Influence of prenatal iron and zinc supplements on supplemental iron absorption, red blood cell iron incorporation, and iron status in pregnant Peruvian women

BACKGROUND: It is estimated that 60% of pregnant women worldwide are anemic. OBJECTIVE: We aimed to examine the influence of iron status on iron absorption during pregnancy by measuring supplemental iron absorption, red blood cell iron incorporation, and iron status in pregnant women. DESIGN: Subjects were 45 pregnant Peruvian women (33+/-1 wk gestation), of whom 28 received daily prenatal supplements containing 60 mg Fe and 250 microg folate without (Fe group, n = 14) or with (Fe+Zn group, n = 14) 15 mg Zn, which were were consumed from week 10 to 24 of gestation until delivery. The remaining 17 women (control) received no prenatal supplementation. Iron status indicators and isotopes were measured in maternal blood collected 2 wk postdosing with oral (57Fe) and intravenous (58Fe) stable iron isotopes. RESULTS: Maternal serum ferritin and folate concentrations were significantly influenced by supplementation (P < 0.05). Serum iron was also significantly higher in the Fe than in the Fe+Zn (P < 0.03) or control (P < 0.001) groups. However, the supplemented groups had significantly lower serum zinc concentrations than the control group (8.4+/-2.3 and 10.9+/-1.8 micromol/L, respectively, P < 0.01). Although percentage iron absorption was inversely related to maternal serum ferritin concentrations (P = 0.036), this effect was limited and percentage iron absorption did not differ significantly between groups. CONCLUSIONS: Because absorption of nonheme iron was not substantially greater in pregnant women with depleted iron reserves, prenatal iron supplementation is important for meeting iron requirements during pregnancy.     

Kinetic analysis shows that iron deficiency decreases liver vitamin A mobilization in rats

In view of evidence that nutritional status of iron and vitamin A may affect the other nutrient's metabolism, we used model-based compartmental analysis to examine effects of iron deficiency on whole-body vitamin A dynamics in rats. Weanling male Sprague-Dawley rats were fed the AIN93G diet with 2.5 nmol retinyl palmitate/g and either 45 [control (CN)] or 4 microg/g Fe [iron-deficient (ID)] for 8 wk. ID rats consumed food ad libitum; CN rats were food-restricted so that their body weights were the same as ID rats. Two rats/group were killed; liver vitamin A was determined and used for vitamin A balance calculations. [(3)H]Retinol-labeled plasma was administered intravenously to remaining rats, and 27 serial blood samples were collected for 7 wk. At killing, plasma vitamin A was 0.52+/-0.12 (ID, n = 5) vs. 1.34+/-0.12 micromol/L (CN, n = 6; P<0.001), and liver vitamin A was 809+/-94 (ID) vs. 112+/-24 nmol (CN, P<0.001). Plasma tracer data were fit to a three- or four-compartment model using the Simulation, Analysis and Modeling computer program and kinetic parameters were calculated. Vitamin A transfer rate between the retinyl ester storage pool [14+/-3 (ID) vs. 24+/-4 nmol/d (CN), P<0.05] and plasma was lower in ID rats. Vitamin A remained longer in the body [44+/-11 (ID) vs. 22+/-3 d (CN), P<0.05]. Adjusted mean disposal rate was lower in ID (10.0) than CN rats (19.9 nmol/d), as was estimated vitamin A absorption efficiency [58% (ID) vs. 76% (CN)]. Our results suggest that iron deficiency inhibits mobilization of vitamin A stores and may decrease the absorption and irreversible utilization of vitamin A.     

Maternal iron status influences iron transfer to the fetus during the third trimester of pregnancy

