Effect of phytase on zinc absorption from a millet-based porridge fed to young Burkinabe children.

BACKGROUND/OBJECTIVES: Fortifying cereal staples with zinc is a strategy for increasing zinc intake in young children in developing countries. However, phytic acid (PA) naturally present in cereals strongly decreases zinc absorption. A stable-isotope zinc absorption study was conducted in young children to investigate the ability of the PA-degrading enzyme phytase to improve zinc absorption, when added to a cereal porridge immediately before consumption. SUBJECTS/METHODS: Fractional absorption of zinc (FAZ) was estimated in 35 young healthy Burkinabe children using the double-isotopic tracer ratio method with 67Zn as oral tracer and 70Zn as intravenous tracer, in a crossover design. The test meals were: (a) a millet-based porridge containing 1.4 mg total zinc (native plus 1 mg added as ZnSO4) with a PA:Zn molar ratio of 7.7; (b) the same porridge with the enzyme phytase (20.5 phytase units (FTU)) added immediately before consumption. The exchangeable zinc pool (EZP) was determined as a potential measure of long-term zinc intake in 20 of the 35 children and compared with FAZ. RESULTS: Mean FAZ increased from 9.5±3.4 to 16.0±5.1% (P<0.0001), when phytase was added to the meal. The mean EZP was 3.6±0.5 mg/kg. There was no correlation between the EZP and FAZ values for either of the two test meals. CONCLUSIONS: Adding phytase immediately prior to consumption of a zinc-fortified cereal-based complementary food can improve zinc absorption in young children.

A comparison of the bioavailability of ferrous fumarate and ferrous sulfate in non-anemic Mexican women and children consuming a sweetened maize and milk drink.

BACKGROUND/OBJECTIVES: Ferrous fumarate is recommended for the fortification of complementary foods based on similar iron absorption to ferrous sulfate in adults. Two recent studies in young children have reported that it is only 30% as well absorbed as ferrous sulfate. The objective of this study was to compare iron absorption from ferrous fumarate and ferrous sulfate in infants, young children and mothers. SUBJECTS/METHODS: Non-anemic Mexican infants (6-24 months), young children (2-5 years) and adult women were randomly assigned to receive either 4 mg Fe (women) or 2.5 mg Fe (infants and young children) as either [(57)Fe]-ferrous fumarate or [(58)Fe]-ferrous sulfate added to a sweetened drink based on degermed maize flour and milk powder. Iron absorption was calculated based on incorporation of isotopes into erythrocytes after 14 days. RESULTS: Within each population group, no significant differences (P > 0.05) in iron absorption were found between ferrous fumarate and ferrous sulfate. Mean iron absorption from ferrous fumarate vs ferrous sulfate was 17.5 vs 20.5% in women (relative bioavailability (RBV) =86), 7.0 vs 7.2% in infants (RBV = 97) and 6.3 vs 5.9% in young children (RBV = 106). CONCLUSIONS: Ferrous fumarate is as well absorbed as ferrous sulfate in non-anemic, iron sufficient infants and young children, and can be recommended as a useful fortification compound for complementary foods designed to prevent iron deficiency. Further studies are needed to clarify its usefulness in foods designed to treat iron deficiency.

Production and shelf stability of multiple-fortified quick-cooking rice as a complementary food.

Rice-based complementary foods normally contain inadequate amounts of several micronutrients, such as iron, calcium, and zinc. This study aimed at improving the quality of commercially produced rice-based complementary foods. The analysis centered on identifying a rice-based complementary food that is safe, stable, sensory acceptable, and economical in terms of fortificants (iron, calcium, zinc, thiamine, folate) and effectively packaged for industrial production and distribution. Product colors were mostly in green-yellow tone and slightly changed to more yellow during storage. Sensory acceptability was affected by changes in odor and rancidity but not in color. Rancidity scores were low in aluminum foil laminated plastic bags (ALU). Lipid oxidation significantly increased during storage, but at a slower rate when sodium citrate and ALU were used. Color differences of raw products were detected but not in the cooked ones. Mineral and vitamin losses during processing were 2% to 11% and 20% to 30%, respectively, but no losses were found during storage. FeSO(4)+ NaFeEDTA added with sodium citrate resulted in the most acceptable product for all packagings. The multiple-fortified quick-cooking rice (MFQCR) developed from this study could be a potentially useful tool for combating micronutrient deficiencies among infants and young children in the countries where rice is the staple food.

