The Potential Role of NaFeEDTA as an Iron Fortificant

Abstract

Ethylene diamine tetraacetic acid (EDTA) is a hexadentate chelator, which can combine with virtually every metal in the periodic table. CaNa2EDTA and Na2EDTA (ADI 2.5 mg EDTA/kg body weight/day) are widely used as sequestering agents in canned products, while NaFeEDTA is a promising iron fortificant. Binding of EDTA with iron is favored in the acid milieu of the stomach, irrespective of whether the EDTA is administered as CaNa2EDTA, Na2EDTA, or NaFeEDTA, but in the more alkaline medium of the duodenum the iron is exchanged, in part, with other metals. The iron released from EDTA is absorbed by the normal physiological mechanisms. When NaFeEDTA is present in a meal, the iron moiety exchanges with the intrinsic food iron and the EDTA partially protects the iron in this common non-heme iron pool from the effects of inhibitors of iron absorption, such as phytates and polyphenols. When iron is added as NaFeEDTA to an inhibitory meal, it is two to three times better absorbed than is iron added as ferrous sulfate. It also has a similar effect on the intrinsic food iron in the meal. Fortification with NaFeEDTA is most efficacious when administered with cereal- and legume-based diets but offers no advantages over other fortificants when added to meals of high bioavailability. Its potential as a fortificant has been confirmed in five extended fortification trials carried out in developing countries. There is no evidence that NaFeEDTA in the dose range proposed for food fortificants (5 to 10 mg iron daily) will have any direct toxic effects. Na2EDTA and CaNa2EDTA have proved safe over a number of years, while the Joint FAO/WHO Expert Committee on Food Additives concluded in 1999 that NaFeEDTA "could be considered safe when used in supervised fortification programs". Animal and human studies, including the results of two fortification trials, suggest that NaFeEDTA has little or no effect on overall zinc metabolism. Indeed, if anything, it increases zinc and possibly copper absorption. Data on potentially toxic metals, such as lead mercury, aluminum, and manganese, are limited but the evidence that is available is uniformly negative thus far. Further studies in this field are desirable. The long-term potential of NaFeEDTA fortification to cause iron overload is conjectural but the available evidence suggests that homeostatic controls would prevent excess iron accumulation in the normal population. NaFeEDTA, which is pale yellow in color, causes fewer organoleptic changes in a number of stored vehicles, including cereals, than do other soluble iron salts. Other potential vehicles include condiments, several of which have been successfully used in fortification trials. What is currently lacking is a consolidated body of published evidence on the stability of NaFeEDTA during processing, storage, and household cooking in widely consumed food vehicles, coupled with standardized testing of consumer acceptance of each fortified vehicle. While NaFeEDTA seems to be an appropriate fortificant for developing countries, its cost is about...

Redox-active labile iron in fortified flours from the Brazilian market

“…Iron thus effectively competes with H 3 O + for the ligand-binding sites at low pH, but with increasing alkalinity it tends to be mobilized from the complex due to the formation of stable polymeric (hydr)oxides (in the extreme case 21 , solid Fe(OH) 3 ; K sp =2.0x10 -39 ). This is the thermodynamic reason underlying previous observations that the absorption of iron fortificants is prevented in the stomach and favored in the more alkaline environment of the duodenum 22 . Among the natural chelating agents present in flours, phytic acid (PA; myoinositol-6-phosphate) is the most prominent, forming very stable .…”

Replacing electrolytic iron in a fortification-mix with NaFeEDTA increases both iron and zinc availabilities in traditional African maize porridges

“…The iron and zinc availabilities in fermented porridge fortified with the NaFeEDTA were significantly higher (p≤0.05) than those of other fermented porridges (3.35 vs ≈2.5% and 3.04 vs ≈2.6%, respectively) ( Table 4).Because phytate has a limited inhibitory effect on the availability of EDTA-mineral complexes (Bothwell and MacPhail, 2004), the increases were probably not due to phytate reduction during fermentation (Table 3). Also, while there were substantial differences in the phytate:iron (4-20) and phytate:zinc (6-24) molar ratios of the other fermented porridges (ratios both above and below the critical limits), there were no significant differences (p>0.05) between the iron and zinc availabilities (Table 4).…”

“…The stability constants for EDTA with ferric iron (25.1) and zinc (16.1) have been found to be high, resulting in stable bioavailable complexes. The complex stability is, however, pH dependant with the optimal pH for complexing at 1 and 4, for ferric iron and zinc, respectively (Bothwell and MacPhail, 2004). It is possible that the pH changes during digestion, from ≈6 (maize) to 2 (stomach digestion) and then ≈7 (intestinal digestion), that some of the NaFeEDTA dissociates and forms stable complexes with zinc.…”

“…EDTA is a hexa-coordinating complexing agent, binding to almost any metal (at different stability constants) with four carboxylate, and two tertiary amine groups (Bothwell and MacPhail, 2004). The stability constants for EDTA with ferric iron (25.1) and zinc (16.1) have been found to be high, resulting in stable bioavailable complexes.…”

“…Ferric sodium ethylenediaminetetraacetate (NaFeEDTA)is a popular fortificant because the iron is highly bioavailable, even in high phytate foods, so less has to be added. Also, addition of NaFeEDTA could increase zinc availability, but results from the limited research is contradictory with outcomes depending on the food vehicle (Bothwell and MacPhail, 2004).…”