BACKGROUND: The effect of maternal iron status on fetal iron deposition is uncertain. OBJECTIVE: We used a unique stable-isotope technique to assess iron transfer to the fetus in relation to maternal iron status. DESIGN: The study group comprised 41 Peruvian women. Of these women, 26 received daily prenatal supplements containing iron and folate (n = 11; Fe group) or iron, folate, and zinc (n = 15; Fe+Zn group) from week 10-24 of pregnancy to 1 mo postpartum. The remaining 15 women (control group) received iron supplementation only during the final month of pregnancy. During the third trimester of pregnancy (+/- SD: 32.9 +/- 1.4 wk gestation) oral 57Fe (10 mg) and intravenous 58Fe (0.6 mg) stable iron isotopes were administered to the women, and isotope enrichment and iron-status indicators were measured in cord blood at delivery. RESULTS: The net amount of 57Fe in the neonates' circulation (from maternal oral dosing) was significantly related to maternal iron absorption (P < 0.005) and inversely related to maternal iron status during the third trimester of pregnancy: serum ferritin (P < 0.0001), serum folate (P < 0.005), and serum transferrin receptors (P < 0.02). Significantly more 57Fe was transferred to the neonates in non-iron-supplemented women: 0.112 +/- 0.031 compared with 0.078 +/- 0.042 mg in the control group (n = 15) and the Fe and Fe+Zn groups (n = 24), respectively (P < 0.01). In contrast, 58Fe tracer in the neonates' circulation was not significantly related to maternal iron status. CONCLUSION: The transfer of dietary iron to the fetus is regulated in response to maternal iron status at the level of the gut.     

Prenatal iron supplements impair zinc absorption in pregnant Peruvian women

Prenatal iron supplements may adversely influence zinc absorption during pregnancy. To examine the impact of prenatal iron supplements on supplemental zinc absorption, fractional zinc absorption was measured in 47 pregnant Peruvian women during the third trimester of pregnancy (33 +/- 1 wk gestation). Of these 47 women, 30 received daily prenatal supplements from wk 10-24 of pregnancy until delivery. Supplements contained 60 mg of Fe and 250 microg of folate without [iron group (Fe), n = 16] or with [iron and zinc supplemented group (Fe + Zn), n = 14] 15 mg of Zn. The remaining 17 women [unsupplemented control group (C)] received no prenatal supplementation. Zinc concentrations were measured in plasma, urine and cord blood and percentage zinc absorption was determined following dosing with oral ((67)Zn) and intravenous ((70)Zn) stable zinc isotopes. Percentage zinc absorption was significantly lower than controls in fasting women receiving iron- containing prenatal supplements (20.5 +/- 6.4 vs. 20.2 +/- 4.6 vs. 47.0 +/- 12.6%, Fe, Fe + Zn and C groups, respectively, P: < 0.0001, n = 40). Plasma zinc concentrations were also significantly lower in the Fe group compared to the C group (8.2 +/- 2.2 vs. 9.2 +/- 2.2 vs. 10.9 +/- 1. 8 micromol/L, Fe, Fe + Zn and C groups, respectively, P: = 0.002), and cord zinc concentrations were significantly related to maternal plasma Zn levels (y = 6.383 + 0.555x, r = 0.486, P: = 0.002). The inclusion of zinc in prenatal supplements may reduce the potential for iron supplements to adversely influence zinc status in populations at risk for deficiency of both these nutrients.     

Ascorbic acid: effect on ongoing iron absorption and status in iron-depleted young women

The effect of ascorbic acid on iron retention from a diet with predicted low iron bioavailability (containing minimal meat and ascorbic acid) was investigated in iron-depleted premenopausal women. Eleven women were depleted of storage iron (indicated by serum ferritin) through a combination of diet (5.0 mg Fe/2000 kcal for 67-88 d) and phlebotomy. They then consumed a diet containing 13.7 mg Fe/2000 kcal, supplemented with placebo or ascorbic acid three times daily (1500 mg total) with meals for 5.5 wk. Ascorbic acid improved apparent iron absorption (balance method) [38 +/- 2% (means +/- SEM) vs 27 +/- 2%]. Ascorbic acid also improved hemoglobin, erythrocyte protoporphyrins, and serum iron but not hematocrit, serum ferritin, iron-binding capacity, or transferrin saturation. In iron-depleted women consuming a diet with predicted poor iron availability, ascorbic acid supplementation enhanced body iron retention for 5.5 wk.     