Adiposity in women and children from transition countries predicts decreased iron absorption, iron deficiency and a reduced response to iron fortification.

BACKGROUND: Overweight is increasing in transition countries, while iron deficiency remains common. In industrialized countries, greater adiposity increases risk of iron deficiency. Higher hepcidin levels in obesity may reduce dietary iron absorption. Therefore, we investigated the association between body mass index (BMI) and iron absorption, iron status and the response to iron fortification in populations from three transition countries (Thailand, Morocco and India). METHODS: In Thai women (n=92), we examined the relationship between BMI and iron absorption from a reference meal containing approximately 4 mg of isotopically labeled fortification iron. We analyzed data from baseline (n=1688) and intervention (n=727) studies in children in Morocco and India to look for associations between BMI Z-scores and baseline hemoglobin, serum ferritin and transferrin receptor, whole blood zinc protoporphyrin and body iron stores, and changes in these measures after provision of iron. RESULTS: In the Thai women, 20% were iron deficient and 22% were overweight. Independent of iron status, a higher BMI Z-score was associated with decreased iron absorption (P=0.030). In the Indian and Moroccan children, 42% were iron deficient and 6.3% were overweight. A higher BMI Z-score predicted poorer iron status at baseline (P<0.001) and less improvement in iron status during the interventions (P<0.001). CONCLUSIONS: Adiposity in young women predicts lower iron absorption, and pediatric adiposity predicts iron deficiency and a reduced response to iron fortification. These data suggest the current surge in overweight in transition countries may impair efforts to control iron deficiency in these target groups. Interactions of the 'double burden' of malnutrition during the nutrition transition may have adverse consequences.

Low anemia prevalence in school-aged children in Bangalore, South India: possible effect of school health initiatives.

OBJECTIVE: Anemia is a serious public health problem in Indian school children. Since 2003, simple health intervention programs such as antihelminthic treatment and vitamin A supplementation have been implemented in primary schools in the Bangalore region, Karnataka, India. This study examines the prevalence of anemia in school children who are beneficiaries of this program. DESIGN: Cross-sectional survey. SETTING: Bangalore district, South India. SUBJECTS: A total of 2,030 boys and girls, aged 5-15 years, attending schools in the Bangalore district. INTERVENTIONS: School-based, twice yearly intervention: deworming (albendazole 400 mg, single oral dose) and vitamin A supplementation (200,000 IU, single oral dose). MAIN OUTCOME MEASURES: Anemia prevalence based on measure of blood hemoglobin (Hb). RESULTS: Mean age and blood Hb concentration of all children were 9.5+/-2.6 years and 12.6+/-1.1 g/dl (range 5.6-16.7), respectively. The overall anemia prevalence in this group was 13.6%. Anemia prevalence was lower in boys than girls (12.0%; n=1037 vs 15.3%; n=993 respectively, P<0.05). There was no significant difference in anemia prevalence between children in urban and rural locations (14.6 and 12.3%, respectively). CONCLUSIONS: The current low anemia prevalence in Bangalore could be due to the impact of school-based intervention programs that have been in place since 2003. The beneficial interactions of deworming and vitamin A supplementation could have widespread implications for current preventive public health initiatives. There is now need for the development of clear policy guidelines based on these simple and integrated interventions.

Iron absorption by human subjects from different iron fortification compounds added to Thai fish sauce.

