The effect of altitude of residence on dietary iron absorption in iron depleted women of reproductiv

Diego MORETTI1, Reyna LIRIA3, Pornpimol SCHEUCHZER1, Gabriela BOURGOS4, Christophe ZEDER2, Nicole STOFFEL2,5, Michael ZIMMERMANN5

1University of Applied Sciences of South Switzerland (SUPSI) / Swiss Distance University of Applied Sciences (FFHS), Zürich, Switzerland
2Laboratory of Nutrition and Metabolic Epigenetics, Zürich, Switzerland
3Instituto de Investigation Nutritional, Lima, Peru
4International Potato Center (CIP), Lima, Peru
5MRC Translational Immune Discovery Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom

Background: Acute changes in altitude cause increase systemic iron clearance, erythropoiesis and iron absorption, but whether long-term high-altitude residents have higher iron requirements and iron absorption, has not been investigated in detail.

​Objectives: To assess and compare dietary iron absorption from iron biofortified potatoes in people living and Huancavelica (3670 m) and Lima (sea level) matched for iron status.

Methods: We aimed to recruit 40 generally health women of reproductive age in each study site with low plasma ferritin (PF<25 µg/L). Fasting subjects consumed identical, standardized 500g of potato based meals divided in breakfast and lunch labelled with 57FeSO4 on 5 consecutive days. Iron absorption was assessed by measuring the shift in iron isotopic composition in red blood cells 14 days after the last test me​al administration. ​Results: We recruited 40 subjects in each study site and 38 subjects completed the study. At high altitude, unadjusted Hemoglobin (15.0 vs 11.2 g/dl), EPO (16.6 vs 4.4 iU/L) and retinol binding protein (1.4 vs 1.2 µmol/L) were higher than in the group at sea level (P<0.05). There were no differences in PF, %TSat, Erythroferrone or inflammation but hepcidin tended to be higher at high-altitude (P=0.053). Fractional iron absorption from biofortified potatoes adjusted for iron status (PF=15 µg/L) was 9.1% at high altitude vs 6.8% at sea level (P<0.05). Conclusion: These data suggest one of the chronic adaptations to high altitude is an increase in fractional iron absorption from the diet, possibly to maintain the higher RBC mass needed at high altitude.