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A comparison of methods for estimating the bioavailability of elemental iron food fortificants
Author(s) -
Lynch Sean
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a623
Subject(s) - bioavailability , ferrous , dissolution , chemistry , particle size , pharmacology , biology , organic chemistry
We evaluated the physical properties (particle size, surface area, Fisher subsieve size, apparent and pycnometric density) and bioavailability based on five screening procedures (dissolution rate in 0.1 mol/L HCl, relative biological value with respect to ferrous sulfate by the AOAC rat hemoglobin repletion method (RBV), dialyzability and Caco‐2 cell iron uptake both after simulated in vitro digestion, and plasma iron tolerance in human volunteers) of nine commercial elemental iron powder food fortificants. Particle size distribution, surface area, Fisher subsieve size, dissolution rate and RBV were significantly correlated and consistent for powders of the same production type, but varied significantly between powder types. Carbonyl and electrolytic iron powders had the highest predicted bioavailability values; results for the reduced iron products were lower and variable. The predictive values of dissolution rate and RBV were confirmed for electrolytic and hydrogen reduced iron in a six month human efficacy trial; relative absorption values, compared with ferrous sulfate, were 77% and 49% in the human trial. The comparable values for dissolution rate and RBV were 73% and 38%, and 54% and 42% respectively. Dialysis, Caco‐2 cell iron uptake and plasma iron tolerance tests did not provide data that would have improved the precision of predicted bioavailability estimates. We conclude that the bioavailiability of commecial iron powders used for food fortification varies significantly and that the dissolution rate in HCl under standardized conditions is the most practical and cost effective method for initial screening for bioavailability.