Iron deficiency, but not anemia, upregulates iron absorption in breast-fed peruvian infants

Iron absorption in adults is regulated by homeostatic mechanisms that decrease absorption when iron status is high. There are few data, however, regarding the existence of a similar homeostatic regulation in infants. We studied 2 groups of human milk-fed infants using (57)Fe (given as ferrous sulfate without any milk) and (58)Fe (given at the time of a breast-milk feeding) stable isotopes to determine whether healthy infants at risk for iron deficiency would regulate their iron absorption based on their iron status. We studied 20 Peruvian infants at 5-6 mo of age and 18 infants at 9-10 mo of age. We found no effect of infant hemoglobin concentration on iron absorption with 5-6 mo-old infants absorbing 19.2 +/- 2.1% and 9- to 10-mo-old infants absorbing 25.8 +/- 2.6% of the (57)Fe dose. For (58)Fe, 5- to 6-mo-old infants absorbed 42.6 +/- 5.0% and 9 to 10-mo-old infants absorbed 51.9 +/- 10.3%. Following log transformation, iron absorption from (57)Fe (r = -0.61, P = < 0.001) and (58)Fe (r = -0.61, P = < 0.001) were inversely correlated to serum ferritin (S-Ft). For both the (57)Fe and (58)Fe doses, infants with S-Ft <12 mg/L (n = 11) had significantly higher iron absorption than those with S-Ft >12 mg/L. We concluded that iron absorption in infants is related to iron status as assessed by serum ferritin but not hemoglobin concentration. Infants with low iron status upregulate iron absorption from breast milk at both 5-6 and 9-10 mo of age.     

Na2EDTA enhances the absorption of iron and zinc from fortified rice flour in Sri Lankan children

Rice flour was proposed as a vehicle for iron and zinc fortification in Sri Lanka. Although widely consumed, rice flour has not been evaluated as a fortified food, and the absorption of minerals including iron and zinc from this flour is unknown. Determination of the bioavailability of these nutrients is a critical step before commencing a fortification program. We randomly divided 53 Sri Lankan schoolchildren ages 6-10 y into 4 groups that consumed a local dish prepared with 25 g of fortified rice flour labeled with one of the following: 1) (58)FeSO(4) 2) (58)FeSO(4) + Na(2)EDTA 3) (58)FeSO(4) + (67)ZnO or, 4) (58)FeSO(4) + Na(2)EDTA + (67)ZnO. The levels of iron and zinc were 60 mg/kg; the rice flour also contained folate at 2 mg/kg in each group. Na(2)EDTA was added at a Fe:Na(2)EDTA, 1:1 molar ratio. A total of 48 children completed the trial. Absorption of (58)Fe from a meal was significantly greater (P < 0.01) in the groups administered FeSO(4) + Na(2)EDTA (4.7 +/- 3.6%) than in those administered FeSO(4) without Na(2)EDTA (2.2 +/- 1.3%). Fractional absorption of zinc was 13.5 +/- 6.0% in the FeSO(4) + Na(2)EDTA group and 8.8 +/- 2.0% in the FeSO(4) group (P = 0.037). Although zinc absorption was low, our results demonstrated a benefit in using Na(2)EDTA to improve both iron and zinc absorption. We conclude that the fortification of rice flour is feasible, although additional strategies such as dephytinization or an increase in the level of iron and zinc fortification should be considered to obtain a higher proportion of the daily requirement of total absorbed iron and zinc.     

Erythrocyte iron incorporation but not absorption is increased by intravenous iron administration in erythropoietin-treated premature infants

Because critically ill premature infants experience significant iron loss due to phlebotomy and have high iron needs for growth, Fe absorption and incorporation studies are clinically important. A prospective, controlled, randomized, open 21-d study was conducted in infants with birth weight <1300 g and gestational age < 31 wk to assess the efficacy of combining intravenous (IV) sucrose iron (Fe) with erythropoietin (EPO) for increasing Fe absorption, RBC Fe incorporation, and erythropoiesis. Three clinically stable groups were enrolled at 3-4 wk of age: Control, EPO [2100 U EPO/(kg.wk)]; and IV Fe+EPO [2 mg IV sucrose Fe/(kg.d) plus 2100 U EPO/(kg.wk)]. All subjects received 9 mg/(kg.d) of oral Fe polymaltose. Subjects were not allowed RBC transfusions. Indicators of iron status and erythropoiesis were assessed before and 18 d after treatment. On d 4, tracer doses of oral polymaltose (57)Fe and IV sucrose (58)Fe were administered, and stool and blood samples were collected for Fe absorption and incorporation determinations. Compared with the Control group, the EPO group demonstrated greater hemoglobin (Hb) concentration and reticulocyte count, but no difference in Fe incorporation. In contrast, the IV Fe+EPO group demonstrated greater total Fe incorporation, Hb concentration, plasma ferritin, and reticulocyte count compared with the Control and EPO groups. Absorption of (57)Fe and nonisotopic polymaltose Fe did not differ among the groups (range: 48-58%, and 41-47%, respectively). We conclude that IV sucrose Fe administered in combination with EPO to very-low-birth weight premature infants significantly increases RBC Fe incorporation and erythropoiesis more than EPO alone, but without increasing iron absorption.     