OBJECTIVES: (a) To measure iron absorption by human subjects from citric acid stabilized fish sauce fortified with ferrous sulfate, ferric ammonium citrate or ferrous lactate and (b) to identify the effect of added citric acid (3 g/l) on iron absorption from ferrous sulfate fortified fish sauce. DESIGN: Iron absorption from the intrinsically labeled compounds was determined via erythrocyte incorporation of isotopic labels ((57)Fe and (58)Fe) using a randomized crossover design. In three separate absorption studies, 10 adult women each consumed a basic test meal of rice and vegetable soup seasoned with isotopically labeled, iron fortified fish sauce. RESULTS: Iron absorption was significantly lower from ferrous lactate and from ferric ammonium citrate fortified fish sauce than from ferrous sulfate fortified fish sauce. Fractional iron absorption (geometric mean; -1s.d., +1s.d.) was 8.7(3.6; 21.4)% for ferrous lactate compared to 13.0(5.4; 31.4)% from ferrous sulfate, P = 0.003 (study 1) and 6.0(2.5; 14.3)% from ferric ammonium citrate relative to 11.7(4.4; 30.7)% from ferrous sulfate, P < 0.001, in study 2. Citric acid added at a molar ratio of approximately 2.5 to iron had no effect on iron absorption from ferrous sulfate (study 3). Iron absorption in the presence of citric acid was 14.1(6.4; 30.8)% compared to 12.0(5.8; 24.7)% in its absence (P = 0.26). CONCLUSIONS: Iron absorption was 50-100% higher from ferrous sulphate fortified fish sauce than from fish sauce fortified with ferric ammonium citrate or ferrous lactate. In the presence of citric acid as a chelator, ferrous sulfate would appear to be a useful fortificant for fish sauce. SPONSORSHIP: International Atomic Energy Agency (IAEA), Vienna, Austria.

A national survey of iron and folate status in pregnant women in Switzerland.

Women often do not meet the increased iron and folate needs of pregnancy. Maternal iron-deficiency anemia is associated with poor maternal and infant outcomes, including preterm delivery and low birth weight. Poor folate status increases risk for maternal anemia, spontaneous abortion, and congenital defects. Because of this, supplemental iron and folate are often recommended during pregnancy. There are few data on iron and folate status in pregnant women in Switzerland. We measured iron and folate status in a national sample of Swiss pregnant women, estimated the prevalence of anemia, and determined if supplement use is associated with iron and/or folate status in this group. A 3-stage probability to size cluster sampling method was used to obtain a representative national sample of pregnant women (n = 381) in the second and third trimester. We measured hemoglobin, hematocrit, mean corpuscular volume, and serum folate and ferritin concentrations. Serum transferrin receptor concentration was determined in anemic subjects. The use of iron and folate supplements was evaluated by questionnaire. Mean hemoglobin (+/- SD) in the sample was 123 g/L (+/- 1.0). The prevalence of anemia was 6%. Of the 21 anemic women, 11 were iron-deficient, giving an iron-deficiency anemia prevalence of 3%. Nineteen percent of women had low serum ferritin concentrations (< 12 micrograms/L) and 4% had low serum folate concentration (< 2.5 micrograms/L). Supplements containing iron were taken by 65% of women, and 63% were taking folate-containing supplements. Women in the second and third trimester taking folate-containing supplements had significantly higher serum folate concentrations compared to those not taking a folate supplement (p < 0.001). In the third trimester, women taking iron-containing supplements had significantly higher serum ferritin concentrations compared to those not taking an iron-containing supplement (p < 0.01). Our findings indicate that iron and folate status appears to be adequate in the majority of pregnant women in Switzerland, and that use of iron and folate supplements may have a positive impact on status.

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).

Iron bioavailability in infants from an infant cereal fortified with ferric pyrophosphate or ferrous fumarate.

