Glycosaminoglycans isolated from fish muscle enhance iron uptake by Caco‐2 cells

Abstract

Numerous attempts have been made to identify the factor in muscle tissue that enhances Fe absorption but the nature of the promoter remains controversial. Previous research suggested that sulfated glycosaminoglycans (GAGs) from fish muscle promote Fe uptake in Caco‐2 cells (1). This study continues that research to confirm that GAGs enhance Fe uptake by Caco‐2 cells.Fish haddock filets were cooked and lyophilized. GAGs were isolated and separated into low and high sulfur fractions (2). Enzymatic digestion with chondroitinase ABC (50 mU/mg, 1h, 37ºC) and reverse phase chromatography (RP‐HPLC) were used to characterize the GAGs. Nonheme Fe was added to the isolated fractions and to whole cooked fish and an in vitro digestion/Caco‐2 cell model was used to assess their effect on Fe uptake (1).RP‐HPLC analyses showed that retention times of the main components in the high sulfur fraction were consistent with chondroitin/dermatan sulfate‐related structures. This fraction increased Fe uptake up to 185% relative to controls exposed to nonheme Fe. Treatment of the isolated fraction with chondroitinase eliminated the enhancing effect. Unfractioned fish caused a 40% higher Fe uptake than caused by GAG isolates.These results indicate that specific GAGs contribute to the enhancing effect of fish on Fe uptake by Caco‐2 cells but that other factors are also involved.