non-compliance, drug or alcohol abuse,
  • Inability to follow the procedures of the studies, e.g. due to language problems, psychological disorders, dementia, etc. of the participant,
  • Participation in another study with investigational drug within the 30 days preceding and during the present studies,
  • Enrolment of the investigator, his/her family members, employees and other dependent persons

Treatment and study plan

Iron chlorophyllin + no-matrix

Other

Water with labelled Fe chlorophyllin (54Fe)

SoyHb + no-matrix

Other

Water with labelled soy hemoglobin (58Fe)

FeSO4 + no-matrix

Other

Water with labelled ferrous sulfate (58Fe)

Hb + no-matrix

Other

Water with labelled porcine hemoglobin (57Fe)

Iron chlorophyllin + meal-matrix

Other

Maize porridge with labelled Fe chlorophyllin (54Fe)

SoyHb + meal-matrix

Other

Maize porridge with labelled soy hemoglobin (58Fe)

FeSO4 + meal-matrix

Other

Maize porridge with labelled ferrous sulfate (57Fe)

Hb + meal-matrix

Other

Maize porridge with labelled porcine hemoglobin (57Fe)

Primary outcomes

  1. Fractional Iron Absorption (percent)

    Time frame: Day 22

    Fractional iron absorption will be calculated based on the shift of the iron isotope ratios in the collected blood samples after the administration of the intervention products. Fractional iron absorption will be measured as erythrocyte incorporation of the naturally occurring iron forms with different masses used to label the iron supplements.

  2. Fractional Iron Absorption (percent)

    Time frame: Day 43

    Fractional iron absorption will be calculated based on the shift of the iron isotope ratios in the collected blood samples after the administration of the intervention products. Fractional iron absorption will be measured as erythrocyte incorporation of the naturally occurring iron forms with different masses used to label the iron supplements.

  3. Fractional Iron Absorption (percent)

    Time frame: Day 64

    Fractional iron absorption will be calculated based on the shift of the iron isotope ratios in the collected blood samples after the administration of the intervention products. Fractional iron absorption will be measured as erythrocyte incorporation of the naturally occurring iron forms with different masses used to label the iron supplements.

Secondary outcomes

  1. Hemoglobin (g/dL)

    Time frame: Day 1

    Iron status marker

  2. Hemoglobin (g/dL)

    Time frame: Day 22

    Iron status marker

  3. Hemoglobin (g/dL)

    Time frame: Day 43

    Iron status marker

  4. Hemoglobin (g/dL)

    Time frame: Day 64

    Iron status marker

  5. Serum Ferritin (µg/L)

    Time frame: Day 1

    Iron status marker

  6. Serum Ferritin (µg/L)

    Time frame: Day 22

    Iron status marker

  7. Serum Ferritin (µg/L)

    Time frame: Day 43

    Iron status marker

  8. soluble Transferrin Receptor (mg/L)

    Time frame: Day 1

    Iron status marker

  9. soluble Transferrin Receptor (mg/L)

    Time frame: Day 22

    Iron status marker

  10. soluble Transferrin Receptor (mg/L)

    Time frame: Day 43

    Iron status marker

  11. C-reactive protein (mg/L)

    Time frame: Day 1

    Chronic inflammation marker

  12. C-reactive protein (mg/L)

    Time frame: Day 22

    Chronic inflammation marker

  13. C-reactive protein (mg/L)

    Time frame: Day 43

    Chronic inflammation marker

  14. Alpha-1-acid Glycoprotein (g/L)

    Time frame: Day 1

    Acute inflammation marker

  15. Alpha-1-acid Glycoprotein (g/L)

    Time frame: Day 22

    Acute inflammation marker

  16. Alpha-1-acid Glycoprotein (g/L)

    Time frame: Day 43

    Acute inflammation marker

  17. Hepcidin (ng/mL)

    Time frame: Day 1

    A major regulator of iron absorption

  18. Hepcidin (ng/mL)

    Time frame: Day 22

    A major regulator of iron absorption

  19. Hepcidin (ng/mL)

    Time frame: Day 43

    A major regulator of iron absorption

Sponsors and collaborators

Lead sponsor

ETH Zurich

Other

Registry information

Official study title

Iron Absorption From Plant-Derived Heme Iron: An Experimental Study in Iron-Deficient Women (PHIA)

Acronym: PHIA

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Aug 27, 2025
Registry last updated
Jun 2, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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