BACKGROUND: Infant cereals are commonly fortified with insoluble iron compounds with low relative bioavailability, such as ferric pyrophosphate, because of organoleptic changes that occur after addition of water-soluble iron sources. OBJECTIVE: Our objective was to compare iron bioavailability from ferric pyrophosphate with an alternative iron source that is soluble in dilute acid, ferrous fumarate, and to evaluate the influence of ascorbic acid on iron bioavailability from ferrous fumarate in infants. DESIGN: Iron bioavailability was measured as the incorporation of stable iron isotopes into erythrocytes 14 d after administration of labeled test meals (25 g dry wheat and soy infant cereal, 100 g water, and 2.5 mg Fe as [57Fe]ferric pyrophosphate or [57Fe]ferrous fumarate). Ascorbic acid was added to all test meals (25 mg in study 1 or 25 or 50 mg in study 2). Infants were fed each test meal on 4 consecutive days under standardized conditions. The 2 different test meals within each study were administered 2 wk apart in a crossover design. RESULTS: Geometric mean iron bioavailability was significantly higher from [57Fe]ferrous fumarate than from [57Fe]ferric pyrophosphate [4.1% (range: 1.7-14.7%) compared with 1.3% (range: 0. 7-2.7%); n = 8, P = 0.008]. In this study, doubling the ascorbic acid content did not further enhance iron bioavailability; the geometric means (range) were 3.4% (1.9-6.6%) and 4.2% (1.2-18.7%) for the test meals with 25 and 50 mg ascorbic acid added, respectively (n = 9). CONCLUSION: Iron bioavailability from iron-fortified infant cereals can be improved by using an iron compound with high relative bioavailability and by ensuring adequate ascorbic acid content of the product.

Effect of oral iodized oil on thyroid size and thyroid hormone metabolism in children with concurrent selenium and iodine deficiency.

OBJECTIVES: To determine the efficacy of oral iodized oil in goitrous children who are both selenium (Se) and iodine deficient; to investigate if Se status modifies the response of iodine deficient, goitrous children to oral supplementation with iodized oil. DESIGN: A longitudinal intervention trial. SETTING: Two rural villages in the western Côte d'Ivoire. SUBJECTS: 51 goitrous non-anemic schoolchildren with both iodine and Se deficiency. INTERVENTION: Each child received an oral dose of 0.4 ml iodized poppyseed oil containing 200 mg of iodine. They were followed for 1 y with measurements of urinary iodine (UI), thyrotropin (TSH), thyroxine (T4), and thyroid volume by ultrasound. RESULTS: At baseline all children were goitrous and Se deficient; median UI was 29 microg/l and mean serum Se (s.d.) was 14.8 (10.7) microg/l. After receiving iodized oil, thyroid volume decreased significantly vs baseline at 10, 15, 30 and 50 weeks (P<0.001). At 50 weeks mean percentage change in thyroid volume from baseline was-46.6% and only five children remained goitrous. Median TSH values at 5, 10, 15, 30 and 50 weeks were reduced significantly (P<0.001) compared to baseline. Among individual children the severity of Se deficiency predicted the degree of response to iodized oil. Baseline serum Se and percentage change in thyroid volume from baseline at 50 weeks were strongly correlated (r2=0.554). Baseline Se and percentage decrease in TSH from baseline at 30 weeks were also well-correlated (r2=0.467). CONCLUSION: Although more severe Se deficiency partially blunts the thyroid response to iodine supplementation, oral iodized oil is an effective method for iodine repletion in goitrous children who are Se deficient. SPONSORSHIP: The Swiss Federal Institute of Technology, Zürich, the Foundation for Micronutrients in Medicine, Rapperswil, Switzerland, and the Thrasher Research Fund, Salt Lake City, USA.

Erythrocyte incorporation of iron by infants: iron bioavailability from a low-iron infant formula and an evaluation of the usefulness of correcting erythrocyte incorporation values, using a reference dose or plasma ferritin concentrations.

Bioavailability of iron (Fe) from a low-Fe infant formula was determined by erythrocyte incorporation of 58Fe 14 d after administration in ten healthy, non-Fe-deficient infants. Two feeding protocols were compared, with each infant acting as his/her own control. At 140 and 154 d of age, infants were fed 1000 g of 58Fe-labelled formula (1.44 mg total Fe/1000 g) as six feeds over 24 h (Protocol A) or as two feeds/day on three consecutive days (Protocol B). A water solution with 57Fe and ascorbic acid was given separately as a reference dose in both study protocols. Erythrocyte incorporation of 58Fe and 57Fe was determined by thermal ionisation mass spectrometry. Geometric mean 58Fe incorporation was 7.6% (range 3.3-13.5%) with Protocol A as compared to 10.6% (range 6.7-18.6%) with Protocol B (P = 0.05); paired t test. Inter-individual variability of 58Fe was not reduced by correcting for the incorporation of 57Fe from the reference dose, or by correcting for plasma ferritin concentration. Fractional erythrocyte incorporation of Fe from low-Fe infant formula was in the same range as our earlier published data on erythrocyte incorporation of Fe from human milk extrinsically labelled with 58Fe (Davidsson et al. 1994a). The methodological evaluations included in this study clearly indicate the importance of using standardised study protocols when evaluating Fe bioavailability in infants. Corrections of erythrocyte incorporation data based on plasma ferritin or erythrocyte incorporation of Fe from a reference dose were not found to be useful.

