From binding with substances such as phytate which render the iron unavailable for absorption. However, the complexes may be unstable during 
food processing and storage, and/or cause discoloration of the food products. Alginates bind divalent metals and could provide an alternative delivery system to maximise iron absorption in iron fortification programmes. Alginates are natural copolymers present in the cell walls of brown seaweed as sodium, potassium, calcium and magnesium salts of alginic acid. They are comprised of varying ratios of two different acids: D-mannuronic and L-guluronic acid, and due to the variable length of the polymer chains they Ginsenoside-F2 exhibit differing physiochemical properties. Alginates are widely used in variety of applications, including the food industry and drug delivery systems. They have been shown to bind divalent and trivalent cations and form a stable complex with iron over a range of different pH values, and therefore may provide a useful vehicle for soluble iron compounds used to Lithium citrate fortify foods. Previous in vitro studies demonstrated that alginate solutions had an enhancing effect on iron uptake in a Caco-2 cell model system, and alginate beads containing ferrous gluconate delivered more available iron than beads containing ferric ammonium citrate. In contrast, studies in ileostomy patients suggested a potential inhibitory effect of alginate on iron absorption; but as the study was underpowered no clear conclusions could be drawn. The aim of this work was to examine the effect of alginate on iron absorption in order to determine whether it could be a useful mechanism for fortifying selected foods with iron. Iron absorption from alginate beads saturated with ferrous gluconate and ferrous gluconate on its own were compared in a group of human volunteers. In addition, the effect of calcium on iron absorption was investigated. Calcium is required for alginate bead production but is a known inhibitor of iron absorption in single meal studies. The first hypothesis tested was that alginate in ironcontaining alginate beads conferred protection to the iron in the gastrointestinal tract and delivered more available iron for absorption into the mucosal cells of the duodenum than ferrous gluconate administered in a gelatine capsule. The second hypothesis tested was that calcium in the gut lumen would bind to alginate thereby reducing its inhibitory effect on iron absorption. Following on from the human study, in vitro experiments were performed to identify possible explanations for the in vivo findings. The human study results were not consistent with the earlier in vitro results which showed that alginate enhanced iron uptake in epithelial cells. Calcium exerted a very powerful negative effect on iron absorption, which was greater with ferrous gluconate solution than with the alginate beads due, presumably, to the fact that alginate had already reduced iron absorption by 33%. The possible reasons for the conflicting findings between the earlier cell studies and the human study might be the higher level of calcium in the beads plus cola jelly test meal, and also the lower iron content of the beads following washing to remove iron adhering to the outside of the beads. Calcium has a strongly inhibitory effect on iron absorption in vivo and in vitro. One proposed explanation for the enhancing effect of alginate in the previous Caco-2 cell studies was that it bound calcium in the culture medium, thereby reducing the inhibitory effect of calcium on iron uptake. In the human study, the calcium dose selected was 600 mg, because this quantity of calcium was required to achieve a calcium:iron molar ratio of 11:1 with the minimum dose of iron required to produce a measurable serum response.