title: Iron absorption from soybean ferritin in nonanemic women.
abstract: BACKGROUND
  Dietary ferritin, a protein cage around an iron mineral, is an underestimated source of bioavailable iron. Plant ferritin, the most common dietary ferritin, has not been studied. Iron from animal ferritin is absorbed as well as is iron from FeSO4 in women.
  
  
  OBJECTIVE
  The objective was to examine iron absorption from purified soybean ferritin.
  
  
  METHODS
  Healthy, nonanemic women (n = 16) were fed a standardized meal (bagel, cream cheese, and apple juice) containing 1 microCi 59Fe/meal as FeSO4 or (extrinsically labeled) as iron-free soybean ferritin reconstituted with the high phosphate characteristic of plant ferritin (iron:phosphorus = 4:1). Iron-free, apo-soybean ferritin was prepared (with the use of thioglycolic acid and extensive dialysis) from purified ferritin. In a randomized crossover design, the other labeled meal, which contained FeSO4 or ferritin, was given after 4 wk. The subjects received 140 microg Fe as ferritin (2.5 mg) or as FeSO4. After 28 d, whole-body 59Fe and 59Fe in red blood cells were measured before and after dosing.
  
  
  RESULTS
  There was no significant difference in whole-body iron absorption from soybean ferritin (29.9 +/- 19.8%) and that from FeSO4 (34.3 +/- 23.6%) or in iron absorption calculated from red blood cell incorporation (33.0 +/- 20.1% for soybean ferritin and 35.3 +/- 23.4% for FeSO4), which confirmed previous results with animal ferritin that was mineralized and labeled similarly. An inverse relation was observed between serum ferritin and iron absorption from both ferritin and FeSO4, which suggested that sensors regulating iron absorption respond similarly to iron provided as ferrous salts or as ferritin mineral.
  
  
  CONCLUSIONS
  Iron from soybean ferritin is well absorbed and may provide a model for novel, utilizable, plant-based forms of iron for populations with a low iron status.
authors.affiliation: Department of Nutrition, University of California, Davis, Davis, CA 95616, USA. bllonnerdal@ucdavis.edu
authors.forename: Bo
authors.initials: B
authors.lastname: Lönnerdal
authors.forename: Annika
authors.initials: A
authors.lastname: Bryant
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Liu
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Theil
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001682:Biological Availability; D018592:Cross-Over Studies; D004912:Erythrocytes / Q000737:chemistry*; D005260:Female; D005293:Ferritins / Q000097:blood / Q000378:metabolism / Q000493:pharmacokinetics*; D005296:Ferrous Compounds / Q000097:blood / Q000378:metabolism / Q000493:pharmacokinetics*; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects*; D007504:Iron Radioisotopes; D019266:Iron, Dietary / Q000097:blood / Q000378:metabolism / Q000493:pharmacokinetics*; D009752:Nutritional Status; D013025:Glycine max / Q000737:chemistry
chemical_list: D005296:Ferrous Compounds; D006454:Hemoglobins; D007504:Iron Radioisotopes; D019266:Iron, Dietary; C020748:ferrous sulfate; D005293:Ferritins