Effects of high compared with low calcium intake on calcium absorption and incorporation of iron by red blood cells in small children.

BACKGROUND: The potential benefits of increasing calcium intake in small children must be balanced with the potential risk to iron utilization from high calcium intakes. OBJECTIVE: This study was designed to evaluate the relation between calcium intake and calcium absorption and iron incorporation into red blood cells. DESIGN: We performed a multitracer, crossover study of the absorption of calcium and red blood cell incorporation of iron in 11 preschool children aged 3-5 y who had been adapted for 5 wk to low- (502 +/- 99 mg) and high- (1180 +/- 117 mg) calcium diets. Stable-isotope studies were performed by using 44Ca and 58Fe given orally with meals and 46Ca given intravenously. RESULTS: Iron incorporation into red blood cells 14 d postdosing was similar (6.9 +/- 4.2% compared with 7.9 +/- 5.5%; NS) with the low- and high-calcium diets, respectively. Total calcium absorption (181 +/- 50 compared with 277 +/- 91 mg/d; P = 0.002) was greater in children with the higher calcium intake. CONCLUSIONS: Our findings indicate that small children may benefit from calcium intakes similar to those recommended for older children without adverse effects on dietary iron utilization.     

Effect of low zinc intake on absorption and excretion of zinc by infants studied with 70Zn as extrinsic tag

The effect of low dietary intake of zinc was studied in six normal infants with the use of 70Zn as an extrinsic tag. Of the two study formulas, one provided a zinc intake similar to that of customary infant formulas ("high" intake), whereas the other provided a "low" zinc intake. Two zinc absorption studies were performed with each formula (sequence: high-low-low-high). Extrinsically labeled formula was fed for 24 h and excreta were collected for 72 h. Zinc isotope ratios were determined by inductively coupled plasma mass spectrometry (ICP/MS). When zinc intake was high, net zinc absorption was 9.1 +/- 8.7% (mean +/- SD) of intake and net zinc retention was 74 +/- 91 micrograms/(kg.d). True zinc (70Zn) absorption was 16.8 +/- 5.8% of intake and fecal excretion of endogenous zinc was 78 +/- 56 micrograms/(kg.d). When zinc intake was low, net absorption of zinc increased significantly (P less than 0.001) to 26.0 +/- 13.0% of intake, but net retention was not significantly different at 42 +/- 33 micrograms/(kg.d). True absorption of zinc also increased significantly (P less than 0.001) to 41.1 +/- 7.8% of intake, whereas fecal endogenous zinc decreased (P less than 0.05) to 34 +/- 16 micrograms/(kg.d) during low zinc intake. Thus, infants maintain zinc balance in the face of low zinc intake through increased efficiency of absorption and decreased excretion of endogenous zinc.     

The effect of past and current dietary Zn intake on Zn absorption and endogenous excretion in the rat

Effects of previous dietary Zn (or body Zn stores) and current dietary Zn intake on absorption and endogenous excretion of Zn were studied by using radioisotope dilution. Rats were fed diets containing 1.5, 12.6 or 50.3 mg Zn/kg for 19 d (dietary period I). Total body Zn in the three groups was 1870 +/- 340, 3953 +/- 698 and 4126 +/- 844 micrograms Zn/rat. Each group was divided into four subgroups fed 3.6, 12.6, 20.5 or 50.3 mg Zn/kg diet for 3 wk (dietary period II). Rats were injected intramuscularly with 65Zn after 7 d of dietary period II. True absorption and endogenous excretion were calculated by isotope dilution. Zinc intake, urinary and fecal excretion, balance and percent Zn absorption were significantly affected only by dietary Zn in dietary period II (P less than 0.01). Endogenous excretion was affected by both past dietary Zn deficiency (body Zn stores) and by dietary Zn in dietary period II (P = 0.0001). Total body Zn at the end of the experiment was significantly affected by both periods of dietary treatment (P less than 0.001), but total body Zn concentration was affected only by the final dietary treatment (P less than 0.05). These results show that Zn absorption is affected by the current diet, but that turnover of Zn (endogenous excretion) is regulated by both current Zn intake and past Zn intake, probably through an effect on body Zn stores.     