An evaluation of EDTA compounds for iron fortification of cereal-based foods.

Fe absorption was measured in adult human subjects consuming different cereal foods fortified with radiolabelled FeSO4, ferrous fumarate or NaFeEDTA, or with radiolabelled FeSO4 or ferric pyrophosphate in combination with different concentrations of Na2EDTA. Mean Fe absorption from wheat, wheat-soyabean and quinoa (Chenopodium quinoa) infant cereals fortified with FeSO4 or ferrous fumarate ranged from 0.6 to 2.2%. For each infant cereal, mean Fe absorption from ferrous fumarate was similar to that from FeSO4 (absorption ratio 0.91-1.28). Mean Fe absorption from FeSO4-fortified bread rolls was 1.0% when made from high-extraction wheat flour and 5.7% when made from low-extraction wheat flour. Fe absorption from infant cereals and bread rolls fortified with NaFeEDTA was 1.9-3.9 times greater than when the same product was fortified with FeSO4. Both high phytate content and consumption of tea decreased Fe absorption from the NaFeEDTA-fortified rolls. When Na2EDTA up to a 1:1 molar ratio (EDTA:Fe) was added to FeSO4-fortified wheat cereal and wheat-soyabean cereal mean Fe absorption from the wheat cereal increased from 1.0% to a maximum of 5.7% at a molar ratio of 0.67:1, and from the wheat-soyabean cereal from 0.7% to a maximum of 2.9% at a molar ratio of 1:1. Adding Na2EDTA to ferric pyrophosphate-fortified wheat cereal did not significantly increase absorption (P > 0.05). We conclude that Fe absorption is higher from cereal foods fortified with NaFeEDTA than when fortified with FeSO4 or ferrous fumarate, and that Na2EDTA can be added to cereal foods to enhance absorption of soluble Fe-fortification compounds such as FeSO4.

Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages.

The effects of different polyphenol-containing beverages on Fe absorption from a bread meal were estimated in adult human subjects from the erythrocyte incorporation of radio-Fe. The test beverages contained different polyphenol structures and were rich in either phenolic acids (chlorogenic acid in coffee), monomeric flavonoids (herb teas, camomile (Matricaria recutita L.), vervain (Verbena officinalis L.), lime flower (Tilia cordata Mill.), pennyroyal (Mentha pulegium L.) and peppermint (Mentha piperita L.), or complex polyphenol polymerization products (black tea and cocoa). All beverages were potent inhibitors of Fe absorption and reduced absorption in a dose-dependent fashion depending on the content of total polyphenols. Compared with a water control meal, beverages containing 20-50 mg total polyphenols/serving reduced Fe absorption from the bread meal by 50-70%, whereas beverages containing 100-400 mg total polyphenols/serving reduced Fe absorption by 60-90%. Inhibition by black tea was 79-94%, peppermint tea 84%, pennyroyal 73%, cocoa 71%, vervain 59%, lime flower 52% and camomile 47%. At an identical concentration of total polyphenols, black tea was more inhibitory than cocoa, and more inhibitory than herb teas camomile, vervain, lime flower and pennyroyal, but was of equal inhibition to peppermint tea. Adding milk to coffee and tea had little or no influence on their inhibitory nature. Our findings demonstrate that herb teas, as well as black tea, coffee and coca can be potent inhibitors of Fe absorption. This property should be considered when giving dietary advice in relation to Fe nutrition.

