title: Increased iron bioavailability from lactic-fermented vegetables is likely an effect of promoting the formation of ferric iron (Fe(3+)).
abstract: BACKGROUND
  Lactic fermentation of foods increases the availability of iron as shown in a number of studies throughout the years. Several explanations have been provided such as decreased content of inhibitory phytate, increased solubility of iron, and increased content of lactic acid in the fermented product. However, to our knowledge, there are no data to support that the bioavailability of iron is affected by lactic fermentation.
  
  
  OBJECTIVE
  The objective of the present study was to investigate whether the bioavailability of iron from a vegetable mix was affected by lactic fermentation and to propose a mechanism for such an event, by conducting human and cell (Caco-2, HepG2) studies and iron speciation measurements (voltammetry). We also investigated whether the absorption of zinc was affected by the lactic fermentation.
  
  
  RESULTS
  In human subjects, we observed that lactic-fermented vegetables served with both a high-phytate and low-phytate meal increased the absorption of iron, but not zinc. In vitro digested fermented vegetables were able to provoke a greater hepcidin response per ng Fe than fresh vegetables, indicating that Fe in the fermented mixes was more bioavailable, independent on the soluble Fe content. We measured that hydrated Fe(3+) species were increased after the lactic fermentation, while there was no significant change in hydrated Fe(2+). Furthermore, lactate addition to Caco-2 cells did not affect ferritin formation in response to Fe nor did lactate affect the hepcidin response in the Caco-2/HepG2 cell system.
  
  
  CONCLUSIONS
  The mechanism for the increased bioavailability of iron from lactic-fermented vegetables is likely an effect of the increase in ferric iron (Fe(3+)) species caused by the lactic fermentation. No effect on zinc bioavailability was observed.
authors: Department of Biology and Biological Engineering, Food and Nutrition Science, Chalmers University of Technology, 412 96, Gothenburg, Sweden. nathalie.scheers@chalmers.se.
authors: Nathalie
authors: N
authors: Scheers
authors: Department of Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg, Box 459, 405 30, Gothenburg, Sweden.
authors: Lena
authors: L
authors: Rossander-Hulthen
authors: Faculty of Food Science and Nutrition, University of Iceland and Unit for Nutrition Research, National University Hospital, Reykjavík, Iceland.
authors: Inga
authors: I
authors: Torsdottir
authors: Department of Biology and Biological Engineering, Food and Nutrition Science, Chalmers University of Technology, 412 96, Gothenburg, Sweden.
authors: Ann-Sofie
authors: AS
authors: Sandberg
mesh_terms: D000328:Adult; D001682:Biological Availability; D018938:Caco-2 Cells; D004305:Dose-Response Relationship, Drug; D005260:Female; D005285:Fermentation; D005293:Ferritins / Q000378:metabolism; D005511:Food Handling; D056945:Hep G2 Cells; D064451:Hepcidins / Q000378:metabolism; D006801:Humans; D019266:Iron, Dietary / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics*; D019344:Lactic Acid / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010833:Phytic Acid / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics; D014675:Vegetables / Q000737:chemistry; D055815:Young Adult; D015032:Zinc / Q000008:administration & dosage / Q000493:pharmacokinetics
chemical_list: D064451:Hepcidins; D019266:Iron, Dietary; D019344:Lactic Acid; D010833:Phytic Acid; D005293:Ferritins; D015032:Zinc
keywords: Absorption; Bioavailability; Ferric; Iron; Lactic fermentation