Ferrous sulfate is more bioavailable among preschoolers than other forms of iron in a milk-based weaning food distributed by PROGRESA, a national program in Mexico

After 1 y of distributing a milk-based fortified weaning food provided by the Mexican social program PROGRESA, positive effects on physical growth, prevalence of anemia, and several vitamin deficiencies were observed. There was no effect on iron status, which we hypothesized was related to the poor bioavailability of the reduced iron used as a fortificant in PROGRESA. The objective of this study was to compare the iron bioavailability from different iron sources added as fortificants to the weaning food. Children (n = 54) aged 2-4 y were randomly assigned to receive 44 g of the weaning food fortified with ferrous sulfate, ferrous fumarate, or reduced iron + Na(2)EDTA. Iron absorption was measured using an established double-tracer isotopic methodology. Iron absorption from ferrous sulfate (7.9 +/- 9.8%) was greater than from either ferrous fumarate (2.43 +/- 2.3%) or reduced iron + Na(2)EDTA (1.4 +/- 1.3%) (P < 0.01). The absorption of log-(58)Fe sulfate given with the iron source correlated with serum ferritin (s-ferritin) concentration (n = 13, r = 0.63, P = 0.01) and log-(57)Fe absorption (reference dose) (n = 14, r = -0.52, P = 0.02). Absorption from ferrous fumarate and reduced iron + Na2EDTA did not correlate with s-ferritin or absorption of (57)Fe. The recommended daily portion of the fortified complementary food provides an average of 0.256, 0.096, 0.046 mmol (1.44, 0.54, and 0.26 mg) of absorbed iron, if fortified with sulfate, fumarate and reduced iron + Na(2)EDTA, respectively. Ferrous sulfate was more bioavailable than either ferrous fumarate or reduced iron + Na(2)EDTA when added to the milk-based fortified food and more readily met the average daily iron requirements for children 2-3 y of age.     

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 is more closely related to iron status than to daily iron intake in 12- to 48-mo-old children

Few studies have evaluated iron absorption in small children after the first year of life. Our objectives were to examine the relations among iron intake, iron absorption, and iron status in a group of healthy children. We studied 28 children, ages 12 to 48 mo, after a 7-d home adaptation to a diet representative of their usual daily mineral intake. A multi-tracer stable isotope study was performed to assess iron absorption both from a meal ((58)Fe) and from a reference iron dose ((57)Fe) given with ascorbic acid without a meal. Iron intake was 6.9 +/- 2.4 mg, approximately the 35th percentile of typical U.S. intakes. Absorption of (58)Fe was related to serum ferritin (r(2) = 0.319, P = 0.0018) and more so to reference dose iron absorption (r(2) = 0.653, P < 0.0001). Iron absorption was negatively correlated with zinc intake (r(2) = 0.090, P = 0.0049) but was not correlated with iron intake (P = 0.20). However, zinc intake was not correlated with measures of iron status, including reference dose iron absorption and serum ferritin (r(2) < 0.1, P > 0.25). Total absorbed iron was similar to needs estimated by the Institute of Medicine. We conclude that iron absorption in young children is more closely related to iron status than to iron intake. Reference dose iron absorption may be superior to serum ferritin as a surrogate measure for iron status in this age group. Although zinc intake may affect iron absorption from a meal, it does not appear to have a detectable effect on overall iron status in otherwise well-nourished children.     

Sodium iron NaFeEDTA as an iron fortification compound in Central America. Absorption studies.