Sodium iron EDTA [NaFe(III)EDTA] as a food fortificant does not influence absorption and urinary excretion of manganese in healthy adults.

NaFe(III)EDTA is a promising iron (Fe) compound for food fortification programs because of its high Fe bioavailability from meals containing dietary inhibitors of Fe absorption such as phytic acid. However, this Fe compound is not currently used in any large-scale fortification program because of concern over its possible negative influence on the metabolism of other essential minerals or its possible influence on the absorption of potentially toxic elements, such as manganese (Mn). In this study, Mn absorption and urinary excretion were studied in adults after intake of an Fe-fortified weaning cereal labeled with 54Mn. In a crossover design, the fortification of the weaning cereal with Fe as NaFeEDTA was compared with ferrous sulfate. Manganese absorption was measured by extrapolation from whole-body retention data 10-30 d after intake, and urinary excretion of 54Mn was measured over 7 d. No significant differences in 54Mn absorption or urinary excretion were found; 1.1 +/- 0.15 and 0.91 +/- 0.35% of the ingested dose was absorbed from the cereal fortified with NaFe(III)EDTA and FeSO4, respectively. Urinary excretion of 54Mn was very low; the total radioactivity in urine represented 1.1 +/- 0.55% of the absorbed dose with NaFe(III)EDTA and 0.72 +/- 0.53% of the absorbed dose with FeSO4. Until now, Fe-fortification programs have met with only limited success. The introduction of NaFeEDTA as a food fortificant could be a useful tool to provide bioavailable Fe to vulnerable groups in the population and thus aid in combating Fe deficiency.

Influence of ascorbic acid on iron absorption from an iron-fortified, chocolate-flavored milk drink in Jamaican children.

The influence of ascorbic acid on iron absorption from an iron-fortified, chocolate-flavored milk drink (6.3 mg total Fe per serving) was evaluated with a stable-isotope technique in 20 6-7-y-old Jamaican children. Each child received two test meals labeled with 5.6 mg 57Fe and 3.0 mg 58Fe as ferrous sulfate on 2 consecutive days. Three different doses of ascorbic acid (0, 25, and 50 mg per 25-g serving) were evaluated in two separate studies by using a crossover design. Iron isotope ratios were measured by negative thermal ionization mass spectrometry. In the first study, iron absorption was significantly greater (P < 0.0001) after the addition of 25 mg ascorbic acid: geometric mean iron absorption was 1.6% (range: 0.9-4.2%) and 5.1% (2.2-17.3%) for the test meals containing 0 and 25 mg ascorbic acid, respectively. In the second study, a significant difference (P < 0.05) in iron absorption was observed when the ascorbic acid content was increased from 25 to 50 mg: geometric mean iron absorption was 5.4% (range: 2.7-10.8%) compared with 7.7% (range: 4.7-16.5%), respectively. The chocolate drink contained relatively high amounts of polyphenolic compounds, phytic acid, and calcium, all well-known inhibitors of iron absorption. The low iron absorption without added ascorbic acid shows that chocolate milk is a poor vehicle for iron fortification unless sufficient amounts of an iron-absorption enhancer are added. Regular consumption of iron-fortified chocolate milk drinks containing added ascorbic acid could have a positive effect on iron nutrition in population groups vulnerable to iron deficiency.

Influence of ascorbic acid on iron absorption from a iron-fortified, chocolate-flavored milk drink in Jamaican children

