Isotope dilution mass spectrometry of microelectronically relevant heavy metal traces in high-purity cobalt

Sodium iron EDTA [NaFe(III)EDTA] as a food fortificant: erythrocyte incorporation of iron and apparent absorption of zinc, copper, calcium, and magnesium from a complementary food based on wheat and soy in healthy infants

BACKGROUND

Phytic acid is a strong inhibitor of iron absorption from fortified foods. In adults, this inhibitory effect can be overcome by adding ascorbic acid with the iron fortificant or by using a "protected" iron compound such as NaFeEDTA. In addition, the use of NaFeEDTA as an iron fortificant has been reported to increase zinc absorption in adult women. No information is available on iron bioavailability from NaFeEDTA or the influence of NaFeEDTA on minerals and trace elements in infants.

OBJECTIVE

We aimed to compare iron bioavailability from a complementary food based on wheat and soy fortified with either NaFeEDTA or ferrous sulfate plus ascorbic acid. The apparent absorption of zinc, copper, calcium, and magnesium was evaluated in parallel.

DESIGN

Stable-isotope techniques were used in a crossover design to evaluate erythrocyte incorporation of iron 14 d after administration of labeled test meals and the apparent absorption of zinc, copper, calcium, and magnesium on the basis of fecal monitoring in 11 infants.

RESULTS

Geometric mean erythrocyte incorporation of iron was 3.7% (NaFeEDTA) and 4.9% (ferrous sulfate plus ascorbic acid) (P = 0.08). No significant differences in the apparent absorption of zinc, copper, calcium, or magnesium were observed between test meals (n = 10).

CONCLUSIONS

Iron bioavailability from a high-phytate, cereal-based complementary food fortified with either NaFeEDTA or ferrous sulfate plus ascorbic acid was not significantly different. NaFeEDTA did not influence the apparent absorption of zinc, copper, calcium, or magnesium. NaFeEDTA does not provide any nutritional benefit compared with the combination of a highly bioavailable iron compound and ascorbic acid.

The effect of retinyl palmitate added to iron-fortified maize porridge on erythrocyte incorporation of iron in African children with vitamin A deficiency

Retinyl palmitate added to Fe-fortified maize bread has been reported to enhance Fe absorption in adult Venezuelan subjects but not in Western Europeans. It is not known to what extent these results were influenced by differences in vitamin A status of the study subjects. The objective of the present study was to evaluate the influence of retinyl palmitate added to Fe-fortified maize porridge on erythrocyte incorporation of Fe in children with vitamin A deficiency, before and after vitamin A supplementation. Erythrocyte incorporation of Fe-stable isotopes was measured 14 d after intake of maize porridge (2.0 mg Fe added as ferrous sulfate) with and without added retinyl palmitate (3.5 micromol; 3300 IU). The study was repeated 3 weeks after vitamin A supplementation (intake of a single dose of 210 micromol retinyl palmitate; 'vitamin A capsule'). Vitamin A status was evaluated by the modified relative dose-response (MRDR) technique. Retinyl palmitate added to the test meal reduced the geometric mean erythrocyte incorporation of Fe at baseline from 4.0 to 2.6 % (P=0.008, n 13; paired t test). At 3 weeks after vitamin A supplementation, geometric mean erythrocyte incorporation was 1.9 and 2.3 % respectively from the test meal with and without added retinyl palmitate (P=0.283). Mean dehydroretinol:retinol molar ratios were 0.156 and 0.125 before and after intake of the single dose of 210 micromol retinyl palmitate; 'vitamin A capsule' (P=0.15). In conclusion, retinyl palmitate added to the labelled test meals significantly decreased erythrocyte incorporation of Fe in children with vitamin A deficiency at baseline but had no statistically significant effect 3 weeks after vitamin A supplementation. The difference in response to retinyl palmitate added to Fe-fortified maize porridge on erythrocyte incorporation of Fe before and after intake of the vitamin A capsule indicates, indirectly, changes in vitamin A status not measurable by the MRDR technique. The lack of conclusive data on the effect of retinyl palmitate on Fe absorption indicates the complexity of the interactions between vitamin A status, dietary vitamin A and Fe metabolism.

Iron bioavailability from iron-fortified Guatemalan meals based on corn tortillas and black bean paste

BACKGROUND

Corn masa flour is widely consumed in Central America and is therefore a potentially useful vehicle for iron fortification.

OBJECTIVE

The goal was to evaluate the bioavailability of iron from meals based on corn tortillas and black bean paste that were fortified with ferrous fumarate, ferrous sulfate, or NaFeEDTA and to investigate the potential of Na(2)EDTA to increase the bioavailability of iron from ferrous fumarate.

DESIGN

With use of a crossover study design, iron bioavailability was measured in Guatemalan girls aged 12-13 y by a stable-isotope technique based on erythrocyte incorporation 14 d after intake.

RESULTS

Geometric mean iron bioavailability from test meals fortified with ferrous fumarate was 5.5-6.2% and was not improved significantly by the addition of Na(2)EDTA at molar ratios of 1:1 relative to fortification iron or to the total iron content of the fortified corn masa flour. Geometric mean iron bioavailability from test meals fortified with ferrous sulfate was 5.5% and was significantly higher in test meals fortified with NaFeEDTA (9.0%; P = 0.009, paired t test).