Studies were performed in seven children and 98 adults to compare the proportion of iron absorbed when administered as ferric sulfate (Fe2(SO4)3), NaFeEDTA, hemoglobin (Hb), and ferrous ascorbate. Studies in children (mostly iron deficient) showed that when the compounds were given with a milk-rice-sugar formula totalling 5 mg Fe, iron from hemoglobin was absorbed best, followed by NaFeEDTA and by Fe2(SO4)3 (mean percent absorption +/-SD = 34.5 +/- 1.5, 8.6 +/- 1.9 and 3.3 +/- 1.5, respectively). Studies in normal or iron deficient adults also demonstrated a better absorption of iron from NaFeEDTA than from Fe2(SO4)3 whether these compounds were given in an aqueous solution (5 mg Fe) or with a standard meal consisting of beans, tortillas, bread, and coffee providing also a total of 5 mg Fe. Hb iron under the same conditions was absorbed in the same proportion to the reference iron ascorbate, always being higher than iron absorbed from the other compounds. Fe2(SO4)3 and NaFeEDTA mixed in the same meal were absorbed in the same proportion as when NaFeEDTA alone was added to the meal and 2 to 3 times better than when Fe2(SO4)3 alone was added to the meal. Addition of desferrioxamine depressed iron absorption from Fe2(SO4)3 and NaFeEDTA, the latter being less affected. Addition of ascorbic acid increased absorption from both. When the compounds were added to the meal to provide 50 mg of iron, percent absorption was depressed in relation to the smaller iron dose in the case of Fe2(SO4)3 and Hb but remained unaltered in the case of NaFeEDTA. Addition of 45 mg Fe as Fe2(SO4)3 or NaFeEDTA to 0.4 mg Fe from the Hb in the meal did not change Hb iron absorption. Addition of 45 mg Fe as Hb or NaFeEDTA to 0.4 mg Fe from Fe2(SO4)3 in the meal enhanced iron absorption from the latter in the same proportions. Addition of 45 mg Fe as Fe2(SO4)3 and Hb to 0.4 mg Fe as NaFeEDTA in the meal respectively depressed and enhanced iron absorption from NaFeEDTA. These studies indicate that NaFeEDTA, Fe2(SO4)3 and nonheme food iron from a common pool different from the heme pool but which is changed in its characteristics by the presence of NaFeEDTA, resulting in a better absorption of iron.     

12～14岁男童体内强化去植酸豆粉中钙铁锌的吸收利用率研究

目的　为了解我国少年儿童对豆粉、去植酸豆粉和牛奶中钙、铁、锌的吸收利用率 ,通过普及饮用豆粉 ,改善我国居民蛋白质和矿物质的营养状况提供理论依据。方法　选择 57名 1 2～ 1 4岁男童 ,按年龄、身高、体重和血红蛋白含量匹配 ,分成 3组 ,分别给予强化豆粉、强化去植酸豆粉和强化牛奶 2 2 0ml,其中含钙 2 70mg、铁 4mg、锌 4mg。给予受试者用稳定性核素4 4Ca、58Fe和70 Zn标记的受试物 ,以亮蓝和镝标记粪便 ,收集粪便样品 ,测量强化去植酸豆粉、豆粉和强化牛奶中钙、铁、锌的吸收率 ;使用热离子化质谱法测定粪便中4 4Ca含量 ;应用感应耦合等离子质谱法测定粪便中58Fe和70 Zn的丰度及镝的含量 ,计算铁、锌的表观吸收率 ,并以镝的回收率进行校正。结果　豆粉组、牛奶组和去植酸豆粉组的铁吸收率分别为 (6 7± 3 8) %、(1 5 5± 9 2 ) %和 (2 0 6± 7 3) % ,钙吸收率分别为 (43 5±1 0 7) %、(64 2± 1 1 4) %和 (50 9± 6 6) % ,锌吸收率分别为 (1 1 3± 6 5) %、(31 2± 1 0 4) %和 (2 0 1±7 4) %。强化豆粉经去除植酸处理后 ,钙、铁、锌的吸收率显著高于未去植酸的豆粉 ;牛奶中钙和锌的吸收率高于去植酸强化豆粉 ;经去除植酸处理后的豆粉中铁吸收率高于牛奶 ,但差异无显著性。我国儿童由于     