The influence of ascorbic acid on iron absorption from an iron-fortified, chocolate-flavored milk drink (6.3 mg total Fe per serving) was evaluated with a stable-isotope technique in 20 6-7-y-old Jamaican children. Each child received two test meals labeled with 5.6 mg 57Fe and 3.0 mg 58Fe as ferrous sulfate on 2 consecutive days. Three different doses of ascorbic acid (0, 25, and 50 mg per 25-g serving) were evaluated in two separate studies by using a crossover design. Iron isotope ratios were measured by negative thermal ionization mass spectrometry. In the first study, iron absorption was significantly greater (P < 0.001) after the addition of 25 mg ascorbic acid; geometric mean iron absorption was 1.6 percent (range; 0.9-4.2 percent) and 5.1 percent (2.2-17.3 percent) for the test meals containing 0 and 25 mg ascorbic acid, respectively. In the second study, a significant difference (P < 0.05) in iron absorption was observed when the ascorbic acid content was increased from 25 to 50 mg: geometric mean iron absorption was 5.4 percent (range: 2.7-10.8 percent) compared with 7.7 percent (range: 4.7-16.5 percent), respectively. The chocolate drink contained low iron absorption without added ascorbic acid shows that chocolate milk is a poor vehicle for iron fortification unless sufficient amounts of an iron-absorption enhancer are added. Regular consumption of iron-fortified chocolate milk drinks containing added ascorbic acid could have a possible effect on iron nutrition in population groups vulnerable to iron deficiency(AU)

Preventing iron deficiency through food fortification.

One way to prevent iron deficiency anemia in developing countries is through the fortification of food products with iron. In addition to avoiding undesirable color and flavor changes, the main challenge is to protect the fortification iron from potential inhibitors of iron absorption present in commonly fortified foods.

The influence of different cereal grains on iron absorption from infant cereal foods.

Iron absorption from various cereal grains was evaluated in the present study to identify possible preferences for the preparation of infant weaning foods. In six separate studies, four radioiron absorption tests were performed in each of 57 volunteer subjects by using a sequential double-isotopic method. Serum ferritin concentration was used to adjust for the effect of differences in the iron status of subjects participating in separate studies. Identical commercial processing and test meal composition were used to evaluate iron absorption from 50 g cooked cereal prepared from rice, wheat, maize, oats, millet, and sweet or bitter quinoa. In an initial evaluation of cereals fortified with 2.5 mg Fe as FeSO4, geometric mean absorption values were uniformly < 1% for all cereals and were not significantly different. In subsequent studies, percentage iron absorption was enhanced by either eliminating the fortifying iron or adding 50 mg ascorbic acid to the test meal. The effect was similar for most of the cereals tested with a composite mean increase in absorption of 37% when fortifying iron was removed and 270% when ascorbic acid was added. There was a strong inverse correlation between iron absorption and the phytate content of different cereals. Except for a modestly lower absorption of iron from quinoa and a remarkably higher absorption from one lot of maize, we conclude that the type of cereal grain has little influence on iron bioavailability of infant cereals. On the other hand, modification in the milling and processing methods for cereal grains that reduce their content of phytic acid is likely to improve iron availability significantly.

Zinc absorption in adult humans: the effect of iron fortification.

The effect of Fe fortification on the absorption of Zn was studied by radioisotopic labelling of single meals, followed by measurements of whole-body retention of 65Zn at 14 d after intake. Healthy adult volunteers participated in the study. Weaning cereal, wheat bread and infant formula, foods that are all frequently Fe-fortified, were evaluated in the study. The amounts of Fe added as FeSO4 were similar to the levels in commercial products in Europe and the USA, and were 200 or 500 mg Fe/kg (weaning cereal), 65 mg Fe/kg (white wheat flour) and 12 mg Fe/l (infant formula). For comparison, Zn absorption was measured in the same subjects, from identical test meals containing no added Fe. No statistically significant differences were found when Zn absorption from the Fe-fortified test meals was compared with that from non-Fe-fortified test meals. Fractional Zn-absorption values from Fe-fortified v. non-fortified meals were 31.1 (SD 11.9) v. 30.7 (SD 7.0)% (weaning cereal; 200 mg Fe/kg), 37.7 (SD 16.6) v. 30.2 (SD 9.9)% (weaning cereal; 500 mg Fe/kg), 36.5 (SD 14.4) v. 38.2 (SD 18.1)% (bread; 65 mg Fe/kg flour) and 41.6 (SD 8.1) v. 38.9 (SD 14.5)% (infant formula; 12 mg Fe/l). The addition of Fe to foods at the currently used fortification levels was thus not associated with impaired absorption of Zn and the consumption of these Fe-fortified foods would not be expected to have a negative effect on Zn nutrition.