CONCLUSIONS

The bioavailability of iron from ferrous fumarate was not improved by the addition of Na(2)EDTA, contrary to what was previously shown for ferrous sulfate in other cereal-based meals. However, the bioavailability of iron from the test meal was significantly enhanced when NaFeEDTA replaced ferrous sulfate. These results support the use of NaFeEDTA in the fortification of inhibitory staple foods such as corn masa flour.

Improving iron absorption from a Peruvian school breakfast meal by adding ascorbic acid or Na2EDTA

BACKGROUND

Iron-fortified school breakfasts have been introduced in Peru to combat childhood iron deficiency.

OBJECTIVE

We evaluated whether iron absorption from a school breakfast meal was improved by increasing the ascorbic acid content or by adding an alternative enhancer of iron absorption, Na2EDTA.

DESIGN

In a crossover design, iron absorption from test meals was evaluated by erythrocyte incorporation of 58Fe and 57Fe. The test meals (wheat bread and a drink containing cereal, milk, and soy) contained 14 mg added Fe (as ferrous sulfate) including 2.0-2.6 mg 58Fe or 4.0-7.0 mg 57Fe.

RESULTS

Geometric mean iron absorption increased significantly from 5.1% to 8.2% after the molar ratio of ascorbic acid to fortification iron was increased from 0.6:1 to 1.6:1 (P < 0.01; n = 9). Geometric mean iron absorption increased significantly from 2.9% to 3.8%, from 2.2% to 3.5%, and from 2.4% to 3.7% after addition of Na2EDTA at molar ratios relative to fortification iron of 0.3:1, 0.7:1, and 1:1, respectively, compared with test meals containing no added enhancers (P < 0.01; n = 10 for all). Iron absorption after addition of ascorbic acid (molar ratio 0.6:1) was not significantly different from that after addition of Na2EDTA (molar ratio 0.7:1).

CONCLUSIONS

Ascorbic acid and Na2EDTA did not differ significantly in their enhancing effects on iron absorption at molar ratios of 0.6:1 to 0.7:1 relative to fortification iron. Additional ascorbic acid (molar ratio 1.6:1) increased iron absorption significantly. Increasing the molar ratio of Na2EDTA to fortification iron from 0.3:1 to 1:1 had no effect on iron absorption.

Iron absorption from experimental infant formulas based on pea (Pisum sativum)-protein isolate: the effect of phytic acid and ascorbic acid

Infant formula based on pea (Pisum sativum)-protein isolate has been suggested as an alternative to soybean formula in countries where soybean is not a native crop, or when soybean protein cannot be used due to allergic reactions or intolerances. In the present study, Fe absorption from experimental infant formulas based on pea-protein isolate was measured in healthy non-anaemic young women. The influence of phytic acid and ascorbic acid on Fe absorption was evaluated, using a stable-isotope technique based on incorporation of Fe stable-isotope labels into erythrocytes 14 d after administration. Geometric mean Fe absorption increased from 20.7 (+1 SD 41.6, -1 SD 10.3) % to 33.1 (+1 SD 58.6, -1 SD 18.7) %; (P < 0.0001; n 10) after enzymic degradation of virtually all phytic acid. Doubling the molar ratio Fe:ascorbic acid from 1:2.1 to 1:4.2 in the infant formula with native phytic acid content also increased Fe absorption significantly (P < 0.0001; n 10); geometric mean Fe absorption increased from 14.8 (+1 SD 32.1, -1 SD 6.8) % to 22.1 (+1 SD 47.2, -1 SD 10.4) %. These results confirm the inhibitory and enhancing effects of phytic acid and ascorbic acid respectively on Fe absorption, but also indicate relatively high fractional Fe absorption from the pea-protein-based formulas. After adjusting for differences in Fe status, our data indicate that Fe absorption from dephytinised pea protein might be less inhibitory than dephytinised soybean protein as measured in a previous study (Hurrell et al. 1998).

The influence of meat on nonheme iron absorption in infants

During weaning the infant has a high iron requirement, and highly available dietary iron is needed to ensure optimal iron status. Muscle tissue has been identified as an enhancer of nonheme iron absorption in adults, although the influence of meat on nonheme iron absorption in infants has not been previously reported. The effect of the addition of 25 g of meat (lean beef) on nonheme iron absorption from a home-prepared vegetable purée meal (80 g of vegetables) was investigated in infants in the present study. The meals did not differ in their contents of other known enhancers or inhibitors of nonheme iron absorption. Incorporation of stable isotopes of iron (57Fe and 58Fe) into red blood cells 14 d after intake was used to measure iron absorption, using a cross-over design in eight healthy infants 43-49 wk of age. Nonheme iron absorption was significantly increased (p = 0.002) from the vegetable purée with added meat (geometric mean 15.0%) compared with the puréed vegetables (geometric mean 9.9%). These results thus suggest that meat is also an enhancer of nonheme iron absorption in infants and that nonheme iron absorption from weaning foods can be increased by the addition of meat.