Absorption of iron from recombinant human lactoferrin in young US women

BACKGROUND: Lactoferrin is a major protein component of human milk, and it binds iron with high affinity. Because the human small intestine has receptors for lactoferrin, a role for it in iron absorption has been suggested. OBJECTIVE: The objective was to study the absorption of iron from extrinsically labeled purified recombinant human lactoferrin produced in rice and to compare it with the absorption of iron from ferrous sulfate. DESIGN: On 2 occasions 4 wk apart, healthy young women (n = 20) were fed a standardized meal supplemented in randomized order with 59Fe as lactoferrin or as ferrous sulfate. Ten subjects received lactoferrin that had been heat-treated, and 10 subjects received untreated lactoferrin. Iron absorption was measured in a whole-body counter after 14 and 28 d and also was measured by red blood cell incorporation after 28 d. RESULTS: The difference in whole-body iron absorption between heat-treated (24.6 +/- 20.8%; n = 10) and untreated (16.2 +/- 4.4%; n = 10) lactoferrin was not significant. The difference in whole-body iron absorption between the groups given lactoferrin (20.4 +/- 15.3%; n = 20) or ferrous sulfate (18.8 +/- 13.2%; n = 20) also was not significant. Serum ferritin and iron absorption were inversely correlated in subjects when they received either lactoferrin or ferrous sulfate, which suggested that iron is absorbed from the 2 sources by a similar mechanism. CONCLUSIONS: Iron is equally well absorbed from lactoferrin (whether heat-treated or untreated) and ferrous sulfate. Thus, iron provided by dietary lactoferrin is likely to be well utilized in human adults.     

Utilization of iron from an animal-based iron source is greater than that of ferrous sulfate in pregnant and nonpregnant women

Heme iron absorption during pregnancy and the role of hepcidin in regulating dietary heme iron absorption remains largely unexplored. The objective of this research was to examine relative differences in heme (animal based) and nonheme (ferrous sulfate) iron utilization. This study was undertaken in 18 pregnant (ages 16-32 y; wk 32-35 of gestation) and 11 nonpregnant women (ages 18-27 y). Women were randomly assigned to receive both an animal-based heme meal (intrinsically labeled (58)Fe pork) and labeled ferrous sulfate ((57)Fe) fed on alternate days. Blood samples obtained 2 wk postdosing were used to assess iron status indicators and serum hepcidin and iron utilization based on RBC incorporation of iron isotopes. Heme iron utilization was significantly greater than nonheme iron utilization in the pregnant (47.7 ± 14.4 vs. 40.4 ± 13.2%) and nonpregnant women (50.1 ± 14.8 vs. 15.3 ± 9.7%). Among pregnant women, utilization of nonheme iron was associated with iron status, as assessed by the serum transferrin receptor concentration (P = 0.003; r(2) = 0.43). In contrast, heme iron utilization was not influenced by maternal iron status. In the group as a whole, women with undetectable serum hepcidin had greater nonheme iron utilization compared with women with detectable serum hepcidin (P = 0.02; n = 29); however, there were no significant differences in heme iron utilization. Our study suggests that iron utilization from an animal-based food provides a highly bioavailable source of dietary iron for pregnant and nonpregnant women that is not as sensitive to hepcidin concentrations or iron stores compared with ferrous sulfate.     

Iron intake and iron nutritional status of infants fed iron-fortified beikost with meat

We compared iron intake and iron nutritional status of two groups of healthy term infants who received meat-containing baby foods fortified with ferrous sulphate (2 mg Fe/100 g). One group received an Fe-fortified formula (1.6 mg Fe/100 kcal) and the other a nonfortified formula. Fe intake of the group fed the nonfortified formula was significantly lower (p less than 0.0001). These infants received Fe mainly from fortification Fe with beikost (75-86%) and less than 10% met the recommended intake of 1 mg.kg-1.d-1; whereas 80-85% of the infants fed the Fe-fortified formula did. Hb, Hct, FEP, and ferritin were similar in both groups with the exception of lower ferritin values at age 365 d (p less than 0.05) in the group fed the nonfortified formula. No infant had hemoglobin less than 100 g/L. We conclude that regular consumption of commercially prepared Fe-fortified beikost with meat prevents most healthy term infants from Fe deficiency even if Fe intake is substantially below the recommended intake.     

稳定性同位素评价藏族青年男子膳食铁的吸收率

目的用铁的稳定性同位素示踪剂评价藏族青年男子膳食铁的吸收率,为改善该人群膳食铁吸收的提供参考数据。方法于现场进行人体代谢试验,受试者口服稳定性同位素示踪铁剂(浓集57Fe的FeSO4)及稀土元素镝,粪便监测法收集示踪剂排出粪样;用感耦等离子体质谱仪测定粪样57Fe56Fe的比值,分析评价该人群膳食铁的吸收率。结果口服同位素评价藏族青年男子膳食铁的吸收率为13.4%±6.4%;每日示踪剂铁和镝排出呈良好相关性。结论稀土元素镝与未吸收的示踪剂铁在消化道有一致的排出过程,前者的回收率能很好反映粪样收集情况;藏族成年男子膳食铁的吸收较好。